The effect of post weld heat treatment (PWHT) on residual stresses, yield strength and toughness as well as on microstructural features of submerged are weld metal was studied with three types of C-Mn-steels. All techniques used for measuring residual stress reduction in PWHT were found insufficient to adequately characterise the stress distribution. The yield and ultimate strength were not significantly affected by the PWHT (600 °C/2 h) applied. No improvement in the toughness as determined by the COD was found. Slight coarsening of the microstructure was, however, observed. With the submerged are welding method and the C-Mn-steels used in this study no other advantages of PWHT can be expected than reduced risk to brittle fracture through stress relief.