Investigations on microstructural characteristics and mechanical properties of 316 L stainless steel welded joints using nickel coated filler material by gas tungsten arc welding

Abstract

Abstract The main objective of this present study is to weld the 316 L stainless steel (SS) joints by gas tungsten arc welding (GTAW) process using nickel coated filler materials. The existing modified filler metals with flux coatings used in GTAW are generally accompanied with more complications. Therefore it is essential to suppress complications and enhance the welding strength which significantly depends on filler metals properties. In this work, the filler materials used in GTAW are coated with nickel in several grades for welding process. The results of these filler metals are compared with the Plain-316 filler metal. Ni-304 filler metal shows better uniformed weldment and heat affected zone (HAZ) with less planer slip micorstrucutre on its surface. The tensile test results reveal that Ni-316, Ni-304 & Ni-308 filler metals produces fracture on the parent metal. Among the various filler metals used, Ni-304 filler metal shows the highest impact toughness of 69.10 J and it is 71% higher toughness than Plain-316 filler. Average hardness of Ni-308 filler metal is 2.78% higher than the Plain-316 filler metal. Scanning electron microscope (SEM) images of weldments and HAZ were analysed to investigate the effect of nickel on the microstructure changes.