喷丸强化对DD6单晶合金典型力学性能的影响

Effect of shot peening on typical mechanical properties of DD6 single crystal superalloy

对DD6单晶合金试样进行喷丸强化后分别采用光学轮廓仪、粗糙度仪、显微硬度计、扫描电镜分析了单晶合金试样喷丸前后的表面形貌、表面粗糙度、硬度梯度以及显微组织。测试了单晶合金喷丸前后在550℃、600℃、650℃和760℃下的缺口疲劳性能、650℃和850℃光滑拉伸性能和650℃/900 MPa条件下的光滑持久性能。结果表明:喷丸强化可去除DD6单晶合金表面的磨削刀痕,喷丸后表面粗糙度为由Ra0.194μm增加到Ra0.904μm。喷丸后单晶合金表面产生剧烈塑性形变,强化层表面显微硬度较基体的450HV提高50%~60%,深度为250μm。喷丸显著提高了DD6单晶合金在550℃~760℃的疲劳性能,疲劳极限提高9%以上。喷丸对DD6单晶合金的拉伸强度、屈服强度、拉伸塑性和光滑持久性能无明显影响。

The surface morphology, surface roughness, microhardness gradient and microstructure of DD6 single crystal superalloy specimens were analyzed by optical profiler, roughness tester, microhardness tester and scanning electron microscope before and after SP. The notch fatigue properties at 550 ℃、600 ℃、650 ℃ and 760 ℃, smooth tensile properties at 650 ℃ and 850 ℃ and smooth endurance properties at 650 ℃/900 MPa of single crystal superalloy were tested before and after SP. The results show that the grinding tool marks on the surface of DD6 single crystal superalloy can be removed by SP, and the surface roughness increases from Ra0.194 μm to Ra0.904 μm after SP. After shot peening, the surface of single crystal alloy undergoes severe plastic deformation. The surface microhardness of the strengthened layer increases by 50%-60% than that of the matrix 450 HV, and the depth is 250 μm. Shot peening significantly improves the fatigue properties of DD6 single crystal alloy at 550 ℃ ~760 ℃, and the fatigue limit increases by more than 9%. Shot peening has no obvious effect on the tensile strength, yield strength, tensile plasticity and smooth durability of DD6 single crystal superalloy.