Mechanical and microstructural characterization of solid wire undermatched multilayer welded S1100MC in different positions

This paper examines the mechanical and microstructural properties of thermomechanical rolling and direct quenched ultra high strength steel (UHSS) joints in the butt welded with different position applications. The influence of heat inputs according to the welding position on solidification appearance, microstructure, impact toughness, hardness, and tensile properties are investigated. Weld metal (WM) microstructure belonging to both PA (horizontal) and PF (vertical) positions consists of acicular ferrite mainly that morphology of them altered depending on heat input and cooling time. Besides acicular ferrite, martensite/austenite constituents (M/A) happened in PF-WM microstructure and it partially affects impact toughness. Heat affected zone (HAZ) size is less than PA except for root because of applied weaving amplitude on PF position affected heat flow and decreased exposed average peak temperature time. Martensite phase is dominant where HAZ of next to the last bead with high hardness values for top and bottom. Furthermore, necklace type M/A constituents were formed when the HAZ of the prior weld passes was reheated with subsequent weld passes.