Effect of heat treatment on microstructure, hardness and rollability of V55Ti30Ni15 alloy membranes

• NiTi precipitated and dissolved in the V-matrix heat treated at various temperature.
• Microstructural change resulted in the alloy hardness variation after heat treatment.
• The as-cast alloy can be softened by precipitation of NiTi during heat treatment.
• The alloy heat treated at 800 °C for 18 h have a better rollability.

The effect of heat treatment on the microstructure, hardness and rollability of V55Ti30Ni15 alloy membranes has been investigated in this study. The microstructure resulting from different heat treatment conditions has a great influence on hardness. Fine NiTi particles precipitate from the supersaturated V-matrix solid solution at temperatures above 600 °C, increase in quantity until 800 °C, then dissolve back into the V-matrix with a further increase in temperature up to 950 °C. The resultant hardness decreases with temperature until 800 °C, and then increases from 800 to 950 °C. In the present study, a comparison has been made between the rollability of the as-cast and the heat treated state selected for deformation at different rolling temperatures. The percent reduction in thickness of the heat-treated alloy (800 °C/18 h) has been found to be up to 30% higher than that of the as-cast alloy, even at room temperature (cold rolling).