SKD11 and D2 properties
A high-carbon, high-chromium cold-work tool steel. It air hardens, has very high wear resistance and stays dimensionally stable through heat treatment. Toughness is low by design, so it's used for cutting and forming, and kept away from shock loads.
- TypeCold-work tool steel, roughly 1.4–1.6 % C with 11–13 % Cr, plus molybdenum and vanadium
- StandardsJIS G4404 SKD11 · AISI D2 · UNS T30402 · EN X153CrMoV12 (1.2379) · GB Cr12Mo1V1
- Density7.70 g/cm³
- AnnealedTypically 217–255 HB as supplied. This is the condition we machine in
- HardenedTypically 58–62 HRC after harden and temper. Higher is possible and costs toughness
- HardeningAir hardening, which is why it moves less in heat treatment than an oil-hardening grade
- WearVery high, from the chromium carbides. This is the property you are buying
- ToughnessModerate at best. Not for impact, shock loading or hot work
- CorrosionNone worth relying on. The 12 % chromium is locked up in carbides and does little for the surface
- CertificateMill test certificate to EN 10204 3.1 on request, plus our own hardness reading
Cr12MoV is not D2. It's a Chinese cold-work grade with different carbon, molybdenum and vanadium, and it's widely offered as D2 or SKD11 across the region. The true GB equivalent is Cr12Mo1V1. When your drawing calls for D2, SKD11 or 1.2379, we check the mill certificate against the composition before we buy. A die cut from the wrong steel is the one that chips early.
SKD11 and the grades sold as it
| Grade | JIS (Japan) | US (ASTM / AISI / UNS) | GB/T (China) | EN / DIN (Europe) | Cross-reference |
|---|---|---|---|---|---|
| SKD11 the JIS designation | SKD11 (JIS G4404) | D2 · UNS T30402 · ASTM A681 | Cr12Mo1V1 (GB/T 1299) | X153CrMoV12 · EN 1.2379 | Standard equivalent |
| Cr12MoV the common local substitute | No JIS equivalent | Not D2 (different C, Mo and V) | Cr12MoV (GB/T 1299) | No clean EN equivalent | Check the MTC |
| SKD61 hot work, tougher | SKD61 (JIS G4404) | H13 · UNS T20813 | 4Cr5MoSiV1 | X40CrMoV5-1 · EN 1.2344 | Standard equivalent |
| SKS3 oil hardening, cheaper | SKS3 (JIS G4404) | O1 · UNS T31501 | 9CrWMn | 100MnCrW4 · EN 1.2510 | Standard equivalent |
Designations taken from JIS G4404, ASTM A681, GB/T 1299 and EN ISO 4957. SKD61 and SKS3 are listed because they're the two grades most often proposed as alternatives: SKD61 when the tool takes impact or heat, SKS3 when budget is tight and the run is short. Last reviewed 13 September 2026.
Typical SKD11 and D2 applications
Blanking and forming dies
Punches, dies, stripper plates and forming inserts on long production runs in sheet steel. The chromium carbides take the abrasion.
Mould components and wear parts
Slides, inserts, gauges, guide blocks and slitter knives. Wire cut after hardening and ground to size, which is the route we run most.
Not for impact or shock
SKD11 chips before it bends. A punch that hammers instead of shearing, or a tool that takes side load, needs a tougher grade such as SKD61 or an S-series shock-resisting steel.
Not for hot work
It softens and cracks under thermal cycling. Die casting, hot forging and extrusion tooling should be SKD61 / H13, which is made for that duty.
Not a corrosion-resistant steel
The chromium is tied up in carbides. SKD11 rusts in humid storage like any tool steel, so it needs oil, VCI packing or a coating between operations and in the container.
Do not machine it hardened unless you have to
Roughing hardened SKD11 with cutters is slow and expensive. We machine it annealed, harden it, then wire cut and grind the features that must hold size.
Machining process
On this steel the route matters more than the tooling. The part is machined annealed, hardened, then EDM cut and ground, with stock left on purpose on the features that have to be exact.
- SequenceMachine annealed · leave grinding stock · harden and temper · wire cut and grind to size
- MillingDoosan, Haas, Hision and FANUC RoboDrill machining centres, 3, 4 and 5-axis, in the annealed condition
- Wire EDMSodick wire cut through hardened material to ±0.003 mm, for sharp internal corners and tight radii
- Die sinkSodick die-sink EDM for cavities and features a cutter cannot reach
- GrindingOkamoto and Chevalier surface and NC grinding to 500 × 200 × 250 mm, ±0.005 mm typical
- StockTypically 0.2–0.5 mm left on ground faces before hardening, because the part grows and moves slightly
- HardnessEvery hardened batch checked on our Mitutoyo QMH 14BX before packing, and the reading reported
- InspectionMitutoyo CRYSTA-APEX V CMM in a climate-controlled lab, reported in inch and millimetre
Typical figures from normal production, not a blanket specification. On a hardened part they apply to the features cut or ground after heat treatment, so mark those features on the drawing. If a die needs a polished EDM surface instead of an as-cut one, say so. EDM leaves a recast layer, taking it off means stoning or polishing, and that's an extra operation with its own price.
Hardening and surface
- HardenHarden and temper to the drawing hardness, checked on our Mitutoyo QMH 14BX before shipping
- CryogenicDeep freeze between tempers where the drawing calls for maximum dimensional stability
- Stress reliefAfter heavy roughing and before hardening, so the part does not move on the finishing cuts
- PolishingStoning and polishing of EDM surfaces where the recast layer must come off
- PVDTiN, TiCN and similar coatings, where die life is the objective
- Black oxideLight protection on tooling that's stored between runs
- PackingOiled, VCI paper and film, foam partitioned. Ground faces are protected individually
A hardness number on its own does not specify a die. The tempering temperature sets the balance between hardness and toughness. 62 HRC wears better than 58 HRC and is also more brittle, so harder is not automatically better. Tell us what the tool does and the hardness range you want, and we'll specify the cycle to match. Full finishing and heat treatment list →
Stock and lead time
- Flat and blockAnnealed SKD11 flat stock and blocks available from Vietnamese tool steel suppliers
- Round barAvailable in common diameters; large sections confirmed per job
- VerificationMill certificate checked against the composition before purchase where the drawing names D2, SKD11 or 1.2379
- QuoteWithin 24 business hours of a complete RFQ
- Lead timeStandard 14 days after PO plus one hardening cycle and the grinding that follows it
- CertificateEN 10204 3.1 mill certificate on request, plus our own hardness reading on the hardened batch
Cr12MoV and SKD11 look identical in the rack, and the price difference is real. We check the mill certificate before purchase and do not use Cr12MoV against a D2 drawing without your written approval.
Common questions
Is SKD11 the same as D2?
Yes. SKD11 to JIS G4404, AISI D2 and EN 1.2379 cross-reference as standard equivalents. The one to watch is Cr12MoV, a different Chinese steel that's commonly offered as D2.
How do you know the material really is D2?
We check the composition on the mill certificate against the standard before purchase. If what's available locally does not meet it, nothing is bought without your written approval.
What hardness should I specify?
58 to 62 HRC covers most cold-work tooling. Going harder gives more wear resistance and more brittleness. Tell us what the tool does (shearing, forming, guiding) and we'll suggest a range.
Can you machine SKD11 in the hardened condition?
Features that have to be cut after hardening go on Sodick wire and die-sink EDM and Okamoto grinding, not on cutters. Roughing hardened tool steel with an end mill can be done, but it's rarely sensible.
Does the part change size when it's hardened?
Slightly. SKD11 moves less than most grades because it air hardens, but we still leave 0.2–0.5 mm of grinding stock on faces that have to be exact.
Do you check the hardness before shipping?
Yes, every hardened batch, on our Mitutoyo QMH 14BX micro hardness tester. The reading goes out with the inspection documents.
My die is chipping. Is SKD11 the wrong grade?
Possibly. Chipping usually means the tool is taking impact or side load that a high-carbon, high-chromium steel cannot absorb, and that points to SKD61 or a shock-resisting grade. Send the tool drawing and a photo of the failure with the RFQ.
Related information
4140 / SCM440 alloy steel
The loaded structural steel. It hardens through the section and stays tough where tool steel is brittle.
17-4PH stainless steel
When a hardened part also has to resist corrosion, and ageing replaces quenching.
Finishing and heat treatment
The full heat treatment table, including tool steel hardening and the hardness we check before shipping.