(西北有色金属研究院，西安 710016)
摘 要: 采用激光冲击强化工艺对近α型Ti834高温钛合金进行表面处理，研究激光冲击前后合金表层组织结构及显微硬度的变化，测试合金的室温拉伸性能及疲劳寿命，并采用扫描电镜分析合金激光冲击前后的疲劳断口特征。结果表明，激光冲击后合金表层位错密度显著增加，晶粒细化。合金室温拉伸强度略有升高，疲劳寿命提高约1~1.5倍。观察疲劳断口发现，未经冲击处理的试样疲劳源区位于试样表面，而冲击后疲劳源区位于试样的中心位置。激光冲击处理后合金表面形成的硬化层可延缓疲劳裂纹的萌生与扩展。
关键字: 高温钛合金；激光冲击强化；显微组织；拉伸性能；疲劳
（Northwestern Institute for Nonferrous Metal Research, Xi’an 710016, China）
Abstract:The near α titanium alloy Ti834 was shock-processed by the high intensity laser. The surface microstructures of specimens were characterized and the micro-hardness was measured before and after shock processing. The room-temperature tensile properties and the fatigue life of the alloy were tested. The fractographs of fatigue specimens were observed by SEM. The results show that, after the laser shock processing (LSP), the dislocation density is enhanced and the microstructure is refined in the surface layer of the alloy. The room-temperature tensile strength has a little increase and the fatigue life increases by about 1-1.5 times. The characteristics of the fatigue fractographs are changed after LSP. The fatigue crack initiates on the surface of the specimens without shock-processing, while the crack initiates at the center of the specimens after LSP. It is believed that the formation of the hardened layer after laser shock processing can delay the initiation and growth of the fatigue crack.
Key words: high-temperature titanium alloy; laser shock processing; microstructure; tensile properties; fatigue
