Applications This popular steel is widely used in many industries due to its relatively low cost and high quality. It is widely used in making gears, pinions, shafts, piston, pins and cams but all these parts would not be as long lasting as parts made from high alloyed steel grades. Hardening and Tempering Heat the component up to 840-870°C and quench in oil afterwards. For tempering, heat the component 150-200°C and let it cool down in still air.

Applications It is suitable to produce parts for such as locomotives, cranes, rolling mills, coal cutting machinery etc. where good strength and fatigue resistance is required. Other applications for 4340 are found in gear making, die casting and hot metal working, such as die bolsters, racks and pinions, hot stamping dies for aluminum stamping, die beds for steel stamping, lower temperature nut, bolt and rivet heading dies, large section drop forging dies. It is widely used in the plastic and rubber mounding industries for moulds (particularly rubber moulds), hob retaining rings, patens, retaining rings for built up moulds, stop pins for moulds. Hardening and Tempering This grade should be heated slowly to 830-850°C and after adequate soaking at this temperature, quench in oil. Temper as soon as tools reach room temperature. Hardening from a neutral salt bath, will reduce the possibility of scaling or decarburization. AISI 4340 alloy steel should be in normalized or heat treated condition before tempering. Tempering temperatures depend upon the desired strength level.

Applications 4140 was originally introduced in machine tool and motor industries for gears, pinions, shafts, spindles and the like. Later its applications became much more extended and it is now widely used in areas such as oil and gas industries. Overall, it is suitable for applications such as gears, bolts, studs and a wide variety of applications where a good quality high tensile steel grade is suited. Hardening and Tempering This grade should be heated slowly to 860-890°C and after adequate soaking at this temperature, quench in oil. Temper as soon as tools reach room temperature. Tempering should be done at 480-595°C. Soak at the temperature for 2 hours per 25mm of ruling section, and then allow cooling in air. Tempering between 250-375°C is not advised as tempering within this range will reduce the impact value.

Applications It is used in mechanical engineering and automotive industry for making severely stressed components. It is also suitable for heavy and high strained gear parts with high demands on toughness. Overall, it is used in making heavy-duty arbors, bushings, wear pins, bearings, sprockets, gears and shafts or can be used for high tensile applications. Hardening and Tempering For core hardening, heat the component up to 830°C -870°C . Let it cool down in air or quench in oil as required. For case hardening, heat the component up to 780°C -820°C and soak in water. Heat the component up to 880°C -980°C for carburizing. Temper the component at 150°C -200°C to improve case toughness with minimum effect on hardness. Let it cool down in still air.