激光喷丸强化ZK60变形镁合金的疲劳性能研究

Research on Fatigue Properties of ZK60 Wrought Magnesium Alloy Treated by Laser Shot Peening

为研究激光喷丸对高强度变形镁合金ZK60疲劳性能的影响机理,使之适应交变应力结构件的工作需要,进行了激光喷丸强化表面改性和拉伸疲劳性能实验。实验结果表明,在激光喷丸强化区域获得有益的残余压应力,产生硬化效应,表面塑性变形的微小区域,变形轮廓曲线波动范围较基体小,增加喷丸次数可增强激光喷丸的强化效应。经3次激光喷丸后,中心孔疲劳试样的平均疲劳寿命由未喷丸试样的78023次提高到125641次,寿命增益达61%。从断口来看,激光喷丸强化主要是改变了裂纹源萌生位置,延缓了裂纹扩展速率,对瞬断区无明显影响。激光喷丸强化为镁合金的抗疲劳制造提供了新的途径。

In order to study the influence mechanism of laser shot peening（LSP） on the fatigue properties of wrought magnesium alloy ZK60 with high intensity,which can adapt the need of structural parts under alternate stress,the surface modification of ZK60 by LSP and the tensile fatigue test are carried out.The results show that the beneficial residual compressive stress is obtained and hardening effect is produced on the strengthening region by LSP.The profile curve fluctuation in the microscopic region of plastic deformation is less than that in magnesium matrix.With the increment of peening number,the strengthening effect of LSP can be enhanced.The average fatigue life of specimen with center hole increases from 78023 cycles to 125641 cycles after 3 LSP modifications,showing the gain of 61%.The compressive residual stress induced by LSP changes the position of fatigue crack initiation,and delays the fatigue growth rate,but it has less effect on the fast fracture area.LSP technology provides a new method for anti-fatigue manufacture of magnesium alloy.