Hybrid Approach of Flux-Cored Root Pass with Subsequent Pass of Metal-Cored or Solid Wire in Multifiller Gas Metal Arc Welding

Abstract

In the present study, gas metal arc welding was applied to SA516 Gr70 carbon steel by hybrid root pass and filler pass, wherein the rest of the process parameters were kept as it is. Flux-cored filler wire is applied at the root pass, while the subsequent filler pass was applied by solid, metal-cored and flux-cored wires in order to form three different welded joints. Macro-graphic examination, microstructures, tensile testing, impact testing, bend testing, and hardness variations were carried out to evaluate the performance of the welds. The results show that the hybrid approach of multipass GMAW of flux-cored root pass–metal-cored filler pass has improved process performances by reducing an overall heat input and output current. Angular distortion was reported minimum at hybrid weld of flux-cored root pass–metal-cored filler pass that was reported as 1.72°. Minor improvement in tensile properties such as tensile strength and yield strength was reported for FS and FM welds relative to FF weld. Minor decrease in fracture to the elongation was reported for FS hybrid weld relative to FM and FF weld. Maximum tensile strength and yield strength of 568 MPa and 385.45 MPa were reported for FS weld, respectively. Impact toughness was observed maximum for the hybrid weld of flux-cored root pass–solid filler pass. Higher macro-hardness was reported at the weld of FF weld relative to FS and FM welds. Hybridization of filler wire of GMAW can enhance overall cost and time reduction, with acceptable properties.