激光冲击抗疲劳断裂对比试验研究

Studies on the Constrast Experiment of Resistance to Fatigue Fracture by Laser Shock-processing

采用小型、调Q、高功率密度的钕玻璃激光装置对2024T62铝合金试件进行双面激光冲击处理。激光功率密度为（0．539～1．8）×1013W／m2，脉宽约为50ns。当功率密度达到5×1012W／m2时，激光冲击诱导的冲击波峰压大于试件的动态屈服强度，因而在激光冲击区产生高密度位错和稳定的表面残余压应力，从而有效地抑制了裂纹的扩展，提高了疲劳寿命。实验结果表明：2024T62铝合金试件经激光冲击处理后，其疲劳寿命最大可提高2．47倍，平均提高0．76倍。

A Q switched,small and needymium glass laser with high power density was used to laser shock-process(LSP)both sides of test specimen 2024T62 at power density of (0. 539~1. 8)× 103W/m2 for a pulse duration of about 50 nanoseconds. When power density was 5 ×1012W/m2, the peak stress of the shock wave induced by laser shocking exceeded the dynamic yield strength of the aluminum alloy 2024T62,which caused high density dislocations and stable residual compressive surface stresses in the laser-shock-processed area,therefore preventing effectively the surface cracks for propagating and causing fracture. The results of the experiment showed that laser shocking produced a maximal increase in 2024T62 fatigue life by a factor of 2. 47 and an average increase by a factor of 0. 76.