Microstructure and tensile properties of submerged arc welded 1.25Cr-0.5Mo steel joints

This article describes the effect of heat input (controlled by welding current and welding speed) on the microstructure and tensile properties of high strength low alloy (HSLA) steel weldments produced by submerged arc welding (SAW). The SAW process was used for welding of 16mm thick 1.25Cr-0.5Mo steel (ASTM A387 gr-11) plates. The weld joints were prepared by varying the welding current (500-700A) and welding speed (200-300mm/min). The increase in the heat input affects the proportions of different microconstituents both in the weld metal and heat affected zone (HAZ). It is observed that the tensile strength (UTS, YS) decreases with increase in heat input. The scanning electron microscopy (SEM) of tensile test fractured surfaces usually exhibited ductile failure.