Effect of Niobium/Molybdenum Microalloying on SS316LN Steel

Abstract

In recent years SS316LN microalloyed stainless steel is preferred for use as jacket material for Nb3Sn superconductor strands/wires. In the present investigation, microalloyed SS316LN is prepared in a vacuum induction melting furnace; Niobium and Molybdenum in their ferroalloy stage are considered as alloying element. This microalloyed steels are cast in water cooled copper mould. The tensile strength and elongation are measured and the fracture surface is studied under scanning electron microscope. It is observed that, there is a reduction of tensile strength and decrease in hardness of the steels prepared with addition of either/both the alloying elements; however there is an increase in ductility, which is helpful for cold rolling operation. From the micrographs it is observed that nitride precipitates are formed along the grain boundary, but formation of chromium carbide precipitates is reduced.