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AISI 4340 Alloy Steel

  • Sunday, 29 December 2024
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AISI 4340 Alloy Steel

AISI 4340 alloy steel has very good ductility in the annealed condition, allowing it to be bent or formed by pressing or spinning.aisi 4340 alloy steel This makes it useful in many applications where other alloys would be less suitable due to their lower tensile/yield strength. The material is also readily machinable by all conventional methods, and it can be heat treated to enhance its toughness and fatigue strength properties. This material is often used in industrial machinery, aerospace equipment and hydraulic parts.

The AISI 4340 alloy steel is a medium carbon, low alloy nickel chromium molybdenum alloy steel that is commonly supplied in the hardened and tempered condition with a tensile range of 930 - 1080 Mpa. It can be further hardened by flame or induction hardening to obtain a case hardness of Rc 50, and nitriding can produce a hardness of up to Rc 60. AISI 4340 has very good shock and impact resistance as well as wear and abrasion resistance in the hardened and tempered condition.

Forging of AISI 4340 steel is possible but should be done above the minimum forging temperature 850 degC. Care should be taken during heating and holding the forging temperature as the steel shows a susceptibility to cracking. It is recommended that the material be preheated to a point just below the forging temperature and held there until it is thoroughly heated throughout. It is also suggested that the work piece be cooled slowly in still air or in sand after forging to avoid any possible cracking.

Welding of AISI 4340 steel is possible using either fusion or resistance welding techniques. However, it is not recommended that welding be carried out on the material in the hardened and tempered condition as this could cause quench cracking. If welding is necessary on the hardened and tempered material, it should be immediately stress relieved afterward at a rate of up to 15 degC below the original tempering temperature.

AISI 4340 is a very versatile material that can be worked and machined in its annealed state, but it is best utilized when it is heat treated to improve its tensile/yield strength and toughness. If the material is not heat treated it will become increasingly brittle and have a much lower tensile strength. Hot working on the AISI 4340 alloy will significantly reduce its tensile and yield strength, so it is important to consult the steel supplier about the proper methods of hot working for this grade of alloy steel. This will include appropriate furnace and cooling rates as well as the tempering process to achieve the desired tensile strength level.

Tags:aisi 12l14 carbon steel | aisi 4140 alloy steel | alloy sheet | future steel

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