Effect of post weld heat treatment on the oxide scaling of Cr-Mo steel weldments

Welding of 'chromium-molybdenum' ferritic steels often causes steep modifications in the microstructure of the weld heat affected zone (HAZ). The paper presents results to establish the role of such microstructural variations on inhomogeneous scaling across the weldments of 2.25Cr-1Mo and 9Cr-1Mo steels, as well as further degradation in microstructure during oxidation of the weldments. Microstructure of different regions of the steel weldments was characterized by electron/optical microscopy. Oxidation of different weldment regions in air and steam environments have clearly suggested variations in scaling rates across the weldment regions, and further microstructural degradation in the HAZ. The paper also presents a report of the effect of post weld heat treatment on oxide scaling behavior. This paper contributes in the correlation between welding parameters and oxidation behavior.