Study on the effect of high-temperature ceramic fiber insulating board to weld grade P-91 steel

Bead-on-plate (BOP) welding was carried out using an autogenous tungsten inert gas (TIG) welding to weld P91 steel plates of dimension 100 mm × 50 mm × 6 mm thick. P91, is generally subjected to post-weld heat treatment (PWHT) to improve the mechanical properties. PWHT has to be carried out within a narrow window of parameters, else, the mechanical properties deteriorate. To overcome this difficulty of maintaining a narrow range of parameters to perform PWHT, in the present study, welded samples were insulated as soon as welding was over by utilizing High-Temperature Rigid Ceramic Fiber Board (HTRCFB). The results of this study were compared with the result of the same material welded by normal TIG welding in an earlier study. This study found that, weld bead geometry, microstructure of the heat insulated TIG welding was higher compared to those of a normal TIG welding. The hardness of heat insulted welding, however decreased marginally over the normal TIG welded samples.