The Effect of Nickel on the Mechanical Properties of High-Oxygen Underwater Wet Welds

Abstract

The use of oxidizing electrodes for wet welding of offshore structural steels, in spite of their low susceptibility to hydrogen HAZ cracking, is limited, in part, by the poor mechanical properties of their weld deposits. Low levels of carbon, manganese, and other deoxidizers, together with high oxygen contents seems to be one of the reasons for this low performance. This work investigated the influence of nickel additions on the tensile strength and impact resistance of wet welds deposited at 1.1 m of water depth. It was found that welds with nickel contents between 2 and 3 weight percent exhibited maximum toughness and tensile strength. Nickel additions also had a strong effect in reducing the grain size of equiaxed ferrite in the reheated region of underwater wet welds, thereby improving their mechanical properties. The drop of mechanical properties for nickel contents higher than 3 weight percent was associated with weld metal solidification cracking.