Studies on A-TIG welding of 2.25Cr-1Mo (P22) steel

•P22 steel so far joined using various processes mainly GTAW process.•The present work makes a detailed analysis of ATIG process on joining of P22 steel.•There is no literary information on joining of P22 steel using ATIG process.•There was an improvement of toughness of welds using ATIG process in the as-weld condition as well as PWHT condition. In the present study, 12mm thick double side square butt joint was fabricated on 2.25Cr-1Mo (P22) steel plates using A-TIG welding process with in-house developed activated fluxes. Microstructure and mechanical properties of the weld joint were characterized. Effect of post weld heat treatment (PWHT) on the impact toughness was studied. In the as-welded condition toughness was found to be 133J. There was no proeutectoid ferrite in the weld. After PWHT, the toughness of weld was increased to 177J due to dissolution and coarsening of existing precipitates. A-TIG weld joint of 2.25Cr-1Mo steel exhibited high hardness and good impact toughness in the as welded condition.