1: different materials, different equipment, different process parameters, the organization, and quality after heat treatment are also different. Even if the material brand, equipment and process parameters are the same, due to different upper and lower limits of chemical composition content, upper and lower limits of heat treatment temperature, upper and lower limits of heat preservation time, the structure and quality of heat treatment will be different. Even if the upper and lower limits of chemical composition content, upper and lower limits of heat treatment temperature and upper and lower limits of heat preservation time are the same, due to the different process, quality and organization of cold and hot processing in the early stage of heat treatment, the organization and quality after heat treatment will also be different. Therefore, problems should be analyzed on a case-by-case basis, that is, to split into two.
2. Two diagrams: Fe-C phase diagram and C curve. The fe-c phase diagram is the necessary knowledge for dealing with steel, and the C curve is the microstructure transformation diagram of steel after heating and cooling. These two diagrams are the basis of heat treatment. Only by grasping these two figures, can we have a deep understanding of these two figures, dry heat treatment and heat treatment can be introduced.
3, three processes: namely heating, heat preservation, cooling these three processes. These three processes run through all the heat treatment processes, and the quality of these three processes determines the quality of the final heat treatment. Once these three processes are understood thoroughly, heat treatment is the beginning.
4, four fire: namely annealing, normalizing, quenching, tempering. These four fires are the most conventional heat treatment, the quality of the four fires, to a certain extent, reflects the level of heat treatment. If these four fires are good, you’re a heat treatment technician.
5, five organizations: austenite, cementite, martensite, bainite, pearlite. After a deep understanding of the characteristics, morphology, precipitation (formation) conditions and properties of these five issues, the technical level of heat treatment can be improved.
6, six defects: namely oxidation, decarbonization, overheating, over-burning, deformation, cracking six defects, which in the work of the most taboo to produce over-burning and cracking defects, because these two defects are irreparable defects, the other four should also be avoided as far as possible, although can be made up, but significantly increased the workload and production costs. Engaged in heat treatment can avoid or reduce these six defects is a qualified heat treatment engineer.
7. Seven phase transitions: Pearlite to austenite (P – > A), austenite to pearlite (A – P), austenite transformed into sorbate (A – S), austenite transformed into flexion (Tora) austenite (A – > T) austenite into martensite (A – M), austenite to bainite (A and B), the martensitic transformation is tempered martensite (M – M back to) hold the seven-phase change heat treatment It’s a high level.
8, eight processes: annealing process, normalizing process, quenching process, tempering process, surface quenching process, chemical heat treatment process, vacuum heat treatment process, special heat treatment process (laser, ion nitriding, PCD, CVD, ion plating, etc.) can grasp these eight processes, heat treatment is an expert!
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