17CrNiMo6 vs 18CrNiMo7-6
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.
17CrNiMo6
Alloy & Engineering Steel
17CrNiMo6 is the classic German case-hardening steel for large, heavily loaded gears, now carried in EN 10084 as 18CrNiMo7-6 with a slightly widened carbon and manganese window. The two designations describe the same grade family under successive standards.
Standards: DIN 17CrNiMo6 (DIN 17210; EN successor 18CrNiMo7-6, 1.6587) · AISI 4320 (near)
18CrNiMo7-6
Alloy & Engineering Steel
18CrNiMo7-6 is the EN 10084 case-hardening steel (1.6587) for the largest, most heavily loaded gears in wind, marine and industrial service. Its high Cr-Ni-Mo content keeps case and core properties uniform in very large sections.
Standards: DIN 1.6587 (18CrNiMo7-6) · AISI 4320 (near)
Chemical composition compared (%)
| Element | 17CrNiMo6 | 18CrNiMo7-6 |
|---|---|---|
| C | 0.14–0.19 | 0.15–0.21 |
| Si | ≤0.40 | ≤0.40 |
| Mn | 0.40–0.70 | 0.50–0.90 |
| P | ≤0.025 | ≤0.025 |
| S | ≤0.035 | ≤0.035 |
| Cr | 1.50–1.80 | 1.50–1.80 |
| Ni | 1.40–1.70 | 1.40–1.70 |
| Mo | 0.25–0.35 | 0.25–0.35 |
Properties compared
| Property | 17CrNiMo6 | 18CrNiMo7-6 |
|---|---|---|
| Case hardness (carburized) | 58–62 HRC | 58–62 HRC |
| Core tensile strength | 900–1200 MPa (typ.) | 900–1200 MPa (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: 17CrNiMo6 · 18CrNiMo7-6. Substitution decisions for certified parts stay with the design authority.