Welding residual stresses can predominantly damage the reliability and performance of the welded structures. In this experimental study the effect of constant and pulse arc TIG welding processes, the development of thermal fields and residual stresses in dissimilar weldments of SS 316 and Monel 400 are investigated. During the welding process, the temperature distribution over the surface of the weldments has been captured using Infra-Red Thermography. The developed residual stresses have been measured experimentally by using the x-ray diffraction technique. The nature of residual stresses in constant and pulse arc weldments have been observed and compared. The experimental results of constant current weldments are validated against finite element analysis using ANSYS software. Transient thermal analysis is performed to determine heat dissipation during the welding process in different modes such as conduction, convection and radiation. Also, the elemental birth and death techniques are considered for the effect of filler wire owing simulation. From the results, the experimental and numerical analysis of constant arc welding process show good agreement to each other in temperature fields and residual stresses. © 2019 IOP Publishing Ltd.