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Heat treatment picture sharing to let everyone know about heat treatment

by:Kehua     2022-07-28
Heat treatment is a very important content in modern industrial production. Are you very familiar with heat treatment? If you want to know more, let us share the content of heat treatment pictures together, which will definitely give you a better understanding of heat treatment. Heat treatment picture 1. Heat treatment Kehua pointed out that heat treatment refers to a metal thermal processing process in which the chemical composition and structure of the surface or interior of the material are changed by means of heating, heat preservation and cooling in a solid state, and the required properties are obtained. 2. Classification of heat treatment The metal heat treatment process can be roughly divided into three categories: overall heat treatment, surface heat treatment and chemical heat treatment. According to the different heating medium, heating temperature and cooling method, each category can be divided into several different heat treatment processes. The same metal adopts different heat treatment processes to obtain different structures and thus have different properties. Steel is the most widely used metal in industry, and the microstructure of steel is also the most complex, so there are many types of steel heat treatment processes. Heat treatment pictures 3. The role of heat treatment 1. Preliminary heat treatment Kehua believes that the purpose of preliminary heat treatment is to improve processability, eliminate internal stress and prepare a good metallographic structure for final heat treatment. The heat treatment process includes annealing, normalizing, aging, quenching and tempering, etc. (1) Annealing and normalizing Annealing and normalizing are used for hot worked blanks. Carbon steel and alloy steel with carbon content greater than 0.5% are often annealed in order to reduce their hardness and easy to cut; carbon steel and alloy steel with carbon content less than 0.5%, in order to avoid sticking to the knife when their hardness is too low, And use normalizing treatment. Annealing and normalizing can still refine grains and uniform structure to prepare for subsequent heat treatment. Annealing and normalizing are usually scheduled after blank fabrication and before rough machining. (2) Aging treatment Aging treatment is mainly used to eliminate the internal stress generated in blank manufacturing and machining. In order to avoid excessive transportation workload, for parts with general precision, it is sufficient to arrange an aging treatment before finishing. However, for parts with high precision requirements (such as the box of the coordinate boring machine, etc.), two or several aging treatment procedures should be arranged. Simple parts are generally not subject to aging treatment. In addition to castings, for some precision parts with poor rigidity (such as precision lead screws), in order to eliminate the internal stress generated during processing and stabilize the machining accuracy of the parts, multiple aging treatments are often arranged between roughing and semi-finishing. For some shaft parts processing, aging treatment should be arranged after the straightening process. ( 3 ) Quenching and tempering is to carry out high temperature tempering treatment after quenching, which can obtain a uniform and fine tempered sorbite structure, and prepares for reducing deformation during subsequent surface quenching and nitriding treatment, so quenching and tempering also Can be used as a preliminary heat treatment. Due to the good comprehensive mechanical properties of the parts after quenching and tempering, some parts that do not require high hardness and wear resistance can also be used as the final heat treatment process. 2. Final heat treatment The purpose of final heat treatment is to improve mechanical properties such as hardness, wear resistance and strength. (1) Quenching Quenching includes surface quenching and integral quenching. Among them, surface quenching is widely used because of less deformation, oxidation and decarburization, and surface quenching also has the advantages of high external strength and good wear resistance, while maintaining good internal toughness and strong impact resistance. In order to improve the mechanical properties of surface hardened parts, heat treatment such as quenching and tempering or normalizing is often required as a preliminary heat treatment. The general process route is: blanking - forging - normalizing (annealing) - roughing - quenching and tempering - semi-finishing - surface quenching - finishing. ( 2 ) Carburizing and quenching Carburizing and quenching is suitable for low carbon steel and low alloy steel. First, increase the carbon content of the surface layer of the part. After quenching, the surface layer can obtain high hardness, while the core still maintains a certain strength and high hardness. toughness and plasticity. Carburizing is divided into overall carburizing and local carburizing. When local carburizing, anti-seepage measures (copper plating or anti-seepage material plating) should be taken for the non-carburized part. Due to the large deformation of carburizing and quenching, and the carburizing depth is generally between 0.5 and 2mm, the carburizing process is generally arranged between semi-finishing and finishing. The process route is generally: blanking - forging - normalizing - rough and semi-finishing - carburizing and quenching - finishing. When the non-carburized part of the local carburized part adopts the process plan of removing the excess carburized layer after increasing the allowance, the process of removing the excess carburized layer should be arranged after carburizing and before quenching. (3) Nitriding treatment Nitriding is a treatment method in which nitrogen atoms penetrate into the metal surface to obtain a layer of nitrogen-containing compounds. Nitriding layer can improve the hardness, wear resistance, fatigue strength and corrosion resistance of the part surface. Because the nitriding temperature is low, the deformation is small, and the nitriding layer is thin (generally no more than 0.6~0.7mm), the nitriding process should be arranged as far back as possible. In order to reduce the deformation during nitriding, it is generally necessary to High temperature tempering for stress relief. The content of the heat treatment picture is as mentioned above. From the above, you can learn that heat treatment is the heating-related treatment of metal materials, and heat treatment can well improve the processing technology.
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