Microstructure and hot deformation behavior of two-phase boron-modified titanium alloy VT8

Abstract

The results of studying the microstructure, compressive mechanical characteristics, and evolution of the microstructure of the cast two-phase titanium alloys VT8-xB (with x = 0, 0.2, and 0.4 wt %) during hot deformation are presented. Alloying with boron leads to the formation of borides, which are predominantly located at the boundaries of β grains and give rise to a considerable refinement of the original cast structure. The results of high-temperature compressive tests have shown that the strength characteristics of the boron-modified alloys noticeably exceed those of the base VT8 alloy. The experiments on the multiple isothermal forging of VT8 and VT8-0.4B alloys carried out at temperatures of 700–650°C have revealed the acceleration of the kinetics of dynamic recrystallization due to the presence of borides, which were efficiently refined during deformation. The alloying of the VT8 alloy with boron has been discussed from the viewpoint of improving the efficiency of the deformation treatment and final service properties of two-phase titanium alloys.