湿喷丸强化对TC4钛合金表面状态及疲劳性能的影响

Effects of wet shot peening on surface morphology and fatigue property of Ti-6Al-4V alloy

采用陶瓷湿喷丸强化技术对TC4合金进行表面改性处理,研究湿喷丸强度对钛合金表面状态及拉拉疲劳寿命的影响规律。结果表明,湿喷丸强化在材料表面引入残余压应力场,随喷丸强度增加残余压应力层变深。喷丸强度为0.1～0.2 mm N时,材料表面机加工痕迹得到有效去除,且表面粗糙度降低。湿喷丸强化后,材料表层位错密度增加,晶粒细化。湿喷丸强化能够明显改善TC4合金疲劳性能,改善效果和喷丸强度间不是单调关系,即存在最优喷丸工艺参数。在喷丸强度0.3 mm N条件下,疲劳寿命是基材的1.93倍,改善效果最明显。

TC4 alloy was treated by wet shot peening using ceramic beads and water. Effect of wet shot peening intensity on surface morphology and fatigue property of Ti-6Al-4V alloy was investigated. The results demonstrate that wet shot peening effectively induce highly compressive residual stress on the surface layer. With improving the shot peening intensity,the depth of compressive residual stress layer increases. By wet shot peening of 0. 1 and 0. 2 mm N intensity,the surface maching scratches of specimen disappear and Rais lower than base metal. The dislocation density is enhanced and the microstructure is refined in the surface layer after wet shot peening. Wet shot peening can improve the fatigue life of TC4 alloy,but there is no monotonous relation between the increasement of fatigue life and shot peening intensity.The optimized shot peening intensity is 0. 3 mm N under which the fatigue life is 1. 93 times of the substrate.