This paper aims at a systematic comparison of effect of single, double and triple pass welding on heat affected zone and tensile strength of AISI 304 stainless steel and chrome-manganese austenitic stainless steel. Degree of sensitization (DOS) increased with increase in number of passes and highest DOS (35.53%) was obtained for triple pass welding of chrome-manganese austenitic stainless steel. The decrease in tensile strength is relatively more in chrome-manganese austenitic stainless steel as compared to AISI 304 SS. The mode of failure for AISI 304 SS was ductile fracture, whereas chrome-manganese austenitic stainless steel failed due to intergranular brittle fracture.KEY WORDS: AISI 304 stainless steel; chrome-manganese austenitic stainless steel; shielded metal arc welding; heat affected zone; fractography; electron probe micro analysis.

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The use of Chrome-Manganese austenitic stainless steel (Cr-Mn ASS) has tremendously increased in past few years in applications like home accessories, office appliances, light poles, etc and it is serving as an alternative to 300 series. But, the study related to sensitization behavior of these steels is scanty. Therefore, this paper aims a systematic comparison on intergranular corrosion of AISI 304 stainless steel and Cr-Mn ASS. The qualitative and quantitative comparison of degree of sensitization of these steels was carried out on the basis of optical microscopy (ASTM standard A-262 practice A test) and electrochemical test (double loop electrochemical potentiokinetic reactivation (DLEPR)) respectively. The isothermal time-temperature-sensitization diagrams were used to compare the effect of heat treatment on sensitization zone of both the steels. The DLEPR results showed that the AISI 304 SS starts to recover from sensitization when ageing time is prolonged beyond 2 880 min. (at 700°C), whereas for Cr-Mn ASS, the degree of sensitization keeps on increasing to a very high value of 60.70% (11 520 min.). Chromium depleted zone was identified and compared using Electron Probe Micro-analyzer (EPMA) line scan of both the steels. The depleted region of sensitized Cr-Mn ASS is found to be much wider than that of AISI 304 SS.