焊前预热及焊后热处理的作用（Pre weld preheating and post weld heat treatment）.docVIP

焊前预热及焊后热处理的作用（Pre weld preheating and post weld heat treatment） In order to avoid its low hardness, the knife is glued while cutting and normalizing is adopted. Annealing and normalizing can refine grain and uniform microstructure, and prepare for future heat treatment. Annealing and normalizing are usually performed prior to rough manufacturing and prior to roughing. (2) aging treatment is mainly used to eliminate the internal stress produced in rough manufacturing and machining. In order to avoid excessive transportation workload, for the general precision parts, before finishing, arrange a aging treatment. But the higher precision parts (such as coordinate boring machine box, etc.) should be arranged two times or several times aging process. Simple parts generally do not undergo aging treatment. In addition to casting, precision parts for some low rigidity (such as precision screw), in order to eliminate the internal stress generated during machining, stable machining precision, often arranged several times in the aging treatment between roughing semi finishing. Some shaft parts processing, straightening process should be arranged after aging treatment. (3) and high temperature tempering is tempering after quenching, it can obtain uniform tempered sorbite structure to reduce deformation of surface quenching and nitriding treatment for the future, it can also be used for pre heat treatment tempering. Due to the better mechanical properties of parts after quenching and tempering, parts with little hardness and wear resistance can also be used as final heat treatment processes. 2. the ultimate heat treatment of final heat treatment is to improve the mechanical properties such as hardness, wear resistance and strength. (1) quenching and quenching include surface quenching and integral quenching. Surface hardening is widely used because of its small deformation, oxidation and decarburization. Surface hardening also has the advantages of high external strength and good