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Cr-Mo Steel Spec Table
Cr-Mo Steel KS Specifications — 4 sizes
KS D 3867
KSCr-Mo Steel
4 sizes| Name | Type | Tensile | Yield | Hardness | Use |
|---|---|---|---|---|---|
| SCM415 | Cr-Mo Steel | 830~1080 | ≥635 | HRC30~38 | Gear, Shaft, CarburizingParts, Pin |
| SCM420 | Cr-Mo Steel | 980~1180 | ≥785 | HRC32~40 | Gear, Shaft, Parts |
| SCM435 | Cr-Mo Steel | 930~1130 | ≥785 | HRC28~36 | High StrengthBolt, , Shaft |
| SCM440 | Cr-Mo Steel | 980~1180 | ≥835 | HRC30~38 | High StrengthBolt, , Gear |
SCM440 (KS/JIS) = 42CrMo4 (DIN) = 4140 (ANSI): equivalent high-strength alloy steels. Achieves over 1000 MPa tensile strength after quenching and tempering.
Practical Notes
- SCM440 achieves ≥1000MPa tensile after Q&T. Primary material for high-strength bolts (grade 10.9).
- Normalizing before heat treatment is recommended. Grain refinement improves toughness.
Key Features
- SCM435/440 equivalent to DIN 34CrMo4/42CrMo4 and ANSI 4135/4140; standard high-strength alloy steels
- Cr+Mo additions provide excellent hardenability and toughness; uniform hardening even in thick cross-sections
- SCM415/420 are for carburizing; SCM435/440 are used as QT-treated high-strength components
Key Applications
High-strength bolts, gear shafts, crankshafts, aircraft structural members, machine tool spindles
FAQ
Difference between SCM435 and SCM440?
Carbon content difference. SCM435 (C=0.33–0.38%) slightly better weldability; SCM440 (C=0.38–0.43%) higher strength. SCM440 is standard for grade 10.9 bolts.