EFFECT OF STRAIN RATE ON THE EVOLUTION OF MICROSTRUCTURE OF DEFORMED TI-15V-3CR-3SN-3AL ALLOY

Abstract

Ti-15V-3Cr-3Al-3Sn (Ti-15-3) is a metastable β alloy which has good formability, high strength to weight ratio, desirable corrosion resistance, and excellent fatigue resistance. This alloy is mainly used in many aircfraft components. The role of strain rate on the deformation behaviour and microstructural changes in beta titanium alloys is not well documented. The understanding of the role of strain rate on microstructural changes and micromechanisms of deformation is crucial to efficiently select the processing route such as forging, rolling, extrusion etc.Therefore, the present study aims to understand the role of strain rate during room temperature deformation on the deformaton behavior and the microstructural changes. The Ti-15-3 alloy was compressively deformed at room temperature for different strain rates ranging from 0.001 s-1 to 3 s-1. All the samples are characterized in a FE-SEM to observe the deformation characteristics. Deformation bands of varying intra-grain misorientations were observed. Transition bands comprising severe microstrain is observed inbetween the deformation bands. X-ray diffraction and electron backscattered difraction (EBSD) studies were carried out to evaluate the extent of microstrain and their orientation dependance. The grains with high intra grain misorientations were mostly <001> oriented grains, while low intra-grain misorientation regions comprised both <001> and <111> oriented grains. The local mechanical properties were characterized using nano-indentation measurements.