强激光冲击铝合金改性处理研究

Research of Material Modification Induced by Laser Shock Processing on Aluminum Alloy

利用新型聚偏1,1-二氟乙烯(PVDF)压电传感器,实现了对激光引发的冲击波压力的实时测量,得到激光引发的冲击波峰压在铝中成指数型的衰减规律;观测了不同约束层材料在铝靶表面产生的激光冲击波,研究了不同约束层对冲击效果的影响;最后用激光冲击强化装置对7050-T7451航空铝合金结构材料进行了冲击强化处理,对试件激光冲击区存在的残余压应力及位错密度进行了测量.结果显示经激光冲击处理的试件表面具有极高的残余压应力,可达-200 MPa以上.激光冲击处理后铝合金的位错密度得到显著的提高,疲劳寿命提高到175%～428%.这些重要结果对激光冲击改性处理技术的实际应用具有指导性作用.

Using a new poly（vinylidene fluoride） （PVDF） piezoelectricity gauge, the real-time measurement of pressure of the laser-induced shock wave is realized. The attenuation of peak pressure of the laser-induced shock wave in aluminum is an exponential function. Laser-induced shock waves on surface of aluminum targets different in confining materials are observed, and the effects of different confining materials are studied. At last, the 7050-T7451 aerial aluminum alloy material is shock-strengthened by laser shock-strengthening processing （LSP） technique with the device which is developed by authors, and the residual, compressive stress and dislocation density of LSP area are tested, the test results show that test piece will have very high residual compressive stress after LSP, the residual compressive stress can exceed -200 MPa. There is a distinct increase in the dislocation density of aluminum alloy, the fatigue life is improved by 175% - 428%. These experiments have guide meaning to the practical engineering applications of LSP technique.