Hot ductility behavior of vanadium containing steels

The hot ductility of four plain carbon steels containing different levels of V have been obtained after solution treating at 1330 °C, cooling to test temperatures in the range 700–1000 °C, and testing at a strain rate of 3×10−3 s−1. The obtained ductility troughs were compared with that obtained from Nb containing steel. Raising the V level from 0.009–0.1% (through 0.048 and 0.07%) was found to deteriorate the ductility as the obtained trough becomes wider and deeper with increasing V content, due to the increased amount of VN precipitation in the steel, but the lowest ductility obtained does not approach the low value exhibited by Nb containing steel. The recovery of ductility at high temperature side of the trough corresponds to dynamic recrystallization and the greater the degree of precipitation, the higher the recrystallization temperature. Ductility improved as well when the test temperature falls so that there is a sufficient transformation induced ferrite present to prevent strain concentration.