Abstract
The relationship between alloying elements, microstructure and corrosion characteristics of SUS 304 stainless steel has been investigated through repeated electron-beam melting. The contents of Cu, Mn, C and O in the steel decrease in proportion to the number of electron-beam irradiation, but the contents of S, P, Cr and Ni are not largely changed. The thermodynamic consideration has been carried out for the change in the contents of alloying elements with electron-beam irradiation. General corrosion testing in boiling 5% H2SO4, inter-granular corrosion testing in Streicher's solution and anodic polarization measurements have been made for comparison between the steel before and after electron-beam melting. By electron-beam melting, the steel becomes susceptible to general corrosion but less susceptible to inter-granular corrosion after sensitization heat treatment. The present study suggests that Cu is a beneficial alloying element to avoid general corrosion and that decarburization by electron-beam melting improves inter-granular corrosion resistance.
