The purpose of quenching

Quenching is the purpose of strengthening steel, give full play to the potential of steel performance. Such as: improve the mechanical performance of steel, such as hardness, wear resistance, elastic limit, fatigue strength, improve the physical and chemical properties of some special steel, such as enhance the ferromagnetism of magnetic steel, improve the corrosion resistance of stainless steel, etc. The main purpose of the quenching and annealing, quenching, 1: the purpose of the material from ferrite to austenite, fast cooling after imbalance martensite phase transformation, with high hardness and strength of 2, annealing: the purpose of the material from ferrite to austenite, but slow way according to the equilibrium phase after the formation of ferrite, reduce the hardness to facilitate processing. What are the purpose of annealing hardening tempering steel quenching is one of the steel is heated to the critical temperature Ac3 ( Hypoeutectoid steel) Or Ac1 ( Hypereutectoid steel) Above a certain temperature, holding time, austenitizing in whole or in part, and then to greater than the critical cooling rate of cold faster cooling below Ms ( Isothermal near or Ms) Martensite ( Or bainite) Heat treatment process of transformation. Quenching is the purpose of the supercooled austenite to martensite and bainite transformation, get martensite and bainite, and cooperate with different temperature tempering, to significantly improve the strength of steel, hardness, wear resistance, fatigue strength and toughness, etc. , to meet different application requirements of various kinds of machinery parts and tools. Also can satisfy some special steel by quenching of ferromagnetic, corrosion resistance and other special physical and chemical properties. Annealing: the metal slowly heated to a certain temperature, keep enough time, then cooling (with appropriate speed Is usually a slow cooling, sometimes is to control the cooling) A kind of metal heat treatment process. Purpose is to make after casting, forging, rolling, welding or cutting of the material or softening of workpiece, to improve the plasticity and toughness, the chemical composition of homogenization, remove residual stress, or get the desired physical properties. Annealing process on different purposes and there are many, such as recrystallization annealing, isothermal annealing, homogenizing annealing, spheroidizing annealing, remove stress annealing, the recrystallization annealing, as well as stabilizing annealing, magnetic field annealing and so on. Tempering is also called PeiHuo. Will be reheated after hardening of the workpiece to the appropriate temperature below the lower critical temperature, heat preservation for a period of time after cooling in air or water, oil and other medium of metal heat treatment. Or will the alloy after quenching of heating to proper temperature, heat preservation several time, and then slowly or fast cooling. Purpose: general to reduce or eliminate the internal stress of hardened steel, or reduce the hardness and strength, in order to improve the ductility and toughness. According to the different requirements can be used in the low temperature tempering, or high temperature tempering temperature tempering. Usually with the increase of tempering temperature, the hardness and strength, ductility and toughness increased gradually. What is the purpose of the quenching steel tempering? After quenching steel, and then heated to Ac1 points under a certain temperature, heat preservation time, and then cooled to room temperature of heat treatment process called tempering. Hardened steel tempering purpose is as follows: 1, eliminate the internal stress. Through the tempering to reduce or eliminate the internal stress of workpiece during quenching produce, prevent the workpiece deformation and cracking in the process of use. 2, obtain required mechanical properties. By tempering can improve the toughness of the steel, properly adjust the strength and hardness of the steel, make the workpiece has better comprehensive mechanical properties. 3, a stable organization and size. The organization can make the steel tempering stability, to ensure the workpiece size in use process stability.