17CrNiMo6 or 18CrNiMo7-6 on the certificate?

Same steel family: 17CrNiMo6 is the older DIN 17210 name, 18CrNiMo7-6 (1.6587) is the current EN 10084 name with marginally wider C and Mn ranges. Mills commonly dual-certify.

Grades · Alloy & Engineering Steel · 17CrNiMo6

17CrNiMo6

Data under review

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.

DIN17CrNiMo6 (DIN 17210; EN successor 18CrNiMo7-6, 1.6587)

AISI4320 (near)

CategoryAlloy & Engineering Steel

Chemical composition

Element	Content (%)
C	0.14–0.19
Si	≤0.40
Mn	0.40–0.70
P	≤0.025
S	≤0.035
Cr	1.50–1.80
Ni	1.40–1.70
Mo	0.25–0.35

Weight percent, per the governing standard ranges. Actual values per heat are on the mill certificate.

Properties

Case hardness (carburized)	58–62 HRC
Core tensile strength	900–1200 MPa (typ.)
Density	7.85 g/cm³

Heat treatment

Carburize 900–940 °C; quench 800–830 °C oil; temper 150–200 °C.

Equivalent grades

Standard	Designation
din	17CrNiMo6 (DIN 17210; EN successor 18CrNiMo7-6, 1.6587)
aisi	4320 (near)

Compare side by side: 17CrNiMo6 vs 18CrNiMo7-6 · 17CrNiMo6 vs 4320

Equivalents overlap in chemistry and use but are not always identical — see our equivalents guide before substituting in certified designs.

Applications & Processing

Applications: Large transmission and wind-energy gears, heavy pinions, marine gearing.

Processing: Deep, uniform case in big sections; grind after hardening; check which designation the drawing cites before ordering.

FAQ

17CrNiMo6 or 18CrNiMo7-6 on the certificate?: Same steel family: 17CrNiMo6 is the older DIN 17210 name, 18CrNiMo7-6 (1.6587) is the current EN 10084 name with marginally wider C and Mn ranges. Mills commonly dual-certify.

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Source: DIN 17210 / EN 10084 published ranges · Last updated 2026-11-03. Data is indicative — verify critical values against the governing standard and mill certificate before use.