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为查明挖掘机支座断裂失效的原因,首先对支座断口部位及未完全断裂部位进行了宏、微观分析,结果表明支座断面属于多源起动的疲劳失效。化学成分分析表明,材质不符合国标要求。为确定主要裂纹源,分别在断裂面和未完全断裂面附近截取小试样进行熔深分析,结果表明,焊缝根部未完全熔合,裂纹从这里产生并扩展,加之焊缝处存在的多种缺陷加速了裂纹的扩展,导致最终断裂。
In order to find out the reason of the failure of the excavator’s bearing, the macroscopical and microscopic analysis of the fractured parts of the bearing and the incompletely fractured parts were carried out. The results show that the bearing section belongs to the fatigue failure of multi-source starting. Chemical composition analysis shows that the material does not meet the national standard requirements. In order to determine the main source of cracks, small samples were taken from the fracture surface and the incomplete fracture surface respectively for penetration analysis. The results show that the root of the weld is not completely fused and the cracks are generated and extended from here. In addition, Defects accelerate the expansion of the crack, resulting in the final fracture.