Abstract
	Sensitisation behavior of austenitic stainless steels are greatly influenced by several metallurgical factors such a chemical composition, degree of prior deformation, grain size, aging temperature-time. AISI type 316 stainless steel with two different chemical composition (varying mainly in carbon) were considered for the present study. The plates of analyzed steels were cut into strips of 150 x 100 mm and solution annealed (1100°C/1 h, water quenched) to eliminate any carbide precipitates formed during processing. The as-received material in mill-annealed condition was taken as reference corresponding to cold working of 0%. The as received sheets were cold rolled at ambient temperature to various levels of reduction in thickness ranging to 40%. In austenitic stainless steels 316 and 316 L were studied influence of prior deformation on degree of sensitization after isothermal sensitization in the temperature range from 500 to 900°C using different holding times from 0,02 to 100 h. 
	For determination the steels sensitivity to intergranular corrosion an oxalic acid etched test (ASTM A262 practice A) was used. The specimens were electrolytically etched in 10% oxalic acid for 90 sec. at a current density of 1 A/cm2. The etched structure is then examined at  250 x and was characterized as step, dual or ditch structure. The specimen showing step or dual structure was considered to be free from sensitization whereas the specimen showing ditch structure was classified as sensitized.
	The sensitisation behaviour of AISI 316 and 316L austenitic stainless steels having different chemical composition was studied for various degrees of CW ranging 0% to 40% reduction in thickness. From the results obtained TTS diagrams were constructed. 
	These diagrams were obtained by plotting sensitisation tests results on a temperature versus log soaking time axes and drawing a line which demarcates the sensitized and non-sensitized regions.
	The results showed, that effects of plastic deformation accelerated sensitization, and kinetics precipitation of secondary phases, especially chromium rich carbides (Fe,Cr)23C6. Precipitation of secondary phases in the deformated material was observed at the GB and intragranularly within the matrix too.
	Minimum  time required for sensitisation at nose temperature (tmin) was determined at 800°C for AISI 316 and at 750°C for AISI 316L. For AISI 316 and 40 % CW goes C-curve to lower times by the same temperature. For AISI 316L, the TTS diagrams are shifted towards lesser time and lower temperature than that of  0 % CW material.