Analysis of softening zone on the surface of 20Mn2SiCrMo bainitic railway switch

The surface softening phenomenon of 20Mn2SiCrMo railway switch was studied using lab scale thermal simulation experiments followed by hardness measurement and macroscopic characterization. The thermal simulation experiments successfully reproduced the softening behavior observed in real manufacture processes. The softening zone formation mechanism is revealed by the comparison between thermal simulation experiments and real rail analysis under a series of inducting heating temperatures at different measurement locations. It is also found that the width of softening zone is related to induction heating temperature and cooling rate.