剧烈摩擦对半固态AZ91D汽车零件表层裂纹影响

Effects of Severe Friction on the Surface Layer Cracks of the Semi-solid Rheomolding AZ91D Auto Parts

制造了半固态流变成形AZ91D汽车轮胎主动安全装置零件,进行"疲劳试验"、"25000 km路试试验"和"乘用车突然放气继续行驶50 km路试试验",研究了剧烈滚动摩擦对半固态流变成形AZ91D汽车零件表层微裂纹的影响。结果表明,其表层微裂纹根据形成机理可分为塑性应变萌生微裂纹和疲劳微裂纹两类。剧烈滚动摩擦引起零件表层温度剧升而塑性增大,且受较大外载荷作用,引起局部发生剧烈塑性应变不协调是表层塑性应变萌生微裂纹的重要因素。距零件基体表面距离大于20μm的表层微裂纹,主要以微裂纹群分布,大部分微裂纹为非扩展微裂纹且长度小于33μm,整条微裂纹处于塑性状态是形成表层非扩展微裂纹的重要因素。

The semi-solid rheomolding AZ91 D auto tire active safety device parts were prepared.The effects of severe rolling friction on the surface layer microcracks of the semi-solid rheomolding AZ91 D auto parts were investigated by“the fatigue experiment”,“25000 km road test of cars equipping with the sample parts”,and“50 km road test of cars after sudden deflation of their tires”.The results indicate that according to the formation mechanism,the microcracks in the surface layer can be divided into plastic strain initiation microcrack and fatigue microcrack.The key factor is that severe rolling friction could cause the increase of temperature of the parts sharply and the plasticity of the parts,and the part can be subjected to great external load,leading to local violent plastic strain incongruity to generate microcracks.The microcracks in the surface layer with a distance more than 20μm from the surface,is mainly distributed as micro-crack group,where most of the microcracks are non-propagation microcrack with the length less than 33μm.The whole microcrack in plastic state is the key factor for the formation of the non-propagation microcracks in the surface layer.