AISI D2 cold-work tool steel (EN 1.2379, X153CrMoV12) D2 (UNS T30402, EN 1.2379)

spore: profile
id: tool-steel-d2
spore_version: 0.2
family: tool-steels
name: AISI D2 cold-work tool steel (EN 1.2379, X153CrMoV12)
abbreviation: D2 (UNS T30402, EN 1.2379)
role: cold-work tool steel
category: metals
type: steels-and-stainless
summary: AISI D2 (EN 1.2379, X153CrMoV12, JIS SKD 11) is a high-carbon, about 12 percent chromium cold-work tool steel. Hard carbides give it very good abrasive wear resistance, and it is used for blanking, forming and cutting tools. Its hardness and toughness depend entirely on heat treatment, and it is not a stainless steel.
best_for: Blanking, punching, forming and cutting tools that need high wear resistance more than toughness
weakest_at: 'Toughness and corrosion: rather limited cracking resistance (Uddeholm), and corrosion resistance below that of stainless steel (Wikipedia)'
identity:
  formula: Fe balance; 1.40 to 1.60 C, 0.10 to 0.60 Si, 0.10 to 0.60 Mn, 11.00 to 13.00 Cr, 0.70 to 1.20 Mo, 0.50 to 1.10 V, 0.00 to 0.03 P, 0.00 to 0.03 S (wt%, composition ranges from the Steel Service Krefeld SDS, section 3); typical analysis 1.55 C, 0.3 Si, 0.4 Mn, 11.3 Cr, 0.8 Mo, 0.8 V (wt%, Uddeholm)
  designations:
    - system: AISI
      code: D2
    - system: Name
      code: D2
    - system: EN
      code: '1.2379'
    - system: EN name
      code: X153CrMoV12
    - system: UNS
      code: T30402
    - system: JIS
      code: SKD 11
    - system: Name
      code: Cr12MoV
    - system: Name
      code: Cr12Mo1V1
    - system: Name
      code: THYRODUR 2379
  source: uddeholm-sverker21
  where: 'Page 3, General: typical analysis and standard specification AISI D2, W.-Nr. 1.2379; composition ranges from SDS section 3; designations from the Dörrenberg datasheet (Code X153CrMoV12), the Total Materia cross-reference table (UNS, DIN, JIS, GB and trade names, some marked implicit there) and the SDS title'
tags:
  environments: []
  stresses: []
  applications:
    - mechanisms
properties:
  - benchmark: density
    label: Density at 20 C
    value: 7700
    unit: kg/m3
    scope: material
    conditions:
      heat_treatment: hardened and tempered to 62 HRC (the sheet's state for physical data)
      temperature: 20 C (68 F)
    method: Physical data table as printed (7 700 kg/m3, 20 C column)
    status: ground
    source: uddeholm-sverker21
    where: Page 3, Physical data table, Density row, 20 C column
  - benchmark: density
    label: Density at 400 C
    value: 7600
    unit: kg/m3
    scope: material
    conditions:
      heat_treatment: hardened and tempered to 62 HRC (the sheet's state for physical data)
      temperature: 400 C (750 F)
    method: Physical data table as printed (7 600 kg/m3, 400 C column)
    status: ground
    source: uddeholm-sverker21
    where: Page 3, Physical data table, Density row, 400 C column
  - benchmark: elastic_modulus
    label: Modulus of elasticity at 20 C
    value: 210000
    unit: MPa
    scope: material
    conditions:
      heat_treatment: hardened and tempered to 62 HRC (the sheet's state for physical data)
      temperature: 20 C (68 F)
    method: Physical data table as printed (210 000 MPa, 20 C column); 30 450 ksi alongside
    status: ground
    source: uddeholm-sverker21
    where: Page 3, Physical data table, Modulus of elasticity row, MPa, 20 C column
  - benchmark: elastic_modulus
    label: Modulus of elasticity at 400 C
    value: 180000
    unit: MPa
    scope: material
    conditions:
      heat_treatment: hardened and tempered to 62 HRC (the sheet's state for physical data)
      temperature: 400 C (750 F)
    method: Physical data table as printed (180 000 MPa, 400 C column)
    status: ground
    source: uddeholm-sverker21
    where: Page 3, Physical data table, Modulus of elasticity row, MPa, 400 C column
  - benchmark: specific_heat
    label: Specific heat at 20 C
    value: 460
    unit: J/kg °C
    scope: material
    conditions:
      heat_treatment: hardened and tempered to 62 HRC (the sheet's state for physical data)
      temperature: 20 C (68 F)
    method: Physical data table as printed (460 J/kg °C; 0.110 Btu/lb F alongside); the other two columns are not given
    status: ground
    source: uddeholm-sverker21
    where: Page 3, Physical data table, Specific heat row, 20 C column
  - benchmark: cte
    label: Thermal expansion, 20 to 200 C, after low-temperature tempering
    value: 12.3
    unit: ppm/K
    scope: material
    conditions:
      heat_treatment: hardened and tempered to 62 HRC, low-temperature tempering (the temperature is not defined in the sheet)
      temperature: 20 to 200 C (68 to 390 F)
      unit_in_source: 10-6 per degC, printed as 12.3 x 10-6
    method: Physical data table, 'at low temperature tempering' row, per degC from 20 C, 200 C column; the printed number is the same as ppm/K
    status: ground
    source: uddeholm-sverker21
    where: Page 3, Physical data table, coefficient of thermal expansion, low-temperature tempering, 200 C column
  - benchmark: cte
    label: Thermal expansion, 20 to 200 C, after high-temperature tempering
    value: 11.2
    unit: ppm/K
    scope: material
    conditions:
      heat_treatment: hardened and tempered to 62 HRC, high-temperature tempering (the temperature is not defined in the sheet)
      temperature: 20 to 200 C (68 to 390 F)
      unit_in_source: 10-6 per degC, printed as 11.2 x 10-6
    method: Physical data table, 'at high temperature tempering' row, per degC from 20 C, 200 C column; the printed number is the same as ppm/K
    status: ground
    source: uddeholm-sverker21
    where: Page 3, Physical data table, coefficient of thermal expansion, high-temperature tempering, 200 C column
  - benchmark: cte
    label: Thermal expansion, 20 to 400 C, after high-temperature tempering
    value: 12
    unit: ppm/K
    scope: material
    conditions:
      heat_treatment: hardened and tempered to 62 HRC, high-temperature tempering (the temperature is not defined in the sheet)
      temperature: 20 to 400 C (68 to 750 F)
      unit_in_source: 10-6 per degC, printed as 12 x 10-6
    method: Physical data table, 'at high temperature tempering' row, per degC from 20 C, 400 C column; the printed number is the same as ppm/K
    status: ground
    source: uddeholm-sverker21
    where: Page 3, Physical data table, coefficient of thermal expansion, high-temperature tempering, 400 C column
  - benchmark: thermal_conductivity
    label: Thermal conductivity at 20 C
    value: 20
    unit: W/mK
    scope: material
    conditions:
      heat_treatment: hardened and tempered to 62 HRC (the sheet's state for physical data)
      temperature: 20 C (68 F)
    method: Physical data table, Thermal conductivity W/m °C row, 20 C column, printed as 20,0 with a decimal comma; 139 Btu in/ft2 h F alongside
    status: ground
    source: uddeholm-sverker21
    where: Page 3, Physical data table, Thermal conductivity row, 20 C column
  - benchmark: thermal_conductivity
    label: Thermal conductivity at 200 C
    value: 21
    unit: W/mK
    scope: material
    conditions:
      heat_treatment: hardened and tempered to 62 HRC (the sheet's state for physical data)
      temperature: 200 C (390 F)
    method: Physical data table, Thermal conductivity W/m °C row, 200 C column, printed as 21,0 with a decimal comma
    status: ground
    source: uddeholm-sverker21
    where: Page 3, Physical data table, Thermal conductivity row, 200 C column
  - benchmark: thermal_conductivity
    label: Thermal conductivity at 400 C
    value: 23
    unit: W/mK
    scope: material
    conditions:
      heat_treatment: hardened and tempered to 62 HRC (the sheet's state for physical data)
      temperature: 400 C (750 F)
    method: Physical data table, Thermal conductivity W/m °C row, 400 C column, printed as 23,0 with a decimal comma
    status: ground
    source: uddeholm-sverker21
    where: Page 3, Physical data table, Thermal conductivity row, 400 C column
  - benchmark: compressive_yield_strength
    label: Compressive yield strength (Rc0.2) at 62 HRC
    value: 2200
    unit: MPa
    scope: material
    conditions:
      heat_treatment: hardness 62 HRC (the table does not state the tempering temperature)
      basis: figures are approximate, as the sheet prints them
    method: Compressive strength table, Compressive yield strength Rc0,2 MPa column, 62 HRC row, printed as 2200 MPa (319 ksi)
    status: ground
    source: uddeholm-sverker21
    where: Page 3, Compressive strength table, 62 HRC row
  - benchmark: compressive_yield_strength
    label: Compressive yield strength (Rc0.2) at 50 HRC
    value: 1650
    unit: MPa
    scope: material
    conditions:
      heat_treatment: hardness 50 HRC (the table does not state the tempering temperature)
      basis: figures are approximate, as the sheet prints them
    method: Compressive strength table, Compressive yield strength Rc0,2 MPa column, 50 HRC row, printed as 1650 MPa (239 ksi)
    status: ground
    source: uddeholm-sverker21
    where: Page 3, Compressive strength table, 50 HRC row
  - benchmark: hardness_rockwell_c
    label: Hardness before tempering after hardening at 990 C
    value: 63
    unit: HRC
    scope: material
    conditions:
      heat_treatment: austenitized at 990 C for 60 min soaking time, hardness before tempering
      note: quench medium not stated for this row
    method: Hardening table, Hardness before tempering column, printed as approx. 63 HRC
    status: ground
    source: uddeholm-sverker21
    where: Page 4, Hardening table, 990 C (1815 F) row
  - benchmark: hardness_rockwell_c
    label: Hardness before tempering after hardening at 1010 C
    value: 64
    unit: HRC
    scope: material
    conditions:
      heat_treatment: austenitized at 1010 C for 45 min soaking time, hardness before tempering
      note: quench medium not stated for this row
    method: Hardening table, Hardness before tempering column, printed as approx. 64 HRC
    status: ground
    source: uddeholm-sverker21
    where: Page 4, Hardening table, 1010 C (1850 F) row
  - benchmark: hardness_rockwell_c
    label: Hardness before tempering after hardening at 1030 C
    value: 65
    unit: HRC
    scope: material
    conditions:
      heat_treatment: austenitized at 1030 C for 30 min soaking time, hardness before tempering
      note: quench medium not stated for this row
    method: Hardening table, Hardness before tempering column, printed as approx. 65 HRC
    status: ground
    source: uddeholm-sverker21
    where: Page 4, Hardening table, 1030 C (1885 F) row
  - benchmark: hardness_rockwell_c
    label: Hardness before tempering after hardening at 1080 C
    value: 64
    unit: HRC
    scope: material
    conditions:
      heat_treatment: austenitized at 1080 C for 30 min soaking time, hardness before tempering
      note: quench medium not stated for this row
    method: Hardening table, Hardness before tempering column, printed as approx. 64 HRC
    status: ground
    source: uddeholm-sverker21
    where: Page 4, Hardening table, 1080 C (1975 F) row
  - benchmark: hardness_brinell
    label: Hardness, soft-annealed delivery condition
    value: 210
    unit: HB
    scope: material
    conditions:
      heat_treatment: 'soft annealed: 850 C, furnace cooled at 10 C per hour to 650 C, then air cooled'
      basis: delivery condition, approximate as printed
    method: Typical analysis table, Delivery condition row, printed as soft annealed to approx. 210 HB
    status: ground
    source: uddeholm-sverker21
    where: Page 3, Typical analysis table, Delivery condition row; annealing cycle on page 4, Soft annealing
  - benchmark: surface_hardness_hv
    label: Surface hardness after nitriding at 525 C
    value: 1250
    unit: HV1
    scope: material
    conditions:
      heat_treatment: nitrided at 525 C (time not stated for this value)
      basis: figures refer to hardened and tempered material, as printed
    method: Nitriding paragraph, printed as approx. 1250 HV1
    status: ground
    source: uddeholm-sverker21
    where: Page 5, Nitriding and nitrocarburizing, 525 C sentence
  - benchmark: surface_hardness_hv
    label: Surface hardness after nitrocarburizing at 570 C
    value: 950
    unit: HV1
    scope: material
    conditions:
      heat_treatment: nitrocarburized at 570 C for 2 h
      basis: figures refer to hardened and tempered material, as printed
    method: Nitriding paragraph, printed as approx. 950 HV1
    status: ground
    source: uddeholm-sverker21
    where: Page 5, Nitriding and nitrocarburizing, 570 C sentence
  - benchmark: case_depth
    label: Nitrided case depth at 525 C for 30 h
    value: 0.3
    unit: mm
    scope: material
    conditions:
      heat_treatment: nitrided at 525 C for 30 h
      basis: case depth table, approximate as printed
    method: Nitriding table, 525 C, 30 h row, printed as 0.30 mm (0.012 in)
    status: ground
    source: uddeholm-sverker21
    where: Page 5, Nitriding table, 525 C, 30 h row
  - benchmark: hardness_brinell
    label: Maximum hardness, soft-annealed delivery condition
    value: 255
    bound: upper
    unit: HB
    scope: material
    conditions:
      heat_treatment: soft annealed at 820 to 850 C, furnace cooled
      basis: delivery condition, maximum as printed
    method: Condition of delivery and Soft annealing rows, printed as max. 255 HB
    status: ground
    source: doerrenberg-1-2379
    where: Heat treatment table, Soft annealing row, and Condition of delivery (Dörrenberg datasheet)
  - benchmark: hardness_rockwell_c
    label: Hardness after tempering at 100 C
    value: 63
    unit: HRC
    scope: material
    conditions:
      heat_treatment: tempered at 100 C; tempering time and hardening temperature not stated in the table
      basis: curve from the thesis's reference 6, as printed
    method: Table 2.3, D2 hardness in HRC against tempering temperature, value as printed
    status: ground
    source: thesis-d2-tempering
    where: Section 2.1.4.3, Table 2.3, column T 100 C
  - benchmark: hardness_rockwell_c
    label: Hardness after tempering at 200 C
    value: 61
    unit: HRC
    scope: material
    conditions:
      heat_treatment: tempered at 200 C; tempering time and hardening temperature not stated in the table
      basis: curve from the thesis's reference 6, as printed
    method: Table 2.3, D2 hardness in HRC against tempering temperature, value as printed
    status: ground
    source: thesis-d2-tempering
    where: Section 2.1.4.3, Table 2.3, column T 200 C
  - benchmark: hardness_rockwell_c
    label: Hardness after tempering at 300 C
    value: 58
    unit: HRC
    scope: material
    conditions:
      heat_treatment: tempered at 300 C; tempering time and hardening temperature not stated in the table
      basis: curve from the thesis's reference 6, as printed
    method: Table 2.3, D2 hardness in HRC against tempering temperature, value as printed
    status: ground
    source: thesis-d2-tempering
    where: Section 2.1.4.3, Table 2.3, column T 300 C
  - benchmark: hardness_rockwell_c
    label: Hardness after tempering at 400 C
    value: 58
    unit: HRC
    scope: material
    conditions:
      heat_treatment: tempered at 400 C; tempering time and hardening temperature not stated in the table
      basis: curve from the thesis's reference 6, as printed
    method: Table 2.3, D2 hardness in HRC against tempering temperature, value as printed
    status: ground
    source: thesis-d2-tempering
    where: Section 2.1.4.3, Table 2.3, column T 400 C
  - benchmark: hardness_rockwell_c
    label: Hardness after tempering at 500 C
    value: 59
    unit: HRC
    scope: material
    conditions:
      heat_treatment: tempered at 500 C; tempering time and hardening temperature not stated in the table
      basis: curve from the thesis's reference 6, as printed
    method: Table 2.3, D2 hardness in HRC against tempering temperature, value as printed
    status: ground
    source: thesis-d2-tempering
    where: Section 2.1.4.3, Table 2.3, column T 500 C
  - benchmark: hardness_rockwell_c
    label: Hardness after tempering at 550 C
    value: 56
    unit: HRC
    scope: material
    conditions:
      heat_treatment: tempered at 550 C; tempering time and hardening temperature not stated in the table
      basis: curve from the thesis's reference 6, as printed
    method: Table 2.3, D2 hardness in HRC against tempering temperature, value as printed
    status: ground
    source: thesis-d2-tempering
    where: Section 2.1.4.3, Table 2.3, column T 550 C
  - benchmark: hardness_rockwell_c
    label: Hardness after tempering at 600 C
    value: 51
    unit: HRC
    scope: material
    conditions:
      heat_treatment: tempered at 600 C; tempering time and hardening temperature not stated in the table
      basis: curve from the thesis's reference 6, as printed
    method: Table 2.3, D2 hardness in HRC against tempering temperature, value as printed
    status: ground
    source: thesis-d2-tempering
    where: Section 2.1.4.3, Table 2.3, column T 600 C
  - benchmark: hardness_rockwell_c
    label: Hardness after tempering at 700 C
    value: 35
    unit: HRC
    scope: material
    conditions:
      heat_treatment: tempered at 700 C; tempering time and hardening temperature not stated in the table
      basis: curve from the thesis's reference 6, as printed
    method: Table 2.3, D2 hardness in HRC against tempering temperature, value as printed
    status: ground
    source: thesis-d2-tempering
    where: Section 2.1.4.3, Table 2.3, column T 700 C
  - benchmark: hardness_rockwell_c
    label: Hardness after hardening, approximate range
    value: 62
    value_high: 64
    bound: range
    unit: HRC
    scope: material
    conditions:
      heat_treatment: as hardened from 1000 to 1040 C per the text; quench medium not specified in that sentence
      basis: approximate, as printed in the text that cites reference 6
    method: Text of section 2.1.4.3, printed as approximately between 62 and 64 HRC after hardening
    status: ground
    source: thesis-d2-tempering
    where: Section 2.1.4.3, text before Table 2.3
  - benchmark: elastic_modulus
    label: Modulus of elasticity, preview range
    value: 190
    value_high: 210
    bound: range
    unit: GPa
    scope: material
    conditions:
      heat_treatment: not shown in the free preview
      temperature: not shown in the free preview (the page has four temperature bands)
    method: Physical properties table of the free preview, Module d'elasticite row, printed as 190 — 210
    status: ground
    source: totalmateria-d2
    where: Propriétés physiques table (free preview), Module d'elasticite row
  - benchmark: density
    label: Density, preview range
    value: 7.72
    value_high: 8
    bound: range
    unit: kg/dm3
    scope: material
    conditions:
      heat_treatment: not shown in the free preview
      temperature: not shown in the free preview (the page has four temperature bands)
    method: Physical properties table of the free preview, Densité row, printed as 7.72 — 8 kg/dm³
    status: ground
    source: totalmateria-d2
    where: Propriétés physiques table (free preview), Densité row
  - benchmark: poissons_ratio
    label: Poisson's ratio, preview range
    value: 0.27
    value_high: 0.3
    bound: range
    unit: '-'
    scope: material
    conditions:
      heat_treatment: not shown in the free preview
      temperature: not shown in the free preview (the page has four temperature bands)
    method: Physical properties table of the free preview, Coefficient de Poisson row, printed as 0.27 — 0.3
    status: ground
    source: totalmateria-d2
    where: Propriétés physiques table (free preview), Coefficient de Poisson row
  - benchmark: density
    label: Relative density, typical value
    value: 7.85
    unit: g/cm3
    scope: material
    conditions:
      heat_treatment: not stated; ground flat stock
      basis: typical value, not a specification, as printed
      unit_in_source: relative density, printed with no unit
    method: Section 9, Physical and Chemical Properties, Relative density row, printed as 7.85
    status: ground
    source: ssk-sds-d2
    where: Section 9, Relative density
corrosion:
  - environment: Atmosphere and humidity (general, no test given)
    headline: 'D2 is not stainless: its corrosion resistance is below that of stainless steel (Wikipedia).'
    effect: Wikipedia says that certain D-type tool steels, with 10 to 13 percent chromium, are often considered stainless or semi-stainless, but their corrosion resistance is less than stainless steel, because most of the chromium and carbon are precipitated as carbides. The SDS says the stock is usually slightly oil coated to protect it from rust. No numeric corrosion rate for D2 was read in this run.
    rating: unknown
    conditions:
      basis: qualitative statements, no test conditions
    source: wikipedia-tool-steel
    where: Tool steel article, D-series paragraph; SDS section 1 for the oil coating
  - environment: Strong acids (listed as incompatible)
    headline: The SDS lists strong acids as incompatible with the stock.
    effect: Section 10 of the Steel Service Krefeld SDS gives strong acids as the incompatible product. It gives no concentration, temperature or corrosion rate.
    rating: unknown
    conditions:
      basis: SDS section 10, incompatible products; no test conditions
    source: ssk-sds-d2
    where: Section 10, Stability and Reactivity
  - environment: Nitriding or nitrocarburizing of the surface
    headline: Nitriding gives a hard surface layer that Uddeholm says also increases corrosion resistance.
    effect: Uddeholm says nitriding gives a hard surface layer that is very resistant to wear and erosion, and also increases corrosion resistance. The sheet gives surface hardness after nitriding at 525 C (about 1250 HV1) and nitrocarburizing at 570 C for 2 hours (about 950 HV1), but no corrosion test.
    rating: unknown
    conditions:
      basis: statement in the nitriding section; no corrosion test
      heat_treatment: nitrided or nitrocarburized, hardened and tempered base
    source: uddeholm-sverker21
    where: Page 5, Nitriding and nitrocarburizing
risks:
  hazards:
    - text: Steel Service Krefeld's SDS for D2 ground flat stock (16 March 2021) treats the stock as an article under REACH and says it is not hazardous as supplied. Cutting, milling or grinding can make dust or fumes that may be hazardous if inhaled.
      ghs: []
      source: ssk-sds-d2
      where: Section 2, Potential Hazards, General Statement; Section 15, Regulatory Information
    - text: Fumes or dust from cutting, milling or grinding may cause irritation, difficulty breathing or allergic skin reactions. The SDS adds that fumes, mists or dusts from processing may be carcinogenic if inhaled over a long period.
      ghs: []
      source: ssk-sds-d2
      where: Section 4, First Aid Measures; Section 11, Toxicological Information
    - text: The stock is nonflammable and there is no explosion hazard in a fire. The SDS gives no GHS classification for the stock.
      ghs: []
      source: ssk-sds-d2
      where: Section 5, Fire Fighting Measures; Section 9, Flammability
  failure_risks:
    - mode: Softening after high-temperature tempering
      trigger: Tempering at 550 C or above
      consequence: In the tempering curve cited by the thesis, hardness falls from 56 HRC at 550 C to 51 HRC at 600 C and 35 HRC at 700 C.
      severity: moderate
      source: thesis-d2-tempering
      where: Section 2.1.4.3, Table 2.3
    - mode: Cracking or chipping under impact or bending
      trigger: Impact loads, bending stresses or thick, hard work material
      consequence: Uddeholm says the grade has rather limited cracking resistance and is not the choice where the risk of chipping or cracking is high.
      severity: moderate
      source: uddeholm-sverker21
      where: Page 2, Properties profile and Applications
    - mode: Cracking during sub-zero treatment
      trigger: Sub-zero treatment of tools with intricate shapes
      consequence: Uddeholm warns that avoiding intricate shapes is needed because of the risk of cracking. Sub-zero treatment adds 1 to 3 HRC.
      severity: moderate
      source: uddeholm-sverker21
      where: Page 5, Sub-zero treatment
    - mode: Decarburization and oxidation during hardening
      trigger: Hardening without protecting the part
      consequence: Uddeholm says the part must be protected against decarburization and oxidation during hardening.
      severity: low
      source: uddeholm-sverker21
      where: Page 4, Hardening
    - mode: Lower hardness in real tools
      trigger: Actual tool size and heat-treatment parameters
      consequence: Uddeholm says lower hardness than the tempering curves can be expected in tools and dies, because of actual tool size and heat-treatment parameters.
      severity: low
      source: uddeholm-sverker21
      where: Page 4, note under the tempering graphs
  side_effects: []
  handling:
    - text: Soft anneal at 850 C, cool in the furnace at 10 C per hour to 650 C, then cool freely in air.
      source: uddeholm-sverker21
      where: Page 4, Soft annealing
    - text: Stress relieve at 650 C for 2 hours after rough machining, cool slowly to 500 C, then cool freely in air.
      source: uddeholm-sverker21
      where: Page 4, Stress-relieving
    - text: Preheat at 650 to 750 C. Austenitize at 990 to 1080 C, usually 1000 to 1040 C, with soaking times of 30 to 60 minutes in the hardening table.
      source: uddeholm-sverker21
      where: Page 4, Hardening
    - text: Quench in oil (very simple geometries only), in vacuum with high-speed gas, in forced air or gas, or in a martempering bath or fluidized bed at 180 to 500 C, then cool in air.
      source: uddeholm-sverker21
      where: Page 4, Quenching media
    - text: Temper as soon as the tool reaches 50 to 70 C. Temper twice with intermediate cooling to room temperature, at no less than 180 C, holding at least 2 hours.
      source: uddeholm-sverker21
      where: Page 4, Tempering and note
    - text: Total Materia's preview gives 232 C for the best combination of toughness and hardness and 371 C for more ductility at some loss of hardness. A double temper uses a second temper 13.8 C (25 F) below the first.
      source: totalmateria-d2
      where: Traitement thermique (free preview), Tempering paragraph
    - text: Sub-zero treat at -70 to -80 C for 3 to 4 hours immediately after quenching, then temper, for maximum dimensional stability. Avoid intricate shapes.
      source: uddeholm-sverker21
      where: Page 5, Sub-zero treatment
    - text: For EDM in the hardened and tempered state, give an extra temper about 25 C below the previous tempering temperature.
      source: uddeholm-sverker21
      where: Page 7, Electrical discharge machining
    - text: Weld at a working temperature of 200 to 250 C. Matching consumables are needed if the tool will be polished or photo-etched.
      source: uddeholm-sverker21
      where: Page 7, Welding
    - text: Ventilate well during machining. Wear an FFP 2 or FFP 3 respirator (EN 149) for welding or burning, and safety glasses for cutting, milling or grinding.
      source: ssk-sds-d2
      where: Section 8, Limitation and Monitoring of Exposure
    - text: Avoid dust particles during machining, and avoid sharp edges or heated material.
      source: ssk-sds-d2
      where: Section 7, Handling and Storage
  mitigations:
    - text: Nitriding at 525 C or nitrocarburizing at 570 C gives a hard surface layer. Uddeholm says nitriding is very resistant to wear and erosion and increases corrosion resistance.
      source: uddeholm-sverker21
      where: Page 5, Nitriding and nitrocarburizing
    - text: Sub-zero treatment followed by tempering adds 1 to 3 HRC.
      source: uddeholm-sverker21
      where: Page 5, Sub-zero treatment
    - text: Use the tempering graphs for target hardness, but expect lower hardness in real tools. The Uddeholm curves are for 15 x 15 x 40 mm samples cooled in forced air.
      source: uddeholm-sverker21
      where: Page 4, Tempering graph note
uses:
  - application: mechanisms
    device: Blanking, fine-blanking, punching, cropping, shearing and trimming tools
    example: Uddeholm's cutting table gives tool hardness of 60 to 62 HRC for material under 3 mm thick and 58 to 60 HRC for 3 to 6 mm, with work material under 180 HB; lower hardness is printed for harder work material.
    source: uddeholm-sverker21
    where: Page 3, Applications, cutting table
  - application: mechanisms
    device: Thread-rolling dies and cold-extrusion dies
    example: Uddeholm's forming table lists thread-rolling dies at 58 to 62 HRC and cold-extrusion dies at 58 to 60 HRC.
    source: uddeholm-sverker21
    where: Page 3, Forming table, rows Cold extrusion dies and Thread-rolling dies
  - application: mechanisms
    device: Shear blades, planer blades and industrial cutting tools
    example: Wikipedia says D2 is widely used for shear blades, planer blades and industrial cutting tools, and sometimes for knife blades.
    source: wikipedia-tool-steel
    where: Tool steel article, D2 row of the composition table
  - application: mechanisms
    device: Dies for moulding ceramics, bricks, tiles and grinding wheels, and plastic moulds for abrasive polymers
    example: Uddeholm lists these dies at 58 to 62 HRC. Dörrenberg lists plastic moulds for abrasive polymers among the applications of its 1.2379 grade.
    source: uddeholm-sverker21
    where: Page 3, Forming table, dies for moulding row
supply:
  - subject: Chromium
    abundance: World resources are greater than 12 billion tons of shipping-grade chromite, and 95 percent of world chromium resources are in Kazakhstan and southern Africa. US net import reliance was 79 percent of apparent consumption in 2025e.
    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 (chromium, used in stainless steel)
        listed: true
    recycling: In 2025, recycled chromium in reported stainless-steel scrap receipts accounted for 21 percent of apparent consumption.
    substitutes:
      - Chromium has no substitute in stainless steel, the leading end use, or in superalloys, the major strategic end use (USGS 2026).
    source: usgs-mcs2026-chromium
    where: 'Salient Statistics, net import reliance 2025e; World Mine Production and Reserves, mine production 2025e in thousand t, gross weight: South Africa 23,000, Turkey 9,000, Kazakhstan 7,000, India 3,000, Brazil 2,000, Zimbabwe 2,000, Finland 1,900, world total 51,000 (rounded); shares calculated by Space Mushroom as printed tonnage over 51,000 t; World Resources; Substitutes; Recycling. List status from usgs-critical-2025 (read with WebFetch in this run)'
  - subject: Molybdenum
    abundance: World reserves were 17,000 thousand t. Identified resources are about 5.4 million t in the United States and about 20 million t in the rest of the world. Molybdenum is used principally as an alloying agent in cast iron, steel 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
        listed: false
    recycling: Molybdenum recycled as part of new and old steel and other scrap may be as much as 30 percent of the apparent supply (USGS 2026).
    substitutes:
      - There is little substitution for molybdenum in steels and cast irons. Potential substitutes include boron, chromium, niobium and vanadium in alloy steels, and tungsten in tool steels (USGS 2026).
    source: usgs-mcs2026-molybdenum
    where: 'Domestic Production and Use; World Mine Production and Reserves, mine production 2025e in metric tons of molybdenum content: China 97,000, Chile 42,000, United States 40,000, Peru 39,000, Mexico 17,000, world total 260,000 (rounded); shares calculated by Space Mushroom as printed tonnage over 260,000 t; Reserves column; World Resources; Substitutes; Recycling. List status from usgs-critical-2025 (read with WebFetch in this run; the page summary names no molybdenum entry)'
  - subject: Vanadium
    abundance: World resources of vanadium exceed 63 million tons, and world reserves were 21,000 thousand t (rounded). More than 90 percent of reported domestic consumption in 2025 was metallurgical, mainly as an alloying agent for iron and steel. US net import reliance was 41 percent of apparent consumption in 2025e.
    producers:
      - country: China
        share_percent: 74.5
        year: 2025
      - country: Russia
        share_percent: 19.1
        year: 2025
      - country: Brazil
        share_percent: 4.8
        year: 2025
      - country: South Africa
        share_percent: 4.5
        year: 2025
    critical_lists:
      - list: USGS 2025 List of Critical Minerals (vanadium, used to strengthen iron and steel)
        listed: true
    recycling: Recycling of vanadium is mainly associated with reprocessing vanadium catalysts into new catalysts (USGS 2026).
    substitutes:
      - Steels with other combinations of alloying elements can be substituted for vanadium steels. Manganese, molybdenum, niobium, titanium and tungsten are to some degree interchangeable with vanadium as alloying elements in steel (USGS 2026).
    source: usgs-mcs2026-vanadium
    where: 'Domestic Production and Use; Salient Statistics, net import reliance 2025e; World Mine Production and Reserves, mine production 2025e in metric tons of vanadium content: China 82,000, Russia 21,000, Brazil 5,300, South Africa 5,000, world total 110,000 (rounded). The printed national figures add to about 113,300 t, so the shares below, calculated by Space Mushroom over the printed total, sum to more than 100 percent. Reserves column; World Resources; Substitutes; Recycling. List status from usgs-critical-2025 (read with WebFetch in this run)'
media: []
documents:
  - title: Uddeholm Sverker 21 technical datasheet (AISI D2, W.-Nr. 1.2379), edition 13, 04.2019
    type: datasheet
    url: https://uddeholm.com/app/uploads/sites/247/2024/09/Tech-Uddeholm-Sverker-21-EN.pdf
    year: 2019
  - title: Dörrenberg Edelstahl datasheet 1.2379 X153CrMoV12 (English)
    type: datasheet
    url: https://doerrenberg.de/fileadmin/special_steel/files/pdf_en_products_neues_Design/1.2379_en.pdf
  - title: Steel Service Krefeld (USA) safety data sheet, precision ground flat stock of tool steel 1.2379 (AISI D 2), rev 0, 16 March 2021 (copy on zoro.com)
    type: sds
    url: https://www.zoro.com/static/cms/enhanced_pdf/Steel%20Service%20Krefeld%20USA%20Inc_SafetyxxDataxxSheetxxGroundxxFlatxxStockxxD2xx97e26f.pdf
    year: 2021
  - title: 'Total Materia: PROPRIETARY D2 Tool Steel (free preview, last updated 2022-03)'
    type: database
    url: https://www.totalmateria.com/fr/material/1350104
  - title: Določanje popustnih karakteristik orodnega jekla D2 (tempering characteristics of D2 tool steel), bachelor's thesis, University of Ljubljana, May 2024
    type: report
    url: https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=186121&dn=
    year: 2024
  - title: Estudo da resistência ao desgaste de aço VD2 com diferentes revenimentos (ABM Proceedings, wear of D2 with different tempering, English abstract)
    type: paper
    url: https://abmproceedings.com.br/en/article/estudo-da-resistncia-ao-desgaste-de-ao-vd2-com-diferentes-revenimentos
  - 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: Molybdenum'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-molybdenum.pdf
    year: 2026
  - title: 'USGS Mineral Commodity Summaries 2026: Vanadium'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-vanadium.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
gaps:
  - No numeric wear rate or volume loss for D2 was read in this run. The ABM pin-on-disc study gives its test conditions and a qualitative result in the English abstract; its full text was not reached, and the download link is a page, not a PDF.
  - No numeric corrosion rate for D2 was read. The 2020 Al-Qawabah et al. paper on D2 and O1 in 0.1 M HCl (Materiali in tehnologije 54(6), 785-790) was located through its dLib record, but the article text returned an HTML page, so no value from it is used.
  - Melting point is not recorded as a property. The SDS prints it as 1.530 C with a period as the thousands separator, which the source check cannot match to 1530, and no other fetched page gives a melting point.
  - Dörrenberg's thermal expansion (10,5 to 13,0 x 10-6 per K, from 20 to 100 C through 20 to 400 C) and thermal conductivity (16,7 W/mK at 20 C, 20,5 at 350 C, 24,2 at 700 C) are printed with decimal commas, so they are not recorded as values. They disagree with Uddeholm (20.0 W/mK at 20 C; 11.2 to 12.3 ppm/K at 20 to 200 C).
  - 'The thesis''s own tempered samples were softer than its cited curve: its Table 4.1 gives 53,7 HRC after 2 x 2 h at 200 C in oil, against 61 HRC in Table 2.3. Those values carry decimal commas and are not recorded. The hardening temperature behind the cited curve is not stated in its table.'
  - The tempering graphs in the Uddeholm sheet and the tempering diagram in the Dörrenberg datasheet are images without printed values, so they were not read as numbers.
  - 'Composition differs by supplier. Uddeholm typical analysis: 11.3 Cr, 0.8 Mo, 0.8 V. Dörrenberg: 12.00 Cr, 0.80 Mo, 0.90 V. Thesis: 12.00 Cr, 1.00 Mo, 0.85 V. Wikipedia: 11.0 to 13.0 Cr, 0.9 Mo, 1.0 V. The recipe uses the SDS ranges; the ASTM A681 and EN ISO 4957 texts were not reached.'
  - 'Density differs by source: 7700 kg/m3 at 20 C (Uddeholm, hardened and tempered), 7.85 (SDS typical value) and 7.72 to 8 kg/dm3 (Total Materia preview).'
  - Toughness wording differs. Dörrenberg says good toughness; Uddeholm says rather limited cracking resistance; Wikipedia says not as tough as lower-alloyed steels. This profile reports each as printed.
  - Total Materia shows only a free preview. Its temperature bands and heat-treatment detail (205 property entries) need registration, so its E, density and Poisson ranges carry no condition.
  - UNS T30402 and JIS SKD 11 come from the Total Materia cross-reference table only; no UNS, ASTM or JIS G4404 text was read directly. Some of its equivalents are marked implicit there.
  - Critical-mineral lists come from the USGS 2025 list page, which refused the curl request (403) and was read with WebFetch. The membership reading is the page summary's; the list itself was not read as raw text.
  - The USGS vanadium world total (110,000 t, 2025e) is smaller than the sum of the printed national figures (about 113,300 t), so vanadium shares sum to more than 100 percent when calculated over the printed total.
  - No flight, space, vacuum, radiation, cryogenic or hydrogen data for D2 were read. The uses are terrestrial tooling, and the application slug mechanisms is the closest fit in the site taxonomy.
  - No safety data sheet from a D2 steel mill was read. The SDS is from a stock distributor for ground flat stock (2021) and gives no GHS classification; the composition of welding fumes is not sourced.
  - The thesis cites reference 6 for its physical data and tempering table. That reference was not identified, so those values are recorded as printed by the thesis.
  - 'Property names not in property-canon: hardness_rockwell_c, hardness_brinell, compressive_yield_strength, surface_hardness_hv and case_depth. identity.designations is not in the site schema, so the site will not display it until the schema is extended.'
sources:
  uddeholm-sverker21:
    title: Uddeholm Sverker 21 (AISI D2, W.-Nr. 1.2379), technical datasheet, Bohler-Uddeholm
    id: Edition 13, 04.2019
    url: https://uddeholm.com/app/uploads/sites/247/2024/09/Tech-Uddeholm-Sverker-21-EN.pdf
    year: 2019
    kind: datasheet
    license: supplier datasheet, cited not reproduced
  doerrenberg-1-2379:
    title: 'Dörrenberg Edelstahl: 1.2379 X153CrMoV12 datasheet (English, similar to AISI D2)'
    id: Material No. 1.2379, code X153CrMoV12
    url: https://doerrenberg.de/fileadmin/special_steel/files/pdf_en_products_neues_Design/1.2379_en.pdf
    kind: datasheet
    license: supplier datasheet, cited not reproduced
  ssk-sds-d2:
    title: 'Steel Service Krefeld (USA) Inc.: safety data sheet, precision ground flat stock of tool steel 1.2379 (AISI D 2), rev 0'
    id: 16 March 2021
    url: https://www.zoro.com/static/cms/enhanced_pdf/Steel%20Service%20Krefeld%20USA%20Inc_SafetyxxDataxxSheetxxGroundxxFlatxxStockxxD2xx97e26f.pdf
    year: 2021
    kind: datasheet
    license: supplier safety data sheet, linked not reproduced
  totalmateria-d2:
    title: 'Total Materia: PROPRIETARY D2 Tool Steel (free preview)'
    id: Total Materia material 1350104, last updated 2022-03
    url: https://www.totalmateria.com/fr/material/1350104
    kind: database
    license: Total Materia terms, cited not reproduced
  thesis-d2-tempering:
    title: Določanje popustnih karakteristik orodnega jekla D2 (Determining the tempering characteristics of D2 tool steel), bachelor's thesis, Faculty of Mechanical Engineering, University of Ljubljana (in Slovenian)
    id: Jakob Jakše, May 2024
    url: https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=186121&dn=
    year: 2024
    kind: report
    license: university repository copy, cited not reproduced
  abm-vd2-wear:
    title: Estudo da resistência ao desgaste de aço VD2 com diferentes revenimentos (ABM Proceedings), English abstract read
    id: ABM Proceedings, article page
    url: https://abmproceedings.com.br/en/article/estudo-da-resistncia-ao-desgaste-de-ao-vd2-com-diferentes-revenimentos
    kind: paper
    license: publisher page, cited not reproduced
  wikipedia-tool-steel:
    title: Tool steel (Wikipedia), D-series paragraph and D2 row of the composition table
    id: en.wikipedia.org/wiki/Tool_steel
    url: https://en.wikipedia.org/wiki/Tool_steel
    kind: web
    license: CC BY-SA 4.0 (Wikipedia)
  usgs-mcs2026-chromium:
    title: 'USGS Mineral Commodity Summaries 2026: Chromium'
    id: mcs2026-chromium, February 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-chromium.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  usgs-mcs2026-molybdenum:
    title: 'USGS Mineral Commodity Summaries 2026: Molybdenum'
    id: mcs2026-molybdenum, February 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-molybdenum.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  usgs-mcs2026-vanadium:
    title: 'USGS Mineral Commodity Summaries 2026: Vanadium'
    id: mcs2026-vanadium, February 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-vanadium.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  usgs-critical-2025:
    title: 'USGS: About the 2025 List of Critical Minerals (final list)'
    id: 2025 List of Critical Minerals
    url: https://www.usgs.gov/programs/mineral-resources-program/science/about-2025-list-critical-minerals
    year: 2025
    kind: web
    license: public domain (USGS)
license: CC-BY-4.0
updated: '2026-10-24'
review:
  status: draft
  method: assistant
  checked_values: 35
  unreachable: 4
  caveats: 4
  note: 'Read by an AI assistant on 2026-10-24 from pages fetched in this run. Each value carries its heat-treatment or test state in conditions. Not reached: the Xometry datasheet (403), the dLib article text (HTML only), steeldata.info (empty) and the CROSBI wear record (empty). The USGS list page refused curl and was read with WebFetch.'
story:
  recipe:
    line: 'AISI D2 is an iron-based steel with about 1.5 percent carbon and 12 percent chromium, with molybdenum and vanadium as the other alloying additions. The SDS prints the composition ranges used here: carbon 1.40 to 1.60 percent, chromium 11.00 to 13.00 percent, molybdenum 0.70 to 1.20 percent, vanadium 0.50 to 1.10 percent, silicon and manganese 0.10 to 0.60 percent each, and phosphorus and sulphur 0.00 to 0.03 percent. Heat treatment, not composition alone, sets the hardness.'
    parts:
      - name: Iron
        symbol: Fe
        share_note: balance (the rest)
        role: Matrix of the steel. The SDS lists iron as the base.
      - name: Carbon
        symbol: C
        share_percent: 1.4
        share_high: 1.6
        source: ssk-sds-d2
        where: Section 3, Chemical composition
        role: Part of the high volume of hard carbides that gives the steel its wear resistance (Dörrenberg).
      - name: Silicon
        symbol: Si
        share_percent: 0.1
        share_high: 0.6
        source: ssk-sds-d2
        where: Section 3, Chemical composition
        role: Small addition listed in the composition.
      - name: Manganese
        symbol: Mn
        share_percent: 0.1
        share_high: 0.6
        source: ssk-sds-d2
        where: Section 3, Chemical composition
        role: Small addition listed in the composition.
      - name: Chromium
        symbol: Cr
        share_percent: 11
        share_high: 13
        source: ssk-sds-d2
        where: Section 3, Chemical composition
        role: About 12 percent. Uddeholm calls it a 12 percent chromium steel; chromium is tied up in carbides, so the steel is not stainless (Wikipedia).
      - name: Molybdenum
        symbol: Mo
        share_percent: 0.7
        share_high: 1.2
        source: ssk-sds-d2
        where: Section 3, Chemical composition
        role: Alloying addition, listed with vanadium in the Uddeholm sheet.
      - name: Vanadium
        symbol: V
        share_percent: 0.5
        share_high: 1.1
        source: ssk-sds-d2
        where: Section 3, Chemical composition
        role: Alloying addition, listed with molybdenum in the Uddeholm sheet.
      - name: Phosphorus
        symbol: P
        share_percent: 0
        share_high: 0.03
        share_note: printed as 0.00 to 0.03
        source: ssk-sds-d2
        where: Section 3, Chemical composition
        role: Impurity held low.
      - name: Sulphur
        symbol: S
        share_percent: 0
        share_high: 0.03
        share_note: printed as 0.00 to 0.03
        source: ssk-sds-d2
        where: Section 3, Chemical composition
        role: Impurity held low.
  risk_groups:
    - title: For people
      level: 1
      verdict: Dust and fumes from processing are the watch point
      lead: The SDS says the stock is not hazardous as supplied. The risk comes from dust and fumes when it is cut, ground or welded.
      points:
        - label: Stock as supplied
          line: The SDS treats the ground flat stock as an article under REACH and says it is not hazardous as supplied. It is nonflammable.
        - label: Processing
          line: Cutting, milling, grinding or welding can make dust or fumes that may be hazardous if inhaled. The SDS says fumes and dusts from processing may be carcinogenic if inhaled over a long time.
        - label: Respirator
          line: For welding or burning, the SDS calls for an FFP 2 or FFP 3 respirator (EN 149) and face shields.
    - title: Heat treatment
      level: 2
      verdict: Hardness and toughness follow the cycle
      lead: The same steel can be soft, hard or tough depending on the cycle. These results come from datasheets and a thesis, not from field use.
      points:
        - label: Tempering
          line: In the tempering curve cited by the thesis, hardness falls from 61 HRC at 200 C to 56 HRC at 550 C, 51 HRC at 600 C and 35 HRC at 700 C.
        - label: Hardening
          line: Hardening from 990 to 1080 C gave about 63 to 65 HRC before tempering in the Uddeholm table.
        - label: Cracking
          line: Uddeholm warns of limited cracking resistance and says intricate shapes that are sub-zero treated risk cracking.
    - title: Corrosion
      level: 2
      verdict: Not stainless; the stock is oil coated
      lead: D2 has about 12 percent chromium, but most of it is tied up in carbides, so it is not a stainless steel.
      points:
        - label: Stainless?
          line: Wikipedia says certain D-type tool steels are often considered stainless or semi-stainless, but their corrosion resistance is less than stainless steel.
        - label: Acids
          line: The SDS lists strong acids as incompatible with the stock.
        - label: Storage
          line: The SDS says the stock is usually slightly oil coated to protect it from rust.
  why: 'AISI D2 (EN 1.2379, X153CrMoV12) is a high-carbon, 12 percent chromium steel. Its many hard carbides give very high abrasive and adhesive wear resistance, and Uddeholm calls it the bulk grade for cold-work tooling. The trade-off is toughness: the Uddeholm sheet says it has rather limited cracking resistance. Hardness and toughness depend on the heat treatment, so each value in this profile carries its own condition.'
  uses:
    - where: Blanking and trimming tools
      line: Uddeholm lists blanking, fine-blanking, punching, cropping, shearing and trimming tools in its cutting table, with tool hardness of 54 to 62 HRC depending on material thickness and work-material hardness.
    - where: Thread-rolling and cold-extrusion dies
      line: Uddeholm lists thread-rolling dies at 58 to 62 HRC and cold-extrusion dies at 58 to 60 HRC.
    - where: Shear, planer and cutting blades
      line: Wikipedia says D2 is widely used for shear blades, planer blades and industrial cutting tools, and sometimes for knife blades.
  can_do:
    - label: Hardness
      line: 'Hardening from 990 to 1030 C gives about 63 to 65 HRC before tempering (Uddeholm). Tempering then sets the working hardness: the thesis curve gives 61 HRC after 200 C and 51 HRC after 600 C.'
    - label: Stiffness
      line: The modulus of elasticity is about 210 GPa at 20 C, falling to about 180 GPa at 400 C (Uddeholm).
    - label: Compressive strength
      line: Compressive yield strength is about 2200 MPa at 62 HRC and about 1650 MPa at 50 HRC (Uddeholm, approximate values).
    - label: Wear
      line: Very high abrasive and adhesive wear resistance from a high volume of hard carbides (Dörrenberg). Uddeholm rates its abrasive wear resistance as very good.
    - label: Surface hardening
      line: Nitriding at 525 C gives about 1250 HV1 at the surface, and nitrocarburizing at 570 C for 2 hours gives about 950 HV1 (Uddeholm).
    - label: Dimensional stability
      line: The Dörrenberg datasheet calls it very good in dimensional stability, and Uddeholm says it hardens through in all standard sizes.
  compare: 'Among the datasheets for this grade, the modulus agrees: about 210 GPa at 20 C in Uddeholm and 190 to 210 GPa in the Total Materia preview. Density is 7700 kg/m3 in Uddeholm, 7.85 in the SDS typical value and 7.72 to 8 kg/dm3 in the Total Materia preview. Thermal expansion and conductivity differ between datasheets, so quote the source with each value. Toughness wording also differs: Dörrenberg says good toughness, Uddeholm says rather limited cracking resistance, and Wikipedia says D2 is not as tough as lower-alloyed steels.'
  compare_rows:
    - label: Stiffness
      benchmark: elastic_modulus
    - label: Density
      benchmark: density
    - label: Compressive strength
      benchmark: compressive_yield_strength
  handling:
    - Soft anneal at 850 C, cool in the furnace at 10 C per hour to 650 C, then air cool.
    - Stress relieve at 650 C for 2 hours after rough machining.
    - Preheat at 650 to 750 C, then harden from 990 to 1080 C, usually 1000 to 1040 C.
    - Quench in oil only for very simple shapes; vacuum with high-speed gas, forced air or gas, and martempering at 180 to 500 C are the other options.
    - Temper twice, at no less than 180 C, holding at least 2 hours each time.
    - Protect the part against decarburization and oxidation during hardening.
    - For EDM in the hardened and tempered state, temper again about 25 C below the previous tempering temperature.
    - Wear an FFP 2 or FFP 3 respirator (EN 149) for welding or burning, and ventilate well during machining (SDS).
  good_for:
    - Blanking, punching and trimming tools where abrasive wear limits tool life (Uddeholm).
    - Thread-rolling and cold-extrusion dies at 58 to 62 HRC (Uddeholm).
    - Shear blades, planer blades and industrial cutting tools (Wikipedia).
  watch_out:
    - 'Toughness: rather limited cracking resistance (Uddeholm), and not as tough as lower-alloyed steels (Wikipedia).'
    - 'Corrosion: not stainless. Wikipedia says its corrosion resistance is less than stainless steel, and the SDS lists strong acids as incompatible.'
    - 'Tempering: in the thesis curve, hardness falls from 56 HRC at 550 C to 35 HRC at 700 C.'
  verdict: AISI D2 is the bulk cold-work steel for wear-critical tooling. It trades toughness and corrosion resistance for hardness and wear resistance. Quote the heat-treatment condition with every value, and avoid it where chipping or impact is the main risk.