SCM420 vs SCM435
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.
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)
SCM435
Alloy & Engineering Steel
SCM435 is the JIS Cr-Mo through-hardening steel matching AISI 4135 and EN 34CrMo4 — one step below SCM440/4140 in carbon, with slightly easier welding and machining at nearly the same Q&T strength level. It is a staple of Japanese bolt, shaft and machinery production.
Standards: DIN 1.7220 (34CrMo4) · AISI 4135 · JIS SCM435 (JIS G4053) · GB 35CrMo
Chemical composition compared (%)
| Element | SCM420 | SCM435 |
|---|---|---|
| C | 0.18–0.23 | 0.33–0.38 |
| Si | 0.15–0.35 | 0.15–0.35 |
| Mn | 0.60–0.90 | 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 | 0.15–0.30 |
Properties compared
| Property | SCM420 | SCM435 |
|---|---|---|
| Case hardness (carburized) | 58–63 HRC | — |
| Density | 7.85 g/cm³ | 7.85 g/cm³ |
| Hardness (Q&T) | — | 28–38 HRC typical |
| Tensile strength | — | ≥930 MPa (Q&T reference) |
| Yield strength | — | ≥785 MPa (Q&T reference) |
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: SCM420 · SCM435. Substitution decisions for certified parts stay with the design authority.