Abstract
This study investigates the combined effect of the Tungsten Inert Gas (TIG) and Metal Inert Gas (MIG) arcs in achieving improved mechanical and microstructural properties compared with the standalone TIG and MIG arcs based on optimum parameters setting for the TIG and MIG welding processes. TIG and MIG Miller welding machines with a maximum capacity of 400 A were used as the combined heat source. The welds produced by the TIG-MIG, TIG and MIG welding processes were characterized via tensile and hardness testing, macrostructural investigations, microstructural analysis, and X-ray diffraction analysis. The results from the characterization show that the TIG-MIG hybrid joint had better tensile strength, yield strength and percentage elongation properties than the standalone MIG and TIG welded joints, respectively. The fractograph of the TIG-MIG joint was characterized with uniform fine dimples showing a more ductile failure characteristic. Macrostructural evaluation revealed that the heat-affected zone of the TIG-MIG hybrid joint was larger than those of the individual TIG and MIG processes. The microstructure of the TIG-MIG joint showed an abundant presence of acicular ferrite with cementite on the boundaries of ferrite grain. Martensite phases diffracted at higher intensity peaks in the TIG weld while iron phases diffracting at high-intensity peaks in the MIG weld, and lastly, the TIG-MIG welded joint showed only iron phases which accounted for its lowest hardness value when compared with standalone MIG and TIG joints.