描述
4340 steel is a type of high-strength alloy structural steel that exhibits excellent tensile strength, toughness, and fatigue resistance. The chemical composition of this steel primarily includes elements such as carbon (C), silicon (Si), manganese (Mn), phosphorus (P), sulfur (S), chromium (Cr), nickel (Ni), and molybdenum (Mo). It is commonly used in the manufacture of high-load and high-strength components, such as aircraft engine parts, automotive steering rods, marine transmission systems, high-load shafts for mining machinery, turbine shafts, helicopter rotor shafts, turbine shafts for turbojet engines, blades, high-load transmission parts, crank fasteners, and gears.
4340 Steel composition introduction
The machinability of 4340 steel is relatively poor. Due to its low plasticity and toughness, during high-speed cutting, the cutting force and the generated cutting heat are concentrated near the cutting edge, which may lead to increased wear on the tool tip and thereby reduce its machinability. Therefore, 4340 steel can be considered a typically difficult material to process.
4340 steel Welding Capacity
The welding capacity of 4340 steel is relatively good, allowing for connections through various welding processes such as metal inert gas welding and tungsten inert gas welding. However, due to certain characteristics of 4340 steel, such as temper brittleness and high susceptibility to white spots, it is necessary to perform high-temperature preheating before welding and stress relief treatment after welding. These characteristics may affect its welding performance.
During the welding process, special attention needs to be paid to controlling the welding current, voltage, and welding speed to ensure welding quality. Adhering to appropriate preheating and post-heating welding procedures is also crucial, as it helps reduce potential stress and cracks during welding and improves the strength and toughness of the welded joint.
4340 Steel Equivalent Grades
| US | EU | China | Germany | Japan | France | England | ltaly | Russia | Russia |
|---|---|---|---|---|---|---|---|---|---|
| 4340 | 34CrNiMo6 | 40CrNiMo | 1.6582 | SNCM447 | 35NCD6 | 817M40 | 35CrNiMo6 | 40KHN2MA | 40KHN2MA |
4340 Steel composition
| Element | C | Si | Cr | Mo | Mn | Fe | Ni |
|---|---|---|---|---|---|---|---|
| percentage (%) | 0.3%-0.5% | 0.5 % max | 0.6%-1.2% | 0.5 % max | 0.80% | BAL. | 1.25%-2.0% |
4340 steel mechanical properties
| MIM 4340 HT | Density (g/cm3) | YS (MPa） | UTS(MPa） | Elongation (%) | Macro Hardness |
|---|---|---|---|---|---|
| Properties | 7.5 | 1100 | 0.6%-1.2% | 0.5 % max | 40-45 HRC |
