Effect of high-pressure torsion process on mechanical properties of TC4-0.55Fe-0.08O alloy

Abstract

In the present study, the disc-shaped samples of TC4-0.55Fe-0.08O alloy were severely deformed by high-pressure torsion (HPT) under pressure of 6 GPa for 0.5, 1, 2 and 5 revolutions. The experimental results showed that the microhardness of TC4-0.55Fe-0.08O alloy treated with HPT was significantly increased by about 30% to 402 HV. The microhardness values were extremely heterogeneous along the diameter of the discs in the early stages of HPT and increased with the increase of the distance from the center to edges of the discs. Increasing the number of revolutions resulted in higher values and more uniform distribution of microhardness. The tensile properties of the HPT processed TC4-0.55Fe-0.08O alloy were investigated by unidirectional tensile testing at room temperature. It was found that the ultimate tensile strength of TC4-0.55Fe-0.08O alloy increased significantly with the increase in the number of HPT revolutions, from the initial 936 MPa to 1423 MPa after 2 revolutions, and then decreased slightly when the number of revolutions was increased to 5 revolutions. The elongation increased from the initial 11% to 13% after 1 revolution but then decreased sharply with the increase in the number of HPT revolutions. However, the ductility did not drop below 7%. The observations in this study indicated that the mechanical properties of TC4-0.55Fe-0.08O alloy can be improved as a result of HPT processing, which is of great significance for the practical production and application of TC4-0.55Fe-0.08O alloy.