EN36 and SAE 8620 are both case hardening steels — carburised to a hard, wear-resistant surface over a tough core. The difference is nickel: EN36 carries 3.00–3.75%, 8620 carries 0.35–0.75%. That single difference decides core strength, toughness and cost, and it is the deciding factor when specifying gears, pinions and camshafts.
| Property | EN36 (655M13 / 14NiCr14) | 8620 (805M20 / 20NiCrMo2-2) |
|---|---|---|
| Carbon content | 0.08–0.16% | 0.17–0.23% |
| Nickel content | 3.00–3.75% | 0.35–0.75% |
| Other key additions | Cr 0.60–1.00% | Cr 0.35–0.65%, Mo 0.15–0.25% |
| Case hardness | 58–63 HRC | 58–62 HRC |
| Core tensile after case hardening | ~930–970 N/mm² | ~620–800 N/mm² |
| Core yield after case hardening | ~700–720 N/mm² | ~375–550 N/mm² |
| Core toughness / shock resistance | Excellent — high-Ni core | Good |
| Large-section suitability | Better — Ni aids deep hardenability | Standard sections |
| Machinability before hardening | Good | Very good |
| Relative cost | Higher (3.5% Ni premium) | Lower |
| Typical applications | Heavy-duty gears, aerospace & defence transmissions | Automotive gears, pinions, general case hardened parts |
| Specification family | BS 970 655M13 | SAE/AISI 8620 — global standard |
| DIN equivalent | 14NiCr14 | 20NiCrMo2-2 |
| 3.1 cert available | Yes | Yes |
After carburising and hardening, both grades reach a near-identical surface hardness — around 58–63 HRC. The wear surface is not where they differ. The difference is underneath: EN36's 3.5% nickel core reaches roughly 930–970 N/mm² tensile, where 8620's core sits at roughly 620–800 N/mm².
8620's advantages are economic and practical: it is the global automotive standard, it machines slightly more freely before hardening, and the nickel premium is avoided. For the majority of case hardened components — standard gears, pinions, sprockets, kingpins — 8620's core properties are entirely sufficient.
Need an even higher specification? EN36C (832M13) adds molybdenum to the EN36 chemistry — the highest specification case hardening grade we stock. For the full picture, see the grade selector tool.
EN36 and SAE 8620 case hardening bar from stock at Sherwood Park. Cut to length from one piece. 3.1 certs available on both.