Effect of forced cooling on the tensile properties and impact toughness of the coarse-grained heat-affected zone of a high-strength structural steel

The effects of forced cooling, i.e., forced cooling rate and forced cooling finish temperature, on the tensile and impact toughness properties of simulated weld coarse-grained heat-affected zones has been explored in the case of a low-carbon thermomechanically processed steel with a yield strength of 700 MPa. The forced cooling finish temperatures that were studied were 400, 300, 200, and 100 °C and the forced cooling rates were 50 and 15 °C/s. Coarse-grained heat-affected zones were simulated using a Gleeble 3800 thermomechanical simulator. For the steel concerned, strength and impact toughness improved significantly when the steel was cooled rapidly to 200 or 100 °C. The results indicate that it may be possible to substantially improve welding productivity by using forced cooling to reduce interpass times.