新型高温渗碳不锈航空齿轮钢齿轮的弯曲疲劳失效机理

以新型高温渗碳不锈航空齿轮钢圆柱齿轮为研究对象，采用国标GB/T 14230-1993规定的“B试验法”开展了齿轮弯曲疲劳试验，并对轮齿的断裂的失效机理进行了研究。分析结果发现存在三种造成轮齿断裂失效的诱因:表面碳化物、表面缺陷和内部碳化物。其中，表面碳化物对轮齿弯曲疲劳寿命的影响比内部碳化物和表面加工缺陷都要严重。当齿面没有碳化物和加工缺陷时，在长时间循环应力作用下会产生内部碳化物，进而造成裂纹萌生和扩展，较小尺寸碳化物会形成粗糙的“鱼眼”区形貌。采用航空新型高温渗碳不锈航空齿轮钢的齿轮要得到较高的寿命，应当在加工过程中控制轮齿表面及近表面碳化物尺寸、数量及形状系数和表面加工缺陷，以避免在轮齿表面形成裂纹源。 

Bending fatigue failure mechanism of the new high temperature carburizing stainless aviation steel gear

The fracture failure mechanism for new high temperature carburizing stainless aviation steel cylindrical gears was studied.The bending fatigue test for gear was carried out using“B test method”based on the stipulated GB/T 14230-1993.The results showed that the carbides in surface carburizing layer，the surface machining defects and interior carbides were main inducement factors in the tooth fracture failure.The carbides in surface carburizing layer were the most serious reason.When the carbides and surface machining defects did not exist in the surface，the interior carbides could be generated under alternating stresses，resulting in initiation and propagation for crack.The smaller size carbides generated the rough “fish-eye” zone morphology.In order to obtain the higher service life of new high temperature carburizing stainless aviation steel cylindrical gears，the size，amount，shape factor of the carbides and surface machining defects on the tooth surface should be controlled during the whole surface machining.The crack initiation in surface should be avoided.