SKS3
Data verifiedSKS3 is the JIS oil-hardening alloy tool steel — the Japanese counterpart of AISI O1 / DIN 1.2510, a Mn-Cr-W grade that hardens in oil with low distortion for gauges and short-run cold work tooling.
Chemical composition
| Element | Content (%) |
|---|---|
| C | 0.90–1.00 |
| Si | ≤0.35 |
| Mn | 0.90–1.20 |
| P | ≤0.030 |
| S | ≤0.030 |
| Cr | 0.50–1.00 |
| W | 0.50–1.00 |
Weight percent, per the governing standard ranges. Actual values per heat are on the mill certificate.
Properties
| Delivery condition | Annealed |
| Hardness (hardened) | 58–62 HRC |
| Density | 7.85 g/cm³ |
Heat treatment
Harden 800–850 °C oil; temper 150–250 °C. Simple, forgiving oil hardening.
Equivalent grades
| Standard | Designation |
|---|---|
| din | 1.2510 (105WCr6, near) |
| aisi | O1 |
| jis | SKS3 (JIS G4404) |
| gb | 9CrWMn |
Compare side by side: SKS3 vs O1
Equivalents overlap in chemistry and use but are not always identical — see our equivalents guide before substituting in certified designs.
Applications & Processing
Applications: Gauges, measuring tools, bushings, short-run blanking and forming dies, taps and hand tools.
Processing: Machines well annealed; oil hardening with modest, predictable size change — the reason it stays popular for precision gauges.
FAQ
- SKS3 = O1?
- Counterpart grades: SKS3 allows slightly wider Cr and W windows (0.50–1.00% each) and omits O1’s small vanadium addition, but hardening practice and working hardness are the same.
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Ask for a quotationVisit NasteelSource: JIS G4404 published ranges · Last updated 2026-11-03. Data is indicative — verify critical values against the governing standard and mill certificate before use.