SOME INVESTIGATIONS ON THE MECHANICAL CHARACTERISATION OF BIMETALLIC WELDS

Abstract

Dissimilar metallic welds between carbon steels and austenitic stainless steel are widely used in steam generator of nuclear power plants and is of great area of interest amongst the researchers. Stainless steel tubes are used in high temperature sections in combination with pressure and corrosive environment. In the lower temperature region of the plant, less expensive carbon steels with better creep resistance are used. For the safer operation of the plant we must ensure about the safety aspects of the bimetallic weld joint between the carbon steel and austenitic stainless steel. In this study German steel grade 20MnMoNi55 and AISI 304 austenitic stainless steel were joined by submerged arc welding (SAW) process using a stainless steel (ER316L) filler wire. The welding was performed with different flux combinations to study the influence of flux Basicity. After welding, ultrasonic non-destructive testing was carried out on welded plates to ensure the defect free weld joint. Tensile and Charpy tests were conducted using UTM and Impact testing machine to estimate the tensile and impact property of the as-welded samples. To study the effect of heat treatment on mechanical properties, heat treatment of as-welded samples was done. SEM analysis of tensile test fractured samples was performed to study the failure mechanisms and is discussed in details.