Role of power ratio on ductility-dip cracking of Ni-Cr-Fe weld

Abstract

n an austenitic Ni-Cr-Fe weld, the susceptibility for ductility-dip cracking increased with increasing power ratio for a given heat input. The solidification sub-grain width increases with increasing power ratio. Only in the case of relatively high power ratio which is defined as the power divided by the cross-sectional area of deposited metal, Auger electron spectroscope specimens show the solidification sub-grain boundary cracking, and the freshly fractured surface shows the strong sulfur and oxygen peaks. While the temperature gradient might be low in the high power ratio and thus the thermal tensile stress be overall low, the susceptibility for ductility-dip cracking increases with increasing power ratio. This may be attributed to the impurities more enriched at the solidification sub-grain boundaries resulting from the high power ratio.