Dissimilar Welding of Low Alloy Steels Welded Joints: Effect of Run-Off and Run-On Plates

Abstract

The steel run-off plates attached at the start and end of a weld usually have the same material, shape, and groove as the base metal according to the rules for designing and constructing ship steel structures. However, rather than using the same grade of base steel, readily available steel is often used for these plates to increase material utilization. When using dissimilar grade steel as a run-off plate, the physical properties of the base metal may be diluted if the weld joint of the base plate is penetrated, thereby lowering the physical property value of the joint. If the physical properties of the welded part of the real structure are lowered because of the dilution of the properties of the dissimilar grade steel material, the safety of the entire structure can be affected. Therefore, in this study, analyses of the metal microstructure, hardness, impact, and chemical composition were performed on surfaces where the run-off plate was removed after welding to examine the effect of dissimilar run-off plate. The results of this study reveal that the properties of the run-off plate were not diluted toward the base metal and the Charpy impact value at the weld end was up to 48% greater than the impact value at the start of the weld at a temperature of −40 °C.

Keywords

• run-off plate
• butt welding
• metal microstructure
• dissimilar welding
• component analysis
• dilution