Ti6Al4V合金超声深滚层的组织结构特征

Microstructure Characteristics of Ultrasound-Aided Deep Rolling Treated Ti6Al4V Alloy

摘要:

采用超声深滚技术对Ti6Al4V合金进行表面机械强化处理，使用扫描电镜、硬度分析、X射线衍射和透射电镜等分析手段研究超声深滚处理Ti6Al4V合金表面层的组织结构特征。结果表明：超声深滚处理后，材料表层组织严重细化，形成了纳米结构层，表面晶粒尺寸小于20 nm。晶粒细化层的深度约为0.15 mm，在0.15 mm深度处，虽然晶界结构保持完整但晶粒内部位错密度增加。分析了组织结构细化对于改善疲劳性能的意义

Abstract:

Ti6Al4V alloy was treated by ultrasound-aided deep rolling (UADR) for surface mechanical strengthening. The microstructure evolution of the UADR treated specimen was characterized by scanning electron microscopy (SEM), hardness test, X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results show that obvious grain refinement is found after UADR treatment and a nano-structured surface layer is formed with an average grain size less than 20 nm in the immediate surface. Grain boundaries at about 150 μm away from the surface become distinguishable. In this area, although grain boundary structure keeps unchanged, there is an increase of dislocation density in those grains. The effect of grain refinement on fatigue performance was also discussed