4340 equivalent grades: ASTM, EN, JIS, GB, DIN
Cross-reference for 4340 across standard systems. Each match is graded so you can see how safe the substitution is. Nickel-chromium-molybdenum low-alloy steel, deep hardening — full 4340 data sheet.
Cross-reference table
| Grade | System | Match | Why / differences |
|---|---|---|---|
| 817M40 (EN24) | BS (superseded British) | Identical | BS 970 817M40: C 0.36–0.44, Ni 1.30–1.70, Cr 1.00–1.40, Mo 0.20–0.35. |
| 40CrNiMoA | GB/T (China) | Identical | GB/T 3077 40CrNiMoA: C 0.37–0.44, Ni 1.25–1.65, Cr 0.60–0.90, Mo 0.15–0.25 (Ni slightly lower). |
| 40KhN2MA | GOST (Russia/CIS) | Identical | GOST 4543 40KhN2MA: C 0.37–0.44, Ni 1.25–1.65, Cr 0.60–0.90, Mo 0.15–0.25. |
| SNCM439 | JIS (Japan) | Identical | JIS G4053 SNCM439: C 0.36–0.43, Ni 1.60–2.00, Cr 0.60–1.00, Mo 0.15–0.30. |
| 300M | AISI / SAE | Near | Si-V modified 4340 for 1900–2100 MPa (landing gear, high-strength bolts). |
| 4330V / 4330 Mod | AISI / SAE | Near | Lower-carbon (0.30 %) V-modified version with better weldability and toughness for oilfield and aerospace. |
| 34CrNiMo6 | EN (European) | Near | 1.6582: C 0.30–0.38, Ni 1.30–1.70, Cr 1.30–1.70, Mo 0.15–0.30 — lower carbon/nickel, higher chromium; similar hardenability and strength; the standard European substitute. |
| 36CrNiMo4 | EN (European) | Near | 1.6511: C 0.32–0.40, Ni 0.90–1.20, Cr 0.90–1.20, Mo 0.15–0.30 — closer on Cr, lower Ni. |
| 4140 | AISI / SAE | Functional | Ni-free: same carbon, lower hardenability and toughness; adequate below ~75 mm and 1200 MPa. |
Identical = same composition and mechanical limits within rounding. Near = one limit differs (e.g. carbon max or impact temperature). Functional = interchangeable for most uses after an engineering check.
How the matches are graded
Identical means the chemical composition windows overlap so that material certified to one specification meets the other without deviation, and the mechanical minimums are the same or the other is inside them — mills usually dual-certify. Near means one limit differs (a carbon maximum, an impact temperature, a strength minimum or a delivery condition) and a substitution needs a one-line engineering check. Functional means the grades serve the same purpose but are not the same steel — a designer can often use one for the other, but only after re-checking the design.
4340 in BS (superseded British)
- 817M40 (EN24) — Identical BS 970 817M40: C 0.36–0.44, Ni 1.30–1.70, Cr 1.00–1.40, Mo 0.20–0.35.
4340 in GB/T (China)
- 40CrNiMoA — Identical GB/T 3077 40CrNiMoA: C 0.37–0.44, Ni 1.25–1.65, Cr 0.60–0.90, Mo 0.15–0.25 (Ni slightly lower).
4340 in GOST (Russia/CIS)
- 40KhN2MA — Identical GOST 4543 40KhN2MA: C 0.37–0.44, Ni 1.25–1.65, Cr 0.60–0.90, Mo 0.15–0.25.
4340 in JIS (Japan)
- SNCM439 — Identical JIS G4053 SNCM439: C 0.36–0.43, Ni 1.60–2.00, Cr 0.60–1.00, Mo 0.15–0.30.
4340 in AISI / SAE
- 300M — Near Si-V modified 4340 for 1900–2100 MPa (landing gear, high-strength bolts).
- 4330V / 4330 Mod — Near Lower-carbon (0.30 %) V-modified version with better weldability and toughness for oilfield and aerospace.
- 4140 — Functional Ni-free: same carbon, lower hardenability and toughness; adequate below ~75 mm and 1200 MPa.
4340 in EN (European)
- 34CrNiMo6 — Near 1.6582: C 0.30–0.38, Ni 1.30–1.70, Cr 1.30–1.70, Mo 0.15–0.30 — lower carbon/nickel, higher chromium; similar hardenability and strength; the standard European substitute.
- 36CrNiMo4 — Near 1.6511: C 0.32–0.40, Ni 0.90–1.20, Cr 0.90–1.20, Mo 0.15–0.30 — closer on Cr, lower Ni.
Superseded names for 4340
- G43400 / E4340 — UNS / AMS 6414: E = electric-furnace (aircraft quality); 4340H = H43400 hardenability band.
- 34CrNiMo6 / 1.6582 — EN 10083-3: Nearest European grade; 36CrNiMo4 (1.6511) and 40NiCrMo7 (Italy) also quoted.
- 817M40 / EN24 — BS 970: EN24 (BS 970 1955) is still the everyday UK/India name; 817M40 is the 1970+ designation.
- SNCM439 — JIS G4053: Formerly SNCM8.
- 300M — AMS 6257 / 6419: Si-V modified 4340 for 1900–2100 MPa (landing gear).
Key data for 4340
Full composition, mechanical properties by thickness, heat treatment and applications for 4340 →
Verified against ASTM A29/A29M-20 (SAE J404 chemistry). Last checked: September 2026.