Stress relaxation under tension by accompanyed current in ultrafine-grain titanium

Abstract

The article studies the effect of stress relaxation caused by strain stops and pulsed current on the tensile deformation behavior of Grade 4 ultrafine-grained titanium. The samples were deformed in the following modes: without current; continuously with current; with periodic current supply, periodic current supply during stops of strain. The microhardness of the working zone of the tested specimens was studied. Fracture studies of the failure zone were carried out. It is shown that, as a result of the continuous introduction of current during tension, the flow stresses decrease, and the elongation to failure increases. Periodic introduction of current, accompanied by strain stops, leads to a maximum increase in the relative elongation to failure due to stress relaxation. The relaxation effect of the pulsed current is manifested in a decrease in microhardness and the transition of the fracture type from a dimple-cup fracture to a predominantly dimple fracture.

Keywords

• stress relaxation
• tension
• titanium
• nanostructure
• electroplastic effect
• pulsed current
• microhardness
• fractography