Performance and Characterization of Bimetallic Joints through Conventional and Non-Coventional Welding Processes

Abstract

The purpose of this work is to study the performance of bimetallic joint processed through conventional (TIG welding) and non -conventional technique (microwave energy). The hot corrosion behaviour of the samples was also studied in simulated (40% Na2SO4-40% K2SO4-1O%Nacl-10%KCl) as well as in the actual environment of the boiler. Characterization of joints was done by XRD, SEM-EDS. Tensile testing and Vickers micro hardness were carried out. Tensile strength and micro hardness value of the microwave processed sample have a higher value as compared to the TIG welded sample. In a simulated environment of the boiler, 25 cycles were performed in a laboratory furnace at a temperature of 750℃. Each cycle is of 1 h 20 min in which 1 h is of heating duration and 20 min is of cooling at room temperature. Weight of the samples was noted down after each cycle. Study of hot corrosion in the actual environment is performed in a husk fired boiler power plant working at Nectar Pvt.Ltd., Dera bassi, Chandigarh. XRD, SEM-EDS and X-Ray mapping were used to characterize the product of corrosion. The results show that microwave welded joints performed better in both simulated and actual boiler environment. Although the surface oxide formed on both the cases were porous. However, XRD analysis revealed the formation of sulphides, which cause the sulphidation reaction leading to catastrophic failure of weld joints of the TIG welded samples.