40CrMnMoS8-6
1.2312Free-machining variant of 40CrMnMo7 (1.2311/P20) — sulfur addition (0.05-0.10%) for significantly improved machinability. Same pre-hardened delivery condition (28-32 HRC). 30-40% faster machining than 1.2311. Slight trade-off in polishability due to MnS inclusions. Used where machining cost matters more than mirror polish: large mold frames, structural mold components, and prototype molds.
International equivalents
| Flag | Standard | Country | Grade | Number | Match |
|---|---|---|---|---|---|
| 🇺🇸 | AISI | USA | P20+S (modified) | — | REF |
| 🇪🇺 | EN | Europe | 40CrMnMoS8-6 / 1.2312 | 1.2312 | 100% |
Sources: ASTM A681, EN ISO 4957
Chemical composition comparison (wt%)
Side-by-side: 40CrMnMoS8-6 (EN) (EN ISO 4957) vs 40CrMnMoS8-6 / 1.2312 (EN) (EN ISO 4957)
| Element | 40CrMnMoS8-6 (EN) | 40CrMnMoS8-6 / 1.2312 (EN) | Overlap |
|---|---|---|---|
| C | 0.35–0.45% | 0.35–0.45% | OK |
| Si | 0.2–0.4% | 0.2–0.4% | OK |
| Mn | 1.3–1.6% | 1.3–1.6% | OK |
| S | 0.05–0.1% | 0.05–0.1% | OK |
| Cr | 1.8–2.1% | 1.8–2.1% | OK |
| Mo | 0.15–0.25% | 0.15–0.25% | OK |
Mechanical properties
Pre-hardened (delivered)
| Property | Value | Unit |
|---|---|---|
| Tensile Strength | 900–1050 | MPa |
| Hardness HRC | 28–32 | HRC |
| Elastic Modulus | ≥ 210 | GPa |
| Density | ≥ 7.85 | g/cm3 |
Compatibility verdict
40CrMnMoS8-6 and 40CrMnMoS8-6 / 1.2312: 100% 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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