喷丸对DD6单晶合金表层状态及低周疲劳性能的影响

研究喷丸强化对单晶合金表面粗糙度、残余应力及梯度和组织形态等表层性能的影响，并通过低周疲劳性能实验评价喷丸参数的影响，结合表层性能和断口分析，探讨喷丸强化机理。结果表明:改进侧倾法适用于测试DD6单晶喷丸强化后的表面残余应力，极图法适用于测试喷丸强化残余应力梯度；经喷丸强化后，DD6单晶的低周缺口疲劳寿命明显提高，其中采用陶瓷丸、喷丸强度0.20 mmA试样的疲劳寿命最高，其平均寿命较原始试样提高6.5倍；随着喷丸强度提高，虽表面粗糙度增大，但DD6单晶残余压应力深度及表层位错密度增加，使其疲劳寿命延长。

Influence of Shot Peening on Surface State and Low-cycle Fatigue Performance of DD6 Single Crystal Superalloy

The effect of shot peening on the surface state of DD6 single crystal superalloy was investigated, including surface roughness, residual stress gradient and microstructure. And low-cycle fatigue test was used to evaluate the effect of shot peening parameters. Combined with surface state and fracture analysis, the strengthening mechanism of shot peening was analyzed. The results show that the modified χ method is suitable for testing the surface residual stress of DD6 single crystal superalloy after shot peening, while the pole figure method is suitable for testing the residual stress gradient. After shot peening, the low-cycle notch fatigue life of DD6 is significantly improved. Among them, the fatigue life of the specimens under ceramic shot and shot peening strength of 0.20 mm A is the highest, and its average life is 6.5 times longer than that of the original specimens. With the rise of shot peening intensity, the surface roughness increases, but the depth of compressive residual stress and surface dislocation density of DD6 also increase, so its fatigue life is prolonged.