Effects of Equal Channel Angular Extrusion (ECAE) Process on the Mechanical Property and Erosion Resistance of Ti-5Al-5Mo-5V-3Cr Alloy

摘要

High-strength near-beta-phase titanium alloys, including Ti-5Al-5Mo-5V-3Cr, are considered the material of choice for large components that demand weight reduction and high strength. The erosion resistance of Ti5Al-5Mo-5V-3Cr alloy is essential for many components exposed to solid particles and marine environment, but is rarely investigated. In this study, we investigate the erosion resistance and mechanical properties of Ti-5Al-5Mo-5V3Cr alloy against silica slurry, which is formed by an equal channel angular extrusion (ECAE) process in beta-phase temperature range, followed by quenching and annealing treatments. It was found that ECAE and subsequent heat treatments promote the precipitation of extremely fine alpha-phase particles inside beta-phase grains, which lead to increased tensile strength and elongation due to the function of the alpha-precipitates as obstacles for dislocation sliding and the refined beta-grains that avoid the stress propagation. Both the fracture toughness and impact toughness are improved as measured by the tensile test and impact test. The erosion mechanisms were analysed by the morphological analyses of the eroded surfaces, while the material microstructures were observed by a scanning electron microscope, which proved the existence of fine alpha-precipitates in the beta-phase. Erosion resistance test was conducted, and mass loss was measured in comparison with non-ECAE-treated sample.