IMPROVED CREEP RESISTANCE OF Ti-6Al-4V ALLOY BY ELECTRON BEAM WELDING PROCESS PLUS ANNEALING TREATMENT AND ITS MICROSTRUCTURE ANALYSIS

摘要

In this study, we investigated the effect of annealing treatments on the creep resistance of Ti-6Al-4V alloy following electron beam welding (EBW) process under the applied stresses of 350, 400, 450, and 500 MPa at 500 °C. It appears that when the applied stress is less than 500 MPa, the newly formed α2-Ti3Al and γ-TiAl phases present in the fusion zone may provide stronger resistance to dislocation climbing and gliding during creep, leading to enhanced weld properties. It may explain the superior creep resistance of present Ti-6Al-4V EBW weldments than the unwelded Ti-6Al-4V alloy reported in the literature. Moreover, we report for the first time that α2-Ti3Al formed in the base metal of the annealed Ti-6Al-4V EBW weldment. The correlation between microstructural evolution and creep properties are analyzed and discussed.