Short answer: EN36A and EN36B are old BS 970 names for a 3% nickel-chromium case-hardening steel that is supplied today as 655M13. EN36C is the same family with 0.10–0.25% molybdenum added, and is supplied today as 832M13. If your drawing says EN36C or 832M13, you need the molybdenum grade; if it says EN36, EN36A, EN36B or 655M13, you need the plain nickel-chromium grade.
In this guide: Where the names come from · Side-by-side · What molybdenum changes · Equivalents · Applications · Which to buy · FAQ
Where the EN36A, EN36B and EN36C names come from
The "EN" numbers come from the original British Standard BS 970, which listed steels from EN1 to EN58. In the 1950s, suffix letters were added to create variations of a base grade — which is how EN36 became EN36A, EN36B and EN36C. In the 1970s the letters were replaced by six-character codes that describe the steel: in 655M13 and 832M13, the first three digits identify the alloy type, "M" means the steel is specified by mechanical properties, and "13" is the nominal carbon content (0.13%).
BS 970 itself was withdrawn in 2006, but both the EN names and the six-character codes are still used every day on Indian drawings and purchase orders — which is exactly why the variants get mixed up.
EN36A vs EN36B vs EN36C side by side
| Old name | BS 970 code today | Alloy type | Key point |
|---|---|---|---|
| EN36 / EN36A | 655M13 | 3% nickel-chromium | No molybdenum |
| EN36B | 655M13 | 3% nickel-chromium | Supplied against the same 655M13 code as EN36A |
| EN36C | 832M13 | 3% nickel-chromium-molybdenum | 0.10–0.25% Mo for higher hardenability |
Typical chemical composition of the two grades you can actually buy today:
| Element (%) | 655M13 (EN36A / EN36B) | 832M13 (EN36C) |
|---|---|---|
| Carbon (C) | 0.10–0.16 | 0.12–0.18 |
| Silicon (Si) | 0.10–0.40 | 0.10–0.35 |
| Manganese (Mn) | 0.35–0.60 | 0.30–0.60 |
| Nickel (Ni) | 3.00–3.75 | 3.00–3.75 |
| Chromium (Cr) | 0.70–1.00 | 0.80–1.20 |
| Molybdenum (Mo) | — | 0.10–0.25 |
Ranges vary slightly between sources and mill specifications; always check the certificate against the standard on your drawing. Full EN36C data is on our EN36C / 832M13 datasheet.
What the molybdenum in EN36C changes
All three are carburising steels: the part is machined, carburised to put extra carbon into the surface, then hardened and tempered. The result is a very hard, wear-resistant case over a tough core that can take shock loads. The high nickel content is what makes this family so tough.
The small molybdenum addition in EN36C increases hardenability — the depth to which the steel hardens when quenched. In practice that means:
- More uniform core strength in larger sections, where 655M13 may not harden fully through.
- Better resistance to temper embrittlement during heat treatment.
- A typical EN36C result of 60–62 HRC at the surface with a core of roughly 900–1200 MPa tensile strength.
For small, lightly loaded parts the difference is minor. For big gears, shafts and heavily shock-loaded parts, it is the reason EN36C is specified.
EN36 equivalent grades
| Standard | 655M13 (EN36A / EN36B) | 832M13 (EN36C) |
|---|---|---|
| BS 970 (old) | EN36, EN36A, EN36B | EN36C |
| European (EN 10084) | 15NiCr13 | 14NiCrMo13-4 / 1.6657 |
| German (DIN) | 14NiCr14 / 1.5752 | — |
| French (AFNOR) | — | 16NCD13 |
| Japanese (JIS) | SNC815 | — |
| US (SAE) | 3310 / 3415 (older grades) | 9310 is often quoted as the nearest match |
These are close equivalents, not exact matches. For safety-critical parts, order against the standard your customer specifies.
Applications
EN36 steels are chosen when a part needs a hard wearing surface and a core that will not crack under shock:
- Heavy-duty gears and pinions for trucks, tractors, mining and industrial gearboxes
- Crankshafts, gear shafts and camshafts
- Gudgeon pins, king pins, track rod pins and steering worms
- Roller-bearing components and cams
- Aircraft and defence gearing
For medium-duty gears and shafts, lower-nickel case-hardening steels such as EN353 and SAE 8620 are more economical. EN36C is the step up when loads, shock or section size demand it.
Which one should you buy?
- Drawing says EN36C or 832M13: buy EN36C / 832M13. Do not substitute 655M13 — it has no molybdenum.
- Drawing says EN36, EN36A, EN36B or 655M13: 655M13 is the direct match. EN36C is usually an acceptable upgrade, but get the substitution approved first.
- No grade fixed yet: for large sections or heavily shock-loaded gears, EN36C is the safer choice; for smaller parts, compare it against EN353 or SAE 8620 on cost.
- Supply condition: as-rolled bar is fine if you will normalise or anneal before machining; order annealed bar if you want to machine straight away.
- Always: check the mill test certificate for nickel and molybdenum — they are the quickest way to tell 655M13 and 832M13 apart.
EN36A, EN36B and EN36C: frequently asked questions
What is the difference between EN36A, EN36B and EN36C?
EN36A and EN36B are old BS 970 names for a 3% nickel-chromium case-hardening steel that is supplied today as 655M13. EN36C is the version with 0.10–0.25% molybdenum added, supplied today as 832M13. The molybdenum gives EN36C better hardenability in larger sections.
Is EN36C the same as 832M13?
Yes. 832M13 is the six-character BS 970 designation that replaced the old name EN36C. The closest European equivalent is 14NiCrMo13-4 (material no. 1.6657).
What is EN36 called in the BS 970 six-character system?
Plain EN36, EN36A and EN36B are all supplied as 655M13 today. Only EN36C, the molybdenum-bearing version, became 832M13.
Can EN36C be used in place of EN36A or 655M13?
Usually yes — EN36C has the same nickel and chromium plus molybdenum, so it hardens at least as well. Because heat-treatment response is not identical, get the substitution approved by whoever owns the drawing, especially for gears and safety parts.
What hardness does EN36C reach after case hardening?
Typically 60–62 HRC at the carburised surface, with a tough core of roughly 900–1200 MPa tensile strength. Actual values depend on section size and the heat-treatment cycle.
Do you stock EN36C in Mumbai?
Yes. We keep EN36C / 832M13 round bar from Ø14 to Ø205 mm in ready stock at Darukhana, Mumbai, in the as-rolled condition; annealed bar is supplied against orders. Minimum order is 100 kg and every dispatch comes with a mill test certificate.
Buy EN36C from Sai International
We keep EN36C / 832M13 round bar from Ø14 to Ø205 mm in ready stock at our Darukhana godown in Mumbai, in the as-rolled condition. Annealed EN36C is supplied against orders. Minimum order is 100 kg. Cutting is available if the balance piece is also taken, and is charged extra. Prices are ex-Darukhana; loading, transport and cartage are extra at actuals. Every dispatch comes with a mill test certificate.
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Values above are typical figures for guidance under BS 970 / EN 10084 and are not a guarantee; actual properties depend on size, heat treatment and heat. Please confirm suitability for your application with our team.