To Study the Optical Metallography for Austenitic Stainless-Steel Grade 304 - A Review

In most industries Austenitic stainless steels equipment fails due to intergranular stress corrosion cracking (IGSCC) in long service life of equipment. IGSCC is due to the formation of chromium carbide along the grain boundary at temperature of 500°C to 800 °C during welding. Chromium carbide formation cause chromium depletion below 13 wt. % mainly in heat affected zone(HAZ). But when this welded stainless steels in which chromium carbide already exists are used in industries at temperature below 500°C, chromium carbide grow and cause more chromium depletion called Low Temperature Sensitization. Failures of equipment like furnace tube, compressor blades etc. is due to LTS. To increases the resistance for sensitization, stainless steels containing low carbon are used. Because of low carbon, formation of chromium carbide is also less and minimized the sensitization. In this paper, the optical metallography of austenitic stainless steel is done to study chromium carbide depletion. This is done by using low temperature sensitization heat treatment.