Quantification of Residual Stresses in Relation with Microstructural Changes during Hot Rolling of Titanium Alloys

Abstract

A fully recrystallized titanium alloy (Ti-6Al-4V) was hot rolled at different reduction rates of 20%, 40% and 60% deformation. The samples were prepared with the help of mechanical polishing followed by electro-polishing for subsequent characterization. A gradient in microstructure have been observed which is reflect in residual stress development across the thickness of the rolled sheet. The above measurements were done using EBSD technique and X-ray diffraction, respectively. It has been observed that the as received material contains bimodal grain structure. A grain refinement has been observed across the thickness of the rolled sheet with increase in percentage of deformation. Finer grains were observed at 60% deformation at mid-thickness (T/2). The stress gradient in the rolling direction (RD0increases from top surface (T0) to mid-thickness (T/2) of the rolled sheet. However, it showed a decrease in gradient in the perpendicular direction. The stresses were compressive in nature throughout the thickness.