Investigation of welding of dissimilar high thickness SA106 Gr.C carbon steel and SA335P12 alloy steel to eradicate the failure in boiler components fabricated through SAW and SMAW processes

•A study of dissimilar joints between SA335P12 and SA106Gr.C has not been reported.•Columnar grains of ferrite and carbides with inter-bead refinement are revealed.•Reduction of 29.9 HV (15%) hardness value at weld metal by SAW process.•The presence of 7% Silicon was responsible for cracking in the SMAW method.•Consumes 37.8% less electrical energy when welded by submerged arc welding.