| AISI 4340 | |
 | |
| Category | Steel |
| Class | Alloy steel |
| Type | Standard |
| Common Names | Nickel-chromium-molybdenum steel |
| Designations |
Germany: DIN 1.6565 Japan: JIS SNCM 8 United Kingdom: B.S. 2 S 119 , B.S. 3 S 95 , B.S. 3111 Type 6 , B.S. 817 M 40 United States: AMS 5331 , AMS 6359 , AMS 6359B , AMS 6414 , AMS 6414A , AMS 6415 , AMS 6415G , ASTM A322 , ASTM A331 , ASTM A505 , ASTM A519 , ASTM A547 , ASTM A646 , MIL SPEC MIL-S-16974 , SAE J404 , SAE J412 , SAE J770 , UNS G43400 |
| Composition | |
| |
| Element | Weight % |
| C | 0.38-0.43 |
| Mn | 0.60-0.80 |
| P | 0.035 (max) |
| S | 0.04 (max) |
| Si | 0.15-0.30 |
| Cr | 0.70-0.90 |
| Ni | 1.65-2.00 |
| Mo | 0.20-0.30 |
| Mechanical Properties | |
| |
| Properties | Conditions | ||
| T (°C) | Treatment | ||
| Density (×1000 kg/m3) | 7.7-8.03 | 25 | |
| Poisson's Ratio | 0.27-0.30 | 25 | |
| Elastic Modulus (GPa) | 190-210 | 25 | |
| Tensile Strength (Mpa) | 744.6 | 25 | annealed at 810°C more |
| Yield Strength (Mpa) | 472.3 | ||
| Elongation (%) | 22.0 | ||
| Reduction in Area (%) | 49.9 | ||
| Hardness (HB) | 217 | 25 | annealed at 810°C more |
| Impact Strength (J) (Izod) |
51.1 | 25 | annealed at 810°C more |
| Thermal Properties | |
| |
| Properties | Conditions | ||
| T (°C) | Treatment | ||
| Thermal Expansion (10-6/ºC) | 11.5 | 20-100 more | oil hardened, tempered 630°C |
| Electric Properties | |
| |