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Resources/Materials & grades/A2 / 1.2363

Materials & grades

A2 / 1.2363 / SKD12 air-hardening tool steel: X100CrMoV5 and BA2 equivalents

A2 is an air-hardening 5 % chromium cold-work tool steel with about 1 % carbon, hardened to about 57–63 HRC for punches, dies and gauges that need good dimensional stability. In Europe it is X100CrMoV5 (1.2363), in the UK BA2, in India X100CrMoV5 under IS 3748 and in Japan SKD12.

Names by standard

What it is called in each region

RegionSystemDesignationStandardMatch
USAAISI / ASTM A681 typeA2ASTM A681Same material
UNST30102—Same material
UKBS EN ISO 4957X100CrMoV5British adoption of the European tool-steel standard.BS EN ISO 4957Equivalent
BS 4659BA2Superseded British name for A2, still searched.BS 4659:1971Equivalent
EUEN 10027-1 nameX100CrMoV5Also written X100CrMoV5-1. Carbon 0.95–1.05 %, chromium about 4.8–5.5 %.EN ISO 4957Equivalent
EN 10027-2 number1.2363Material number of X100CrMoV5. Böhler sells it as K305; Dörrenberg as 1.2363 (P5M); Swiss Steel as Cryodur 2363.EN ISO 4957Equivalent
DIN (legacy)X100CrMoV5-1Older German spelling of the same name, still used on drawings and in Marks and zknives tables.—Equivalent
IndiaIS 3748X100CrMoV5IS 3748:2022 is an identical adoption of ISO 4957:2018. Total Materia lists an IS entry under this name.IS 3748:2022Equivalent
JapanJIS G 4404SKD12Composition limits match X100CrMoV5 almost exactly. Listed against A2 and 1.2363 by Böhler (K305).JIS G 4404:2025Closest equivalent

On equivalence

  • ASTM A681 allows 0.90–1.40 % molybdenum and 0.15–0.50 % vanadium; EN ISO 4957 and JIS SKD12 narrow these to 0.90–1.20 % Mo and 0.15–0.35 % V. Material made to the EN or JIS limits fits inside A2's window except at the margins.
  • EN names vary: Böhler prints 'X100CrMoV5' for 1.2363 with '~X100CrMoV5-1' beside it, Marks prints 'X100CrMoV5-1', and Swiss Steel prints 'X100CrMoV5'. Treat them as one grade.
  • Sources differ on the chromium range: Marks and JIS give 4.80–5.50 %, while Total Materia's EU and DIN listings show 4.5–5.5 % and 4.8–5.5 %. Check the mill certificate.
  • Japanese lists pair A2 with SKD12. Brand grades sold as SKD12 types are tuned inside the JIS limits, so check the mill certificate for the standard it is certified to.
  • Böhler K305, Dörrenberg 1.2363 and Cryodur 2363 are the same type but differ inside the limits. Their datasheet hardness values are typical, not specified.

Chemical composition

Composition limits, mass %

ElementA2 (T30102)USA · ASTM A681-08 (includes product analysis tolerances)X100CrMoV5 (1.2363)EU · EN ISO 4957 (limits as printed by Marks GmbH)X100CrMoV5India · IS 3748:2022 (identical to ISO 4957:2018)SKD12Japan · JIS G 4404:2025
C0.95–1.050.95–1.050.95–1.050.95–1.05
Si0.10–0.500.10–0.400.10–0.400.10–0.40
Mn0.40–1.000.40–0.800.40–0.800.40–0.80
P≤0.030≤0.030≤0.030≤0.030
S≤0.030≤0.030≤0.030≤0.030
Cr4.75–5.504.80–5.504.80–5.504.80–5.50
Mo0.90–1.400.90–1.200.90–1.200.90–1.20
V0.15–0.500.15–0.350.15–0.350.15–0.35
Ni+Cu≤0.75———

Mechanical properties

Strength and hardness

ConditionTensile strengthYield strengthElongationHardness
Annealed (ASTM A681)Specified maximum; cold-drawn bar may be up to 262 HBASTM A681-08, Table 2———≤248 HB
Annealed (JIS G 4404 SKD12)Specified maximum, annealedJIS G 4404:2025 as tabulated by Sekidou Kouhan———≤241 HBW
Annealed (mill delivery, 1.2363)Typical mill maximumMill data sheets listed under sources———≤240 HB (Böhler K305), ≤241 HB (Dörrenberg, Swiss Steel Cryodur 2363)
Hardened and tempered, response test (ASTM A681)Specified minimum after austenitizing at 941–954 °C (1725–1750 °F), air quench, one 2-hour temper at 204 °C (400 °F)ASTM A681-08, Table 3———≥60 HRC
As hardened, then tempered at 100–200 °CTypical, hardened 930–970 °C, small sectionSwiss Steel Cryodur 2363 data sheet———63 HRC after quenching and at 100 °C; 62 HRC at 200 °C
Tempered at 300–500 °CTypical, hardened 930–970 °C; low point near 400 °C, small rise near 500 °CSwiss Steel Cryodur 2363 data sheet———59 HRC at 300 °C, 57 HRC at 400 °C, 59 HRC at 500 °C; 52 HRC at 600 °C
Tempered at 100–600 °C (second mill)Typical, hardened 970 °C, 20 mm section, read from the Böhler chartBöhler K305 tempering chart———≈63.5 HRC at 100 °C, ≈60.5 at 200 °C, ≈58.5 at 300 °C, ≈57 at 400 °C, ≈58 at 500 °C, ≈51.5 at 600 °C

In practice

Behaviour, heat treatment and uses

Characteristics

  • Air hardening: through-hardens in air, so distortion on hardening is low and dimensional stability is good (Dörrenberg, Böhler K305).
  • Medium alloyed with about 1 % carbon and 5 % chromium. Wear resistance is very high and compressive strength very high (Böhler); Dörrenberg also lists good toughness.
  • Better wear resistance and through-hardening than the 1 % carbon, low-chromium grades such as 1.2842. It is used where those are no longer enough but D2 is not yet required (Böhler).
  • Crucible's comparison puts A2 at about 40 ft-lb (53 J) Charpy C-notch at 60 HRC, between D2 (21 ft-lb) and S7 (125 ft-lb at 57 HRC), with adhesive wear resistance of 2–3 against 3–4 for D2.
  • Thermal conductivity about 16 W/(m·K) at 20 °C (Dörrenberg, Cryodur).

Heat treatment

  • Soft annealing: about 800–850 °C (1470–1560 °F), furnace cool 10–20 °C per hour to about 600 °C, then air. Böhler gives 800–850 °C; Dörrenberg and Cryodur 800–840 °C.
  • Stress relieving: about 650 °C (1200 °F), 1–2 hours, furnace cool.
  • Hardening: about 950–980 °C (1740–1800 °F) (Böhler, Dörrenberg), or 930–970 °C (Cryodur). Hold 15–30 minutes after temperature equalization.
  • Quench: air (the intended route), pressure gas, oil or a hot bath at 500–550 °C. Oil is used for large sections.
  • Tempering: choose the temperature from the chart, typically 200–500 °C (Marks gives 200–500 °C). Heat slowly right after hardening, about 1 hour per 20 mm and at least 2 hours. Stress-relief temper 30–50 °C below the highest temper used.

Typical uses

  • Blanking and punching dies and die inserts
  • Thread-cutting tools
  • Machine knives for wood, paper and recycling
  • Forming rolls and bending tools
  • Coining and embossing dies
  • Moulds for plastic processing
  • Gauges and wear parts

Tool steels

Similar grades compared

GradeC %Mn %Cr %Ni %Tensile, first listed condition
A2 / 1.23630.95–1.050.40–1.004.75–5.50——
D2 / 1.23791.40–1.600.10–0.6011.00–13.00——
D3 / 1.20802.00–2.350.10–0.6011.00–13.50——
O1 / 1.25100.85–1.001.00–1.400.40–0.70——
S70.45–0.550.20–0.903.00–3.50——
H11 / 1.23430.33–0.430.20–0.504.75–5.50—1790–1845 MPa
H13 / 1.23440.32–0.450.20–0.604.75–5.50—1730–1845 MPa
M2 / HS6-5-2C0.78–0.880.15–0.403.75–4.50—≤950 MPa
M42 / HS2-9-1-81.05–1.150.15–0.403.50–4.25—≤1010 MPa
P20 / 1.23110.28–0.400.60–1.001.40–2.000.90–1.20950–1100 MPa

Composition from the US standard where one exists, otherwise the first standard listed on each grade's page. Strength conditions differ between grades; open a grade for its full table.

Questions answered

Common questions

What is the equivalent of A2 tool steel?

In Europe A2 is X100CrMoV5 (1.2363), in the UK the old name is BA2, in India IS 3748 uses the European name and in Japan it is SKD12. The EN and JIS limits are slightly narrower than ASTM A681 for molybdenum and vanadium.

What is the difference between A2 and D2?

A2 has about 1 % carbon and 5 % chromium; D2 has about 1.5 % carbon and 12 % chromium. D2 resists abrasive wear better, while A2 is tougher (about 40 ft-lb against 21 ft-lb in Crucible's C-notch test at 60 HRC) and distorts less.

Is A2 air hardening?

Yes. ASTM A681 tests A2 with an air quench from 941–954 °C. Böhler and Dörrenberg also allow gas, oil or a hot bath.

What hardness does A2 reach?

ASTM A681 requires at least 60 HRC after air hardening and a 204 °C temper. Mill curves give about 62–63 HRC at 100–200 °C and about 57–59 HRC at 300–500 °C.

Which JIS grade matches A2?

SKD12 under JIS G 4404. Its limits (0.95–1.05 % C, 4.80–5.50 % Cr, 0.90–1.20 % Mo, 0.15–0.35 % V) match X100CrMoV5 almost exactly.

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Keep reading

D2 / 1.2379D2 is a high-carbon, 12 % chromium cold-work tool steel that is hardened to about 58–62 HRC for dies, punches, shear blades and thread-rolling tools.D3 / 1.2080D3 is a 2 % carbon, 12 % chromium cold-work tool steel that is oil hardened to about 60–64 HRC for blanking dies, thread-rolling dies and wear parts.O1 / 1.2510O1 is an oil-hardening manganese–chromium–tungsten tool steel with about 0.9–1.0 % carbon, hardened to about 58–64 HRC for cutting tools, gauges and general-purpose dies.S7S7 is an air-hardening shock-resisting tool steel with about 0.5 % carbon, 3.25 % chromium and 1.4 % molybdenum that keeps high toughness at about 55–60 HRC, used for chisels, punches, heading dies and shear blades.H13 / 1.2344H13 is the standard 5 % chromium hot-work tool steel, used for die-casting dies, forging dies and extrusion tooling that see repeated heating and cooling.AnnealingAnnealing heats steel to a set temperature, holds it and cools it slowly to make it softer, more ductile and easier to machine or cold form.Quenching and temperingQuenching and tempering hardens steel by cooling it rapidly from the austenite range to form martensite, then reheats it below Ac1 to trade some hardness for toughness.JIS steel designationsJapanese JIS steel symbols start with S for steel and add letters for the steel family or its use, but the number means different things in different standards.EN 10027 names and numbersEuropean steels carry two identifiers under EN 10027: a steel name (Part 1) such as S235JR, C45 or 42CrMo4 that describes the steel's use or chemistry, and a material number (Part 2) such as 1.0503 or 1.7225.BS 970 and the EN seriesBS 970 names steels with a six-character code such as 080M40, in which the first three digits give the steel type, the letter says how the steel is specified and the last two digits give the carbon content.

References

Sources

  1. ASTM A681-08 Standard Specification for Tool Steels Alloy (copy hosted by Fushun Special Steel) — Table 1 composition, Table 2 annealed hardness, Table 3 response to hardening. 2008 edition; check the current revision.
  2. BIS: IS 3748:2022 Tool Steels, Specification (Standard of the Week) — States that IS 3748:2022 is an identical adoption of ISO 4957.
  3. Böhler K305 data sheet (voestalpine) — 1.2363 / X100CrMoV5 / ~T30102 / A2 / SKD12; annealed 240 HB max; hardening 950–980 °C; tempering chart.
  4. Swiss Steel Group: Cryodur 2363 data sheet — X100CrMoV5 / AISI A2; annealed 241 HB max; hardening 930–970 °C; tempering table.
  5. Dörrenberg Edelstahl: 1.2363 data sheet — Typical analysis, annealed 241 HB max, hardening and annealing.
  6. Marks GmbH: 1.2363 Werkstoffblatt — Analysis limits listed under EN ISO 4957 and AISI A2.
  7. JIS G 4404:2025 SKD12 values (Sekidou Kouhan steel table) — Composition and 241 HBW annealed limit as tabulated from JIS G 4404:2025.
  8. Total Materia: IS X100CrMoV5 (IS 3748:2022) — Indian listing of X100CrMoV5.
  9. Crucible S7 data sheet (impact and wear comparison with D2, A2, O1) — Charpy C-notch and adhesive-wear comparison at 60 HRC.
  10. JISF committee document: JIS G 4404 revision (composition and annealed hardness tables, basis of the 2022 edition) — Independent check of the SKD12 limits and annealed hardness; Annex A pairs SKD10 with X153CrMoV12 and SKD11 with no ISO grade.
  11. SIJ Metal Ravne: SIHARD 2363 (A2) data sheet — Independent check: tempering 63 HRC at 100 °C, 62 at 200, 58 at 300, 57 at 400–500, 51 at 600.
  12. Total Materia: ISO X100CrMoV5 (ISO 4957:2018) — Independent check: C 0.95–1.05, Mn 0.40–0.80, Cr 4.8–5.5 under ISO 4957:2018.
  13. Zknives: AISI A2 equivalents — Cross-reference list: BS BA2, DIN X100CrMoV5(-1), JIS SKD12, W-Nr 1.2363.

Values summarize published limits and typical data. The governing standard and the current edition control; check them before specifying.