18CrNiMo7-6 (1.6587) is a case-hardening steel to EN 10084 with 0.15–0.21% carbon, 1.50–1.80% chromium, 1.40–1.70% nickel and 0.25–0.35% molybdenum. The nickel and molybdenum give a tough core and good hardenability in large sections. It is the usual choice for heavy gears and pinions, wind turbine and industrial gearbox shafts, mining machinery gears, large transmission shafts and rail drive components. It was formerly designated 17CrNiMo6.
OneKaizen supplies 18CrNiMo7-6 as forged bars (round Ø 250–1,030 mm), rolled round bars (Ø 16–500 mm), gear blanks (OD 100–1,000 mm), shafts (Ø 25–500 mm) and special forgings, sourced from Indian and international mills and forges. Delivery condition is hot rolled, forged, soft annealed, normalised or annealed (+FP). OneKaizen also machines parts to drawing through partner machine shops.
EQUIVALENT GRADES
18CrNiMo7-6 Equivalents
Direct means the same grade under another name. Close means the same alloy concept with slightly different limits, commonly substituted. Approximate means similar use with real differences: check with us before substituting.
| Standard | Designation | Match |
|---|---|---|
| EN | 18CrNiMo7-6 (1.6587) | Direct |
| DIN W.Nr. | 1.6587 | Direct |
| DIN W.Nr. | 17CrNiMo6 (1.6587) | Direct |
| AISI/SAE | 4320 | Approximate |
| AISI/SAE | 9310 | Approximate |
| JIS | SNCM420 | Approximate |
| GB | 20CrNi2Mo | Approximate |
| UNI | 18CrNiMo7-6 | Direct |
| UNE | 18CrNiMo7-6 | Direct |
| TS | 18CrNiMo7-6 | Direct |
18CrNiMo7-6 Chemical Composition
Per EN 10084 (18CrNiMo7-6)
| Element | Range, wt % | Range chart |
|---|---|---|
| C | 0.15 – 0.21 | |
| Si | ≤ 0.4 | |
| Mn | 0.5 – 0.9 | |
| P | ≤ 0.025 | |
| S | ≤ 0.035 | |
| Cr | 1.5 – 1.8 | |
| Mo | 0.25 – 0.35 | |
| Ni | 1.4 – 1.7 |
Delivery Condition and Heat Treatment
18CrNiMo7-6 is supplied soft annealed or annealed (+FP) so that you can machine gears and shafts before heat treatment. It is also available hot rolled, forged or normalised.
After machining, the part is carburised to build a hard case, then quenched and tempered. The case resists wear and pitting, and the core stays tough. Case depth and core hardness depend on your drawing and process.
This grade is not normally welded, as the carburised case and the alloy content make welds prone to cracking. Parts are forged and machined to shape instead.
What We Supply 18CrNiMo7-6 In
Where 18CrNiMo7-6 Is Used
Industries: Wind energy, Industrial gearboxes, Mining and construction equipment, Rail, Heavy machinery
Compare 18CrNiMo7-6 with Similar Grades
| 18CrNiMo7-6 | SAE 8620 | SAE 4320 | 20MnCr5 | |
|---|---|---|---|---|
| Why consider it | This grade | Lighter section alternative | Nearest SAE grade | Lower cost alternative |
| C % | 0.15–0.21 | 0.18–0.23 | 0.17–0.22 | 0.17–0.22 |
| Si % | ≤ 0.4 | 0.15–0.35 | – | ≤ 0.4 |
| Mn % | 0.5–0.9 | 0.7–0.9 | 0.45–0.65 | 1.1–1.4 |
| Cr % | 1.5–1.8 | 0.4–0.6 | 0.4–0.6 | 1–1.3 |
| Mo % | 0.25–0.35 | 0.15–0.25 | 0.2–0.3 | – |
| Ni % | 1.4–1.7 | 0.4–0.7 | 1.65–2 | – |
18CrNiMo7-6 Questions
Is 18CrNiMo7-6 the same as 17CrNiMo6?
Yes. 17CrNiMo6 is the old designation for 1.6587, which is now 18CrNiMo7-6 in EN 10084. Orders against either name are supplied to the same grade.
Is 18CrNiMo7-6 the same as SAE 4320 or JIS SNCM420?
No. SAE 4320 and JIS SNCM420 are only approximate matches, with lower chromium and nickel. Tell us if your drawing allows a substitute.
What is the difference between 18CrNiMo7-6 and SAE 8620?
SAE 8620 has less alloy and is the lighter section alternative. 18CrNiMo7-6 has more chromium, nickel and molybdenum, so it keeps a hard case and tough core in large gears and shafts.
How is 18CrNiMo7-6 heat treated?
It is machined soft, then carburised, quenched and tempered. We supply it soft annealed or annealed (+FP). Welding is not normally done.
What is 18CrNiMo7-6 used for?
Heavy gears and pinions, wind turbine and industrial gearbox shafts, mining machinery gears, large transmission shafts and rail drive components.
What is the minimum order for 18CrNiMo7-6?
3 tonnes, flexible depending on size and your situation. Send us your size, condition and quantity and we confirm availability and delivery.
What is 18CrNiMo7-6 equivalent to?
18CrNiMo7-6 is the same grade as EN 18CrNiMo7-6, DIN W.Nr. 1.6587, DIN W.Nr. 17CrNiMo6, UNI 18CrNiMo7-6.
In which forms do you supply 18CrNiMo7-6?
OneKaizen supplies 18CrNiMo7-6 as Forged Bars, Round Bars, Gear Blanks, Forgings & Special Components, Shafts, delivered across India and exported to buyers abroad.
Do you supply 18CrNiMo7-6 with a mill test certificate?
Yes. Every lot ships with an EN 10204 3.1 mill test certificate showing chemistry and mechanical properties, traceable to the heat number.
Data compiled by the OneKaizen metallurgy team from the standards named above. Updated 27 October 2026. Equivalents are nearest matches; confirm critical substitutions against the governing standard and mill certificate.