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 degrees C and the forced cooling rates were 50 and 15 degrees 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 degrees C. The results indicate that it may be possible to substantially improve welding productivity by using forced cooling to reduce interpass times.