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Does annealing stress relieve the possibility of compromising the performance of the material in service?

by:Kehua     2022-07-25
Annealing stress relief is used in many industrial applications. Maybe some automotive machine tool welding types have a very high degree of mastery of this skill. Come on! Let Xiaobian join hands with Kehua to share relevant information with you. Everyone is useful. Annealing for stress relief Annealing for stress relief The heat treatment in which the metal after cold deformation is heated below the recrystallization temperature to remove the internal stress but still retains the effect of cold work hardening is called annealing for stress relief, also known as low temperature annealing. The changes in metal structure and properties during stress relief during annealing are equivalent to the recovery stage in the temperature curve. In actual production, the application of the annealing stress relief process is much broader than the above definition. Hot forging, casting, various cold deformation processing, cutting or cutting, welding, heat treatment, and even after assembly of machine parts, without changing the organizational state, retaining cold work, hot work or surface hardening conditions, the steel or machine The process of heating parts at a lower temperature to remove internal stress and reduce the tendency of deformation and cracking can be called annealing to relieve stress. Annealing Stress Relief Principle During press working, casting, welding, heat treatment, machining and other processes, the product may generate internal stress. In most cases, some residual stress will remain in the metal after the process is complete. Residual stress can lead to cracking, deformation or dimensional change of the workpiece. Residual stress also increases the chemical activity of the metal. Under the action of residual tensile stress, it is particularly easy to cause intergranular corrosion cracking. Therefore, residual stress will affect the service properties of the material or cause premature failure of the workpiece. When annealing is carried out to relieve stress, the metal will undergo internal local plastic deformation (when the stress exceeds the yield strength of the material at the temperature) or local relaxation process (when the stress is less than the yield strength of the material at the temperature) under the action of a certain temperature. The residual stress is relaxed to achieve the purpose of elimination. When annealing to relieve stress, the workpiece is generally slowly heated to a lower temperature (500-550 °C for gray cast iron, 500-650 °C for steel, and below the recrystallization start temperature for non-ferrous metal alloy stamping parts), after a period of time, slowly Cooling to prevent new residual stress. Annealing to relieve stress does not completely eliminate the residual stress inside the workpiece, but only mostly eliminates it. To completely eliminate residual stress, the workpiece needs to be heated to a higher temperature. Under such conditions, other tissue changes may be introduced, compromising the performance of the material. Annealing to relieve stress may determine the practicability of a product to a certain extent. After all, welding technology is very important, especially for some device machine tools. If you want to know more, then pay attention to Kehua.
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