Tool steel grade equivalents: AISI, JIS, DIN and GB cross-reference
A drawing that says “D2” and nothing else will get quoted. It will also, in a Vietnamese or Chinese supply chain, sometimes get quoted with an import lead time attached — because the service centre down the road stocks the same steel under a different name and nobody was authorised to substitute it.
Naming the equivalents you accept is a free lead-time saving. Here is the cross-reference.
Cold work grades
| AISI/ASTM | JIS | DIN / EN (W.Nr.) | GB (China) | Typical hardness |
|---|---|---|---|---|
| D2 | SKD11 | 1.2379 (X153CrMoV12) | Cr12MoV | 58-62 HRC |
| D3 | SKD1 | 1.2080 (X210Cr12) | Cr12 | 58-64 HRC |
| A2 | SKD12 | 1.2363 (X100CrMoV5) | Cr5Mo1V | 57-62 HRC |
| O1 | SKS3 | 1.2510 (100MnCrW4) | 9CrWMn | 57-62 HRC |
| O2 | SKS93 | 1.2842 (90MnCrV8) | 9Mn2V | 57-62 HRC |
D2 and Cr12MoV are close but not identical — the Chinese grade usually runs slightly lower carbon and vanadium. For most die work the difference is immaterial; for a high-wear production die it is worth asking for the mill certificate.
Hot work grades
| AISI/ASTM | JIS | DIN / EN (W.Nr.) | GB (China) | Typical hardness |
|---|---|---|---|---|
| H13 | SKD61 | 1.2344 (X40CrMoV5-1) | 4Cr5MoSiV1 | 44-52 HRC |
| H11 | SKD6 | 1.2343 (X37CrMoV5-1) | 4Cr5MoSiV | 44-52 HRC |
| H21 | SKD5 | 1.2581 (X30WCrV9-3) | 3Cr2W8V | 45-55 HRC |
H13 is the most widely stocked tool steel in Asia by a wide margin. If your design can tolerate it, specifying H13 rather than a less common hot work grade will almost always be faster.
Shock and high speed grades
| AISI/ASTM | JIS | DIN / EN (W.Nr.) | GB (China) | Typical hardness |
|---|---|---|---|---|
| S7 | — | 1.2357 (approx.) | 6CrW2Si (approx.) | 54-58 HRC |
| M2 | SKH51 | 1.3343 (HS6-5-2C) | W6Mo5Cr4V2 | 62-65 HRC |
| M42 | SKH59 | 1.3247 (HS2-9-1-8) | W2Mo9Cr4VCo8 | 65-68 HRC |
S7 is the awkward one — there is no exact DIN equivalent in common circulation, and the approximations differ enough in silicon and tungsten to change the heat treat response. If the part is genuinely shock critical, specify S7 to the AISI standard and accept the import.
Mould and pre-hardened grades
| AISI/ASTM | JIS | DIN / EN (W.Nr.) | GB (China) | Supply hardness |
|---|---|---|---|---|
| P20 | — | 1.2311 (40CrMnMo7) | 3Cr2Mo | 28-34 HRC |
| P20+S | — | 1.2312 (40CrMnMoS8-6) | 3Cr2MnNiMo | 28-34 HRC |
| P20+Ni | — | 1.2738 (40CrMnNiMo8-6-4) | 3Cr2MnNiMo | 30-36 HRC |
| 4140 | SCM440 | 1.7225 (42CrMo4) | 42CrMo | 28-32 HRC |
| 420 | SUS420J2 | 1.2083 (X42Cr13) | 4Cr13 | 48-52 HRC |
1.2738 is the block-size version of P20 — nickel added for through-thickness uniformity in large sections. If you are buying a mould base over about 300 mm thick, this is what you want rather than plain 1.2311.
Stainless and bearing grades that end up in tooling
| AISI/ASTM | JIS | DIN / EN (W.Nr.) | GB (China) | Typical hardness |
|---|---|---|---|---|
| 440C | SUS440C | 1.4125 (X105CrMo17) | 11Cr17 | 56-60 HRC |
| 52100 | SUJ2 | 1.3505 (100Cr6) | GCr15 | 60-64 HRC |
| 17-4 PH | SUS630 | 1.4542 | 0Cr17Ni4Cu4Nb | 35-44 HRC |
How to write it on the drawing
Three formats, in decreasing order of usefulness to the shop:
Best: D2 / SKD11 / 1.2379 — equivalent grades acceptable, mill certificate required
Acceptable: D2 or equivalent
Costly: D2 with no further note, plus a general note forbidding substitution.
The first version tells the shop exactly what latitude they have. If a local service centre has 1.2379 in the right section, they cut this week. If your drawing forbids it, they import D2 and you wait.
When not to allow the substitution
There are cases where the equivalent is genuinely not good enough:
- Regulated or qualified tooling where the material spec is part of an approval.
- High-cycle production dies where a small composition difference translates into real wear life.
- Anything you have already validated on a specific grade and cannot revalidate.
In those cases say so explicitly and expect the lead time. Everywhere else, name the equivalents.
Put the acceptable equivalents in the material field when you send the RFQ — it is the single easiest line to write and one of the biggest levers on delivery date. The RFQ checklist covers the other six.