DEVELOPMENT OF WELD BONDS FOR IMPROVED MECHANICAL AND METALLURGICAL PERFORMANCE OF STAINLESS STEEL JOINTS

Abstract

In this invetigation, I did theoritical and experimental study for the adhesive joining and resistance spot welding and weld bonding (combination of adhesive and resistance spot welding) of Stainless Steel of Grade 304 as a work picece (100x25x1 mm) and 2-C Plain Epoxy Resin as a adhesive using PECO Bench Spot welding machine for spot weld and Furnace is used for curing adhesive joint. After preparing the samples by spot and adhesive the Tensile - Shear test was conducting on the Universal Testing Machine (UTM) and observed the effect of surface preparation, effect the adhesive thickness, effect of curing temperature and time on adhesive bond strength, effect of curing time on tensile shear strength of the adhesive joint and effect of welding time on the tensile shear strength on the spot welding joints. By this investigation I concluded that ultimate shear tensile load of adhesive joint is more than the resistance spot weld. It is also observed that shear tensile load of weld-bond is more than the spot welding and adhesive bonding alone and a surface roughness of 220 emery grade gives maximum adhesive joint strength to 304 grade of stainless steel. After the tensile shear test we observed the nugget size, hardness and microstructure of the resistance spot weld and weld bond (which is cured at 120 °C for 60 minutes). Hardness of weld centre, fusion line, Heat affected zone (HAZ) and base metal were studied. Microstructure of resistance spot weld and weld bond were studied in optical micrograph, by microstructure we also observe the defects which is present in weld nugget. It is observed that if we select suitable parameters of weld bond can achieve significantly higher mechanical properties than that observed in resistance spot weld.