Effect of Heat Treatment on Microstructures and Mechanical Properties of a Ti-Al-V-Cr-Fe-Based Alloy

The effects of different processes for heat treatment on microstructures and mechanical properties of a Ti-Al-V-Cr-Fe-based alloy (TLC002) were investigated based on the Ti-6411 alloy designed by Northwest Institute for Nonferrous Metals Research. The results show that the TLC002 alloy treated with solid solution and aging has high strength and low impact toughness. For the annealed specimens, both strength and impact toughness are high. With the rising annealing temperature from 800 °C to 880 °C, the tensile strength (UTS), yield strength (YS), and impact toughness (αu2) increase, especially for the αu2 from 48.7 J/cm2 to 86.0 J/cm2. The tensile and impact specimens treated with both solid solution and aging and annealing are all typical ductile fractures. Both the size dimension and depth of the dimples for the equiaxed structures are greater than those of the bimodal structures, indicating that the plasticity of the equiaxed structures is superior to that of the bimodal structures. The heat treatment that annealing at 880 °C for 1.5 h and then air cooling leads to qualified mechanical properties and a good match of the strength and plasticity of the TLC002 alloy.