Microstructure and Mechanical Properties of TC18 Titanium Alloy

Ti-5Al-5Mo-5V-1Fe-1Cr Ti alloy (TC18) was fabricated via a consumable vacuum arc-remelting furnace, and then subjected to thermo-mechanical processing and heat treatment. The microstructural characteristics and mechanical properties of the heat-treated alloy were investigated. Results show that primary α phase exhibits spherical, near equiaxed, plate- and rod-shaped morphologies after heat treatment. This is associated with boundary segregation of α grain. The alloy presents a good combination of strength and plasticity during tensile test. However, the value of σy/σb of the alloy reaches 0.95. It is suggested that the grain boundaries absorb dislocations during tensile test; therefore, the dislocation strengthening increases very slowly. This is the primary reason for the high value of σy/σb.