The effect of loading rate on deformation of TA1 titanium alloy bars subjected to electromagnetic heading

Abstract

In this paper, the electromagnetic heading (EH) process was proposed. And experimental investigations on the HEH process (high loading rate) and the LEH process (low loading rate) were employed using Φ6mm-TA1 titanium alloy bars. The effect of loading rate on the microstructure evolution and deformation properties was revealed by the contrastive method. Deformation results showed that the HEH process with the relatively higher loading rate caused the fracture failure of the heading tails under very small deformation. Microstructure observations for the heading tails indicated that adiabatic shear bands (ASBs) were a main characteristic of deformed microstructures. The forming mechanism of the ASBs resulted from the adiabatic plastic instability. And the ASB was the root of crack initiation under the larger deformation. The hardness value with the ASB for the HEH process was higher than that of the LEH process, demonstrating that the hardening index increased as the loading rate increased. The rotational dynamic recrystallization mechanism accounted for the formation of recrystallization grains within the ASBs. And the number of dynamic recrystallization grains for the HEH process was more than that of the LEH process, indicating that relatively higher loading rate could promote rotational dynamic recrystallization of sub-grains.