Effect of forced cooling after welding on CGHAZ mechanical properties of a martensitic steel

The effects of forced cooling, meaning forced cooling rate and forced cooling finish temperature, on the tensile and impact toughness properties of simulated weld coarse-grained heat-affected zones have been studied for a commercial grade martensitic steel with a yield strength of 960 MPa. The simulations were done by using a Gleeble 3800 to give forced cooling finish temperatures of 500, 400, 300, 200, and 100 °C and forced cooling rates of 50 and 15 °C/s. For the steel studied, strength significantly increased with no significant negative effects on impact toughness when the steel was cooled rapidly to 200 or 100 °C at 15 °C/s. The results indicate that it may be possible to improve welding productivity and mechanical properties of the steel by using forced cooling down to 100 °C to reduce waiting time between weld passes.