Microstructure and properties of V–5Cr–5Ti alloy after hot forging

Abstract

In this work, the microstructure of V–5Cr–5Ti alloy after hot forging was analyzed by X–ray diffraction, optical microscopy, scanning electron microscopy, and transmission electron microscopy. After hot forging, the microstructure of V–5Cr–5Ti alloy was broken. An axial grain was formed through recrystallization, and the average grain size was approximately 80 μm. With increasing annealing temperature, the grain size increased from 80 μm to 150 μm. The precipitates elongated to form band structures. During annealing, the band structure changed into several small grains enriched in the precipitates. Some short strip–like precipitates were distributed near the grain boundary irregularly. The two types of precipitates in the V–5Cr–5Ti alloy after hot forging were as follows: a) short–strip precipitate (VTi)2(CON) with FCC structure and lattice parameter of 0.4220–0.4259 nm and b) elliptical–shaped precipitate (VTi)2(CON) with FCC structure and lattice parameter of 0.4252–0.4347 nm. The two precipitate types during annealing were as follows. The first type was a rectangular precipitate (VTi)2(CO) with FCC structure and lattice parameter of 0.4186–0.4270 nm. The second type was an elliptical–shaped precipitate (VTi)5(CO) with FCC structure and lattice parameter of 0.4246–0.4344 nm.