EFFECT OF MARTENSITE ON DEFORMATION BEHAVIOR OF Ti-6Al-4V

Abstract

The Ti-6Al-4V alloy is one of the most widely used titanium alloy for its high specific modulus and moderate ductility because of a variety of microstructures (equiaxed, bimodal, lamellar) where a good range of mechanical properties is attained. In order to increase the strength of Ti-6Al-4V, a microstructure having balanced amount of equiaxed as well as lamellar phase is needed. There are conventional ways like ultra-fine grain refinement in order to increase strength as well as ductility. Another method has been proposed in this report using hot deformation along with annealing followed by quenching to incorporate some amount of martensite. Therefore, the present study aims to calculate the best combinations of different fractions of phases to obtain good combination of properties. The project aims to quantify the amount of martensite generated on cooling from different temperatures. The project also aims to study the effect of martensite on the deformation behavior with the help of electron backscatter diffraction (EBSD) and synchrotron x ray diffraction (S-XRD). Thereby, with the proposed quantity of martensite, EBSD analysis and S-XRD results have given insights about the misorientations and texture related information. The EBSD scans for 4 different conditions were taken in order to understand the grain size, aspect ratio, misorientations and axis/angle distribution. The synchrotron results included calculation for lattice strains and the macro strains for two different conditions which in turn proved beneficial to correlate with texture analysis