Microstructual analysis of stress relieving on the thermal deformation behaviors of titanium tailor-welded blanks

Abstract

This paper aims to investigate the microstructual analysis of titanium tailor-welded blanks (Ti-TWBs) undergoing the stress relieving (SR) during a thermal deformation. A modified HILLE machine, with a specific heating device that can adjust the working temperature, was employed in this study. Qualified Ti-TWBs specimens were prepared in different widths and lengths. In order to compare the performance of both SR and non-SR Ti-TWBs, the formability analyses at room temperature and around 550degC were then carried out accordingly. The limit dome heights (LDH) of these specimens were measured and it was found that the ductility of the SR Ti-TWBs was improved due to the removal of the hardening effect as well the working stress during the cold working. Moreover, the fracture surface of the Ti-TWBs also revealed that the microstructure was fine and equaxial after the heat treatment. It can be concluded that the microstructual evolution is useful to enhance the strength of Ti-TWBs.