差速器齿轮断裂分析

Fracture analysis of differential gear

针对汽车在行驶过程中差速器行星齿轮断裂打齿的问题,通过断口形貌观察分析,化学成分分析、表面及基体洛氏硬度试验,非金属夹杂物分析,表面硬化层深度测定、显微组织分析等方法,分析了轮齿断裂原因。结果表明:差速器行星齿轮断裂是由于齿轮热处理加热过程中温度高且保温时间长,组织过热粗化,形成粗大马氏体组织,严重恶化材料综合力学性能,尤其降低塑性和韧性,增加材料内应力,导致齿轮在工作中塑性、韧性、强度不能满足使用要求,最终发生齿轮打齿断裂。

As for the fracture and interfering gear problem of differential planetary gear during the driving process of automobile, gear fracture analysis was conducted through observation and analysis of appearance of fracture, chemical component analysis, surface and substrate rockwell hardness test, non-metallic inclusion analysis, depth determination at the hardened surface layer, microstructure analysis. Results showed the differential planetary gear fracture was caused by high temperature and long thermal insulation time in gear heat treatment, which led to overheating and coarsening, coarse martensite, severe deterioration of general mechanical performance of material, especially the reduction of plasticity and tenacity, internal stress increase of material. All these would make gear not meet the plasticity, toughness and strength requirement in work and lead to gear interfering and fracture.