Eliminating the lamellar microstructure and improving the mechanical properties by optimizing the spheroidization of titanium alloys

Abstract

Spheroidization of lamellar microstructure is the committed step to obtain the microstructure and mechanical properties required by titanium alloys. At present, the spheroidization of titanium alloys is mainly achieved through thermomechanical deformation and traditional heat treatment. This study first conducted hydrogenation treatment on cast Ti-6Al-4V alloy by cold rolling and cast Ti-6-Al-4V alloy by hot rolling. Then, spheroidization is carried out using two different methods: pulsed electric current and traditional heat treatment. The experimental results indicate that under the coupling effect of pulsed electric current and hydrogen, the original lamellar α phase in the cast Ti-6Al-4V alloy is broke, and the original strong preferred orientation disappears. In addition, the continuous lamellar β phase is decomposed into uniformly distributed β particles. Through the coupling effect of pulsed electric current and hydrogen, the mechanical properties of the cast Ti-6Al-4V alloy after spheroidization have also been significantly improved. The above experimental results are mainly attributed to the pulsed electric current promoting the elimination of dislocation and atomic diffusion in deformation cast Ti-6Al-4V alloy. At the same time, recrystallization is accelerated, thereby promoting spheroidization. The spheroidization process of coupling pulsed electric current with hydrogen provides a new and effective method for optimizing the original lamellar titanium alloy.