The ASME SA335 P92 and AISI304 steels find primary applications in constructing superheaters and re-heaters (SH/RH) tubes within ultra-supercritical boilers and renewable energy-based power plants. Given the significance of joining these materials, it's imperative to critically examine the residual stresses induced in the weldment for ensuring the component's safe design. Hence, a thorough numerical analysis has been conducted to scrutinize the formation of residual stress, strain, and the various heat-affected zones generated during dissimilar joining. The analysis employs the element birth and death technique, coupled with a novel approach of prescribing target weld temperatures for thermal and residual stress analysis in the weldment comprising ASME SA335 P92 and AISI304 steel. Observations reveal that the peak temperature gradually decreases from the fusion line towards the base metal region, attributed to differential cooling rates. Notably, the examination of weldment deformation patterns highlights elevated peaks near the weld pool region.