Vinoth Kumar M, Rao AG and Balasubramanian V
Super 304H austenitic stainless steel tubes containing 2.3 to 3 (%wt) of Cu is mainly used in superheaters and reheater of ultra-supercritical boilers. Welding high alloyed steels such as stainless steels can result in local variation of alloying elements within the weld metal and such segregation may affect the high temperature properties of the weld joint. It is preferable to control the solidification structure of the weld by altering the prevailing thermal gradients in the weld pool during welding. The effect of current pulsing on microstructure and hot tensile properties of filler added gas tungsten arc welding (GTAW) of super 304H is studied. Current pulsing is found to be beneficial in improving the hot tensile properties of super 304H GTAW joints at all test temperature, which is attributed to the grain refinement, increase in frequency of high angle grain boundaries, reduced segregation and finer carbonitrides precipitation.
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