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对早期断裂失效的驱动半轴进行了显微组织、化学成分、力学性能的检测及断口形貌的观察与分析。结果表明,表面感应淬硬层过浅,在硬化层过渡区形成较大的拉应力,导致半轴服役中发生低周扭转疲劳断裂;钢材锻造温度偏高,毛坯过热使低熔点杂质向晶界偏聚引发脆性;调质处理效果不佳以及母材中存在大量夹杂物降低了材料的力学性能,加剧了疲劳裂纹扩展进程。提出降低电流频率、增加有效硬化层深度和严格控制锻造加热温度防止过热等措施,从而有效防止半轴早期断裂失效。
The microstructure, chemical composition, mechanical properties of the half-shaft driven by early failure and the observation and analysis of fracture morphology were investigated. The results show that the superficial induction hardened layer is too shallow and the tensile stress is formed in the transition zone of the hardened layer, resulting in low-cycle torsional fatigue fracture during the service of the semi-shaft. The forging temperature of the steel is too high and the overheating of the blank causes the low- Segregation caused by brittleness; quenching and tempering treatment ineffective and the presence of a large number of inclusions in the base material reduces the mechanical properties of materials, exacerbated the fatigue crack growth process. Proposed to reduce the current frequency, increase the effective hardened layer depth and strictly control the forging heating temperature to prevent overheating and other measures to effectively prevent the failure of the early shaft half-shaft rupture.