Grain boundary segregation of antimony in heat affected zones during welding thermal cycles for a Cr-Mo low alloy steel

摘要

Grain boundary segregation of Sb in heat affected zones during welding thermal cycles is examined using field emission gun scanning transmission electron microscopy (FEGSTEM) for an Sb-doped Cr-Mo low alloy steel. A Gleeble-1500 thermomechanical simulator is used to simulate the welding heat affected zone with a peak temperature of 1320℃ for heat inputs of 36, 60 and 100 kJ/cm. The results show that non-equilibrium segregation of Sb occurs during thermal cycles and critical welding heat input is found to be between 36 kJ/cm and 100 kj/cm, at which the maximum segregation of Sb may be obtained during corresponding thermal cycling. If possible, this critical heat input should be avoided in engineering practice.