5120 vs 20MnCr5
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.
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
20MnCr5
Alloy & Engineering Steel
20MnCr5 is the European Mn-Cr carburizing steel for larger gears and shafts, with higher core strength than 16MnCr5.
Standards: DIN 1.7147 (20MnCr5) · AISI 5120 (near) · GB 20CrMnTi family (near)
Chemical composition compared (%)
| Element | 5120 | 20MnCr5 |
|---|---|---|
| C | 0.17–0.22 | 0.17–0.22 |
| Si | 0.15–0.35 | ≤0.40 |
| Mn | 0.70–0.90 | 1.10–1.40 |
| P | ≤0.035 | — |
| S | ≤0.040 | — |
| Cr | 0.70–0.90 | 1.00–1.30 |
Properties compared
| Property | 5120 | 20MnCr5 |
|---|---|---|
| Case hardness (carburized) | 58–62 HRC | 58–64 HRC |
| Core tensile strength | 600–850 MPa (typ.) | — |
| Density | 7.85 g/cm³ | 7.85 g/cm³ |
| Core tensile | — | 800–1100 MPa |
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: 5120 · 20MnCr5. Substitution decisions for certified parts stay with the design authority.