HS6-5-2
1.3343The most widely used high-speed steel worldwide, known as AISI M2. Contains 6% W, 5% Mo and 2% V providing excellent red hardness (retains cutting ability at 600°C+), high wear resistance and good toughness. Hardened to 62–65 HRC. Standard material for twist drills, milling cutters, taps, reamers, broaches, saw blades, cold forming tools and punches. PM (powder metallurgy) variants available for improved toughness and grindability.
International equivalents
| Flag | Standard | Country | Grade | Number | Match |
|---|---|---|---|---|---|
| 🇺🇸 | AISI | USA | M2 | T11302 | REF |
| 🇯🇵 | JIS | Japan | SKH51 | — | 95% |
Sources: ASTM A600, JIS G4403
Chemical composition comparison (wt%)
Side-by-side: HS6-5-2 (EN) (EN ISO 4957) vs SKH51 (JIS)
| Element | HS6-5-2 (EN) | SKH51 (JIS) | Overlap |
|---|---|---|---|
| C | 0.8–0.88% | — | — |
| Si | ≤ 0.45% | — | — |
| Mn | ≤ 0.4% | — | — |
| P | ≤ 0.03% | — | — |
| S | ≤ 0.02% | — | — |
| Cr | 3.8–4.5% | — | — |
| Mo | 4.7–5.2% | — | — |
| V | 1.7–2.1% | — | — |
| W | 5.9–6.7% | — | — |
Mechanical properties
Annealed
| Property | Value | Unit |
|---|---|---|
| Hardness HB | ≤ 255 | HB |
Hardened + Tempered
| Property | Value | Unit |
|---|---|---|
| Hardness HRC | 62–65 | HRC |
General
| Property | Value | Unit |
|---|---|---|
| Density | 8.16 | g/cm³ |
Heat treatment
| Process | Temperature | Medium | Holding Time | Notes |
|---|---|---|---|---|
| Soft annealing | 820–860 °C | Furnace cooling | — | Cool 20°C/h, max 230 HB |
| Hardening | 1180–1220 °C | Oil/Salt bath/Vacuum | — | Preheat 450°C then 850°C, soak 2-5 min at austenitizing |
| Tempering | 540–580 °C | Air | — | Triple temper 1h each, 62-65 HRC |
Compatibility verdict
HS6-5-2 and SKH51: 95% composition match
Close equivalents but NOT identical.
Related materials
P20 / 40CrMnMo7
1.2311Pre-hardened plastic mold steel (usually delivered at 28-34 HRC). The most widely used mold base steel globally. Good machinability in pre-hardened condition, good polishability. Used for injection molds, die-casting dies, extrusion tooling, and structural mold components.
M2 / HS6-5-2
1.3343The most widely used high-speed steel worldwide. W-Mo-Cr-V composition gives excellent red hardness (cuts at temperatures up to 600°C). Used for twist drills, end mills, taps, reamers, bandsaw blades, and general-purpose cutting tools. The benchmark HSS grade.
X45NiCrMo4
1.2767Nickel cold-work tool steel with exceptional toughness from ~4% Ni content. Excellent through-hardenability, polishability, and impact resistance. Used for plastic injection molds (high-gloss), embossing dies, scrap shear blades, punches, cutlery dies, and bending tools.
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