Ti-6Al-4V钛合金陶瓷湿喷丸表面强化微观组织与疲劳性能

Microstructure and fatigue properties of Ti-6Al-4V titanium alloy treated by wet shot peening of ceramic beads

采用陶瓷湿喷丸强化工艺对Ti-6Al-4V合金进行表面处理。结果表明:经湿喷丸后,材料表面硬度由330HV提高到416HV;表面粗糙度由原始的0.35μm增大到0.48μm,较传统的干喷丸相比,粗糙度值小一个数量级;表面残余应力达-749 MPa,且最大压应力位于最表层,残余压应力层深度约为120μm;拉-拉疲劳强度由605 MPa提高到680 MPa。微观组织分析表明:喷丸处理后钛合金表层位错密度显著增加,晶粒细化,基面织构由(100)向(101)转变。陶瓷湿喷丸强化处理可提高Ti-6Al-4V合金的疲劳强度。

Ti-6A1-4V alloy was treated by the wet shot peening using ceramic beads. The results demonstrate that after the wet shot peening the surface hardness increases from 330HV to 416HV. The surface roughness of the alloy increases from 0.34 pm to 0.48 μm during the wet shot peening. After being treated by the wet shot peening, the surface roughness is an order of magnitude lower than that treated by the traditional dry shot peening. The maximum residual compressive stress value in the peened surface reaches -749 MPa and the depth of the residual compressive layer is about 120μm. The fatigue strength increases from 605 MPa to 680 MPa measured by the tension-tension fatigue test. The dislocation density is enhanced remarkablely in the surface layer after the wet shot peening by using ceramic beads. Also, the microstructure is obviously refined into ultra-fine grains in the surface layer. After the treatment the base surface texture changes from （100） to （101）. The wet shot peening using the ceramic beads can improve the fatigue strength of Ti-6A1-4V alloy.