Influence of Heat Treatment and Carbon Content on the Hot Ductility of Nb-Ti Microalloyed Steels

Abstract

The influence of C and heat treatment on the hot ductility of Nb-Ti microalloyed steels, in the temperature range 800 to 1300°C, was investigated by tensile testing at low strain rates. The C range was varied between 0.07 and 0.14 wt% (peritectic composition). The heat treatments involved direct heating to the test temperature, annealing at 1330°C and subsolidus reheating at 1480°C . The increase of the C content to 0.14 wt% slightly affects the hot ductility after the direct heating and annealing treatments. However, after subsolidus reheating, the width of the ductility trough is increased in the 0.14 wt% C steel. This effect is attributed to the coarser austenite structure inherited from this prior heat treatment.