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对某载重汽车用曲轴在使用过程中发生断裂进行失效分析。通过断口宏观及微观观察、低倍组织检验、金相组织检验、力学性能检验以及热处理试验等对失效曲轴进行综合分析。结果表明:该载重汽车曲轴断裂属于疲劳断裂;主轴颈表面碰磨使渗氮层产生的裂纹是导致曲轴断裂的直接原因;而热处理后组织不符合要求降低了曲轴疲劳强度,是导致曲轴断裂的重要原因。
Failure analysis of a broken crankshaft of a truck during use. The failure crankshaft was analyzed comprehensively by macroscopic and microscopic observation of fractures, low magnification microstructure test, microstructure test, mechanical property test and heat treatment test. The results show that the crankshaft fracture of the truck belongs to the fatigue fracture. The main cause of the fracture of the crankshaft is the crack caused by the nitrocarburizing on the surface of the main journal. However, the heat treatment fails to meet the requirements to reduce the fatigue strength of the crankshaft and leads to the fracture of the crankshaft important reason.