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某型20t级挖掘机轴座在使用过程中发生断裂失效。通过对断裂轴座的断口进行宏微观观察,结合对铸件本体及焊接处金相组织检查,确定了轴座的断裂性质及原因。分析表明,轴座本体夹渣太多和焊接热影响区形成的脆性淬火组织是导致轴座断裂的主要原因;轴座调质工艺不当而引起的轴座强度不足是轴座开裂的次要原因。建议适当控制原材料碳当量,调整铸造、调质及焊接工艺,避免出现较多夹渣及脆性组织,以减少该类断裂失效情况的发生。经过改进,无一例断裂失效反馈。
Some type of 20t excavator shaft seat fracture failure occurred during use. Through the macroscopic and microscopic observation of the fracture of the fracture shaft seat, combined with the examination of the microstructure of the casting body and the weld, the fracture properties and causes of the shaft seat were determined. The analysis shows that the main reason of shaft seat fracture is the brittle quenching structure formed by too much slag in the shaft seat body and the heat affected zone formed by welding. The insufficient strength of the shaft seat caused by improper quenching and tempering of the shaft seat is the secondary reason for the shaft seat cracking . It is suggested that the carbon equivalent of raw materials should be properly controlled, the casting, quenching and tempering and welding processes should be adjusted so as to avoid the occurrence of more slag inclusion and brittleness so as to reduce the occurrence of such failure. After the improvement, no one failure fault feedback.