4161 vs 4145
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.
4161
Alloy & Engineering Steel
4161 is a spring-range Cr-Mo steel: 5160-class carbon and chromium with molybdenum added for temper resistance and through-hardening in thicker spring sections. It is less commonly stocked than 5160 but specified for heavier springs.
Standards: DIN 61SiCr7 is Si-type (near family) · AISI 4161 · JIS SUP9 family (near) · GB 60CrMnMoA (near)
4145
Alloy & Engineering Steel
4145 is the high-carbon end of the standard Cr-Mo bar family, widely specified in oilfield practice (drill collars, subs) where 4140 hardness is not enough. The modified 4145H chemistry used by the oil industry is a related but distinct supply grade.
Standards: AISI 4145
Chemical composition compared (%)
| Element | 4161 | 4145 |
|---|---|---|
| C | 0.56–0.64 | 0.43–0.48 |
| Si | 0.15–0.35 | 0.15–0.35 |
| Mn | 0.75–1.00 | 0.75–1.00 |
| P | ≤0.035 | ≤0.035 |
| S | ≤0.040 | ≤0.040 |
| Cr | 0.70–0.90 | 0.80–1.10 |
| Mo | 0.25–0.35 | 0.15–0.25 |
Properties compared
| Property | 4161 | 4145 |
|---|---|---|
| Hardness (spring temper) | 40–50 HRC typical | — |
| Tensile strength | 1200–1500 MPa (Q&T spring temper, typ.) | 950–1200 MPa (Q&T, typ.) |
| Density | 7.85 g/cm³ | 7.85 g/cm³ |
| Hardness (Q&T) | — | 32–44 HRC typical |
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: 4161 · 4145. Substitution decisions for certified parts stay with the design authority.