喷丸强度对TC17及GH4169合金表面完整性和高温疲劳性能的影响

Effect of shot peening intensity on surface integrity and high-temperature fatigue performance of TC17 and GH4169 alloys

对钛合金TC17以及镍基高温合金GH4169光滑旋转弯曲疲劳试样进行喷丸强化,研究了不同喷丸强度下合金的表面粗糙度、表面残余应力和高温疲劳寿命。结果表明,喷丸后两种合金的表面粗糙度随着喷丸强度的增大而上升,当喷丸强度达到0.15 mm A以上时,表面粗糙度显著变大。喷丸后表面残余应力均为压应力,TC17合金的残余压应力的数值随着喷丸强度的增大呈现先增大再减小的趋势,而GH4169合金表面残余压应力数值随喷丸强度的增大而减小。在疲劳性能方面,TC17合金喷丸后的疲劳寿命随喷丸强度的增大呈现先增大再减小的趋势,特别是在高强度条件（大于0.10 mm A）下,喷丸反而降低了疲劳寿命,而GH4169合金的疲劳寿命随喷丸强度的增大而增大,说明不同合金对喷丸强度的优化工艺范围具有差别,钛合金对喷丸强度变化敏感性强。

The rotating-bending fatigue specimens of TC17 titanium alloy and GH4169 superalloy were shot peened to investigate the effect of shot peening intensity on the surface integrity and fatigue performance of both alloys. Surface roughness,surface residual stress and hightemperature fatigue lives of the specimens peened by using different intensities were tested. The results show that surface roughness of both two alloys after peening increased by shot peening intensity,and it raises significantly when the peening intensity is larger than 0. 15 mm A.The compressive residual stress is induced on the surface by peening. For TC17 titanium alloy,the residual stress value increases and then decreases with the increase of the intensity,while the residual stress value is kept reduced by the enlargement of the intensity for GH4169 superalloy. In terms of fatigue performance,with the raise of the intensity,the fatigue life of TC17 alloy edges up and then drops down,and moreover shot peening makes negative effect in the fatigue performance of TC17 titanium alloy such as using a high intensity larger than 0. 10 mm A.Instead,the fatigue life of GH4169 alloy grows up with the intensity raising. The results indicate that the investigated alloys have the suitable shot peening intensity range but titanium alloy has strong sensitivity to shot peening intensity.