Effect of hot rolling by screw mill on microstructure of a Ti-6Al-4V titanium alloy

The constitute analysis of stress–strain state by the finite element method was carried out by using LS-DYNA software for the axis and surface points of bars of titanium alloy Ti-6Al-4V with lamellar microstructure state, which were processed by screw rolling at a temperature of 940°C with reduction in area of 1.25 and 1.56. The features of screw rolling method that promoted workability of material were investigated. The rolling was performed with 6 passes. Rolling bar was reheated to rolling temperature between each passes for 5 min. The microstructure changes were assessed by light and scanning electron microscopy and quantitative microscopy analysis after each pass of rolling. The different types of deformations (monotonic and cyclic) having the strong influence on microstructures of considered points in the rolled bars are explained. The kinetic of globular structure formation during rolling to total reduction in area of 3.8 was clarified in cross section of bar.