4145 vs 4150
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.
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
4150
Alloy & Engineering Steel
4150 is a 0.50% carbon Cr-Mo steel for parts needing high Q&T strength and wear resistance: gun barrels, heavy gears and high-load shafts. Its EN counterpart 50CrMo4 (1.7228) carries the same chemistry concept.
Standards: DIN 1.7228 (50CrMo4) · AISI 4150 · JIS SCM445 (near) · GB 50CrMo
Chemical composition compared (%)
| Element | 4145 | 4150 |
|---|---|---|
| C | 0.43–0.48 | 0.48–0.53 |
| 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 | 0.80–1.10 | 0.80–1.10 |
| Mo | 0.15–0.25 | 0.15–0.25 |
Properties compared
| Property | 4145 | 4150 |
|---|---|---|
| Hardness (Q&T) | 32–44 HRC typical | 34–46 HRC typical |
| Tensile strength | 950–1200 MPa (Q&T, typ.) | 1000–1250 MPa (Q&T, typ.) |
| 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: 4145 · 4150. Substitution decisions for certified parts stay with the design authority.