A process for improving the mechanical properties of ss316ln by micro alloying with no or/and mo

摘要

The present invention provides a vacuum induction melting process to produce micro alloyed stainless steel with significantly improved mechanical properties. Small amounts of Nb or/and Mo were added to SS316 LN from their respective ferro alloys states at charge stage. Melting operation was carried out in N2 and Ar ambience within the furnace chamber. In situ casting of the micro alloyed SS melt was carried out in the furnace under the vacuum condition using oxygen free high conductivity (OFHC) copper mould cooled with chilled water. The cast ingots produced were cold rolled to reduce the cross-sectional area. The cold rolled bars were heat treated in vacuum furnace. Thus, by micro alloying and proper heat treatment of the cold worked SS, it was possible to prevent the growth of Cr23C6 which causes embrittlement in SS. Xray diffraction (XRD), selected area electron diffraction (SAED), field emission scanning electron microscope (FESEM) and energy dispersive spectra (EDS) of x-ray studies of the starting SS and the micro alloyed SS establish significant reduction of the growth of Cr23C6in the SS.