汽车用高强铝合金表面陶瓷丸喷丸残余应力分布特性

Characteristic of Residual Stress Distribution of Surface of High-strength Al Alloy for Automobile by Ceramic Shots Shot Peening

采用新型陶瓷丸对汽车车身用2A12高强铝合金进行表面喷丸,分析表面粗糙度、表层显微硬度及残余应力场的分布特性。研究了应力循环条件下的疲劳寿命改善程度。结果表明,与铸钢丸相比,陶瓷丸喷丸强化引入的表层硬化与残余应力场影响层较浅,但表面应力集中水平低,适用于需要长时承受高周低应力的非钢质合金构件;而在低周大应力条件下陶瓷喷丸层将快速失效,残余压应力场将几乎松弛殆尽。

The shot-peening on the surface of 2A12 Al alloy specimens used for automobile body components was carried out with new type of ceramic shots.The distributions of shot-peened surface roughness,surface micro hardness and residual stress field were analyzed.The degree of enhancements of fatigue life under cyclic loadings improves.The results show that compared with that of cast steel shots,the affected layer of surface hardening and residual stress fields which introduce by shot-peening with ceramic shots is shallow,but the surface stress concentration level is low,which is suitable for non-steel parts bearing long high-cycle low-stress loadings.The shot-peening layer with ceramic shots would quickly encounter failure under low-cycle large-stress loadings,and the residual compressive stress fields almost relax immediately and completely.