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对超塑变形前后TC4钛合金激光叠焊接头的微观组织进行观察与分析。结果表明:在超塑变形过程中,焊缝的马氏体针状组织转变为层片状,变形过程中层片状组织被打断,超塑变形温度越高,层片状组织越碎化;超塑性变形应变速率对钛合金显微组织有重要影响,随着应变速率减小,母材α相的数量减小,而晶间β相数量逐渐增加,且两相都有等轴化趋势,但由于应变速率的减小,使得晶粒有一定程度长大;TC4钛合金激光焊焊缝组织由原始针状组织逐渐发展为层片状组织是超塑变形过程中激光焊焊缝剪切应力、相转变以及变形过程中动态再结晶等因素共同作用的结果。
The microstructure of TC4 titanium laser welded joints before and after superplastic deformation was observed and analyzed. The results show that in the process of superplastic deformation, the martensite acicular structure of the weld changes into a lamellar structure, the lamellar structure is broken during the deformation process, and the delaminated lamellar structure becomes higher as the superplastic deformation temperature increases. The strain rate of superplastic deformation has an important influence on the microstructure of titanium alloy. With the decrease of strain rate, the number of α phase in base metal decreases, while the number of interphase β phase increases gradually, and both phases have equiaxial tendency, However, due to the decrease of strain rate, the grains grow to a certain degree. The microstructure of TC4 titanium laser welding seam is gradually transformed from original acicular tissue to lamellar microstructure. The shear stress of laser welding seam during superplastic deformation , Phase transformation and the dynamic deformation during the recrystallization and other factors together.