Strength, Toughness and Thermomechanical Processings in Ti-15V-3Cr-3Sn-3Al Alloys

Abstract

β type titanium alloy, Ti-15V-3Cr-3Sn-3Al alloy, was conducted with conventional heat treatment, conventional thermomechanical processings and newly proposed thermomechanical processings. Mechanical properties, toughness and microstructures of them were examined by microstructural observations, tensile tests and instrumented Charpy impact tests.
Tensile strength, σ_B, and yield stress, that is, 0.2% proof stress, σ_y, increased with increasing the rolling reduction ratio in the alloys conducted with conventional thermomechanical processing where one or two step aging was carried out after cold rolling while elongation, El, and reduction of area, RA, decreased. Dynamic toughness and maximum load of the alloys conducted with the conventional thermomechanical processing where two step aging was carried out after cold rolling increased with increasing cold rolling reduction ratio while they were decreased in the alloys conducted with the conventional thermomechanical processing where one step aging was carried out after cold rolling. Grain refinement by RI-ITMT was effective for improving toughness and strength of the alloy. Newly proposed thermomechanical processing in the present study gave greater toughness at greater strength level.