Fracture properties of multipass submerged are weld of HSLA steel produced by using flux cored filler wire

Multi pass submerged are welding of 25 mm thick structural steel plates has been carried out at different energy input using flux cored filler wire and basic agglomerated flux resulting the weld deposit having chemical composition confirming that of a high strength low alloy (HSLA) steel. Microstructure and hardness of different microstructural regions of the multipass weld has been studied. Tensile properties of the weld deposit has been found out by carrying out tensile test of the weld joint being fractured from the weld. Fracture toughness (Ka) and fatigue crack growth properties of the weld are studied and correlated with the welding energy input, microstructure and ultimate tensile strength of the weld. The increase in energy input has been found to reduce the hardness, ultimate tensile strength and yield strength, but to enhance the ductility and K-Q of the weld primarily due to its influence on microstructure of the weld deposit. However, the increase in energy input has been found to reduce the da/dN at higher Delta K but, it has been found to enhance the same at lower Delta K. The K-Q and da/dN of the weld are found to be well correlated with its tensile strength, where an increase in tensile strength reduces the K-Q but enhances the da/dN at Delta K higher than 30 MPa root m.