This investigation was carried out with the aim of studying the effect of Post Weld Heat Treatment (PWHT) on the microstructure and the mechanical properties of different types of metallic components. The objective was to reduce or eliminate the residual stress in these components without compromising the strength. Two types of welded materials, AISI-410 and AISI-1020 were fully investigated. In order to optimize the heat treatment conditions, different PWHTs were applied by varying the soaking temperature, heating rate, soaking time duration and cooling rate. To assess the effect of these different heat treatment schemes on the mechanical properties, micro-hardness, tensile strength and notched impact tests have been employed on these welded joints. Metallurgical testing has also been carried out to assess the change in the metal microstructure before and after the heat treatments. A hole drilling method has been used to estimate the magnitude and distribution of residual stresses before and after applying these different kinds of heat treatments. Finite element method has also been used to study the effect of residual stresses on these welded components. To carry out this work a finite element program LUSAS was employed with the objective of studying the effect of the length and width of the welding on the mechanical properties. The results show that there is a substantial reduction in the residual stresses with a good improvement in the mechanical properties for certain schemes of PWHTs.