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我厂521-612分电器螺塞的螺纹加工是在228-33滚丝机上进行的。长期以来,由于模具崩刃严重,使用寿命不高。我们根据钢的组织对断裂韧性的影响,联系到模具脆性断裂的宏观特征与针状马氏体的显微裂纹之间的关系,认为崩刃是由于显微裂纹扩展所造成的,因而选定硬度较高、韧性和塑性较好、没有显微裂纹的下贝氏体组织结构,以期达到提高使用寿命的目的。另外,模具要求 HRC54-56,按一般分级淬火要能准确控制比较困难,加之高温回火造成模具表面腐蚀,这些都试图通过等温淬火加以解决。
I plant 521-612 points plugs screw thread processing is carried out on the 228-33 thread rolling machine. For a long time, due to severe mold collapse edge, life is not high. According to the influence of the microstructure of the steel on the fracture toughness, the relationship between the macroscopic characteristics of the brittle fracture of the mold and the micro-cracks of the acicular martensite is considered, and the collapse is caused by the propagation of the microcrack. Therefore, High hardness, good toughness and ductility, no microstructure of the lower bainite microstructure, in order to achieve the purpose of improving the service life. In addition, the mold requirements HRC54-56, according to the general classification of quenching to be able to accurately control the more difficult, combined with high temperature tempering caused by corrosion of the mold surface, these are trying to be solved by isothermal quenching.