4340 equivalent grades: ASTM, EN, JIS, GB, DIN
4340 is nickel-chromium-molybdenum low-alloy steel, deep hardening specified in ASTM A29. Every grade in the database that can stand in for it is listed below, drawn from 6 standard systems, each with the reason it does or does not match exactly. The full 4340 data sheet carries the composition and mechanical tables.
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4340 is cross-certified with 817M40 (EN24), 40CrNiMoA, 40KhN2MA and 1 more: the composition windows overlap closely enough that one certificate satisfies the other. 300M, 4330V / 4330 Mod, 34CrNiMo6 and 1 more differ on one limit only — a carbon ceiling, an impact temperature or a strength minimum. 4140 serves the same purpose without being the same steel, so a substitution there needs the design re-checked rather than the certificate. Across systems that is 1 in BS (superseded British), 1 in GB/T (China), 1 in GOST (Russia/CIS), 1 in JIS (Japan), 3 in AISI / SAE, 2 in EN (European).
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| 817M40 (EN24) | BS (superseded British) | Identical | BS 970 817M40: C 0.36–0.44, Ni 1.30–1.70, Cr 1.00–1.40, Mo 0.20–0.35.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, near and functional are defined once on the grade index; the reason column below says which limit differs in each case.
4340 in BS (superseded British)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.