Effect of root pass removal procedures on mechanical and microstructural properties of shielded metal arc welded joints

This research investigates the impact of root pass removal procedures, specifically back grinding and back gouging, on the mechanical and microstructural properties of mild steel joints welded through shielded metal arc welding (SMAW). The study employs ASTM A516 grade 70 base metal and E7018 electrode, providing detailed information on welding parameters, joint preparation, and testing methods. Microstructural analysis indicates that the back-gouged joint, with higher heat input, exhibits coarser grains in heat-affected and fusion zones compared to the back-ground joint. Tensile tests reveal superior mechanical properties in the back-ground joint, attributed to grain refinement. Charpy impact tests highlight a 9.5% reduction in impact toughness for the back-gouged joint associated with coarser grains. Microhardness profiles support these findings, emphasizing the importance of welding parameters in achieving desired microstructural outcomes and mechanical performance. The research contributes valuable insights for optimizing welding processes and improving the integrity of welded joints.