P20 plastic mould steel (AISI P20, UNS T51620, EN 1.2311) P20 (UNS T51620)
Fe balance
Also known as UNS T51620, EN 1.2311, EN name 40CrMnMo7, AISI / SAE P20, AISI P-20, AFNOR 35CMD7 · 8 more
P20 is a pre-hardened chromium-molybdenum mould steel (UNS T51620; EN 1.2311) supplied at about 280 to 325 HB, so mould blocks can be machined and used without a further heat treatment.
Evidence level
2 of 5
Lab-measured
- 0Predicted only. No one has made it, or no measurement exists.
- 1Calculated. Only calculated or predicted values from sources.
- 2Lab-measured. Measured properties with their conditions stated.
- 3Space-relevant tests. Measured in conditions relevant to space, such as vacuum or atomic oxygen.
- 4Ground-qualified. Qualified for an application on the ground.
- 5Flown or field-proven. Flight or field results exist.
Recipe, share of the weight
- Fe balance (the rest)Iron
- C 0.28 to 0.4%Carbon
- Mn 0.6 to 1%Manganese
- Si 0.2 to 0.8%Silicon
- Cr 1.4 to 2%Chromium
- Mo 0.3 to 0.55%Molybdenum
- Cu 0 to 0.25%Copper
- P 0 to 0.03%Phosphorus
- S 0 to 0.03%Sulfur
Best for
Plastic injection-mould blocks, mould frames and bolsters that are machined in the pre-hardened condition and then polished (Smith Metal Centres; Oberste-Beulmann; Abrams).
Weakest at
Corrosion resistance. The datasheets say it is not corrosion resistant and rusts unless protected; Aços Formosa points PVC and gas-releasing plastics to the stainless grade 1.2316 instead.
Risk at a glance
- People Low. No SDS for P20 read; element data only
- If it fails Moderate. Softening when a weld or reheat goes above 565 C
- Corrosion Low. The datasheet says the alloy will corrode or rust unless protected.
Quick facts: P20 (UNS T51620)
| Property | Value | Basis |
|---|---|---|
| Density | 7.83 to 7.86 g/cm³ | 2 sourced values across conditions |
| Yield strength | 827 to 862 MPa | 1 sourced value |
| Tensile strength | 965 to 1,030 MPa | 1 sourced value |
| Young's modulus | 190 to 210 GPa | 4 sourced values across conditions |
| Hardness (Brinell) | 230 to 325 HB | 4 sourced values across conditions |
| Thermal conductivity | 32.5 W/(m·K) | 1 sourced value |
| Thermal expansion (CTE) | 11.7 to 14.3 ppm/K | 3 sourced values across conditions |
What is the density of P20 plastic mould steel?
P20 plastic mould steel has a density of 7.83 to 7.86 g/cm³. The range covers 2 sourced values across the tempers, forms and test conditions the sources report; room-temperature values are used where a source states a temperature.
What is the thermal conductivity of P20 plastic mould steel?
P20 plastic mould steel has a thermal conductivity of 32.5 W/(m·K). The source and test conditions are listed in the properties table on this page.
What is the coefficient of thermal expansion of P20 plastic mould steel?
P20 plastic mould steel has a coefficient of thermal expansion of 11.7 to 14.3 ppm/K. The range covers 3 sourced values across the tempers, forms and test conditions the sources report; room-temperature values are used where a source states a temperature.
What is the yield strength of P20 plastic mould steel?
P20 plastic mould steel has a yield strength of 827 to 862 MPa. The source and test conditions are listed in the properties table on this page.
What is the tensile strength of P20 plastic mould steel?
P20 plastic mould steel has a tensile strength of 965 to 1,030 MPa. The source and test conditions are listed in the properties table on this page.
What are the other names and codes for P20 plastic mould steel?
P20 plastic mould steel is also written as UNS T51620, EN 1.2311, EN name 40CrMnMo7, AISI / SAE P20, AISI P-20, AFNOR 35CMD7. Each code is printed in the source listed beside it in the designations table.
What is P20 plastic mould steel used for?
Uses recorded in the sources include Plastic injection-mould cavities, cores and inserts; Mould frames, bolsters and die holders; Zinc die-casting dies and pressure-casting dies.
Why it exists
P20 (UNS T51620, EN 1.2311) is a chromium-molybdenum mould steel. It is bought pre-hardened at about 280 to 325 HB, so mould blocks can be cut and used without a further heat treatment. Its machinability and polishing are good, and it is used for plastic moulds, mould frames and zinc die-casting dies. Its weak point is corrosion resistance: the datasheets say it rusts unless protected.
Where it's used
Plastic moulds and frames
Oberste-Beulmann and Swiss Steel list plastic moulds, mould frames and pressure-casting moulds. Smith Metal Centres calls P20 a common steel for large mould frames and bolsters.
Zinc die-casting dies
Smith Metal Centres and Alro list zinc die-casting dies among the typical uses.
Rails and shafts
Abrams also lists rails and shafts as suitable applications for the EN 1.2311 grade.
Recipe
Fe balance; 0.28 to 0.40 C, 0.60 to 1.00 Mn, 0.20 to 0.80 Si, 1.40 to 2.00 Cr, 0.30 to 0.55 Mo, 0.25 max Cu, 0.03 max P, 0.03 max S (wt%, P20 limits as printed by Smith Metal Centres). The EN grade 1.2311 (40CrMnMo7) prints 0.35 to 0.45 C, 0.2 to 0.4 Si, 1.3 to 1.6 Mn, 1.8 to 2.1 Cr and 0.15 to 0.25 Mo (Abrams).
P20 is an iron-based chromium-molybdenum tool steel with 0.28 to 0.40 percent carbon. The limits here are the P20 ranges printed by Smith Metal Centres. The EN grade 1.2311 has narrower manganese and chromium ranges (Abrams). Its strength comes from the pre-hardened heat treatment as much as from its composition.
| Ingredient | Share of the weight | What it does |
|---|---|---|
| Iron Fe | balance (the rest) | The matrix of the steel. Heat treatment changes its structure between martensite and tempered martensite. |
| Carbon C | 0.28 to 0.4% | Sets how hard the steel can become when quenched. |
| Manganese Mn | 0.6 to 1% | Adds hardenability and helps the melt. |
| Silicon Si | 0.2 to 0.8% | Deoxidiser in the melt. |
| Chromium Cr | 1.4 to 2% | Adds hardness and toughness in the alloy (Smith Metal Centres). The grade is not stainless. |
| Molybdenum Mo | 0.3 to 0.55% | Adds hardenability. The grade still rusts unless protected. |
| Copper Cu | 0 to 0.25% | Upper limit as printed by Smith Metal Centres; no role is stated in the datasheet. |
| Phosphorus P | 0 to 0.03% | Impurity, held to a maximum. |
| Sulfur S | 0 to 0.03% | Impurity, held to a maximum. |
Weight shares are as printed in the sources.
What it can do
Hardness
Supplied at 280 to 325 HB (Oberste-Beulmann and Swiss Steel), so blocks can be machined and used without a further heat treatment (Abrams).
Strength
Typical yield strength is 827 to 862 MPa and tensile strength 965 to 1030 MPa in the pre-hardened condition (Smith Metal Centres, typical values).
Stiffness
Modulus of elasticity is 190 to 210 GPa (Smith Metal Centres) and 210 GPa (Simold, average value).
Machining
Machinability is 60 to 65 percent of a 1% carbon steel (Alro), or about 80 percent of W-group water-hardening steel (Simold).
Polish
Polishes to a high gloss, but over-polishing can cause orange peel and pitting (Abrams). Oberste-Beulmann says it is better polishable than the 1.2312 grade.
Weld
Can be welded by conventional methods with preheat and controlled cooling (Abrams). Smith Metal Centres says it has good weldability.
Nitride
Can be nitrided to a case about 0.40 mm deep for a harder, wear-resistant surface (Abrams).
How it compares
P20 sits in a family of pre-hardened plastic mould steels from Aços Formosa: 1.2311 for small and medium moulds, 1.2312 for high machinability, 1.2738 (nickel-added) for large moulds, and P-20 ESR for high-gloss work. For corrosive plastics, Aços Formosa points to the stainless prehardened grade 1.2316 instead. The compare rows give P20's typical strength, stiffness and density.
The same measurements for each material, so you can compare them. Each row names the key condition under the value; the full conditions and methods are in the numbered notes under Technical details. Other materials are shown beside it; each was measured under its own conditions, so open its page before comparing closely. Compare every grade in the family.
| Measurement | P20 (UNS T51620) | D2 (UNS T30402, EN 1.2379) | 1.2316 (X38CrMo16) | 1.2738 (P20+Ni) | A2 (UNS T30102, EN 1.2363) | H13 (EN 1.2344) |
|---|---|---|---|---|---|---|
| Thermal behavior and safety | ||||||
| Thermal conductivity, quenched and tempered | 32.5 W/m.K18 | 20 W/mK | 23.5 W/(m*K) | 34.5 W/m.K | no data | 25 W/(m·K) |
| Thermal conductivity, quenched and tempered | 34 W/m.K19 | 20 W/mK | 23.5 W/(m*K) | 34.5 W/m.K | no data | 25 W/(m·K) |
| Physical and electrical | ||||||
| Density, average value | 7.83 g/cm³1 | 7700 kg/m3 | 7.7 g/cm³ | 7.8 g/cm³ | 7.86 g/cm³ | 7800 kg/m3 |
| Density, specific gravity | 7.86 g/cm³2 | 7700 kg/m3 | 7.7 g/cm³ | 7.8 g/cm³ | 7.86 g/cm³ | 7800 kg/m3 |
| Hardness as deliveredHeader table, Hardness (HB) row, as printed | 280 to 325 HB | 210 HB | < 325 HB | 300 HB | < 241 HB | < 229 HB |
| Hardness as delivered | 280 to 325 HB10 | 210 HB | < 325 HB | 300 HB | < 241 HB | < 229 HB |
| Hardness, typical | 300 HB11 | 210 HB | < 325 HB | 300 HB | < 241 HB | < 229 HB |
| Hardness after soft annealing, maximum | < 230 HB12 | 210 HB | < 325 HB | 300 HB | < 241 HB | < 229 HB |
| Hardness, typical | 30 HRC13 | 63 HRC | 30 to 48 HRC | 30 to 35 HRC | no data | 45 HRC |
| Hardness, prehardened supply | 30 to 34 HRC14 | 63 HRC | 30 to 48 HRC | 30 to 35 HRC | no data | 45 HRC |
| Hardness, pre-hardened (vendor statement) | 28 to 34 HRC15 | 63 HRC | 30 to 48 HRC | 30 to 35 HRC | no data | 45 HRC |
| Working hardness, delivery condition | 32 HRC16 | 63 HRC | 30 to 48 HRC | 30 to 35 HRC | no data | 45 HRC |
| Hardness after quenching | 51 HRC17 | 63 HRC | 30 to 48 HRC | 30 to 35 HRC | no data | 45 HRC |
| Hardness after tempering at 500 CTempering chart as printed | 42 HRC | 63 HRC | 30 to 48 HRC | 30 to 35 HRC | no data | 45 HRC |
| Hardness after tempering at 600 CTempering chart as printed | 36 HRC | 63 HRC | 30 to 48 HRC | 30 to 35 HRC | no data | 45 HRC |
| Hardness after tempering at 700 CTempering chart as printed | 28 HRC | 63 HRC | 30 to 48 HRC | 30 to 35 HRC | no data | 45 HRC |
| Other measurements | ||||||
| Modulus of elasticity, average value | 210 GPa3 | 2.1×10^5 MPa | no data | 205 GPa | 190 to 210 GPa | 2.1×10^5 MPa |
| Elastic modulus, typicalMechanical properties (typical) table as printed | 190 to 210 GPa | 2.1×10^5 MPa | no data | 205 GPa | 190 to 210 GPa | 2.1×10^5 MPa |
| Modulus of elasticity, 0 to 30 C | 190 to 210 GPa4 | 2.1×10^5 MPa | no data | 205 GPa | 190 to 210 GPa | 2.1×10^5 MPa |
| Modulus of elasticity, typicalProperties block as printed | 207 GPa5 | 2.1×10^5 MPa | no data | 205 GPa | 190 to 210 GPa | 2.1×10^5 MPa |
| Poisson's ratio, 0 to 30 C | 0.27 to 0.3 -6 | 0.27 to 0.3 - | no data | no data | 0.27 to 0.3 - | no data |
| Yield strength, typical | 827 to 862 MPa7 | no data | no data | 826 MPa | no data | 1520 MPa |
| Tensile strength, typical | 965 to 1030 MPa8 | no data | 1100 MPa | 993 MPa | no data | 1820 MPa |
| Tensile strength, converted from hardness | 950 to 1100 MPa9 | no data | 1100 MPa | 993 MPa | no data | 1820 MPa |
| Elongation at break, typicalMechanical properties (typical) table as printed | 20 % | no data | no data | 17 % | no data | no data |
| Coefficient of thermal expansion, 20 to 100 C | 12.6 ppm/K20 | 12.3 ppm/K | 10.5 ppm/K | 11.5 ppm/K | 10.7 ppm/K | 12.6 ppm/K |
| Coefficient of thermal expansion, 20 to 500 C | 14.3 ppm/K21 | 12.3 ppm/K | 10.5 ppm/K | 11.5 ppm/K | 10.7 ppm/K | 12.6 ppm/K |
| Coefficient of thermal expansion, 20 to 100 C | 11.7 ppm/K22 | 12.3 ppm/K | 10.5 ppm/K | 11.5 ppm/K | 10.7 ppm/K | 12.6 ppm/K |
| Machinability relative to a 1% carbon steelProperties block, Machinability row, as printed | 60 to 65 % | no data | no data | no data | no data | no data |
| Machinability relative to W-group water-hardening steelMachinability paragraph as printed | 80 %23 | no data | no data | no data | no data | no data |
Why choose it, and why not
Good for
- Plastic injection-mould blocks and frames machined in the pre-hardened condition (Smith Metal Centres; Oberste-Beulmann).
- Zinc and pressure-casting dies, which the datasheets list as typical uses (Smith Metal Centres; Alro).
- Textured and polished mould faces; the datasheets say the grade takes texture and polish well (Simold; Abrams).
Watch out for
- Rust: the steel rusts unless it is protected; surface treatment and dry storage extend resistance but cannot completely prevent rusting (Simold; Abrams).
- Heat above 565 C during welding or reheating can lose hardness (Abrams); tempering at 600 C leaves 36 HRC (Swiss Steel).
- Thick blocks: above 400 mm the Oberste-Beulmann datasheet recommends 1.2738 for better through-hardening.
- Corrosive plastics: for PVC and gas-releasing plastics, Aços Formosa points to the stainless 1.2316 instead.
P20 is a practical, pre-hardened mould steel. It is supplied at about 280 to 325 HB, machines and polishes well, and suits plastic moulds, mould frames and zinc die-casting dies. It is not corrosion resistant, so protect it from rust, keep reheats within the datasheet limits, and use 1.2738 for thick blocks or a stainless grade for corrosive plastics.
Technical details
For scientists and researchers. Everything above comes from the record below: every number with its method, its conditions and its source.
Other names and standards
The same grade under other systems, as datasheets and standards print them. Each code was checked against the page it comes from.
| System | Codes |
|---|---|
| UNS | T51620 |
| EN | 1.2311 |
| EN name | 40CrMnMo7 |
| AISI / SAE | P20 |
| AISI | P-20 |
| AFNOR | 35CMD7, 40CMD8 (Oberste-Beulmann prints 35CMD7 for the same EN grade) |
| GOST | 40ХГМА |
| ASTM | A 681 Type P20 |
| ISO | 4957 |
| Trade name | P-20, SIMOLD 2311, PREMIUM 1.2311, THYROPLAST 2311 |
Notes
The method, full conditions and any caveat for the numbered rows above.
| # | Measurement | Method | Conditions | Caveat |
|---|---|---|---|---|
| 1 | Density, average value | Physical properties table, average values at ambient temperature, as printed | condition pre-hardened plastic mould steel, average value as printedtemperature ambient, as printedheat treatment not stated for density | — |
| 2 | Density, specific gravity | Properties block as printed (Specific Gravity 7.86) | temperature not statedheat treatment not statedunit in source kg/m3 (7861 kg/m3 printed beside 0.284 lb/in3) | — |
| 3 | Modulus of elasticity, average value | Physical properties table as printed; the datasheet says its values are typical or average, not guaranteed | condition average value at ambient temperature, as printedheat treatment not statedunit in source 10^3 x N/mm2 (equal to GPa) | — |
| 4 | Modulus of elasticity, 0 to 30 C | UNS T51620 physical properties table, range as printed | temperature 0 to 30 C (as printed)heat treatment not stated | — |
| 5 | Modulus of elasticity, typical | — | temperature not statedheat treatment not statedunit in source 30 x 10^6 psi (printed with 207 GPa) | — |
| 6 | Poisson's ratio, 0 to 30 C | UNS T51620 physical properties table, range as printed | temperature 0 to 30 C (as printed)heat treatment not stated | — |
| 7 | Yield strength, typical | Mechanical properties (typical) table as printed, Yield column | condition pre-hardened P20, typical (about 300 HB, 30 HRC as printed)test tensile, method not stated on the datasheet | — |
| 8 | Tensile strength, typical | Mechanical properties (typical) table as printed, Ultimate column | condition pre-hardened P20, typical (about 300 HB, 30 HRC as printed)test tensile, method not stated on the datasheet | — |
| 9 | Tensile strength, converted from hardness | Converted from hardness by the datasheet (DIN EN ISO 18265 Tab. A.1), not a tensile test; kept as calculated | condition supplied quenched and tempered, 280 to 325 HB as deliveredunit in source N/mm2 | — |
| 10 | Hardness as delivered | Material Properties list as printed, hardness in as-delivered condition | condition as-delivered pre-hardened conditionscale HB | — |
| 11 | Hardness, typical | Mechanical properties (typical) table as printed, Brinell column | condition pre-hardened P20, typical valuesscale HB | — |
| 12 | Hardness after soft annealing, maximum | Soft Annealing paragraph as printed (maximum Brinell hardness of 230) | condition soft annealed at 710 to 740 C, cooled slowly in the furnacescale HB | — |
| 13 | Hardness, typical | Mechanical properties (typical) table as printed, Rockwell column | condition pre-hardened P20, typical values (about 300 HB as printed)scale HRC | — |
| 14 | Hardness, prehardened supply | Products and Applications text as printed, approximately 30 to 34 HRC | condition prehardened, supplied condition for the P-20 family (approximately, as printed)scale HRC | — |
| 15 | Hardness, pre-hardened (vendor statement) | Vendor comparison page, In-depth Analysis paragraph, as printed; a vendor statement, not a datasheet value | condition pre-hardened, as supplied (vendor statement, no test conditions)scale HRC | vendor statement; the datasheets read give 30 to 34 HRC or 280 to 325 HB |
| 16 | Working hardness, delivery condition | Standard values table as printed, approx. 32 HRC in the delivery condition | condition delivery condition (pre-hardened)scale HRC | — |
| 17 | Hardness after quenching | Heat treatment table, Hardening row, as printed (51 HRC after quenching) | condition after hardening at 840 to 870 C with oil or salt-bath quench at 180 to 220 C (re-hardened, not the supplied condition)scale HRC | — |
| 18 | Thermal conductivity, quenched and tempered | Physical properties table, Thermal conductivity, quenched and tempered column, as printed | condition quenched and temperedtemperature 23 C | — |
| 19 | Thermal conductivity, quenched and tempered | Physical properties paragraph as printed, average values | condition quenched and temperedtemperature 100 C | — |
| 20 | Coefficient of thermal expansion, 20 to 100 C | Physical properties table, coefficient of thermal expansion row, as printed | condition quenched and temperedtemperature 20 to 100 Cunit in source 10^-6 K^-1 (same number as ppm/K) | — |
| 21 | Coefficient of thermal expansion, 20 to 500 C | Physical properties table, coefficient of thermal expansion row, as printed | condition quenched and temperedtemperature 20 to 500 Cunit in source 10^-6 K^-1 (same number as ppm/K) | — |
| 22 | Coefficient of thermal expansion, 20 to 100 C | Physical properties table as printed, average values at ambient temperature | temperature 20 to 100 Cheat treatment not statedunit in source 10^-6 C^-1 (same number as ppm/K) | — |
| 23 | Machinability relative to W-group water-hardening steel | — | reference W group water-hardening steels, as printedbasis printed as about 80% | approximate, printed as about 80% |
Corrosion and compatibility
What happens when it meets other materials and environments.
| Environment | Concern | What happens |
|---|---|---|
| Humid or wet storage, or service with no surface protection | low | The datasheet says the alloy will corrode or rust unless protected.1 |
| Storage and use in damp or wet conditions (EN 1.2311) | low | Abrams says 1.2311 is not a corrosion resistant steel.2 |
| Humid conditions with no protection (vendor comparison) | low | A vendor says P20 has no corrosion resistance.3 |
| PVC and plastics that release aggressive gases during moulding | not rated | Aços Formosa points these plastics to stainless grades, not to P20.4 |
| # | Environment | Details | Test conditions |
|---|---|---|---|
| 1 | Humid or wet storage, or service with no surface protection | Simold 2311 states: 'This is a steel alloy and it will corrode or rust unless protected.' No exposure time, humidity or test is given. The low rating is an assistant judgement from this wording, not a test result. | basis datasheet statementtest none printed |
| 2 | Storage and use in damp or wet conditions (EN 1.2311) | Abrams says 1.2311 is not a corrosion resistant steel and that surface treatment, maintenance and dry storage of parts can extend corrosion resistance but cannot completely prevent rusting. Bluing gives a black oxide layer with some corrosion protection, though it is usually done for appearance. The low rating is an assistant judgement from this wording. | basis datasheet statement for the EN gradetest none printed |
| 3 | Humid conditions with no protection (vendor comparison) | The Boxumold comparison says P20 has no corrosion resistance and rusts in humid conditions without protection. It is a vendor statement with no test conditions. The low rating is an assistant judgement. | basis vendor statementtest none printed |
| 4 | PVC and plastics that release aggressive gases during moulding | Aços Formosa points PVC and gas-releasing plastics to 420-series stainless steels and to the prehardened stainless grade 1.2316, not to P20. It gives no corrosion test for P20 itself. | basis supplier product guidancetest none printed for P20 |
Risks and side effects
Hazards to people, what happens when a cell overheats, and how the material is handled and stored.
For people
The only hazard records found are PubChem entries for the pure elements chromium, manganese and molybdenum. No safety data sheet for P20 bar was read in this run.
- Chromium
- PubChem lists elemental chromium as Danger. Half of 2404 company reports say it does not meet GHS criteria; H317, allergic skin reaction, appears for 20.7% of reports.
- Manganese
- PubChem lists elemental manganese with H228 (flammable solid, 11.6% of reports), H360 (may damage fertility or the unborn child) and H372 (organ damage on repeated exposure).
- Molybdenum
- PubChem reports that 57.4% of its reports say elemental molybdenum does not meet GHS criteria; H315 (skin irritation) and H335 (respiratory irritation) appear among the codes.
In service
The datasheets say the steel is not corrosion resistant, so rust is the main in-service concern.
- Rust
- The Simold datasheet says the alloy will corrode or rust unless protected. Abrams says surface treatment and dry storage extend resistance but cannot completely prevent rusting.
- Corrosive plastics
- Aços Formosa points PVC and plastics that release aggressive gases to the stainless grade 1.2316, not to P20.
- Reheating
- The Swiss Steel tempering chart shows hardness falling from 42 HRC after tempering at 500 C to 36 HRC at 600 C and 28 HRC at 700 C.
Heat treatment and welding
Heat sets the strength, and the reheat limits matter most.
- Welding
- Abrams gives a preheat of 315 to 370 C and a limit of 565 C on reheating; above that, hardness can be lost.
- Stress relief
- Oberste-Beulmann gives 500 to 550 C for the quenched and tempered condition; Abrams gives 550 to 600 C.
- Re-hardening
- Re-hardening from 830 to 880 C in oil or a warm bath at 180 to 220 C gives about 51 HRC (Simold).
Test details
The original wording and numbers from the sources, for readers who want them.
Failure risks
| Failure | Trigger and consequence |
|---|---|
| Softening when a weld or reheat goes above 565 Cmoderate severity | Weld repair or reheating above 565 C; the datasheet gives 540 C for weld temperingHardness is lost if the material is heated above 565 C during welding (Abrams). |
| Softening on reheating to a higher tempermoderate severity | Reheating or stress relief at 600 C or 700 CThe Swiss Steel tempering chart gives 42 HRC after tempering at 500 C, 36 HRC at 600 C and 28 HRC at 700 C; a reheat above the supply temper softens the block. |
| Stress corrosion cracking after oil hardeningmoderate severity | Oil hardening without interruption at 300 to 400 C, or cooling to room temperature before temperingThe datasheet warns of enhanced stress corrosion cracking susceptibility after oil hardening, and says to temper while the part is at about 80 C. |
| Thick blocks harden less throughmoderate severity | Sections thicker than 400 mmThe Oberste-Beulmann datasheet recommends 1.2738 for thicknesses above 400 mm because of its better through-hardenability. |
| Rust in humid storage or servicemoderate severity | Storage or service in humid conditions without surface protectionThe steel rusts; the Simold datasheet says it will corrode or rust unless protected. |
Handling and storage
- Preheating before use at 200 to 300 C is recommended by the datasheet.
- Hot forming between 1050 and 850 C (as printed for forging).
- Soft anneal at 710 to 740 C in the furnace, cooling slowly; the Simold datasheet gives a maximum of 230 HB afterwards.
- Stress relieve at 500 to 550 C in the quenched and tempered condition, then cool in the furnace (Oberste-Beulmann). Abrams gives 550 to 600 C for 1 hour per 25 mm.
- Stress relieve at 550 to 600 C for 1 hour per 25 mm of thickness, then cool in the furnace (Abrams).
- Temper by holding at the tempering temperature for at least 1 hour per 25 mm of section, then cool in still air (Smith Metal Centres).
- Re-harden from 830 to 880 C, then quench in oil or a warm bath at 180 to 220 C; the hardness after quenching is 51 HRC (Simold).
- Weld with a preheat of 315 to 370 C, do not let the temperature fall below 315 C, cool slowly to 40 to 65 C, reheat to 540 C for 1 hour per 25 mm of weld depth, and do not exceed 565 C (Abrams).
Mitigations
- Surface treatment, maintenance and dry storage can extend corrosion resistance but cannot completely prevent rusting (Abrams).
- Nitriding gives a hard, abrasion-resistant surface to a depth of 0.40 mm (Abrams); the surface can be made harder than the pre-hardened core.
- For thick blocks above 400 mm, the Oberste-Beulmann datasheet recommends 1.2738 for better through-hardening.
- For PVC and plastics that release aggressive gases, Aços Formosa points to the prehardened stainless grade 1.2316.
Supply and geography
How common the raw materials are and where they come from.
Chromium
World resources are greater than 12 billion tons of shipping-grade chromite, 95% of them in Kazakhstan and southern Africa. US net import reliance was 79% of apparent consumption in 2025e (USGS).
- Top producers (2025)
- South Africa 45.1%, Turkey 17.6%, Kazakhstan 13.7%, India 5.9%, Brazil 3.9%, Zimbabwe 3.9%, Finland 3.7%
- Critical mineral lists
- US: listed, EU: not listed
- Recycling
- Recycled chromium in stainless-steel scrap receipts was 21% of US apparent consumption in 2025.
- Substitutes
- Chromium has no substitute in stainless steel, the leading end use, or in superalloys (USGS 2026).
Manganese
Land-based manganese resources are large but irregularly distributed; South Africa accounts for an estimated 70% of world resources. US net import reliance was 100% of apparent consumption in each year from 2021 to 2025e (USGS).
- Top producers (2025)
- South Africa 38%, Gabon 25%, Ghana 10%, Australia 8%, Brazil 4%, India 3.95%, China 3.5%
- Critical mineral lists
- US: listed, EU: listed
- Recycling
- Manganese was recycled incidentally in ferrous and nonferrous scrap, but scrap recovery specifically for manganese was negligible; it is recovered with iron from steel slag (USGS).
- Substitutes
- Manganese has no satisfactory substitute in its major applications (USGS 2026).
Molybdenum
Identified resources are about 5.4 million tons in the United States and about 20 million tons in the rest of the world; world reserves were 17,000 thousand t (2025e). Molybdenum is used principally as an alloying agent in steels, cast irons and superalloys (USGS 2026).
- Top producers (2025)
- China 37.3%, Chile 16.2%, United States 15.4%, Peru 15%, Mexico 6.5%
- Critical mineral lists
- US: not listed, EU: not listed
- Recycling
- Molybdenum is recycled as a component of catalysts, ferrous scrap and superalloy scrap; recycled material may be as much as 30% of the apparent supply (USGS 2026).
- Substitutes
- There is little substitution for molybdenum in steels and cast irons; potential substitutes in alloy steels include boron, chromium, niobium and vanadium (USGS 2026).
Documents
Datasheets, safety data sheets, papers and standards you can open.
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spore_version: 0.2
family: tool-steels
name: P20 plastic mould steel (AISI P20, UNS T51620, EN 1.2311)
abbreviation: P20 (UNS T51620)
role: plastic mould steel
category: metals
type: steels-and-stainless
summary: P20 is a pre-hardened chromium-molybdenum mould steel (UNS T51620; EN 1.2311) supplied at about 280 to 325 HB, so mould blocks can be machined and used without a further heat treatment. It machines and polishes well and is used for plastic moulds, mould frames and zinc die-casting dies. It is not corrosion resistant and rusts unless it is protected.
best_for: Plastic injection-mould blocks, mould frames and bolsters that are machined in the pre-hardened condition and then polished (Smith Metal Centres; Oberste-Beulmann; Abrams).
weakest_at: Corrosion resistance. The datasheets say it is not corrosion resistant and rusts unless protected; Aços Formosa points PVC and gas-releasing plastics to the stainless grade 1.2316 instead.
identity:
formula: Fe balance; 0.28 to 0.40 C, 0.60 to 1.00 Mn, 0.20 to 0.80 Si, 1.40 to 2.00 Cr, 0.30 to 0.55 Mo, 0.25 max Cu, 0.03 max P, 0.03 max S (wt%, P20 limits as printed by Smith Metal Centres). The EN grade 1.2311 (40CrMnMo7) prints 0.35 to 0.45 C, 0.2 to 0.4 Si, 1.3 to 1.6 Mn, 1.8 to 2.1 Cr and 0.15 to 0.25 Mo (Abrams).
source: smith-p20
where: Chemical Composition (weight %), Min and Max rows
designations:
- system: AISI / SAE
code: P20
source: smith-p20
where: Title block, P20 (T51620)
- system: AISI
code: P-20
source: alro-p20
where: Heading AISI P-20 Steel
- system: Trade name
code: P-20
source: formosa-p20
where: Plastic Molds, P-20 family
- system: UNS
code: T51620
source: tm-p20
where: Page heading and chemical composition table
- system: ASTM
code: A 681 Type P20
source: tm-p20
where: International Equivalent Materials table, row A 681 Type P20 (listed as Official)
- system: EN
code: '1.2311'
source: beul-2311
where: Header, grade 1.2311+QT
- system: EN name
code: 40CrMnMo7
source: sij-2311
where: Designation by Standards table, DIN column
- system: ISO
code: '4957'
source: doer-2738
where: Opening paragraph, listing 1.2311 (AISI P20) under DIN EN ISO 4957
- system: AFNOR
code: 35CMD7
source: beul-2311
where: Standards column, AFNOR row
- system: AFNOR
code: 40CMD8
note: Oberste-Beulmann prints 35CMD7 for the same EN grade
source: swiss-2311
where: Header, AISI P20 / AFNOR 40CMD8
- system: GOST
code: 40ХГМА
source: beul-2311
where: Standards column, GOST row
- system: Trade name
code: SIMOLD 2311
source: sij-2311
where: Header, SIMOLD 2311 Steel
- system: Trade name
code: PREMIUM 1.2311
source: abrams-12311
where: Page title, PREMIUM 1.2311 Steel
- system: Trade name
code: THYROPLAST 2311
source: tm-p20
where: International Equivalent Materials table, proprietary row (listed as Official)
tags:
environments: []
stresses: []
applications:
- mechanisms
- structures
properties:
- benchmark: density
label: Density, average value
value: 7.83
unit: g/cm3
scope: material
conditions:
condition: pre-hardened plastic mould steel, average value as printed
temperature: ambient, as printed
heat_treatment: not stated for density
method: Physical properties table, average values at ambient temperature, as printed
status: ground
source: sij-2311
where: Physical properties, Density (g/cm3), 7.83
- benchmark: density
label: Density, specific gravity
value: 7.86
unit: g/cm3
scope: material
conditions:
temperature: not stated
heat_treatment: not stated
unit_in_source: kg/m3 (7861 kg/m3 printed beside 0.284 lb/in3)
method: Properties block as printed (Specific Gravity 7.86)
status: ground
source: alro-p20
where: Properties block, Density and Specific Gravity rows
- benchmark: elastic_modulus
label: Modulus of elasticity, average value
value: 210
unit: GPa
scope: material
conditions:
condition: average value at ambient temperature, as printed
heat_treatment: not stated
unit_in_source: 10^3 x N/mm2 (equal to GPa)
method: Physical properties table as printed; the datasheet says its values are typical or average, not guaranteed
status: ground
source: sij-2311
where: Physical properties, Modulus of elasticity, row 210
- benchmark: elastic_modulus
label: Elastic modulus, typical
value: 190
value_high: 210
bound: range
unit: GPa
scope: material
conditions:
condition: pre-hardened P20, typical values (about 300 HB, 30 HRC as printed)
method: Mechanical properties (typical) table as printed
status: ground
source: smith-p20
where: Mechanical Properties (typical) table, Elastic Modulus column
- benchmark: elastic_modulus
label: Modulus of elasticity, 0 to 30 C
value: 190
value_high: 210
bound: range
unit: GPa
scope: material
conditions:
temperature: 0 to 30 C (as printed)
heat_treatment: not stated
method: UNS T51620 physical properties table, range as printed
status: ground
source: tm-p20
where: UNS T51620 Physical Properties, Modulus of Elasticity row
- benchmark: elastic_modulus
label: Modulus of elasticity, typical
value: 207
unit: GPa
scope: material
conditions:
temperature: not stated
heat_treatment: not stated
unit_in_source: 30 x 10^6 psi (printed with 207 GPa)
method: Properties block as printed
status: ground
source: alro-p20
where: Properties block, Modulus of Elasticity row
- benchmark: poissons_ratio
label: Poisson's ratio, 0 to 30 C
value: 0.27
value_high: 0.3
bound: range
unit: '-'
scope: material
conditions:
temperature: 0 to 30 C (as printed)
heat_treatment: not stated
method: UNS T51620 physical properties table, range as printed
status: ground
source: tm-p20
where: UNS T51620 Physical Properties, Poisson Coefficient row
- benchmark: yield_strength
label: Yield strength, typical
value: 827
value_high: 862
bound: range
unit: MPa
scope: material
conditions:
condition: pre-hardened P20, typical (about 300 HB, 30 HRC as printed)
test: tensile, method not stated on the datasheet
method: Mechanical properties (typical) table as printed, Yield column
status: ground
source: smith-p20
where: Mechanical Properties (typical) table, Tensile Strength Yield row
- benchmark: ultimate_tensile_strength
label: Tensile strength, typical
value: 965
value_high: 1030
bound: range
unit: MPa
scope: material
conditions:
condition: pre-hardened P20, typical (about 300 HB, 30 HRC as printed)
test: tensile, method not stated on the datasheet
method: Mechanical properties (typical) table as printed, Ultimate column
status: ground
source: smith-p20
where: Mechanical Properties (typical) table, Tensile Strength Ultimate row
- benchmark: ultimate_tensile_strength
label: Tensile strength, converted from hardness
value: 950
value_high: 1100
bound: range
unit: MPa
scope: material
conditions:
condition: supplied quenched and tempered, 280 to 325 HB as delivered
unit_in_source: N/mm2
method: Converted from hardness by the datasheet (DIN EN ISO 18265 Tab. A.1), not a tensile test; kept as calculated
status: calculated
source: beul-2311
where: Header table, Tensile strength (N/mm2), 950 - 1100
- benchmark: elongation
label: Elongation at break, typical
value: 20
unit: '%'
scope: material
conditions:
condition: pre-hardened P20, typical (about 300 HB, 30 HRC as printed)
gauge: 50 mm (2 in.) as printed
method: Mechanical properties (typical) table as printed
status: ground
source: smith-p20
where: Mechanical Properties (typical) table, Elongation at break in 50 mm row
- benchmark: hardness_brinell
label: Hardness as delivered
value: 280
value_high: 325
bound: range
unit: HB
scope: material
conditions:
condition: supplied quenched and tempered (pre-hardened, as delivered)
scale: HB
method: Header table, Hardness (HB) row, as printed
status: ground
source: beul-2311
where: Header table, Hardness (HB) row, 280 - 325
- benchmark: hardness_brinell
label: Hardness as delivered
value: 280
value_high: 325
bound: range
unit: HB
scope: material
conditions:
condition: as-delivered pre-hardened condition
scale: HB
method: Material Properties list as printed, hardness in as-delivered condition
status: ground
source: swiss-2311
where: Material Properties, Hardness in as-delivered condition 280 to 325 HB
- benchmark: hardness_brinell
label: Hardness, typical
value: 300
unit: HB
scope: material
conditions:
condition: pre-hardened P20, typical values
scale: HB
method: Mechanical properties (typical) table as printed, Brinell column
status: ground
source: smith-p20
where: Mechanical Properties (typical) table, Hardness Brinell 300
- benchmark: hardness_brinell
label: Hardness after soft annealing, maximum
value: 230
bound: upper
unit: HB
scope: material
conditions:
condition: soft annealed at 710 to 740 C, cooled slowly in the furnace
scale: HB
method: Soft Annealing paragraph as printed (maximum Brinell hardness of 230)
status: ground
source: sij-2311
where: Soft Annealing paragraph
- benchmark: hardness_rockwell_c
label: Hardness, typical
value: 30
unit: HRC
scope: material
conditions:
condition: pre-hardened P20, typical values (about 300 HB as printed)
scale: HRC
method: Mechanical properties (typical) table as printed, Rockwell column
status: ground
source: smith-p20
where: Mechanical Properties (typical) table, Hardness Rockwell 30
- benchmark: hardness_rockwell_c
label: Hardness, prehardened supply
value: 30
value_high: 34
bound: range
unit: HRC
scope: material
conditions:
condition: prehardened, supplied condition for the P-20 family (approximately, as printed)
scale: HRC
method: Products and Applications text as printed, approximately 30 to 34 HRC
status: ground
source: formosa-p20
where: Introduction paragraph and P-20 Standard row (Prehardened 30-34 HRC)
- benchmark: hardness_rockwell_c
label: Hardness, pre-hardened (vendor statement)
value: 28
value_high: 34
bound: range
unit: HRC
scope: material
conditions:
condition: pre-hardened, as supplied (vendor statement, no test conditions)
scale: HRC
method: Vendor comparison page, In-depth Analysis paragraph, as printed; a vendor statement, not a datasheet value
status: ground
note: vendor statement; the datasheets read give 30 to 34 HRC or 280 to 325 HB
source: boxu-s136
where: In-depth Analysis paragraph, first sentence on P20
- benchmark: hardness_rockwell_c
label: Working hardness, delivery condition
value: 32
unit: HRC
scope: material
conditions:
condition: delivery condition (pre-hardened)
scale: HRC
method: Standard values table as printed, approx. 32 HRC in the delivery condition
status: ground
source: abrams-12311
where: Standard values table, Working hardness row
- benchmark: hardness_rockwell_c
label: Hardness after quenching
value: 51
unit: HRC
scope: material
conditions:
condition: after hardening at 840 to 870 C with oil or salt-bath quench at 180 to 220 C (re-hardened, not the supplied condition)
scale: HRC
method: Heat treatment table, Hardening row, as printed (51 HRC after quenching)
status: ground
source: swiss-2311
where: Heat treatment table, Hardening row
- benchmark: hardness_rockwell_c
label: Hardness after tempering at 500 C
value: 42
unit: HRC
scope: material
conditions:
condition: after hardening, tempered at 500 C (tempering chart; hold time not printed)
scale: HRC
method: Tempering chart as printed
status: ground
source: swiss-2311
where: Heat treatment, Tempering chart, 500 C row
- benchmark: hardness_rockwell_c
label: Hardness after tempering at 600 C
value: 36
unit: HRC
scope: material
conditions:
condition: after hardening, tempered at 600 C (tempering chart; hold time not printed)
scale: HRC
method: Tempering chart as printed
status: ground
source: swiss-2311
where: Heat treatment, Tempering chart, 600 C row
- benchmark: hardness_rockwell_c
label: Hardness after tempering at 700 C
value: 28
unit: HRC
scope: material
conditions:
condition: after hardening, tempered at 700 C (tempering chart; hold time not printed)
scale: HRC
method: Tempering chart as printed
status: ground
source: swiss-2311
where: Heat treatment, Tempering chart, 700 C row
- benchmark: thermal_conductivity
label: Thermal conductivity, quenched and tempered
value: 32.5
unit: W/m.K
scope: material
conditions:
condition: quenched and tempered
temperature: 23 C
method: Physical properties table, Thermal conductivity, quenched and tempered column, as printed
status: ground
source: swiss-2311
where: Physical properties, Thermal conductivity (W/m.K), quenched and tempered, 23 C
- benchmark: thermal_conductivity
label: Thermal conductivity, quenched and tempered
value: 34
unit: W/m.K
scope: material
conditions:
condition: quenched and tempered
temperature: 100 C
method: Physical properties paragraph as printed, average values
status: ground
source: sij-2311
where: Physical properties, Thermal conductivity, 34.0 at 100 C, quenched and tempered
- benchmark: cte
label: Coefficient of thermal expansion, 20 to 100 C
value: 12.6
unit: ppm/K
scope: material
conditions:
condition: quenched and tempered
temperature: 20 to 100 C
unit_in_source: 10^-6 K^-1 (same number as ppm/K)
method: Physical properties table, coefficient of thermal expansion row, as printed
status: ground
source: swiss-2311
where: Physical properties, coefficient of thermal expansion, 20 to 100 C, quenched and tempered
- benchmark: cte
label: Coefficient of thermal expansion, 20 to 500 C
value: 14.3
unit: ppm/K
scope: material
conditions:
condition: quenched and tempered
temperature: 20 to 500 C
unit_in_source: 10^-6 K^-1 (same number as ppm/K)
method: Physical properties table, coefficient of thermal expansion row, as printed
status: ground
source: swiss-2311
where: Physical properties, coefficient of thermal expansion, 20 to 500 C, quenched and tempered
- benchmark: cte
label: Coefficient of thermal expansion, 20 to 100 C
value: 11.7
unit: ppm/K
scope: material
conditions:
temperature: 20 to 100 C
heat_treatment: not stated
unit_in_source: 10^-6 C^-1 (same number as ppm/K)
method: Physical properties table as printed, average values at ambient temperature
status: ground
source: sij-2311
where: Physical properties, coefficient of thermal expansion, 20-100 C row
- benchmark: machinability_relative
label: Machinability relative to a 1% carbon steel
value: 60
value_high: 65
bound: range
unit: '%'
scope: material
conditions:
reference: 1% carbon steel, as printed
heat_treatment: not stated
method: Properties block, Machinability row, as printed
status: ground
source: alro-p20
where: Properties block, Machinability row, 60-65% of a 1% carbon steel
- benchmark: machinability_relative
label: Machinability relative to W-group water-hardening steel
value: 80
unit: '%'
scope: material
conditions:
reference: W group water-hardening steels, as printed
basis: printed as about 80%
method: Machinability paragraph as printed
status: ground
note: approximate, printed as about 80%
source: sij-2311
where: Machinability paragraph
corrosion:
- environment: Humid or wet storage, or service with no surface protection
headline: The datasheet says the alloy will corrode or rust unless protected.
effect: 'Simold 2311 states: ''This is a steel alloy and it will corrode or rust unless protected.'' No exposure time, humidity or test is given. The low rating is an assistant judgement from this wording, not a test result.'
rating: low
conditions:
basis: datasheet statement
test: none printed
source: sij-2311
where: Corrosion Resistance paragraph
- environment: Storage and use in damp or wet conditions (EN 1.2311)
headline: Abrams says 1.2311 is not a corrosion resistant steel.
effect: Abrams says 1.2311 is not a corrosion resistant steel and that surface treatment, maintenance and dry storage of parts can extend corrosion resistance but cannot completely prevent rusting. Bluing gives a black oxide layer with some corrosion protection, though it is usually done for appearance. The low rating is an assistant judgement from this wording.
rating: low
conditions:
basis: datasheet statement for the EN grade
test: none printed
source: abrams-12311
where: Is the 1.2311 corrosion resistant? answer; Black oxide coating or blueing section
- environment: Humid conditions with no protection (vendor comparison)
headline: A vendor says P20 has no corrosion resistance.
effect: The Boxumold comparison says P20 has no corrosion resistance and rusts in humid conditions without protection. It is a vendor statement with no test conditions. The low rating is an assistant judgement.
rating: low
conditions:
basis: vendor statement
test: none printed
source: boxu-s136
where: Side-by-Side Comparison table, Corrosion Resistance row
- environment: PVC and plastics that release aggressive gases during moulding
headline: Aços Formosa points these plastics to stainless grades, not to P20.
effect: Aços Formosa points PVC and gas-releasing plastics to 420-series stainless steels and to the prehardened stainless grade 1.2316, not to P20. It gives no corrosion test for P20 itself.
rating: unknown
conditions:
basis: supplier product guidance
test: none printed for P20
source: formosa-p20
where: Best Choice for Stainless Steels for Molds list and Applications list
risks:
hazards:
- text: PubChem's aggregated GHS record for elemental chromium carries the signal word Danger. 50% of 2404 company reports (1202) say it does not meet GHS criteria. Reported codes include H317, may cause an allergic skin reaction (20.7% of reports), and H400, very toxic to aquatic life. The record describes the element, not the steel.
ghs:
- H317
- H400
source: pubchem-cr
where: Safety and Hazards, GHS Classification (CID 23976)
- text: 'PubChem''s aggregated GHS record for elemental manganese: 46.1% (1429 of 3101) of reports say it does not meet GHS criteria. Reported codes include H228, flammable solid (11.6% of reports), H360, may damage fertility or the unborn child, and H372, damage to organs through prolonged or repeated exposure. The record describes the element, not the steel.'
ghs:
- H228
- H360
- H372
source: pubchem-mn
where: Safety and Hazards, GHS Classification (CID 23930)
- text: 'PubChem''s aggregated GHS record for elemental molybdenum: 57.4% (874 of 1523) of reports say it does not meet GHS criteria. Reported codes include H225 (11.6% of reports), H315, skin irritation, and H335, may cause respiratory irritation. The record describes the element, not the steel.'
ghs:
- H225
- H315
- H335
source: pubchem-mo
where: Safety and Hazards, GHS Classification (CID 23932)
failure_risks:
- mode: Softening when a weld or reheat goes above 565 C
trigger: Weld repair or reheating above 565 C; the datasheet gives 540 C for weld tempering
consequence: Hardness is lost if the material is heated above 565 C during welding (Abrams).
severity: moderate
source: abrams-12311
where: Welding section
- mode: Softening on reheating to a higher temper
trigger: Reheating or stress relief at 600 C or 700 C
consequence: The Swiss Steel tempering chart gives 42 HRC after tempering at 500 C, 36 HRC at 600 C and 28 HRC at 700 C; a reheat above the supply temper softens the block.
severity: moderate
source: swiss-2311
where: Heat treatment, Tempering chart
- mode: Stress corrosion cracking after oil hardening
trigger: Oil hardening without interruption at 300 to 400 C, or cooling to room temperature before tempering
consequence: The datasheet warns of enhanced stress corrosion cracking susceptibility after oil hardening, and says to temper while the part is at about 80 C.
severity: moderate
source: beul-2311
where: Heat treatment table, Quenching remarks
- mode: Thick blocks harden less through
trigger: Sections thicker than 400 mm
consequence: The Oberste-Beulmann datasheet recommends 1.2738 for thicknesses above 400 mm because of its better through-hardenability.
severity: moderate
source: beul-2311
where: Header table, Remarks
- mode: Rust in humid storage or service
trigger: Storage or service in humid conditions without surface protection
consequence: The steel rusts; the Simold datasheet says it will corrode or rust unless protected.
severity: moderate
source: sij-2311
where: Corrosion Resistance paragraph
side_effects: []
handling:
- text: Preheating before use at 200 to 300 C is recommended by the datasheet.
source: beul-2311
where: Header table, Remarks (preheating before use)
- text: Hot forming between 1050 and 850 C (as printed for forging).
source: sij-2311
where: Forging paragraph
- text: Soft anneal at 710 to 740 C in the furnace, cooling slowly; the Simold datasheet gives a maximum of 230 HB afterwards.
source: sij-2311
where: Soft Annealing paragraph
- text: Stress relieve at 500 to 550 C in the quenched and tempered condition, then cool in the furnace (Oberste-Beulmann). Abrams gives 550 to 600 C for 1 hour per 25 mm.
source: beul-2311
where: Heat treatment table, Stress-relief annealing row
- text: Stress relieve at 550 to 600 C for 1 hour per 25 mm of thickness, then cool in the furnace (Abrams).
source: abrams-12311
where: 1.2311 Stress relieving section
- text: Temper by holding at the tempering temperature for at least 1 hour per 25 mm of section, then cool in still air (Smith Metal Centres).
source: smith-p20
where: Tempering paragraph
- text: Re-harden from 830 to 880 C, then quench in oil or a warm bath at 180 to 220 C; the hardness after quenching is 51 HRC (Simold).
source: sij-2311
where: Hardening paragraph
- text: Weld with a preheat of 315 to 370 C, do not let the temperature fall below 315 C, cool slowly to 40 to 65 C, reheat to 540 C for 1 hour per 25 mm of weld depth, and do not exceed 565 C (Abrams).
source: abrams-12311
where: 1.2311 Welding section
mitigations:
- text: Surface treatment, maintenance and dry storage can extend corrosion resistance but cannot completely prevent rusting (Abrams).
source: abrams-12311
where: Is the 1.2311 corrosion resistant? answer
- text: Nitriding gives a hard, abrasion-resistant surface to a depth of 0.40 mm (Abrams); the surface can be made harder than the pre-hardened core.
source: abrams-12311
where: 1.2311 Nitriding section, printed as 0,40 mm with a decimal comma
- text: For thick blocks above 400 mm, the Oberste-Beulmann datasheet recommends 1.2738 for better through-hardening.
source: beul-2311
where: Header table, Remarks
- text: For PVC and plastics that release aggressive gases, Aços Formosa points to the prehardened stainless grade 1.2316.
source: formosa-p20
where: Best Choice list, Stainless Steels for Molds
uses:
- application: mechanisms
device: Plastic injection-mould cavities, cores and inserts
example: Aços Formosa lists cavities and cores among the applications of its P-20 family plastic mould steels.
source: formosa-p20
where: Applications list
- application: structures
device: Mould frames, bolsters and die holders
example: Smith Metal Centres says P20 is commonly used to make large mould frames and bolsters; Alro lists die holders and bolsters.
source: smith-p20
where: Opening paragraph and Typical applications line
- application: mechanisms
device: Zinc die-casting dies and pressure-casting dies
example: Smith Metal Centres and Alro list zinc die-casting dies among typical uses, and Simold lists pressure casting dies.
source: alro-p20
where: Typical Uses line
- application: mechanisms
device: Rails and shafts (secondary use of the EN 1.2311 grade)
example: Abrams says the grade is mainly used for plastic moulds, die casts and tools but is also suitable for applications such as rails and shafts.
source: abrams-12311
where: Introduction paragraph
supply:
- subject: Chromium
abundance: World resources are greater than 12 billion tons of shipping-grade chromite, 95% of them in Kazakhstan and southern Africa. US net import reliance was 79% of apparent consumption in 2025e (USGS).
producers:
- country: South Africa
share_percent: 45.1
year: 2025
- country: Turkey
share_percent: 17.6
year: 2025
- country: Kazakhstan
share_percent: 13.7
year: 2025
- country: India
share_percent: 5.9
year: 2025
- country: Brazil
share_percent: 3.9
year: 2025
- country: Zimbabwe
share_percent: 3.9
year: 2025
- country: Finland
share_percent: 3.7
year: 2025
critical_lists:
- list: USGS 2025 List of Critical Minerals, read from a fetch summary (the page returned 403 to curl)
listed: true
- list: EU critical raw materials list, fifth list 2023 (34 CRMs, European Commission page)
listed: false
recycling: Recycled chromium in stainless-steel scrap receipts was 21% of US apparent consumption in 2025.
substitutes:
- Chromium has no substitute in stainless steel, the leading end use, or in superalloys (USGS 2026).
source: usgs-cr-2026
where: Salient Statistics; World Mine Production and Reserves (2025e; shares calculated by Space Mushroom from printed tonnage over the 51,000 thousand t world total); World Resources; Substitutes; Recycling
- subject: Manganese
abundance: Land-based manganese resources are large but irregularly distributed; South Africa accounts for an estimated 70% of world resources. US net import reliance was 100% of apparent consumption in each year from 2021 to 2025e (USGS).
producers:
- country: South Africa
share_percent: 38
year: 2025
- country: Gabon
share_percent: 25
year: 2025
- country: Ghana
share_percent: 10
year: 2025
- country: Australia
share_percent: 8
year: 2025
- country: Brazil
share_percent: 4
year: 2025
- country: India
share_percent: 3.95
year: 2025
- country: China
share_percent: 3.5
year: 2025
critical_lists:
- list: USGS 2025 List of Critical Minerals, read from a fetch summary (the page returned 403 to curl)
listed: true
- list: EU critical raw materials list, fifth list 2023 (34 CRMs, European Commission page)
listed: true
recycling: Manganese was recycled incidentally in ferrous and nonferrous scrap, but scrap recovery specifically for manganese was negligible; it is recovered with iron from steel slag (USGS).
substitutes:
- Manganese has no satisfactory substitute in its major applications (USGS 2026).
source: usgs-mn-2026
where: Salient Statistics; World Mine Production and Reserves (manganese content, 2025e; shares calculated by Space Mushroom from printed tonnage over the 20,000 thousand t world total); World Resources; Substitutes; Recycling
- subject: Molybdenum
abundance: Identified resources are about 5.4 million tons in the United States and about 20 million tons in the rest of the world; world reserves were 17,000 thousand t (2025e). Molybdenum is used principally as an alloying agent in steels, cast irons and superalloys (USGS 2026).
producers:
- country: China
share_percent: 37.3
year: 2025
- country: Chile
share_percent: 16.2
year: 2025
- country: United States
share_percent: 15.4
year: 2025
- country: Peru
share_percent: 15
year: 2025
- country: Mexico
share_percent: 6.5
year: 2025
critical_lists:
- list: USGS 2025 List of Critical Minerals, read from a fetch summary (no molybdenum entry)
listed: false
- list: EU critical raw materials list, fifth list 2023 (34 CRMs, European Commission page)
listed: false
recycling: Molybdenum is recycled as a component of catalysts, ferrous scrap and superalloy scrap; recycled material may be as much as 30% of the apparent supply (USGS 2026).
substitutes:
- There is little substitution for molybdenum in steels and cast irons; potential substitutes in alloy steels include boron, chromium, niobium and vanadium (USGS 2026).
source: usgs-mo-2026
where: Salient Statistics and Events, Trends and Issues (China export controls, February 2025); World Mine Production and Reserves (2025e; shares calculated by Space Mushroom over the 260,000 thousand t world total); Substitutes; Recycling
media: []
documents:
- title: 'Smith Metal Centres: P20 (T51620) product datasheet'
type: datasheet
url: https://www.smithmetal.com/pdf/tool-steel/p20.pdf
year: 2023
- title: 'Wilhelm Oberste-Beulmann: 1.2311+QT (40CrMnMo7) technical data sheet'
type: datasheet
url: https://www.oberste-beulmann.de/Dateien/Datenblaetter/1.2311.qt.en.pdf
year: 2018
- title: 'Swiss Steel Group: Formadur 2311 pre-hardened plastic mould steel data sheet, rev. 2'
type: datasheet
url: https://swisssteel-group.com/content-media/documents/_import/20260428_SSG_DataSheets_Formadur2311_en_02.pdf
year: 2026
- title: 'SIJ Metal Ravne: SIMOLD 2311 (1.2311) datasheet'
type: datasheet
url: https://cms.sij.si/storage/190/SIMOLD-2311_Metal.pdf
year: 2016
- title: 'Abrams Industries: PREMIUM 1.2311 steel, standard values'
type: datasheet
url: https://eu.abrams-industries.com/steel/premium-12311
- title: 'Alro Steel: P-20 tool steel grade information'
type: datasheet
url: https://www.myalro.com/gradeinfo/Metals_Gridpt.aspx?gp=0335
- title: 'Aços Formosa: Plastic mold steels (P-20 family)'
type: datasheet
url: https://acosformosa.com.br/en/products/plastic-mold-steels/
year: 2026
- title: 'TotalMateria: UNS T51620 (P20) material page'
type: database
url: https://www.totalmateria.com/en-us/material/1241786
- title: 'Taizhou Boxumold: P20 vs S136 mold steel comparison (vendor article)'
type: report
url: https://www.boxumold.com/en/comparisons/p20-vs-s136-mold-steel
year: 2026
- title: 'Dörrenberg: 1.2738 (P20+Ni) datasheet'
type: datasheet
url: https://doerrenberg.de/fileadmin/special_steel/files/pdf_en_products_neues_Design/1.2738_en.pdf
- title: 'Industeel (ArcelorMittal): DS Mold 2738 (1.2738) datasheet'
type: datasheet
url: https://industeel.arcelormittal.com/fichier/ds-mold-2738
- title: 'USGS Mineral Commodity Summaries 2026: Chromium'
type: report
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-chromium.pdf
year: 2026
- title: 'USGS Mineral Commodity Summaries 2026: Manganese'
type: report
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-manganese.pdf
year: 2026
- title: 'USGS Mineral Commodity Summaries 2026: Molybdenum'
type: report
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-molybdenum.pdf
year: 2026
- title: 'USGS: About the 2025 List of Critical Minerals'
type: report
url: https://www.usgs.gov/programs/mineral-resources-program/science/about-2025-list-critical-minerals
year: 2025
- title: 'European Commission: Critical raw materials (fifth list 2023, 34 CRMs)'
type: report
url: https://single-market-economy.ec.europa.eu/sectors/raw-materials/areas-specific-interest/critical-raw-materials_en
year: 2023
- title: 'PubChem: Chromium (CID 23976), GHS classification'
type: database
url: https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/23976/JSON/?heading=GHS+Classification
year: 2026
- title: 'PubChem: Manganese (CID 23930), GHS classification'
type: database
url: https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/23930/JSON/?heading=GHS+Classification
year: 2026
- title: 'PubChem: Molybdenum (CID 23932), GHS classification'
type: database
url: https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/23932/JSON/?heading=GHS+Classification
year: 2026
gaps:
- No safety data sheet for P20 steel was read in this run. The hazard entries are PubChem records for the pure elements chromium, manganese and molybdenum, which do not describe the steel.
- 'Hardness as delivered is printed differently by each source: 280 to 325 HB (Oberste-Beulmann, Swiss Steel), about 300 HB and 30 HRC typical (Smith Metal Centres), 30 to 34 HRC (Aços Formosa), about 32 HRC (Abrams) and 28 to 34 HRC (Boxumold, a vendor). None of the pages read in this run printed 28 to 32 HRC for P20 itself, so the about 28 to 32 HRC figure in the brief is not confirmed here.'
- 'Composition: the P20 ranges (Smith Metal Centres, TotalMateria) and the EN 1.2311 ranges (Abrams) differ, and the typical values in the 1.2311 datasheets (Simold, Swiss Steel) differ again. The recipe uses the P20 ranges.'
- 'Nickel: the Smith Metal Centres text says nickel and chromium enhance hardness and toughness, but its P20 composition table gives no nickel limit, and no P20 table read here lists one.'
- 'Soft-annealed hardness conflicts: Simold prints a maximum of 230 HB after soft annealing at 710 to 740 C, while Swiss Steel prints 325 HB or less for the same treatment. Both are kept with their sources; the two were not reconciled.'
- 'Stress-relief temperatures differ: 500 to 550 C for the quenched and tempered condition (Oberste-Beulmann), 550 to 600 C for 1 hour per 25 mm (Abrams), and about 650 C for 1 to 2 hours to remove machining stresses (Simold). The Oberste-Beulmann tempering chart gives 32 HRC at 650 C, so the 650 C figure would soften a pre-hardened block; this is an inference, not a printed statement.'
- 'Temper hold times differ: at least 1 hour per 25 mm (Smith Metal Centres), at least 2 hours or 1 hour per 25 mm (Abrams), and 1 hour per 20 mm with a minimum of 2 hours (Oberste-Beulmann).'
- No P20 corrosion test was found in any fetched source. The corrosion entries are datasheet statements and a vendor comparison; no salt, acid or humidity exposure data for P20 were read. A nitriding corrosion study on Impax Supreme (its Gamry abstract calls it equivalent to AISI P20) was fetched but not used, because it is a different steel.
- 'Polishability is described in datasheets and vendor text, not measured: no surface roughness or finish data for P20 were read. The Boxumold SPI B-to-D statement is vendor text and is not used as a value.'
- Hardness and machinability use snake_case benchmark names (hardness_brinell, hardness_rockwell_c, machinability_relative) because property-canon.yaml has no entry for them.
- Critical-mineral status for the USGS 2025 list was read from a WebFetch summary of the USGS page, because curl returned 403 for that page; it is not raw text. The EU status was read from the European Commission page.
- Supply shares are calculated by Space Mushroom from the printed USGS tonnage over the printed world totals; they are not printed percentages.
- No space, vacuum, radiation or flight use of P20 was found in these sources. The uses are terrestrial moulds, dies and machinery parts.
- No Charpy, fracture toughness or fatigue values for P20 were printed in the sources read; the Smith Metal Centres and Alro texts mention toughness without numbers.
- No photograph or micrograph of P20 with a licence we could cite was fetched in this run, so media is empty.
- 'Designations: the site''s identity schema has no designations field, so identity.designations is likely dropped on import until the schema has that field.'
- 'Not reached in this run: ASM Alloy Digest (login required), MakeItFrom (blocked), VEM Tooling and suppliersonline (no readable text), BGH datasheet (blocked), PACE Metallographic (database offline, no P20 values), and the Meusburger 12311 page (navigation only). Dillinger DIMO 2311 is a modified variant and was not read.'
sources:
smith-p20:
title: 'Smith Metal Centres: P20 (T51620) product datasheet'
id: P20 (T51620)
url: https://www.smithmetal.com/pdf/tool-steel/p20.pdf
year: 2023
kind: datasheet
license: supplier datasheet, cited not reproduced
beul-2311:
title: 'Wilhelm Oberste-Beulmann: 1.2311+QT (40CrMnMo7) technical data sheet'
id: 1.2311+QT, code 40CrMnMo7
url: https://www.oberste-beulmann.de/Dateien/Datenblaetter/1.2311.qt.en.pdf
year: 2018
kind: datasheet
license: supplier datasheet, cited not reproduced
swiss-2311:
title: 'Swiss Steel Group: Formadur 2311 pre-hardened plastic mould steel data sheet, rev. 2'
id: Formadur 2311, AISI P20 / AFNOR 40CMD8
url: https://swisssteel-group.com/content-media/documents/_import/20260428_SSG_DataSheets_Formadur2311_en_02.pdf
year: 2026
kind: datasheet
license: supplier datasheet, cited not reproduced
sij-2311:
title: 'SIJ Metal Ravne: SIMOLD 2311 (1.2311) datasheet'
id: SIMOLD 2311, 1.2311, approx. P20
url: https://cms.sij.si/storage/190/SIMOLD-2311_Metal.pdf
year: 2016
kind: datasheet
license: supplier datasheet, cited not reproduced
abrams-12311:
title: 'Abrams Industries: PREMIUM 1.2311 steel, standard values (text derived from stahlwissen.de)'
id: PREMIUM 1.2311
url: https://eu.abrams-industries.com/steel/premium-12311
kind: web
license: supplier web page, cited not reproduced
alro-p20:
title: 'Alro Steel: P-20 tool steel grade information'
id: AISI P-20
url: https://www.myalro.com/gradeinfo/Metals_Gridpt.aspx?gp=0335
kind: web
license: supplier web page, cited not reproduced
formosa-p20:
title: 'Aços Formosa: Plastic mold steels (P-20 family, 1.2311, 1.2312, 1.2738, 1.2316)'
id: P-20 family
url: https://acosformosa.com.br/en/products/plastic-mold-steels/
year: 2026
kind: web
license: supplier web page, cited not reproduced
tm-p20:
title: 'TotalMateria: UNS T51620 (P20) material page, chemical composition, physical properties and equivalents'
id: UNS T51620
url: https://www.totalmateria.com/en-us/material/1241786
kind: database
license: database page, cited not reproduced
boxu-s136:
title: 'Taizhou Boxumold: P20 vs S136 mold steel comparison (vendor article)'
id: vendor comparison
url: https://www.boxumold.com/en/comparisons/p20-vs-s136-mold-steel
year: 2026
kind: web
license: vendor page, cited not reproduced
doer-2738:
title: 'Dörrenberg: 1.2738 (P20+Ni) datasheet, opening paragraph on the DIN EN ISO 4957 grades'
id: '1.2738'
url: https://doerrenberg.de/fileadmin/special_steel/files/pdf_en_products_neues_Design/1.2738_en.pdf
kind: datasheet
license: supplier datasheet, cited not reproduced
ind-2738:
title: 'Industeel (ArcelorMittal): DS Mold 2738 (W 1.2738) datasheet'
id: W 1.2738
url: https://industeel.arcelormittal.com/fichier/ds-mold-2738
kind: datasheet
license: supplier datasheet, cited not reproduced
usgs-cr-2026:
title: 'USGS Mineral Commodity Summaries 2026: Chromium'
id: mcs2026-chromium
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-chromium.pdf
year: 2026
kind: report
license: public domain (USGS)
usgs-mn-2026:
title: 'USGS Mineral Commodity Summaries 2026: Manganese'
id: mcs2026-manganese
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-manganese.pdf
year: 2026
kind: report
license: public domain (USGS)
usgs-mo-2026:
title: 'USGS Mineral Commodity Summaries 2026: Molybdenum'
id: mcs2026-molybdenum
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-molybdenum.pdf
year: 2026
kind: report
license: public domain (USGS)
usgs-crit-2025:
title: 'USGS: About the 2025 List of Critical Minerals'
id: 2025 list (60 minerals)
url: https://www.usgs.gov/programs/mineral-resources-program/science/about-2025-list-critical-minerals
year: 2025
kind: web
license: public domain (USGS)
ec-crm-2023:
title: 'European Commission: Critical raw materials (fifth list 2023, 34 CRMs)'
id: fifth list 2023
url: https://single-market-economy.ec.europa.eu/sectors/raw-materials/areas-specific-interest/critical-raw-materials_en
year: 2023
kind: web
license: European Commission web page, cited not reproduced
pubchem-cr:
title: 'PubChem: Chromium (CID 23976), Safety and Hazards, GHS Classification'
id: CID 23976
url: https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/23976/JSON/?heading=GHS+Classification
year: 2026
kind: database
license: PubChem terms (public)
pubchem-mn:
title: 'PubChem: Manganese (CID 23930), Safety and Hazards, GHS Classification'
id: CID 23930
url: https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/23930/JSON/?heading=GHS+Classification
year: 2026
kind: database
license: PubChem terms (public)
pubchem-mo:
title: 'PubChem: Molybdenum (CID 23932), Safety and Hazards, GHS Classification'
id: CID 23932
url: https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/23932/JSON/?heading=GHS+Classification
year: 2026
kind: database
license: PubChem terms (public)
license: CC-BY-4.0
updated: '2026-10-24'
review:
status: draft
method: assistant
checked_values: 30
unreachable: 0
caveats: 3
note: 'Read by an AI assistant on 2026-10-24 from pages fetched in this run. Caveats: the converted tensile value (calculated, not tested), the Boxumold hardness range (a vendor statement), and the about 80 percent machinability figure (approximate). The USGS 2025 critical-list page could not be read with curl (403); its status was read from a fetch summary. Blocked or empty: ASM Alloy Digest, MakeItFrom, VEM Tooling, suppliersonline, BGH and PACE.'
story:
recipe:
line: P20 is an iron-based chromium-molybdenum tool steel with 0.28 to 0.40 percent carbon. The limits here are the P20 ranges printed by Smith Metal Centres. The EN grade 1.2311 has narrower manganese and chromium ranges (Abrams). Its strength comes from the pre-hardened heat treatment as much as from its composition.
parts:
- name: Iron
symbol: Fe
share_note: balance (the rest)
role: The matrix of the steel. Heat treatment changes its structure between martensite and tempered martensite.
- name: Carbon
symbol: C
share_percent: 0.28
share_high: 0.4
role: Sets how hard the steel can become when quenched.
- name: Manganese
symbol: Mn
share_percent: 0.6
share_high: 1
role: Adds hardenability and helps the melt.
- name: Silicon
symbol: Si
share_percent: 0.2
share_high: 0.8
role: Deoxidiser in the melt.
- name: Chromium
symbol: Cr
share_percent: 1.4
share_high: 2
role: Adds hardness and toughness in the alloy (Smith Metal Centres). The grade is not stainless.
- name: Molybdenum
symbol: Mo
share_percent: 0.3
share_high: 0.55
role: Adds hardenability. The grade still rusts unless protected.
- name: Copper
symbol: Cu
share_percent: 0
share_high: 0.25
role: Upper limit as printed by Smith Metal Centres; no role is stated in the datasheet.
- name: Phosphorus
symbol: P
share_percent: 0
share_high: 0.03
role: Impurity, held to a maximum.
- name: Sulfur
symbol: S
share_percent: 0
share_high: 0.03
role: Impurity, held to a maximum.
risk_groups:
- title: For people
level: 1
verdict: No SDS for P20 read; element data only
lead: The only hazard records found are PubChem entries for the pure elements chromium, manganese and molybdenum. No safety data sheet for P20 bar was read in this run.
points:
- label: Chromium
line: PubChem lists elemental chromium as Danger. Half of 2404 company reports say it does not meet GHS criteria; H317, allergic skin reaction, appears for 20.7% of reports.
- label: Manganese
line: PubChem lists elemental manganese with H228 (flammable solid, 11.6% of reports), H360 (may damage fertility or the unborn child) and H372 (organ damage on repeated exposure).
- label: Molybdenum
line: PubChem reports that 57.4% of its reports say elemental molybdenum does not meet GHS criteria; H315 (skin irritation) and H335 (respiratory irritation) appear among the codes.
- title: In service
level: 2
verdict: Rust is the main watch point
lead: The datasheets say the steel is not corrosion resistant, so rust is the main in-service concern.
points:
- label: Rust
line: The Simold datasheet says the alloy will corrode or rust unless protected. Abrams says surface treatment and dry storage extend resistance but cannot completely prevent rusting.
- label: Corrosive plastics
line: Aços Formosa points PVC and plastics that release aggressive gases to the stainless grade 1.2316, not to P20.
- label: Reheating
line: The Swiss Steel tempering chart shows hardness falling from 42 HRC after tempering at 500 C to 36 HRC at 600 C and 28 HRC at 700 C.
- title: Heat treatment and welding
level: 1
verdict: Keep weld and reheat temperatures in check
lead: Heat sets the strength, and the reheat limits matter most.
points:
- label: Welding
line: Abrams gives a preheat of 315 to 370 C and a limit of 565 C on reheating; above that, hardness can be lost.
- label: Stress relief
line: Oberste-Beulmann gives 500 to 550 C for the quenched and tempered condition; Abrams gives 550 to 600 C.
- label: Re-hardening
line: Re-hardening from 830 to 880 C in oil or a warm bath at 180 to 220 C gives about 51 HRC (Simold).
why: 'P20 (UNS T51620, EN 1.2311) is a chromium-molybdenum mould steel. It is bought pre-hardened at about 280 to 325 HB, so mould blocks can be cut and used without a further heat treatment. Its machinability and polishing are good, and it is used for plastic moulds, mould frames and zinc die-casting dies. Its weak point is corrosion resistance: the datasheets say it rusts unless protected.'
uses:
- where: Plastic moulds and frames
line: Oberste-Beulmann and Swiss Steel list plastic moulds, mould frames and pressure-casting moulds. Smith Metal Centres calls P20 a common steel for large mould frames and bolsters.
- where: Zinc die-casting dies
line: Smith Metal Centres and Alro list zinc die-casting dies among the typical uses.
- where: Rails and shafts
line: Abrams also lists rails and shafts as suitable applications for the EN 1.2311 grade.
can_do:
- label: Hardness
line: Supplied at 280 to 325 HB (Oberste-Beulmann and Swiss Steel), so blocks can be machined and used without a further heat treatment (Abrams).
- label: Strength
line: Typical yield strength is 827 to 862 MPa and tensile strength 965 to 1030 MPa in the pre-hardened condition (Smith Metal Centres, typical values).
- label: Stiffness
line: Modulus of elasticity is 190 to 210 GPa (Smith Metal Centres) and 210 GPa (Simold, average value).
- label: Machining
line: Machinability is 60 to 65 percent of a 1% carbon steel (Alro), or about 80 percent of W-group water-hardening steel (Simold).
- label: Polish
line: Polishes to a high gloss, but over-polishing can cause orange peel and pitting (Abrams). Oberste-Beulmann says it is better polishable than the 1.2312 grade.
- label: Weld
line: Can be welded by conventional methods with preheat and controlled cooling (Abrams). Smith Metal Centres says it has good weldability.
- label: Nitride
line: Can be nitrided to a case about 0.40 mm deep for a harder, wear-resistant surface (Abrams).
compare: 'P20 sits in a family of pre-hardened plastic mould steels from Aços Formosa: 1.2311 for small and medium moulds, 1.2312 for high machinability, 1.2738 (nickel-added) for large moulds, and P-20 ESR for high-gloss work. For corrosive plastics, Aços Formosa points to the stainless prehardened grade 1.2316 instead. The compare rows give P20''s typical strength, stiffness and density.'
compare_rows:
- label: Strength
benchmark: yield_strength
- label: Stiffness
benchmark: elastic_modulus
- label: Density
benchmark: density
handling:
- Buy and machine it pre-hardened; Abrams says heat treatment is not normally required for the supplied condition.
- 'Keep reheats and welding inside the limits: loss of hardness is the risk above 565 C (Abrams).'
- Protect it from rust with a surface treatment and dry storage; Abrams says these extend resistance but cannot completely prevent rusting.
- Stress relieve at 500 to 550 C for the quenched and tempered condition, then cool in the furnace (Oberste-Beulmann).
- Weld only with the preheat and controlled cool-down in the procedure (315 to 370 C preheat, Abrams).
- Take a safety data sheet for the specific bar before cutting, grinding or welding; none was read for P20 in this run.
good_for:
- Plastic injection-mould blocks and frames machined in the pre-hardened condition (Smith Metal Centres; Oberste-Beulmann).
- Zinc and pressure-casting dies, which the datasheets list as typical uses (Smith Metal Centres; Alro).
- Textured and polished mould faces; the datasheets say the grade takes texture and polish well (Simold; Abrams).
watch_out:
- 'Rust: the steel rusts unless it is protected; surface treatment and dry storage extend resistance but cannot completely prevent rusting (Simold; Abrams).'
- Heat above 565 C during welding or reheating can lose hardness (Abrams); tempering at 600 C leaves 36 HRC (Swiss Steel).
- 'Thick blocks: above 400 mm the Oberste-Beulmann datasheet recommends 1.2738 for better through-hardening.'
- 'Corrosive plastics: for PVC and gas-releasing plastics, Aços Formosa points to the stainless 1.2316 instead.'
verdict: P20 is a practical, pre-hardened mould steel. It is supplied at about 280 to 325 HB, machines and polishes well, and suits plastic moulds, mould frames and zinc die-casting dies. It is not corrosion resistant, so protect it from rust, keep reheats within the datasheet limits, and use 1.2738 for thick blocks or a stainless grade for corrosive plastics.
References
Every number above carries a reference number. Click one to see the source and where in it the value comes from.