Microstructure refinement and enhanced wear-resistance modulated by stress relaxation processing in a metastable β titanium alloy

Hot deformation is an important procedure of metastable β titanium alloy for manufacturing. And it is essential to improve the homogeneity of deformation microstructure in titanium alloy. In this work, the stress relaxation processing accompanied by hot compression in a metastable β titanium alloy is designed to resolve the related mechanisms of stress relaxation by examining the microstructure evolution and improve the wear-resistance. The results demonstrated that the stress relaxation processing leads to the modification and evolution in morphology, size, and volume fraction of α precipitates. The α precipitates distribute randomly in β matrix in a fine and equiaxed shape after stress relaxation. The elimination of deformation bands and formation of sub-grains are the mediated mechanism in the β phase during stress relaxation. The stress relaxation makes a significant contribution to reduce the wear loss and improve the microstructure stability during friction. The lower wear loss can be attributed to the formation of fine β sub-grains and the dispersed crystallographic orientations of α precipitates. This work provides an effective method to microstructure refinement and a valuable solution to enhance the wear-resistance by tailoring the microstructural features.