AISI 4340 steel is a versatile and highly popular alloy known for its exceptional strength, toughness, and wear resistance. It belongs to the family of low-alloy steels and is primarily composed of iron, chromium, nickel, and molybdenum. AISI 4340 steel exhibits excellent hardenability, allowing it to be heat-treated to achieve desired mechanical properties. This steel is widely used in various industries, including aerospace, automotive, oil and gas, and machinery, where high strength and durability are critical. Its exceptional combination of strength and toughness makes it suitable for demanding applications such as gears, shafts, structural components, and crankshafts. Additionally, AISI 4340 steel can be easily machined and welded, further enhancing its versatility in manufacturing processes.
Final chemical, mechanical properties, dimensions and tolerances are confirmed against the governing specification and purchase order.
| C | Si | Mn | P | S | Cr | Ni | Cu | Mo |
|---|---|---|---|---|---|---|---|---|
| 0.38/0.43 | 0.15/0.35 | 0.65/0.85 | 0.025 max | 0.025 max | 0.70/0.90 | 1.65/2.00 | 0.35 max | 0.20/0.30 |
| Delivery condition | Tensile Strength | Yield Strength | Elengation | Hardness / HB |
|---|---|---|---|---|
| Normalized | 1282 MPa / 186 ksi | 862 MPa / 125 ksi | 12.2 | 363 |
| Annealed | 745 MPa / 108 ksi | 470 MPa / 68 ksi | 22 | 217 |
| Quenched & Tempered | 1207 MPa / 175 ksi | 1145 MPa / 166 ksi | 14.2 | 352 |
| ASTM | AISI | JIS | UNS | BS 970 | GOST | AFNOR |
|---|---|---|---|---|---|---|
| A829 4340 | AMS 6359 4340 | SNCM439 | G43400 | EN24 | 40ChN2MА | 40NCD3 |
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