钛合金激光焊接接头超塑变形组织演变表征

研究了超塑性变形过程中TC4钛合金激光焊接接头各区域显微组织演变规律,并对相关参数进行表征。结果表明,随着超塑性变形的进行,接头内针状马氏体组织发生α′→α+β相变,同时针状组织长大为片层,接头各区域显微组织逐渐均匀化,促进超塑性变形的进行;随着变形的进行,等轴化率逐渐升高;随着变形温度的升高或初始应变速率的降低等轴化率逐渐上升,促进焊缝超塑性变形的进行。提出采用平均晶粒尺寸来表征热影响区组织的转变程度。随着变形的进行,平均晶粒尺寸逐渐增大,随变形温度的升高或初始应变速率的降低平均晶粒尺寸减小,这有利于接头组织的均匀化。

Microstructure Evolution Characterization of Weld Joints by Laser Welding for Superplastic Deformation of Titanium Alloy

Microstructure evolution principles of Ti-6Al-4V laser welding joints during superplastic deformation were analyzed, and some involved parameters were proposed to evaluate the forming process. The results indicate that during superplastic deformation the α′ martensite transformed into α+β phases, and needle-like structure transformed into lamellar structure. During superplastic deformation equiaxial rate increased with straining, and also increased with increasing forming temperature and decreasing strain rate. Average grain size was introduced to characterize the microstructure transition extent of HAZ, average grain size increasing with straining, and also increasing with increasing forming temperature and decreasing strain rate.