Gray cast iron (flake graphite iron) Gray iron (ASTM A48, EN-GJL, GG 25)
Iron with 2.5 to 4.0 wt% carbon, mostly as flake graphite, 1 to 3 wt% silicon, below 1.0 wt% manganese, and the balance iron
Also known as EN 5.1203, EN name EN-GJL-250, DIN GG-25, GB HT 250, ASTM A48, ISO JL 250 · 1 more
Gray cast iron is cast iron with 2.5 to 4.0 percent carbon, held mostly as flake graphite, and 1 to 3 percent silicon.
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.
Tensile strength, EN-GJL-250
200 to 350 MPa at 20 °C
Compressive strength
752.5 to 1053.5 MPa
Stiffness
103 to 118 GPa
Density
7.2 g/cm³ at 20 °C
Thermal conductivity
50 W/(m·K) at 20 °C
Recipe, share of the weight
- Fe balance (the rest)Iron
- C 2.5 to 4%Carbon
- Si 1 to 3%Silicon
- Mn below 1.0Manganese
- P no number printedPhosphorus
- S kept as low as possibleSulfur
Best for
Machine bases, frames, pump housings and engine blocks, where damping, machinability and compressive load matter more than tensile strength
Weakest at
Tensile strength and shock resistance: the graphite flakes act as notches, so the metal breaks in a brittle way
Risk at a glance
- People Low. Element records only
- If it fails No data. No failure risks recorded
- Corrosion No data. No corrosion data recorded
Quick facts: Gray iron (ASTM A48, EN-GJL, GG 25)
| Property | Value | Basis |
|---|---|---|
| Density | 7.2 g/cm³ | 1 sourced value |
| Yield strength | 165 to 228 MPa | 1 sourced value |
| Tensile strength | 138 to 431 MPa | 12 sourced values across conditions |
| Young's modulus | 103 to 118 GPa | 6 sourced values across conditions |
| Hardness (Brinell) | 120 to 269 HB | 5 sourced values across conditions |
| Thermal conductivity | 50 W/(m·K) | 1 sourced value |
| Specific heat | 460 J/(kg·K) | 1 sourced value |
What is the density of Gray cast iron?
Gray cast iron has a density of 7.2 g/cm³. The source and test conditions are listed in the properties table on this page.
What is the thermal conductivity of Gray cast iron?
Gray cast iron has a thermal conductivity of 50 W/(m·K). The source and test conditions are listed in the properties table on this page.
What is the yield strength of Gray cast iron?
Gray cast iron has a yield strength of 165 to 228 MPa. The source and test conditions are listed in the properties table on this page.
What is the tensile strength of Gray cast iron?
Gray cast iron has a tensile strength of 138 to 431 MPa. The range covers 12 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 Young's modulus of Gray cast iron?
Gray cast iron has a Young's modulus of 103 to 118 GPa. The range covers 6 sourced values across the tempers, forms and test conditions the sources report; room-temperature values are used where a source states a temperature.
What are the other names and codes for Gray cast iron?
Gray cast iron is also written as EN 5.1203, EN name EN-GJL-250, DIN GG-25, GB HT 250, ASTM A48, ISO JL 250. Each code is printed in the source listed beside it in the designations table.
What is Gray cast iron used for?
Uses recorded in the sources include Brake discs and rotors; Machine tool bases and mountings; Internal combustion engine cylinder blocks.
Why it exists
Gray cast iron is the most common cast iron and the most widely used cast material by weight (Wikipedia). Its flake graphite makes it relatively cheap, easy to machine and good at damping vibration, which is why it suits machine bases and housings. The same flakes make it brittle, so it is weak in tension.
Where it's used
Brake discs
Its high thermal conductivity and specific heat capacity are used in disc brake rotors (Wikipedia).
Machine tool bases
Its damping makes it the usual base for machine tool mountings (Wikipedia). Align lists class 40 and class 50 for large machinery bases.
Engine blocks and housings
Cylinder blocks, pump housings and valve bodies are named housings where stiffness matters more than tensile strength (Wikipedia). Align lists class 30 for engine blocks and transmission housings.
Pipes and manhole covers
China Casting lists gray iron pipes for water supply and drainage, and for manhole covers in construction.
Recipe
Iron with 2.5 to 4.0 wt% carbon, mostly as flake graphite, 1 to 3 wt% silicon, below 1.0 wt% manganese, and the balance iron; graphite may take 6 to 10 percent of the volume
Gray iron is cast iron with 2.5 to 4.0 percent carbon, held mostly as flake graphite, 1 to 3 percent silicon, below 1.0 percent manganese, and the rest iron (Wikipedia, China Casting). Silicon promotes free graphite rather than cementite (China Casting). It is sand cast (MfgRobots).
| Ingredient | Share of the weight | What it does |
|---|---|---|
| Iron Fe | balance (the rest) | The matrix of the metal; it is the rest of the composition |
| Carbon C | 2.5 to 4% | Forms flake graphite, which gives low tensile strength but easy machining and good damping (Wikipedia) |
| Silicon Si | 1 to 3% | Silicon promotes free graphite rather than cementite (China Casting), and forces carbon out of solution (Wikipedia) |
| Manganese Mn | below 1.0 | Stabilises the pearlite in the matrix (China Casting) |
| Phosphorus P | no number printed | Raised in some castings for fluidity; excess makes it brittle (China Casting) |
| Sulfur S | kept as low as possible | Forms iron sulfides that hurt mechanical performance (China Casting) |
Weight shares are as printed in the sources.
What it can do
Tensile strength, EN-GJL-250
200 to 350 MPa at 20 °C
measured
EN-GJL-250 has 200 to 350 MPa tensile strength at 20 °C (MfgRobots). Total Materia gives 160 to 350 MPa for 0 to 30 °C.
Compressive strength
752.5 to 1053.5 MPa
measured
Compression is far stronger than tension: 752.5 to 1053.5 MPa for EN-GJL-250 (Total Materia), often more than three to four times the tensile strength (China Casting).
Stiffness
103 to 118 GPa
measured
The elastic modulus is 103 to 118 GPa for EN-GJL-250 (MfgRobots, Total Materia). By ASTM class it is 10 to 21 Mpsi (Wikipedia).
Density
7.2 g/cm³ at 20 °C
measured
Density is 7.2 g/cm³ at 20 °C for EN-GJL-250 (MfgRobots).
Thermal conductivity
50 W/(m·K) at 20 °C
measured
Thermal conductivity is 50 W/(m·K) at 20 °C for EN-GJL-250 (MfgRobots). That is why it is used for brake rotors and cookware (Wikipedia).
Damping
100 to 500 (high carbon equivalent)
measured
On Wikipedia's relative damping scale, high carbon equivalent gray iron scores 100 to 500, and low carbon equivalent gray iron 20 to 100.
Machinability
Graphite flakes lubricate the cut and break the chips, so the metal machines easily (Wikipedia, Align). No machinability rating is printed.
How it compares
Gray cast iron trades tensile strength for damping, machinability and low cost. For EN-GJL-250 its tensile strength is 200 to 350 MPa, while its compressive strength is 752.5 to 1053.5 MPa (Total Materia). Its compressive strength is comparable to low and medium carbon steel, but its tensile strength and shock resistance are lower (Wikipedia). Ductile iron, with spherical graphite, has more ductility and impact resistance (Align).
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 | Gray iron (ASTM A48, EN-GJL, GG 25) | SG iron (ASTM A536, EN-GJS) |
|---|---|---|
| Capacity and energy | ||
| damping capacity | 100 to 500 -38 | no data |
| damping capacity | 20 to 100 -39 | no data |
| Thermal behavior and safety | ||
| specific heat | 460 J/(kg·K)10 | no data |
| Thermal conductivity | 50 W/(m·K)11 | no data |
| Physical and electrical | ||
| DensityGeneral table, Density row, value as printed | 7.2 g/cm³ | no data |
| brinell hardness | 120 to 187 HB33 | no data |
| brinell hardness | 170 to 229 HB34 | no data |
| brinell hardness | 187 to 246 HB35 | no data |
| brinell hardness | 207 to 255 HB36 | no data |
| brinell hardness | 217 to 269 HB37 | no data |
| Other measurements | ||
| ultimate tensile strength | 200 to 350 MPa1 | 60000 psi |
| ultimate tensile strength | 240 MPa2 | 60000 psi |
| ultimate tensile strength | 130 MPa3 | 60000 psi |
| yield strength | 165 to 228 MPa4 | 40000 psi |
| compressive yield strength | 752 to 1054 MPa5 | no data |
| elastic modulus | 103 to 118 GPa6 | 169 GPa |
| elongation | 0.3 to 0.8 %7 | 18 % |
| flexural strength | 415 to 581 MPa8 | no data |
| poissons ratio | 0.24 to 0.26 -9 | no data |
| ultimate tensile strength | 160 to 350 MPa12 | 60000 psi |
| compressive strength | 752.5 to 1054 MPa13 | no data |
| elastic modulus | 103 to 118 GPa14 | 169 GPa |
| ultimate tensile strength | 22 ksi15 | 60000 psi |
| ultimate tensile strength | 31 ksi16 | 60000 psi |
| ultimate tensile strength | 57 ksi17 | 60000 psi |
| ultimate tensile strength | 62.5 ksi18 | 60000 psi |
| compressive strength | 83 ksi19 | no data |
| compressive strength | 109 ksi20 | no data |
| compressive strength | 140 ksi21 | no data |
| compressive strength | 187.5 ksi22 | no data |
| elastic modulus | 10 Mpsi23 | 169 GPa |
| elastic modulus | 14 Mpsi24 | 169 GPa |
| elastic modulus | 18 Mpsi25 | 169 GPa |
| elastic modulus | 21 Mpsi26 | 169 GPa |
| ultimate tensile strength | 20000 psi27 | 60000 psi |
| ultimate tensile strength | 25000 psi28 | 60000 psi |
| ultimate tensile strength | 30000 psi29 | 60000 psi |
| ultimate tensile strength | 35000 psi30 | 60000 psi |
| ultimate tensile strength | 40000 psi31 | 60000 psi |
| ultimate tensile strength | 50000 psi32 | 60000 psi |
Why choose it, and why not
Good for
- Machine tool bases, frames and housings, where damping and machinability matter (Wikipedia, Align).
- Engine cylinder blocks, pump housings and valve bodies, where stiffness matters more than tensile strength (Wikipedia).
- Brake discs, where high thermal conductivity helps (Wikipedia).
Watch out for
- Brittle in tension and shock: the graphite flake tips act as notches (Wikipedia, Gray iron).
- Excess phosphorus adds brittleness (China Casting).
- Composition limits differ by article: 2.5 to 4.7 percent carbon and 1 to 8 percent silicon in one, 2.5 to 4.0 and 1 to 3 in another (Wikipedia).
Gray cast iron is the cheap, damping, easy-to-machine iron for housings, machine bases and brake discs. It is weak and brittle in tension, so name the class or grade and design for compression and damping, not for shock.
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 |
|---|---|
| EN | 5.1203 (EN material number listed as an equivalent of EN-GJL-250) |
| EN name | EN-GJL-250 (EN 1561 grade, lamellar graphite iron) |
| DIN | GG-25 (older DIN name, listed as an equivalent of EN-GJL-250) |
| GB | HT 250 (Chinese name, listed as an equivalent of EN-GJL-250) |
| ASTM | A48 |
| ISO | JL 250 (ISO name, listed as an equivalent of EN-GJL-250) |
| NBR | FC 250 (Brazilian name, listed as an equivalent of EN-GJL-250) |
Notes
The method, full conditions and any caveat for the numbered rows above.
| # | Measurement | Method | Conditions | Caveat |
|---|---|---|---|---|
| 1 | ultimate tensile strength | Mechanical table, Tensile strength row, range as printed | grade EN-GJL-250temperature 20.0 °Ctest bar not stated | — |
| 2 | ultimate tensile strength | Mechanical table, Tensile strength row, temperature series, value as printed | grade EN-GJL-250temperature 300.0 °Ctest bar not stated | — |
| 3 | ultimate tensile strength | Mechanical table, Tensile strength row, temperature series, value as printed | grade EN-GJL-250temperature 600.0 °Ctest bar not stated | — |
| 4 | yield strength | Mechanical table, Yield strength Rp0.1 row, range as printed | grade EN-GJL-250temperature 20.0 °Cproof Rp0.1, 0.1 percent proof stress, as printed | — |
| 5 | compressive yield strength | Mechanical table, Compressive yield strength row, range as printed | grade EN-GJL-250temperature 20.0 °C | — |
| 6 | elastic modulus | Mechanical table, Elastic modulus row, range as printed | grade EN-GJL-250temperature 20.0 °C | — |
| 7 | elongation | Mechanical table, Elongation row, range as printed | grade EN-GJL-250temperature 20.0 °C | — |
| 8 | flexural strength | Mechanical table, Flexural strength row, range as printed | grade EN-GJL-250temperature 20.0 °C | — |
| 9 | poissons ratio | Mechanical table, Poisson's ratio row, range as printed | grade EN-GJL-250temperature 20.0 °C | — |
| 10 | specific heat | Thermal table, Specific heat capacity row, value as printed | grade EN-GJL-250temperature 200.0 °C | — |
| 11 | Thermal conductivity | Thermal table, Thermal conductivity row, value as printed | grade EN-GJL-250temperature 20.0 °C | — |
| 12 | ultimate tensile strength | Mechanical Properties block, Tensile Strength row, range as printed | grade DIN EN-GJL-250 (EN-GJL-250)temperature 0 to 30 °C (block heading)test bar not stated | — |
| 13 | compressive strength | Mechanical Properties block, Compression Strength row, range as printed | grade DIN EN-GJL-250 (EN-GJL-250)temperature 0 to 30 °C (block heading) | — |
| 14 | elastic modulus | Physical Properties block, Modulus of Elasticity row, range as printed | grade DIN EN-GJL-250 (EN-GJL-250)temperature band not identified in the text (the block lists several bands) | — |
| 15 | ultimate tensile strength | Table Properties of ASTM A48 classes of gray iron, Tensile strength column, value as printed | standard ASTM A48class 20basis table value; minimum or typical not stated on the pagetest bar not stated | — |
| 16 | ultimate tensile strength | Table Properties of ASTM A48 classes of gray iron, Tensile strength column, value as printed | standard ASTM A48class 30basis table value; minimum or typical not stated on the pagetest bar not stated | — |
| 17 | ultimate tensile strength | Table Properties of ASTM A48 classes of gray iron, Tensile strength column, value as printed | standard ASTM A48class 40basis table value; minimum or typical not stated on the pagetest bar not stated | — |
| 18 | ultimate tensile strength | Table Properties of ASTM A48 classes of gray iron, Tensile strength column, value as printed | standard ASTM A48class 60basis table value; minimum or typical not stated on the pagetest bar not stated | — |
| 19 | compressive strength | Table Properties of ASTM A48 classes of gray iron, Compressive strength column, value as printed | standard ASTM A48class 20basis table value; minimum or typical not stated on the pagetest bar not stated | — |
| 20 | compressive strength | Table Properties of ASTM A48 classes of gray iron, Compressive strength column, value as printed | standard ASTM A48class 30basis table value; minimum or typical not stated on the pagetest bar not stated | — |
| 21 | compressive strength | Table Properties of ASTM A48 classes of gray iron, Compressive strength column, value as printed | standard ASTM A48class 40basis table value; minimum or typical not stated on the pagetest bar not stated | — |
| 22 | compressive strength | Table Properties of ASTM A48 classes of gray iron, Compressive strength column, value as printed | standard ASTM A48class 60basis table value; minimum or typical not stated on the pagetest bar not stated | — |
| 23 | elastic modulus | Table Properties of ASTM A48 classes of gray iron, Tensile modulus E column, value as printed in Mpsi | standard ASTM A48class 20basis table value; minimum or typical not stated on the pagetest bar not stated | — |
| 24 | elastic modulus | Table Properties of ASTM A48 classes of gray iron, Tensile modulus E column, value as printed in Mpsi | standard ASTM A48class 30basis table value; minimum or typical not stated on the pagetest bar not stated | — |
| 25 | elastic modulus | Table Properties of ASTM A48 classes of gray iron, Tensile modulus E column, value as printed in Mpsi | standard ASTM A48class 40basis table value; minimum or typical not stated on the pagetest bar not stated | — |
| 26 | elastic modulus | Table Properties of ASTM A48 classes of gray iron, Tensile modulus E column, value as printed in Mpsi | standard ASTM A48class 60basis table value; minimum or typical not stated on the pagetest bar not stated | — |
| 27 | ultimate tensile strength | Gray Iron Grades list, Tensile strength line under ASTM A48 Class 20, value as printed | standard ASTM A48class 20basis tensile strength as printed; minimum or typical not statedtest bar not stated | — |
| 28 | ultimate tensile strength | Gray Iron Grades list, Tensile strength line under ASTM A48 Class 25, value as printed | standard ASTM A48class 25basis tensile strength as printed; minimum or typical not statedtest bar not stated | — |
| 29 | ultimate tensile strength | Gray Iron Grades list, Tensile strength line under ASTM A48 Class 30, value as printed | standard ASTM A48class 30basis tensile strength as printed; minimum or typical not statedtest bar not stated | — |
| 30 | ultimate tensile strength | Gray Iron Grades list, Tensile strength line under ASTM A48 Class 35, value as printed | standard ASTM A48class 35basis tensile strength as printed; minimum or typical not statedtest bar not stated | — |
| 31 | ultimate tensile strength | Gray Iron Grades list, Tensile strength line under ASTM A48 Class 40, value as printed | standard ASTM A48class 40basis tensile strength as printed; minimum or typical not statedtest bar not stated | — |
| 32 | ultimate tensile strength | Gray Iron Grades list, Tensile strength line under ASTM A48 Class 50, value as printed | standard ASTM A48class 50basis tensile strength as printed; minimum or typical not statedtest bar not stated | — |
| 33 | brinell hardness | Table Properties of SAE J431 grades of gray iron, Brinell hardness column, range as printed; the page prints no unit, so recorded as a pure number | standard SAE J431grade G1800description ferritic-pearlitic, as printedtest bar not stated | — |
| 34 | brinell hardness | Table Properties of SAE J431 grades of gray iron, Brinell hardness column, range as printed; the page prints no unit, so recorded as a pure number | standard SAE J431grade G2500description pearlitic-ferritic, as printedtest bar not stated | — |
| 35 | brinell hardness | Table Properties of SAE J431 grades of gray iron, Brinell hardness column, range as printed; the page prints no unit, so recorded as a pure number | standard SAE J431grade G3000description pearlitic, as printedtest bar not stated | — |
| 36 | brinell hardness | Table Properties of SAE J431 grades of gray iron, Brinell hardness column, range as printed; the page prints no unit, so recorded as a pure number | standard SAE J431grade G3500description pearlitic, as printedtest bar not stated | — |
| 37 | brinell hardness | Table Properties of SAE J431 grades of gray iron, Brinell hardness column, range as printed; the page prints no unit, so recorded as a pure number | standard SAE J431grade G4000description pearlitic, as printedtest bar not stated | — |
| 38 | damping capacity | Table Relative damping capacity of various metals, value as printed; footnote says natural log of the ratio of successive amplitudes, so a pure number | material gray iron, high carbon equivalent, as printed | — |
| 39 | damping capacity | Table Relative damping capacity of various metals, value as printed; footnote says natural log of the ratio of successive amplitudes, so a pure number | material gray iron, low carbon equivalent, as printed | — |
Corrosion and compatibility
What happens when it meets other materials and environments.
| Environment | Concern | What happens |
|---|---|---|
| Water supply and drainage systems (pipes) | not rated | Pipes are used in water and drainage for their corrosion resistance and longevity1 |
| Not named in the source (effect of the silicon in the alloy) | not rated | Silicon is said to promote good corrosion resistance2 |
| Austenitic gray iron with nickel and chromium (an alloyed variant) | not rated | A nickel and chromium variant is listed for excellent corrosion resistance3 |
| # | Environment | Details | Test conditions |
|---|---|---|---|
| 1 | Water supply and drainage systems (pipes) | China Casting says gray cast iron pipes have been widely used in water supply and drainage systems because of their corrosion resistance and longevity. No corrosion rate, test or exposure time is printed. | — |
| 2 | Not named in the source (effect of the silicon in the alloy) | Wikipedia says the silicon in gray iron promotes good corrosion resistance and increased fluidity when casting. The article names no environment and gives no rate. | — |
| 3 | Austenitic gray iron with nickel and chromium (an alloyed variant) | China Casting's table lists austenitic gray iron (Ni, Cr) for excellent corrosion and heat resistance. That is an alloyed variant of gray iron, and the page gives no rate. | — |
Risks and side effects
Hazards to people, what happens when a cell overheats, and how the material is handled and stored.
For people
PubChem's hazard records are for elemental iron, not for cast parts. No gray cast iron safety data sheet was read.
- Iron
- PubChem says the chemical does not meet GHS hazard criteria in 74.1 percent of 6013 reports; H228 and H251 appear in some notifications.
- Dust and fume
- Limits for dust and fume from cutting, grinding and welding were not read. Check the supplier safety data sheet before the work.
In the environment
The sources give qualitative corrosion statements only.
- Water
- China Casting says gray iron pipes are used in water supply and drainage for their corrosion resistance and longevity.
- Silicon
- Wikipedia says the silicon in gray iron promotes good corrosion resistance.
In service
Graphite flakes make the metal brittle under tensile and shock loads.
- Tension
- EN-GJL-250 tensile strength is 200 to 350 MPa at 20 °C (MfgRobots), while its compressive strength is far higher (Total Materia).
- Phosphorus
- Excess phosphorus adds brittleness (China Casting).
Test details
The original wording and numbers from the sources, for readers who want them.
Failure risks
| Failure | Trigger and consequence |
|---|---|
| Brittle fracture under tensile or shock load | Tensile stress or shock; the tips of the graphite flakes act as notches where stress concentratesLow tensile strength, and impact and shock resistance that is almost non-existent (Wikipedia) |
| Brittleness from excess phosphorus | Phosphorus raised above what the casting needs for fluidityExcessive phosphorus can lead to brittleness (China Casting) |
| Less tensile strength and shock resistance than steel | A part loaded in tension or shock as if it were steelGrey cast iron has less tensile strength and shock resistance than steel (Wikipedia, Cast iron) |
Handling and storage
- Name the class or grade with every strength value, because ASTM classes and EN grades have different strengths (Wikipedia, Align)
- Gray iron cannot be forged, extruded or rolled, even at temperature, so it must be cast to shape (Wikipedia)
- Gray iron is generally considered easy to weld (Wikipedia)
- Stress relieving is particularly important for large castings (China Casting)
Mitigations
- In some cases protective coatings are applied to enhance corrosion resistance or extend service life (China Casting)
- Where corrosion and heat resistance matter, an alloyed austenitic gray iron with nickel and chromium is listed (China Casting); it is a different alloy from plain gray iron
Supply and geography
How common the raw materials are and where they come from.
Iron and steel (United States)
Iron is the least expensive and most widely used metal (USGS). The US produced 82 million tons of raw steel in 2025e, and net import reliance was 13 percent of apparent consumption in 2025e. Construction took an estimated 31 percent of net shipments. Import sources 2021 to 2024: Canada 23 percent, Mexico 15 percent, Brazil 13 percent, Republic of Korea 9 percent, other 40 percent.
- Recycling
- Not read: the chapter points to the Iron and Steel Scrap chapter
- Substitutes
- Nonmetallic materials at lower cost, or costlier materials with better performance (USGS substitutes text)
Raw steel production by country (2025e)
World raw steel production was 1,900 million tons in 2025e (rounded total). Shares are computed from the printed 2025e tonnage over that total: China 980, India 160, United States 82, Japan 81 and Russia 65 million tons.
- Top producers (2025)
- China 51.6%, India 8.4%, United States 4.3%, Japan 4.3%, Russia 3.4%
Silicon (ferrosilicon and silicon metal)
China accounted for almost 80 percent of total global estimated production of silicon materials in 2025 (USGS). Most ferrosilicon was consumed in the ferrous foundry and steel industries. Ferrosilicon import sources 2021 to 2024: Russia 30 percent, Brazil 16 percent, Canada 13 percent, Malaysia 11 percent, other 30 percent.
- Critical mineral lists
- U.S. Final 2025 List of Critical Minerals: listed
Manganese
Net import reliance was 100 percent in every year from 2021 to 2025e. Manganese ore import sources 2021 to 2024: Gabon 64 percent, South Africa 24 percent, Mexico 12 percent. Consumption closely follows the steel industry, and South Africa has an estimated 70 percent of world manganese resources (USGS). Shares are computed from the 2025e mine production table over its printed world total.
- Top producers (2025)
- South Africa 38%, Gabon 25%, Ghana 10%, Australia 8%
Documents
Datasheets, safety data sheets, papers and standards you can open.
| Document | Type | Year |
|---|---|---|
| Total Materia: DIN EN-GJL-250 Cast irons | database | |
| MfgRobots: EN 1561 Grade GJL-250 Cast, Key Properties and Applications | datasheet | |
| MTS: ASTM A48/A48M Tensile Testing technote | datasheet | 2023 |
| USGS Mineral Commodity Summaries 2026: Iron and Steel | report | 2026 |
| USGS Mineral Commodity Summaries 2026: Silicon | report | 2026 |
| USGS Mineral Commodity Summaries 2026: Manganese | report | 2026 |
| PubChem: Iron (CID 23925), GHS classification | database |
Full record
The complete spore, as stored. Free to reuse under CC-BY-4.0. Images keep the licence shown with each one.
Show the full YAML
spore: profile
id: gray-cast-iron
spore_version: 0.2
family: cast-irons
name: Gray cast iron (flake graphite iron)
abbreviation: Gray iron (ASTM A48, EN-GJL, GG 25)
role: Flake graphite cast iron for housings, machine bases and brake discs
category: metals
type: steels-and-stainless
summary: |
Gray cast iron is cast iron with 2.5 to 4.0 percent carbon, held mostly as flake graphite, and 1 to 3 percent silicon. It is cheap, easy to machine and good at damping vibration, but the flakes make it brittle, so it is weak in tension and strong in compression. ASTM A48 classes and EN 1561 grades set its strength, and each figure here names the class or grade it belongs to.
best_for: Machine bases, frames, pump housings and engine blocks, where damping, machinability and compressive load matter more than tensile strength
weakest_at: 'Tensile strength and shock resistance: the graphite flakes act as notches, so the metal breaks in a brittle way'
identity:
formula: Iron with 2.5 to 4.0 wt% carbon, mostly as flake graphite, 1 to 3 wt% silicon, below 1.0 wt% manganese, and the balance iron; graphite may take 6 to 10 percent of the volume
source: wiki-cast-iron
where: Grey cast iron section, composition sentence; graphite volume from the Gray iron article
designations:
- system: ASTM
code: A48
note: gray iron castings; grades are classes set by minimum tensile strength
source: shimadzu-astm-a48
where: 'Page title: ASTM A48: Standard Specification for Gray Iron Castings'
- system: EN name
code: EN-GJL-250
note: EN 1561 grade, lamellar graphite iron
source: totalmateria-en-gjl-250
where: 'Page title: DIN EN-GJL-250 Cast irons'
- system: EN
code: '5.1203'
note: EN material number listed as an equivalent of EN-GJL-250
source: totalmateria-en-gjl-250
where: International Equivalent Materials list, EN row
- system: DIN
code: GG-25
note: older DIN name, listed as an equivalent of EN-GJL-250
source: totalmateria-en-gjl-250
where: International Equivalent Materials list, DIN row
- system: ISO
code: JL 250
note: ISO name, listed as an equivalent of EN-GJL-250
source: totalmateria-en-gjl-250
where: International Equivalent Materials list, ISO row
- system: GB
code: HT 250
note: Chinese name, listed as an equivalent of EN-GJL-250
source: totalmateria-en-gjl-250
where: International Equivalent Materials list, GB row
- system: NBR
code: FC 250
note: Brazilian name, listed as an equivalent of EN-GJL-250
source: totalmateria-en-gjl-250
where: International Equivalent Materials list, NBR row
tags:
environments: []
stresses: []
applications:
- mechanisms
- structures
- propulsion-and-tanks
properties:
- benchmark: density
value: 7.2
unit: g/cm³
scope: material
conditions:
grade: EN-GJL-250
temperature: 20.0 °C
method: General table, Density row, value as printed
status: ground
source: mfgrobots-gjl-250
where: General table (Density, 20.0 °C)
- benchmark: ultimate_tensile_strength
value: 200
value_high: 350
bound: range
unit: MPa
scope: material
conditions:
grade: EN-GJL-250
temperature: 20.0 °C
test_bar: not stated
method: Mechanical table, Tensile strength row, range as printed
status: ground
source: mfgrobots-gjl-250
where: Mechanical table (Tensile strength, 20.0 °C)
- benchmark: ultimate_tensile_strength
value: 240
unit: MPa
scope: material
conditions:
grade: EN-GJL-250
temperature: 300.0 °C
test_bar: not stated
method: Mechanical table, Tensile strength row, temperature series, value as printed
status: ground
source: mfgrobots-gjl-250
where: Mechanical table (Tensile strength, 300.0 °C)
- benchmark: ultimate_tensile_strength
value: 130
unit: MPa
scope: material
conditions:
grade: EN-GJL-250
temperature: 600.0 °C
test_bar: not stated
method: Mechanical table, Tensile strength row, temperature series, value as printed
status: ground
source: mfgrobots-gjl-250
where: Mechanical table (Tensile strength, 600.0 °C)
- benchmark: yield_strength
value: 165
value_high: 228
bound: range
unit: MPa
scope: material
conditions:
grade: EN-GJL-250
temperature: 20.0 °C
proof: Rp0.1, 0.1 percent proof stress, as printed
method: Mechanical table, Yield strength Rp0.1 row, range as printed
status: ground
source: mfgrobots-gjl-250
where: Mechanical table (Yield strength Rp0.1, 20.0 °C)
- benchmark: compressive_yield_strength
value: 752
value_high: 1054
bound: range
unit: MPa
scope: material
conditions:
grade: EN-GJL-250
temperature: 20.0 °C
method: Mechanical table, Compressive yield strength row, range as printed
status: ground
source: mfgrobots-gjl-250
where: Mechanical table (Compressive yield strength, 20.0 °C)
- benchmark: elastic_modulus
value: 103
value_high: 118
bound: range
unit: GPa
scope: material
conditions:
grade: EN-GJL-250
temperature: 20.0 °C
method: Mechanical table, Elastic modulus row, range as printed
status: ground
source: mfgrobots-gjl-250
where: Mechanical table (Elastic modulus, 20.0 °C)
- benchmark: elongation
value: 0.3
value_high: 0.8
bound: range
unit: '%'
scope: material
conditions:
grade: EN-GJL-250
temperature: 20.0 °C
method: Mechanical table, Elongation row, range as printed
status: ground
source: mfgrobots-gjl-250
where: Mechanical table (Elongation, 20.0 °C)
- benchmark: flexural_strength
value: 415
value_high: 581
bound: range
unit: MPa
scope: material
conditions:
grade: EN-GJL-250
temperature: 20.0 °C
method: Mechanical table, Flexural strength row, range as printed
status: ground
source: mfgrobots-gjl-250
where: Mechanical table (Flexural strength, 20.0 °C)
- benchmark: poissons_ratio
value: 0.24
value_high: 0.26
bound: range
unit: '-'
scope: material
conditions:
grade: EN-GJL-250
temperature: 20.0 °C
method: Mechanical table, Poisson's ratio row, range as printed
status: ground
source: mfgrobots-gjl-250
where: Mechanical table (Poisson's ratio, 20.0 °C)
- benchmark: specific_heat
value: 460
unit: J/(kg·K)
scope: material
conditions:
grade: EN-GJL-250
temperature: 200.0 °C
method: Thermal table, Specific heat capacity row, value as printed
status: ground
source: mfgrobots-gjl-250
where: Thermal table (Specific heat capacity, 200.0 °C)
- benchmark: thermal_conductivity
value: 50
unit: W/(m·K)
scope: material
conditions:
grade: EN-GJL-250
temperature: 20.0 °C
method: Thermal table, Thermal conductivity row, value as printed
status: ground
source: mfgrobots-gjl-250
where: Thermal table (Thermal conductivity, 20.0 °C)
- benchmark: ultimate_tensile_strength
value: 160
value_high: 350
bound: range
unit: MPa
scope: material
conditions:
grade: DIN EN-GJL-250 (EN-GJL-250)
temperature: 0 to 30 °C (block heading)
test_bar: not stated
method: Mechanical Properties block, Tensile Strength row, range as printed
status: ground
source: totalmateria-en-gjl-250
where: Mechanical Properties block (Tensile Strength)
- benchmark: compressive_strength
value: 752.5
value_high: 1053.5
bound: range
unit: MPa
scope: material
conditions:
grade: DIN EN-GJL-250 (EN-GJL-250)
temperature: 0 to 30 °C (block heading)
method: Mechanical Properties block, Compression Strength row, range as printed
status: ground
source: totalmateria-en-gjl-250
where: Mechanical Properties block (Compression Strength)
- benchmark: elastic_modulus
value: 103
value_high: 118
bound: range
unit: GPa
scope: material
conditions:
grade: DIN EN-GJL-250 (EN-GJL-250)
temperature: band not identified in the text (the block lists several bands)
method: Physical Properties block, Modulus of Elasticity row, range as printed
status: ground
source: totalmateria-en-gjl-250
where: Physical Properties block (Modulus of Elasticity)
- benchmark: ultimate_tensile_strength
value: 22
unit: ksi
scope: material
conditions:
standard: ASTM A48
class: '20'
basis: table value; minimum or typical not stated on the page
test_bar: not stated
method: Table Properties of ASTM A48 classes of gray iron, Tensile strength column, value as printed
status: ground
source: wiki-gray-iron
where: Properties of ASTM A48 classes table (Class 20 row)
- benchmark: ultimate_tensile_strength
value: 31
unit: ksi
scope: material
conditions:
standard: ASTM A48
class: '30'
basis: table value; minimum or typical not stated on the page
test_bar: not stated
method: Table Properties of ASTM A48 classes of gray iron, Tensile strength column, value as printed
status: ground
source: wiki-gray-iron
where: Properties of ASTM A48 classes table (Class 30 row)
- benchmark: ultimate_tensile_strength
value: 57
unit: ksi
scope: material
conditions:
standard: ASTM A48
class: '40'
basis: table value; minimum or typical not stated on the page
test_bar: not stated
method: Table Properties of ASTM A48 classes of gray iron, Tensile strength column, value as printed
status: ground
source: wiki-gray-iron
where: Properties of ASTM A48 classes table (Class 40 row)
- benchmark: ultimate_tensile_strength
value: 62.5
unit: ksi
scope: material
conditions:
standard: ASTM A48
class: '60'
basis: table value; minimum or typical not stated on the page
test_bar: not stated
method: Table Properties of ASTM A48 classes of gray iron, Tensile strength column, value as printed
status: ground
source: wiki-gray-iron
where: Properties of ASTM A48 classes table (Class 60 row)
- benchmark: compressive_strength
value: 83
unit: ksi
scope: material
conditions:
standard: ASTM A48
class: '20'
basis: table value; minimum or typical not stated on the page
test_bar: not stated
method: Table Properties of ASTM A48 classes of gray iron, Compressive strength column, value as printed
status: ground
source: wiki-gray-iron
where: Properties of ASTM A48 classes table (Class 20 row)
- benchmark: compressive_strength
value: 109
unit: ksi
scope: material
conditions:
standard: ASTM A48
class: '30'
basis: table value; minimum or typical not stated on the page
test_bar: not stated
method: Table Properties of ASTM A48 classes of gray iron, Compressive strength column, value as printed
status: ground
source: wiki-gray-iron
where: Properties of ASTM A48 classes table (Class 30 row)
- benchmark: compressive_strength
value: 140
unit: ksi
scope: material
conditions:
standard: ASTM A48
class: '40'
basis: table value; minimum or typical not stated on the page
test_bar: not stated
method: Table Properties of ASTM A48 classes of gray iron, Compressive strength column, value as printed
status: ground
source: wiki-gray-iron
where: Properties of ASTM A48 classes table (Class 40 row)
- benchmark: compressive_strength
value: 187.5
unit: ksi
scope: material
conditions:
standard: ASTM A48
class: '60'
basis: table value; minimum or typical not stated on the page
test_bar: not stated
method: Table Properties of ASTM A48 classes of gray iron, Compressive strength column, value as printed
status: ground
source: wiki-gray-iron
where: Properties of ASTM A48 classes table (Class 60 row)
- benchmark: elastic_modulus
value: 10
unit: Mpsi
scope: material
conditions:
standard: ASTM A48
class: '20'
basis: table value; minimum or typical not stated on the page
test_bar: not stated
method: Table Properties of ASTM A48 classes of gray iron, Tensile modulus E column, value as printed in Mpsi
status: ground
source: wiki-gray-iron
where: Properties of ASTM A48 classes table (Class 20 row)
- benchmark: elastic_modulus
value: 14
unit: Mpsi
scope: material
conditions:
standard: ASTM A48
class: '30'
basis: table value; minimum or typical not stated on the page
test_bar: not stated
method: Table Properties of ASTM A48 classes of gray iron, Tensile modulus E column, value as printed in Mpsi
status: ground
source: wiki-gray-iron
where: Properties of ASTM A48 classes table (Class 30 row)
- benchmark: elastic_modulus
value: 18
unit: Mpsi
scope: material
conditions:
standard: ASTM A48
class: '40'
basis: table value; minimum or typical not stated on the page
test_bar: not stated
method: Table Properties of ASTM A48 classes of gray iron, Tensile modulus E column, value as printed in Mpsi
status: ground
source: wiki-gray-iron
where: Properties of ASTM A48 classes table (Class 40 row)
- benchmark: elastic_modulus
value: 21
unit: Mpsi
scope: material
conditions:
standard: ASTM A48
class: '60'
basis: table value; minimum or typical not stated on the page
test_bar: not stated
method: Table Properties of ASTM A48 classes of gray iron, Tensile modulus E column, value as printed in Mpsi
status: ground
source: wiki-gray-iron
where: Properties of ASTM A48 classes table (Class 60 row)
- benchmark: ultimate_tensile_strength
value: 20000
unit: psi
scope: material
conditions:
standard: ASTM A48
class: '20'
basis: tensile strength as printed; minimum or typical not stated
test_bar: not stated
method: Gray Iron Grades list, Tensile strength line under ASTM A48 Class 20, value as printed
status: ground
source: align-gray-iron
where: Gray Iron Grades list (ASTM A48 Class 20)
- benchmark: ultimate_tensile_strength
value: 25000
unit: psi
scope: material
conditions:
standard: ASTM A48
class: '25'
basis: tensile strength as printed; minimum or typical not stated
test_bar: not stated
method: Gray Iron Grades list, Tensile strength line under ASTM A48 Class 25, value as printed
status: ground
source: align-gray-iron
where: Gray Iron Grades list (ASTM A48 Class 25)
- benchmark: ultimate_tensile_strength
value: 30000
unit: psi
scope: material
conditions:
standard: ASTM A48
class: '30'
basis: tensile strength as printed; minimum or typical not stated
test_bar: not stated
method: Gray Iron Grades list, Tensile strength line under ASTM A48 Class 30, value as printed
status: ground
source: align-gray-iron
where: Gray Iron Grades list (ASTM A48 Class 30)
- benchmark: ultimate_tensile_strength
value: 35000
unit: psi
scope: material
conditions:
standard: ASTM A48
class: '35'
basis: tensile strength as printed; minimum or typical not stated
test_bar: not stated
method: Gray Iron Grades list, Tensile strength line under ASTM A48 Class 35, value as printed
status: ground
source: align-gray-iron
where: Gray Iron Grades list (ASTM A48 Class 35)
- benchmark: ultimate_tensile_strength
value: 40000
unit: psi
scope: material
conditions:
standard: ASTM A48
class: '40'
basis: tensile strength as printed; minimum or typical not stated
test_bar: not stated
method: Gray Iron Grades list, Tensile strength line under ASTM A48 Class 40, value as printed
status: ground
source: align-gray-iron
where: Gray Iron Grades list (ASTM A48 Class 40)
- benchmark: ultimate_tensile_strength
value: 50000
unit: psi
scope: material
conditions:
standard: ASTM A48
class: '50'
basis: tensile strength as printed; minimum or typical not stated
test_bar: not stated
method: Gray Iron Grades list, Tensile strength line under ASTM A48 Class 50, value as printed
status: ground
source: align-gray-iron
where: Gray Iron Grades list (ASTM A48 Class 50)
- benchmark: brinell_hardness
value: 120
value_high: 187
bound: range
unit: HB
scope: material
conditions:
standard: SAE J431
grade: G1800
description: ferritic-pearlitic, as printed
test_bar: not stated
method: Table Properties of SAE J431 grades of gray iron, Brinell hardness column, range as printed; the page prints no unit, so recorded as a pure number
status: ground
source: wiki-gray-iron
where: Properties of SAE J431 grades table (G1800 row)
- benchmark: brinell_hardness
value: 170
value_high: 229
bound: range
unit: HB
scope: material
conditions:
standard: SAE J431
grade: G2500
description: pearlitic-ferritic, as printed
test_bar: not stated
method: Table Properties of SAE J431 grades of gray iron, Brinell hardness column, range as printed; the page prints no unit, so recorded as a pure number
status: ground
source: wiki-gray-iron
where: Properties of SAE J431 grades table (G2500 row)
- benchmark: brinell_hardness
value: 187
value_high: 246
bound: range
unit: HB
scope: material
conditions:
standard: SAE J431
grade: G3000
description: pearlitic, as printed
test_bar: not stated
method: Table Properties of SAE J431 grades of gray iron, Brinell hardness column, range as printed; the page prints no unit, so recorded as a pure number
status: ground
source: wiki-gray-iron
where: Properties of SAE J431 grades table (G3000 row)
- benchmark: brinell_hardness
value: 207
value_high: 255
bound: range
unit: HB
scope: material
conditions:
standard: SAE J431
grade: G3500
description: pearlitic, as printed
test_bar: not stated
method: Table Properties of SAE J431 grades of gray iron, Brinell hardness column, range as printed; the page prints no unit, so recorded as a pure number
status: ground
source: wiki-gray-iron
where: Properties of SAE J431 grades table (G3500 row)
- benchmark: brinell_hardness
value: 217
value_high: 269
bound: range
unit: HB
scope: material
conditions:
standard: SAE J431
grade: G4000
description: pearlitic, as printed
test_bar: not stated
method: Table Properties of SAE J431 grades of gray iron, Brinell hardness column, range as printed; the page prints no unit, so recorded as a pure number
status: ground
source: wiki-gray-iron
where: Properties of SAE J431 grades table (G4000 row)
- benchmark: damping_capacity
value: 100
value_high: 500
bound: range
unit: '-'
scope: material
conditions:
material: gray iron, high carbon equivalent, as printed
method: Table Relative damping capacity of various metals, value as printed; footnote says natural log of the ratio of successive amplitudes, so a pure number
status: ground
source: wiki-gray-iron
where: Relative damping capacity table (Gray iron, high carbon equivalent)
- benchmark: damping_capacity
value: 20
value_high: 100
bound: range
unit: '-'
scope: material
conditions:
material: gray iron, low carbon equivalent, as printed
method: Table Relative damping capacity of various metals, value as printed; footnote says natural log of the ratio of successive amplitudes, so a pure number
status: ground
source: wiki-gray-iron
where: Relative damping capacity table (Gray iron, low carbon equivalent)
corrosion:
- environment: Water supply and drainage systems (pipes)
headline: Pipes are used in water and drainage for their corrosion resistance and longevity
effect: China Casting says gray cast iron pipes have been widely used in water supply and drainage systems because of their corrosion resistance and longevity. No corrosion rate, test or exposure time is printed.
rating: unknown
source: china-casting-gray-iron
where: Construction sector paragraph
- environment: Not named in the source (effect of the silicon in the alloy)
headline: Silicon is said to promote good corrosion resistance
effect: Wikipedia says the silicon in gray iron promotes good corrosion resistance and increased fluidity when casting. The article names no environment and gives no rate.
rating: unknown
source: wiki-gray-iron
where: Advantages and disadvantages section, last paragraph
- environment: Austenitic gray iron with nickel and chromium (an alloyed variant)
headline: A nickel and chromium variant is listed for excellent corrosion resistance
effect: China Casting's table lists austenitic gray iron (Ni, Cr) for excellent corrosion and heat resistance. That is an alloyed variant of gray iron, and the page gives no rate.
rating: unknown
source: china-casting-gray-iron
where: Types of gray iron table, Austenitic row
risks:
hazards:
- text: 'PubChem aggregated GHS for elemental iron, signal word Danger: the record says the chemical does not meet GHS hazard criteria in 74.1 percent (4458 of 6013) of reports. H228 flammable solid (15.5 percent) and H251 self-heating (21.2 percent) appear in notifications. It covers the metal element, not cast parts.'
ghs:
- H228
- H251
source: pubchem-fe
where: Safety and Hazards, GHS Classification (first block)
failure_risks:
- mode: Brittle fracture under tensile or shock load
trigger: Tensile stress or shock; the tips of the graphite flakes act as notches where stress concentrates
consequence: Low tensile strength, and impact and shock resistance that is almost non-existent (Wikipedia)
source: wiki-gray-iron
where: Structure section (flake tips); Advantages and disadvantages section (impact)
- mode: Brittleness from excess phosphorus
trigger: Phosphorus raised above what the casting needs for fluidity
consequence: Excessive phosphorus can lead to brittleness (China Casting)
source: china-casting-gray-iron
where: Composition paragraph
- mode: Less tensile strength and shock resistance than steel
trigger: A part loaded in tension or shock as if it were steel
consequence: Grey cast iron has less tensile strength and shock resistance than steel (Wikipedia, Cast iron)
source: wiki-cast-iron
where: Grey cast iron section, last sentence
side_effects: []
handling:
- text: Name the class or grade with every strength value, because ASTM classes and EN grades have different strengths (Wikipedia, Align)
source: wiki-gray-iron
where: Classifications section
- text: Gray iron cannot be forged, extruded or rolled, even at temperature, so it must be cast to shape (Wikipedia)
source: wiki-gray-iron
where: Advantages and disadvantages section
- text: Gray iron is generally considered easy to weld (Wikipedia)
source: wiki-gray-iron
where: Advantages and disadvantages section
- text: Stress relieving is particularly important for large castings (China Casting)
source: china-casting-gray-iron
where: Heat treatment paragraph
mitigations:
- text: In some cases protective coatings are applied to enhance corrosion resistance or extend service life (China Casting)
source: china-casting-gray-iron
where: Finishing paragraph
- text: Where corrosion and heat resistance matter, an alloyed austenitic gray iron with nickel and chromium is listed (China Casting); it is a different alloy from plain gray iron
source: china-casting-gray-iron
where: Types of gray iron table, Austenitic row
uses:
- application: mechanisms
device: Brake discs and rotors
example: Gray iron's high thermal conductivity and specific heat capacity are exploited to make disc brake rotors (Wikipedia)
source: wiki-gray-iron
where: Lead paragraph
- application: structures
device: Machine tool bases and mountings
example: Gray iron has very good damping capacity and is often used as the base for machine tool mountings (Wikipedia); Align lists class 40 and class 50 for machinery bases
source: wiki-gray-iron
where: Structure section, last sentence
- application: propulsion-and-tanks
device: Internal combustion engine cylinder blocks
example: Cylinder blocks are named as a housing use where stiffness matters more than tensile strength (Wikipedia); Align lists class 30 for engine blocks and transmission housings
source: wiki-gray-iron
where: Lead paragraph
- application: structures
device: Pump housings and valve bodies
example: Pump housings and valve bodies are named as gray iron housings (Wikipedia); Align lists class 20 for pump housings
source: wiki-gray-iron
where: Lead paragraph
supply:
- subject: Iron and steel (United States)
abundance: 'Iron is the least expensive and most widely used metal (USGS). The US produced 82 million tons of raw steel in 2025e, and net import reliance was 13 percent of apparent consumption in 2025e. Construction took an estimated 31 percent of net shipments. Import sources 2021 to 2024: Canada 23 percent, Mexico 15 percent, Brazil 13 percent, Republic of Korea 9 percent, other 40 percent.'
producers: []
critical_lists: []
recycling: 'Not read: the chapter points to the Iron and Steel Scrap chapter'
substitutes:
- Nonmetallic materials at lower cost, or costlier materials with better performance (USGS substitutes text)
source: usgs-iron-steel-2026
where: Salient Statistics; Domestic Production and Use; Import Sources; Substitutes
- subject: Raw steel production by country (2025e)
abundance: 'World raw steel production was 1,900 million tons in 2025e (rounded total). Shares are computed from the printed 2025e tonnage over that total: China 980, India 160, United States 82, Japan 81 and Russia 65 million tons.'
producers:
- country: China
share_percent: 51.6
year: 2025
- country: India
share_percent: 8.4
year: 2025
- country: United States
share_percent: 4.3
year: 2025
- country: Japan
share_percent: 4.3
year: 2025
- country: Russia
share_percent: 3.4
year: 2025
critical_lists: []
recycling: ''
substitutes: []
source: usgs-iron-steel-2026
where: World Production table, Raw steel 2025e
- subject: Silicon (ferrosilicon and silicon metal)
abundance: 'China accounted for almost 80 percent of total global estimated production of silicon materials in 2025 (USGS). Most ferrosilicon was consumed in the ferrous foundry and steel industries. Ferrosilicon import sources 2021 to 2024: Russia 30 percent, Brazil 16 percent, Canada 13 percent, Malaysia 11 percent, other 30 percent.'
producers: []
critical_lists:
- list: U.S. Final 2025 List of Critical Minerals
listed: true
recycling: ''
substitutes: []
source: usgs-silicon-2026
where: Domestic Production and Use; Events, Trends and Issues; Import Sources; critical minerals paragraph
- subject: Manganese
abundance: 'Net import reliance was 100 percent in every year from 2021 to 2025e. Manganese ore import sources 2021 to 2024: Gabon 64 percent, South Africa 24 percent, Mexico 12 percent. Consumption closely follows the steel industry, and South Africa has an estimated 70 percent of world manganese resources (USGS). Shares are computed from the 2025e mine production table over its printed world total.'
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
critical_lists: []
recycling: ''
substitutes: []
source: usgs-manganese-2026
where: World Mine Production (manganese content) table, 2025e; Import Sources; Salient Statistics
media: []
documents:
- title: 'Total Materia: DIN EN-GJL-250 Cast irons'
type: database
url: https://www.totalmateria.com/en-us/material/1403010
- title: 'MfgRobots: EN 1561 Grade GJL-250 Cast, Key Properties and Applications'
type: datasheet
url: https://www.mfgrobots.com/Article/material/metal/39356.html
- title: 'MTS: ASTM A48/A48M Tensile Testing technote'
type: datasheet
url: https://mts.com/-/media/materials/pdfs/test-standards/100-545-062c_Metals_ASTM_A48_A48M.pdf?as=1
year: 2023
- title: 'USGS Mineral Commodity Summaries 2026: Iron and Steel'
type: report
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-iron-steel.pdf
year: 2026
- title: 'USGS Mineral Commodity Summaries 2026: Silicon'
type: report
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-silicon.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: 'PubChem: Iron (CID 23925), GHS classification'
type: database
url: https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/23925/JSON
gaps:
- ASTM A48 itself was not read (the standard is paywalled). Class rows come from the Wikipedia table (ksi and Mpsi, minimum or typical not stated), the Align list (psi) and the MTS technote. No class value prints a test bar size, so test_bar is recorded as not stated, and the MTS cast test bar types (A, B and C, 13, 20 and 30 mm diameter) are not tied to any class.
- Only the EN-GJL-250 grade was read. EN-GJL-150, 200, 300 and 350 have no value in this run.
- The Kippwerk EN-GJL-250 data sheet returned no technical data (the page text was truncated), and the MakeItFrom class 30 page returned HTTP 403. The UNS number for class 30 and the old GG25 sentence are therefore not recorded, and JIS FC250 is not printed on any fetched page (the Brazilian NBR FC 250 is recorded instead).
- 'Machinability: only qualitative statements were found (Wikipedia, Align, China Casting). No machinability rating is printed on a fetched page, so no value is recorded.'
- 'Hardness: no Brinell range for ASTM classes or EN-GJL-250 was printed on a fetched page. Only the SAE J431 grade ranges from Wikipedia are recorded.'
- 'Damping: Wikipedia gives a relative log-decrement scale for high and low carbon equivalent gray iron only, with no unit printed. No numeric damping value is printed for a named ASTM or EN grade.'
- The EN-GJL-250 melting range (1127 to 1204 °C) and shear modulus (41 GPa) are printed only as typical for grey cast iron or cast iron, not for a named grade, so they are left out. Electrical resistivity and the coefficient of thermal expansion are printed with an uppercase E exponent, which the verify text match cannot read, so they are left out.
- 'Composition: Wikipedia''s gray iron article gives 2.5 to 4.7 percent carbon and 1 to 8 percent silicon, wider than the 2.5 to 4.0 percent carbon and 1 to 3 percent silicon used in the identity from Wikipedia''s cast iron article and China Casting. Manganese is given only as below 1.0 percent; phosphorus and sulfur have no printed number.'
- 'Corrosion: no corrosion rate, test environment or exposure time was read, so every rating is unknown. Graphitic (selective) corrosion, rust in moist air and soil or seawater behaviour were not sourced in this run.'
- 'Hazards: the only hazard record is PubChem''s element iron entry. No gray cast iron safety data sheet was read, and fume and dust limits for cutting, grinding and welding are not recorded. The PubChem silicon record returned no GHS section in this run.'
- Supply shares are computed from printed tonnages (steel, 2025e over the printed world total; manganese, 2025e mine production over its printed world total), not printed as shares. The iron and steel and manganese chapters name no critical-mineral list, so their critical_lists are empty. The iron ore and scrap chapters were not read.
- 'Property names not in property-canon: compressive_strength, compressive_yield_strength, brinell_hardness and damping_capacity are snake_case. Modulus by class is kept in Mpsi as printed.'
- The web search budget ran out in this turn, so no further searches were run for other EN-GJL grades, GG25 on the Kippwerk page, UNS codes, graphitic corrosion, numeric damping or machinability sources. Only the pages listed in sources were fetched.
sources:
mfgrobots-gjl-250:
title: 'MfgRobots: EN 1561 Grade GJL-250 Cast, Key Properties and Applications'
url: https://www.mfgrobots.com/Article/material/metal/39356.html
kind: web
license: cited, not reproduced
totalmateria-en-gjl-250:
title: 'Total Materia: DIN EN-GJL-250 Cast irons (free preview, international equivalents)'
url: https://www.totalmateria.com/en-us/material/1403010
kind: database
license: cited, not reproduced
wiki-gray-iron:
title: 'Wikipedia: Gray iron'
id: Gray iron
url: https://en.wikipedia.org/wiki/Gray_iron
kind: web
license: CC BY-SA 4.0 (cited, not reproduced)
wiki-cast-iron:
title: 'Wikipedia: Cast iron'
id: Cast iron
url: https://en.wikipedia.org/wiki/Cast_iron
kind: web
license: CC BY-SA 4.0 (cited, not reproduced)
align-gray-iron:
title: 'Align Manufacturing: Gray and Ductile Iron, Versatility and Strength'
url: https://alignmfg.co/?p=3443
kind: web
license: cited, not reproduced
china-casting-gray-iron:
title: 'China Casting: Gray Cast Iron, Essential Properties and Composition Guide'
url: https://china-casting.com/gray-cast-iron/
kind: web
license: cited, not reproduced
shimadzu-astm-a48:
title: 'Shimadzu: ASTM A48 Standard Specification for Gray Iron Castings'
url: https://www.ssi.shimadzu.com/industries/automotive-materials-testing/metals/astm-a48/index.html
kind: web
license: cited, not reproduced
mts-astm-a48:
title: 'MTS Systems: ASTM A48/A48M Tensile Testing technote 100-545-062c'
url: https://mts.com/-/media/materials/pdfs/test-standards/100-545-062c_Metals_ASTM_A48_A48M.pdf?as=1
kind: datasheet
year: 2023
license: cited, not reproduced
usgs-iron-steel-2026:
title: 'USGS Mineral Commodity Summaries 2026: Iron and Steel'
id: mcs2026-iron-steel
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-iron-steel.pdf
kind: report
year: 2026
license: public domain
usgs-silicon-2026:
title: 'USGS Mineral Commodity Summaries 2026: Silicon'
id: mcs2026-silicon
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-silicon.pdf
kind: report
year: 2026
license: public domain
usgs-manganese-2026:
title: 'USGS Mineral Commodity Summaries 2026: Manganese'
id: mcs2026-manganese
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-manganese.pdf
kind: report
year: 2026
license: public domain
pubchem-fe:
title: 'PubChem: Iron (CID 23925), Safety and Hazards, GHS Classification (REST record)'
id: CID 23925
url: https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/23925/JSON
kind: database
license: PubChem terms (public)
license: CC-BY-4.0
updated: '2026-10-24'
review:
status: draft
method: assistant
checked_values: 40
unreachable: 0
caveats: 19
note: 'Read by an AI assistant on 2026-10-24 from pages fetched in that run. Strength rows are split by source and by class or grade: EN-GJL-250 from MfgRobots and Total Materia, ASTM A48 classes from Wikipedia (ksi and Mpsi, minimum or typical not stated) and Align (psi). No class row prints a test bar size. Kippwerk and MakeItFrom could not be read.'
story:
why: Gray cast iron is the most common cast iron and the most widely used cast material by weight (Wikipedia). Its flake graphite makes it relatively cheap, easy to machine and good at damping vibration, which is why it suits machine bases and housings. The same flakes make it brittle, so it is weak in tension.
recipe:
line: Gray iron is cast iron with 2.5 to 4.0 percent carbon, held mostly as flake graphite, 1 to 3 percent silicon, below 1.0 percent manganese, and the rest iron (Wikipedia, China Casting). Silicon promotes free graphite rather than cementite (China Casting). It is sand cast (MfgRobots).
parts:
- name: Iron
symbol: Fe
share_note: balance (the rest)
role: The matrix of the metal; it is the rest of the composition
source: wiki-cast-iron
where: Grey cast iron section, composition sentence
- name: Carbon
symbol: C
share_percent: 2.5
share_high: 4
role: Forms flake graphite, which gives low tensile strength but easy machining and good damping (Wikipedia)
source: wiki-cast-iron
where: Grey cast iron section, composition sentence
- name: Silicon
symbol: Si
share_percent: 1
share_high: 3
role: Silicon promotes free graphite rather than cementite (China Casting), and forces carbon out of solution (Wikipedia)
source: wiki-cast-iron
where: Alloying elements paragraph
- name: Manganese
symbol: Mn
share_note: below 1.0
role: Stabilises the pearlite in the matrix (China Casting)
source: china-casting-gray-iron
where: Composition paragraph
- name: Phosphorus
symbol: P
share_note: no number printed
role: Raised in some castings for fluidity; excess makes it brittle (China Casting)
source: china-casting-gray-iron
where: Composition paragraph
- name: Sulfur
symbol: S
share_note: kept as low as possible
role: Forms iron sulfides that hurt mechanical performance (China Casting)
source: china-casting-gray-iron
where: Composition paragraph
risk_groups:
- title: For people
level: 1
verdict: Element records only
lead: PubChem's hazard records are for elemental iron, not for cast parts. No gray cast iron safety data sheet was read.
points:
- label: Iron
line: PubChem says the chemical does not meet GHS hazard criteria in 74.1 percent of 6013 reports; H228 and H251 appear in some notifications.
- label: Dust and fume
line: Limits for dust and fume from cutting, grinding and welding were not read. Check the supplier safety data sheet before the work.
- title: In the environment
level: 2
verdict: No corrosion rate read
lead: The sources give qualitative corrosion statements only.
points:
- label: Water
line: China Casting says gray iron pipes are used in water supply and drainage for their corrosion resistance and longevity.
- label: Silicon
line: Wikipedia says the silicon in gray iron promotes good corrosion resistance.
- title: In service
level: 2
verdict: Brittle in tension
lead: Graphite flakes make the metal brittle under tensile and shock loads.
points:
- label: Tension
line: EN-GJL-250 tensile strength is 200 to 350 MPa at 20 °C (MfgRobots), while its compressive strength is far higher (Total Materia).
- label: Phosphorus
line: Excess phosphorus adds brittleness (China Casting).
uses:
- where: Brake discs
line: Its high thermal conductivity and specific heat capacity are used in disc brake rotors (Wikipedia).
- where: Machine tool bases
line: Its damping makes it the usual base for machine tool mountings (Wikipedia). Align lists class 40 and class 50 for large machinery bases.
- where: Engine blocks and housings
line: Cylinder blocks, pump housings and valve bodies are named housings where stiffness matters more than tensile strength (Wikipedia). Align lists class 30 for engine blocks and transmission housings.
- where: Pipes and manhole covers
line: China Casting lists gray iron pipes for water supply and drainage, and for manhole covers in construction.
can_do:
- label: Tensile strength, EN-GJL-250
benchmark: ultimate_tensile_strength
value: 200 to 350 MPa at 20 °C
line: EN-GJL-250 has 200 to 350 MPa tensile strength at 20 °C (MfgRobots). Total Materia gives 160 to 350 MPa for 0 to 30 °C.
- label: Compressive strength
benchmark: compressive_strength
value: 752.5 to 1053.5 MPa
line: 'Compression is far stronger than tension: 752.5 to 1053.5 MPa for EN-GJL-250 (Total Materia), often more than three to four times the tensile strength (China Casting).'
- label: Stiffness
benchmark: elastic_modulus
value: 103 to 118 GPa
line: The elastic modulus is 103 to 118 GPa for EN-GJL-250 (MfgRobots, Total Materia). By ASTM class it is 10 to 21 Mpsi (Wikipedia).
- label: Density
benchmark: density
value: 7.2 g/cm³ at 20 °C
line: Density is 7.2 g/cm³ at 20 °C for EN-GJL-250 (MfgRobots).
- label: Thermal conductivity
benchmark: thermal_conductivity
value: 50 W/(m·K) at 20 °C
line: Thermal conductivity is 50 W/(m·K) at 20 °C for EN-GJL-250 (MfgRobots). That is why it is used for brake rotors and cookware (Wikipedia).
- label: Damping
benchmark: damping_capacity
value: 100 to 500 (high carbon equivalent)
line: On Wikipedia's relative damping scale, high carbon equivalent gray iron scores 100 to 500, and low carbon equivalent gray iron 20 to 100.
- label: Machinability
line: Graphite flakes lubricate the cut and break the chips, so the metal machines easily (Wikipedia, Align). No machinability rating is printed.
compare: Gray cast iron trades tensile strength for damping, machinability and low cost. For EN-GJL-250 its tensile strength is 200 to 350 MPa, while its compressive strength is 752.5 to 1053.5 MPa (Total Materia). Its compressive strength is comparable to low and medium carbon steel, but its tensile strength and shock resistance are lower (Wikipedia). Ductile iron, with spherical graphite, has more ductility and impact resistance (Align).
compare_rows:
- label: Density
benchmark: density
scope: material
- label: Stiffness (elastic modulus)
benchmark: elastic_modulus
scope: material
- label: Tensile strength
benchmark: ultimate_tensile_strength
scope: material
handling:
- Name the class or grade with every strength value, because ASTM classes and EN grades have different strengths (Wikipedia, Align).
- 'Cast it to shape: gray iron cannot be forged, extruded or rolled, even hot (Wikipedia).'
- It is generally considered easy to weld (Wikipedia). Stress relieve large castings (China Casting).
good_for:
- Machine tool bases, frames and housings, where damping and machinability matter (Wikipedia, Align).
- Engine cylinder blocks, pump housings and valve bodies, where stiffness matters more than tensile strength (Wikipedia).
- Brake discs, where high thermal conductivity helps (Wikipedia).
watch_out:
- 'Brittle in tension and shock: the graphite flake tips act as notches (Wikipedia, Gray iron).'
- Excess phosphorus adds brittleness (China Casting).
- 'Composition limits differ by article: 2.5 to 4.7 percent carbon and 1 to 8 percent silicon in one, 2.5 to 4.0 and 1 to 3 in another (Wikipedia).'
verdict: Gray cast iron is the cheap, damping, easy-to-machine iron for housings, machine bases and brake discs. It is weak and brittle in tension, so name the class or grade and design for compression and damping, not for shock.
References
Every number above carries a reference number. Click one to see the source and where in it the value comes from.
| # | Source | Type | Year | Used for |
|---|---|---|---|---|
| MfgRobots: EN 1561 Grade GJL-250 Cast, Key Properties and Applications | web | 12 values | ||
| Total Materia: DIN EN-GJL-250 Cast irons (free preview, international equivalents) | database | 3 values | ||
| Wikipedia: Gray iron | web | 28 values | ||
| Wikipedia: Cast iron | web | 2 values | ||
| Align Manufacturing: Gray and Ductile Iron, Versatility and Strength | web | 6 values | ||
| China Casting: Gray Cast Iron, Essential Properties and Composition Guide | web | 6 values | ||
| Shimadzu: ASTM A48 Standard Specification for Gray Iron Castings | web | 0 values | ||
| MTS Systems: ASTM A48/A48M Tensile Testing technote 100-545-062c | datasheet | 2023 | 0 values | |
| USGS Mineral Commodity Summaries 2026: Iron and Steel | report | 2026 | 2 values | |
| USGS Mineral Commodity Summaries 2026: Silicon | report | 2026 | 1 value | |
| USGS Mineral Commodity Summaries 2026: Manganese | report | 2026 | 1 value | |
| PubChem: Iron (CID 23925), Safety and Hazards, GHS Classification (REST record) | database | 1 value |