Abstract

The effect of forced cooling using heat sinks on the mechanical properties and interpass waiting time of two-pass welds has been studied for a martensitic steel with a yield strength of 960 MPa when the interpass temperature was 100 °C. Cross-weld tensile and − 40 °C Charpy-V impact toughness properties were examined. The use of heat sinks is shown to result in a beneficial increase of the cross-weld yield strength but at the expense of the yield-to-tensile strength ratio. Due to its particularly detrimental effect on the heat-affected zone (HAZ) toughness of multipass welds, special attention was given in the Charpy-V toughness of the intercritically reheated coarse-grained HAZ (ICCGHAZ) by also testing simulated ICCGHAZs. It is shown that forced cooling has a beneficial effect in respect of the toughness of this simulated subzone and on the Charpy-V toughness of the HAZ of the actual welds. The interpass cooling time during the two-pass welding was reduced by 37%. The results indicate that, in the case of high-strength steels, it may be possible to simultaneously improve both welding productivity and mechanical properties by using forced cooling down to 100 °C to reduce waiting time between weld passes.