Research on the diffusion of ti-based stabilizer through flux coated GTAW to reduce carbide precipitation in SS304 weldment

Sensitization is a major problem, which leads to intergranular corrosion in stainless steel weldments due to precipitation of Chromium (Cr) carbides. Thus, Cr depleted from heat affected zone (HAZ) results in intergranular corrosion causes failure of structure. In the present research work an attempt has been made by the diffusion of titanium based stabilizer into HAZ during welding of SS 304 by gas tungsten arc welding (GTAW). The Ti powder (< 20μm size) has been used and coated on v-joint before welding in optimized coating thickness. This process is termed as flux coated gas tungsten arc welding (FC-GTAW). The surface microstructure, surface morphology and surface chemistry have been analyzed by Microscope, Field Emission Scanning Electron Microscopy (FESEM) and Energy Dispersive Spectroscopy (EDS). The EDS results along with SEM revealed that Ti has been diffused up to 2mm from the fusion boundary. The EDS line scan has confirmed the depth of Ti diffusion. Intergranular corrosion resistance is evaluated by DLEPR test, as a result of this test the sample coated with flux shows better corrosion resistance. The result indicates that FCGTAW is novel technique for reducing the formation of Cr carbides thus enhancing the corrosion resistance of stainless steel.