Influence of Heat Input on Mechanical Properties of Multipass Low-Alloy Steel Weld Metal

Influence of heat input on the tensile strength and impact toughness of multipass weld metal made with AWS E81T1-Ni1 metal-cored wire was investigated. Welding parameters such as current, voltage and travel speed were varied independently to get different heat inputs. When it was increased by varying current, tensile strength of the weld metal increased even if more primary ferrite and wider columnar grains were observed. The increase is attributed to the higher recovery ratio of deoxidizing elements such as carbon, manganese and silicon due to the shorter reaction time in both wire tip and arc column. It also showed that impact toughness was influenced by the formation of reheated weld metal by subsequent passes and it decreased continuously with an increase of the amount of coarse grained region in the reheated weld metal.