Microstructural Characteristics and Mechanical Properties of Dissimilar Joints of Aisi 316LN Austenitic Stainless Steel and Modified 9Cr-1Mo Steel

Abstract

In liquid metal cooled fast breeder reactors, the dissimilar joint between grade 91 ferritic steel and 316LN stainless steel is frequently encountered. For better integrity assessment, mechanical properties of each region need be evaluated. In the present investigation, dissimilar joints between grade 91 to 316LN SS were fabricated by shielded metal arc welding process using nickel based electrodes. Mechanical properties (Tensile and impact toughness) of different regions were evaluated by placing the notch at each location. Microhardness variation across the dissimilar joint was recorded. Microstructural analyses of various regions were done by optical and scanning electron microscopy. From this investigation, it is understood that the in-homogeneous mechanical properties were observed across the dissimilar joint. The development of complex microstructure at the fusion interfaces will alter the mechanical properties across the dissimilar joint.