D2 vs H13: which one is harder to machine, and why it matters to your quote
Buyers often treat D2 and H13 as interchangeable “hard steels” because both land around 50-58 HRC in service. On a quote sheet they are not close, and the reason is what is in the matrix rather than what the hardness tester reads.
D2 (SKD11, 1.2379): abrasive by design
D2 is a high-carbon, high-chromium cold work steel — roughly 1.5% C and 12% Cr. That chromium forms large carbides, and those carbides are what make it hold an edge in a blanking die. They are also what chews through cutting tools.
- Machinability soft-annealed: poor, roughly 50-60% of 4140.
- Machined hard at 58-62 HRC: CBN territory, low DOC, expect real tool cost in the quote.
- Dimensionally stable through heat treat, which is why die makers accept the grief.
The practical consequence is tool consumption. A shop quoting D2 honestly is pricing inserts as a line item, not absorbing them.
H13 (SKD61, 1.2344): tougher, gummier
H13 is a hot work steel — about 0.4% C, 5% Cr, with vanadium and molybdenum. Fewer and finer carbides, more toughness, and it survives thermal cycling, which is why it ends up in die casting dies and extrusion tooling.
- Machinability soft-annealed: fair, roughly 70-75% of 4140.
- Machined hard at 45-52 HRC: coated carbide handles it; CBN is usually unnecessary.
- More prone to built-up edge and smearing than D2 — finish depends on keeping the edge sharp.
H13 is generally the easier of the two to machine hard, but it is less forgiving on finish. D2 fights the tool; H13 fights the surface.
Side by side
| D2 / SKD11 / 1.2379 | H13 / SKD61 / 1.2344 | |
|---|---|---|
| Type | Cold work | Hot work |
| Carbon | ~1.5% | ~0.4% |
| Chromium | ~12% | ~5% |
| Typical working hardness | 58-62 HRC | 45-52 HRC |
| Dominant wear on tools | Abrasive | Adhesive / thermal |
| Hard machining tool | CBN | Coated carbide |
| Usual application | Blanking, forming, wear parts | Die casting, extrusion, hot forming |
What to put in the RFQ
Naming the grade is not enough on its own. The two lines that change the quote:
- The condition you are sending it in. Annealed bar, pre-hardened block, or already at final hardness — each routes to a different shop.
- The heat treat owner. If the shop hardens it, they carry the distortion risk and price it. If you harden it, they will not warranty dimensions after your oven.
Everything else — tolerance, finish, quantity — behaves the same as any other precision job.
Common substitutions
If lead time on a specific grade is the problem, there is usually a local equivalent sitting in a Vietnamese service centre already:
- D2 ≈ SKD11 ≈ 1.2379 ≈ Cr12MoV
- H13 ≈ SKD61 ≈ 1.2344 ≈ 4Cr5MoSiV1
- A2 ≈ SKD12 ≈ 1.2363
- O1 ≈ SKS3 ≈ 1.2510
Say on the RFQ whether an equivalent is acceptable. It is frequently the difference between a two-week and a seven-week delivery.