What is normalizing, annealing, tempering, quenching? What is the difference between forging parts and casting parts?
For the nodular cast iron, the hardness, strength and wear resistance are improved, such as used in the manufacture of automobile, tractor, diesel engine crankshaft, connecting rod and other important parts. A normalizing and hypereutectoid ball annealing before, can eliminate the mesh two cementite spheroidizing annealing, to ensure that all spheres of cementite. Annealing is a metal heat treatment process, which means the metal is slowly heated to a certain temperature, sufficient for a long time, and then cooled at an appropriate speed. The purpose is to reduce hardness, improve machinability, eliminate residual stress, stabilize size, reduce deformation and crack tendency, refine grain, adjust microstructure and eliminate tissue defects. Its purpose: (1) reduce hardness and improve machinability; (2) eliminate residual stress, stabilize size, reduce deformation and crack tendency; (3) refine grain, adjust microstructure and eliminate tissue defects. In production, annealing process is widely used.
The aim is to make the grain fine and distribute the carbide evenly. The difference between normalizing and annealing is that normalizing cooling rate is slightly faster than annealing cooling rate, so normalizing structure is finer than annealing structure, and its mechanical properties are also improved. In addition, normalizing furnace cooling does not occupy equipment and has higher productivity. Therefore, normalizing may be used instead of annealing as much as possible. The main application areas of normalizing are as follows: for low carbon steel, after normalizing, the hardness is slightly higher than that of annealing, and the toughness is better. It can be used as the pretreatment of cutting. Used for medium carbon steel, instead of quenching and tempering, as the final heat treatment, or as an induction heating method before surface hardening. Used for tool steel, bearing steel, carburizing steel, etc., it can eliminate or restrain the formation of network carbide, so as to obtain the good organization of spheroidizing annealing. For cast steel, the microstructure can be refined and the machinability can be improved. Used for large forgings, which can be used as final heat treatment, so as to avoid larger cracking tendency during quenching.
According to the requirements of the workpiece annealing, there are many kinds of annealing process specifications, such as full annealing, spheroidizing annealing and stress relieving annealing. Steel the steel quenching is heated to the critical temperature Ac3 (hyposteel) or Ac1 (hypereutectoid steel) above a certain temperature, holding time, so that all or part of 1 Austenitic, then the cooling rate is greater than the critical cooling rate of fast cooling to below Ms (or near Ms isothermal) of martensite the body (or bainite transformation) heat treatment process. Aluminum alloys, copper alloys, titanium alloys, tempered glass and other materials are usually treated by solid solution or heat treatment with rapid cooling process. Tempering is a heat treatment process where the workpiece is hardened and heated to a temperature below AC1, which remains cool for a certain period of time and then cools to room temperature. Tempering generally followed by quenching, the purpose is: (a) to eliminate the residual stress caused by quenching, prevent deformation and cracking; (b) hardness, strength, plasticity and toughness of workpiece is adjusted, to use performance requirements; (c) the size of organization and stability, ensure the accuracy improvement; (D) and to improve the processing performance. Tempering is therefore the last important step in obtaining the desired properties of the workpiece. According to the tempering temperature range, tempering can be divided into low temperature tempering, medium temperature tempering and high temperature tempering. This answer is recommended by the questioner
