摘要
为探究激光冲击对AZ31镁合金腐蚀疲劳性能的影响,采用钕玻璃激光器激光冲击处理AZ31镁合金表面,采用透射电子显微镜观察激光冲击后镁合金表层的微观组织,分别在3.5%(wt)氯化钠溶液和空气中测试其三点弯曲腐蚀疲劳性能。微观组织表明激光冲击波导致镁合金表面层产生超高应变速率塑性变形,晶粒内部存在与孪晶相互交叉、相互缠结的高密度位错而导致晶粒细化;腐蚀疲劳曲线表明激光冲击试样疲劳寿命高于冲击前试样,在空气中疲劳寿命提高约38.25%,在溶液中疲劳寿命提高约183.47%,激光冲击AZ31镁合金所产生的微观组织和残余应力是降低其裂纹扩展速率的主要因素。
The effect of laser shock processing( LSP) on the fatigue corrosion of AZ31 magnesium alloy has been analyzed. AZ31 magnesium alloy was processed with Nd: YAG laser with the wavelength of 1064 nm and pulse width of 10 ns. Microstructures were observed with transmission electron microscopy. The fatigue life of AZ31 magnesium alloy after LSP increased about 38. 25% in air and 183. 47% in solution respectively. Transmission electron microscopy observation showed that plastic deformation with ultrahigh strain rate occurred because of laser shock wave at the surface layer of AZ31 magnesium alloy. Meanwhile,extensive dislocations and twins were generated.High density dislocations tangled and intersected with twins,which led to the refinement of grains. Fitting curves show that the fatigue crack propagation rate of LSP samples is less than that of un-LSP samples in air and in 3.5%Na Cl solution. The residual compressive stress,grain refinement and higher corrosion resistance with LSP are main factors to hinder the fatigue crack propagation of AZ31 magnesium alloy.
出处
《机械科学与技术》
CSCD
北大核心
2015年第11期1779-1783,共5页
Mechanical Science and Technology for Aerospace Engineering
基金
国家自然科学基金项目(51275221)资助
关键词
激光技术
镁合金
微观组织
腐蚀疲劳
裂纹扩展速率
laser technique
corrosion,data processing,design of experiments,dislocations(crystals),fatigue crack propagation,fatigue of materials,grain refinement,lasers,magnesium alloys,microstructure,plastic deformation,residual stresses,strain rate,transmission electron microscopy,wavelength
corrosion fatigue
