Influence of pre-torsion and annealing heat treatment on the tensile mechanical properties of TA2

Abstract:

The effects of pre-torsion and annealing heat treatment on the tensile mechanical properties of TA2 were studied in present paper.According to tensile test results,the pre-torsion can significantly enhance the tensile yield strength and ultimate strength of TA2.The yield strength increases with the pre-torsion angle in a certain range，and drops sharply when the pre-torsion angle exceeds a certain value(6π).The ultimate strength increases all the time with the pre-torsion angle. The elongation decreases with pre-torsion angle. Subsequent annealing heat treatment tests of pre-torsion TA2 at different temperatures(350°C-750°C) show that the strength gradually decreases with annealing temperature.When temperature is 650 °C ,the strength has been reduced to the initial value of parent metal.The elongation increases with temperature, but it can"t recover to its initial value of parent material. The observation of fracture surface shows that dimple get smaller and shallower with the increase of pre-torsion,and there are lots of cleavage striation characterized by river pattern when pre-torsion angle is 8π.The observation of SEM shows that twins and deformation tissues after the pre-rotation is the main reason for the increase of TA2 strength.