SCM415 vs SCM420
These two grades are listed as equivalents of each other: their chemistry windows overlap and they serve the same applications. They are not always identical — check the differences below before substituting, especially in certified designs.
SCM415
Alloy & Engineering Steel
SCM415 is the low-carbon Cr-Mo carburizing steel of JIS G4053 — the Japanese gear and pinion grade in the AISI 4118 class. Its 0.15% carbon core stays tough after carburizing while the case reaches the low-60s HRC.
Standards: DIN 1.7262 (15CrMo5, near) · AISI 4118 (near) · JIS SCM415 (JIS G4053) · GB 15CrMo (near)
SCM420
Alloy & Engineering Steel
SCM420 is the 0.20% carbon Cr-Mo carburizing steel of JIS G4053 (AISI 4120 class) — the standard Japanese grade for medium gears and transmission shafts that need a wear-resistant case over a stronger core than SCM415 gives.
Standards: DIN 20CrMo4 type (near) · AISI 4120 (near) · JIS SCM420 (JIS G4053) · GB 20CrMo (near)
Chemical composition compared (%)
| Element | SCM415 | SCM420 |
|---|---|---|
| C | 0.13–0.18 | 0.18–0.23 |
| Si | 0.15–0.35 | 0.15–0.35 |
| Mn | 0.60–0.85 | 0.60–0.90 |
| P | ≤0.030 | ≤0.030 |
| S | ≤0.030 | ≤0.030 |
| Cr | 0.90–1.20 | 0.90–1.20 |
| Mo | 0.15–0.25 | 0.15–0.25 |
Properties compared
| Property | SCM415 | SCM420 |
|---|---|---|
| Case hardness (carburized) | 58–63 HRC | 58–63 HRC |
| Core tensile | ≥835 MPa (Q&T reference) | — |
| Density | 7.85 g/cm³ | 7.85 g/cm³ |
Sourcing either grade?
Nasteel stocks both families from Shenzhen with EN 10204 3.1 mill certificates by heat number.
Ask for a quotationSee full data sheets: SCM415 · SCM420. Substitution decisions for certified parts stay with the design authority.