HS6-5-2-5
1.3243Standard cobalt high speed steel with 5% Co — the most widely used cobalt HSS grade. Also known as M35 or HSS-E/HSSE. Better hot hardness and cutting performance than M2, lower cost than M42. HRC 64-66 hardened. The "go-to upgrade" when M2 performance is insufficient. Used for drill bits (HSS-Co branded), taps, end mills, saw blades, and general-purpose cutting tools for stainless steel and medium-hard alloys.
International equivalents
| Flag | Standard | Country | Grade | Number | Match |
|---|---|---|---|---|---|
| 🇺🇸 | AISI | USA | AISI M35 / UNS T11335 | T11335 | REF |
| 🇪🇺 | EN | Europe | HS6-5-2-5 / 1.3243 | 1.3243 | 100% |
| 🇯🇵 | JIS | Japan | SKH55 | — | 100% |
Sources: ASTM A600, EN ISO 4957, JIS G4403
Mechanical properties — Pro
Hardened Tempered
| Property | Value | Unit |
|---|---|---|
| Hardness HRC | ||
| Elastic Modulus | ||
| Density |
Annealed
| Property | Value | Unit |
|---|---|---|
| Hardness HB |
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