The aim of this work is to study the effect of Post Weld Heat Treatment on the micostructural and strength properties of high chromium steel [AISI 410] components. This work also aims to estimate the magnitude and distribution of the residual stress on the above type of welded components. In introducing this work an extensive literature survey on the historical development and the advantages and disadvantages of welding process has been presented. A review of the different technique which are used to determine the residual stress is also presented. In this work two types of Post Weld Heat Treatment were used. in the first type of heat treatment, the specimen was kept at 316°C for 30 min, then at 427°C for 30 min, and finally, at 546®C for 2 hrs. In the second type of heat treatment the specimen was kept at 760 °C for 2 hrs. Two types of specimens were used to simulate build-up welding and crack repair conditions, each type of these specimens have different parameters (thickness, bead length and width). Stress relaxation technique was used to detemine the magnitude and distribution of the residual stresses for the above specimens. The results show that the first type of heat treatment reduces the hardness in the welding zone by about 15% of the hardness of the as welded specimen and improves the tensile strength. The second type of heat treatment decreases the hardness in the welding zone by about 40% but decreases the tensile strength by about 10%. The residual stress measurements show that there is a tensile stress around the welded zone, and that the greatest value recorded is about 72 N/mm*. These residual stresses decrease as the distance from the welding zone increases.