SCr420 vs 5120
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.
SCr420
Alloy & Engineering Steel
SCr420 is the chromium-only carburizing steel of JIS G4053, the Japanese counterpart of AISI 5120. Without molybdenum it is the economy case steel for small gears and shafts in Japanese and Asian drivetrains.
Standards: DIN 1.7027 (20Cr4, near) · AISI 5120 · JIS SCr420 (JIS G4053) · GB 20Cr
5120
Alloy & Engineering Steel
5120 is a chromium case-hardening steel for small gears and wear parts. With about 0.8% chromium it forms a hard carburized case over a tougher core than plain carbon carburizing grades give.
Standards: DIN 1.7027 (20Cr4, near) · AISI 5120 · JIS SCr420 · GB 20Cr
Chemical composition compared (%)
| Element | SCr420 | 5120 |
|---|---|---|
| C | 0.18–0.23 | 0.17–0.22 |
| Si | 0.15–0.35 | 0.15–0.35 |
| Mn | 0.60–0.90 | 0.70–0.90 |
| P | ≤0.030 | ≤0.035 |
| S | ≤0.030 | ≤0.040 |
| Cr | 0.90–1.20 | 0.70–0.90 |
Properties compared
| Property | SCr420 | 5120 |
|---|---|---|
| Case hardness (carburized) | 58–63 HRC | 58–62 HRC |
| Density | 7.85 g/cm³ | 7.85 g/cm³ |
| Core tensile strength | — | 600–850 MPa (typ.) |
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: SCr420 · 5120. Substitution decisions for certified parts stay with the design authority.