(9037)Effect of Heat Input on IGC of AISI 316L Stainless Steel During MIGW

摘要

In this work the study of intergranular corrosion of welded austenitic stainless steel type AISI 316L plates are carried out. The plates welded at different heat inputs, by controlling the values of voltage, current and torch speed by selecting full automatic MIG technique. To illustrate the effect of heat input on intergranular corrosion behavior of welded AISI 316L austenitic stainless according to ASTM standards, A262-86 test has been selected to calculate intergranular corrosion. Eight heat inputs are selected in order to illustrate the effect of metallurgical aspects associated during metal inert gas welding on intergranular corrosion behavior of austenitic stainless steel AISI 316L. Eight heat inputs are (220, 269, 300, 315, 330, 340, 380 and 395)J/mm. The results showed that there was a strong relation between welding parameters and intergranular corrosion rate. Although during MIGW, filler metal of 316L with nearly the same chemical composition of base metal has been selected, the microstructure of a weld is significantly different from the microstructure of base metal, and microstructure of heat affected zone are alerted by different heat inputs and can also have different corrosion characteristics. The heat input value that provided maximum IGC resistance is 330 J/mm. and the heat input value that caused maximum IGC is 380 J/mm. The results can be attributed to some metallurgical transformation that occur at welded and that affected zone regions which accompanied the different cooling rate in addition to the formation of delta ferrite and precipitation of chromium carbide and dendrite structure in weld region for AISI 316L Stainless Steel. The microstructure of welded and corroded samples indicted that different heat inputs produce different phase in both weld and heat affected zone which preferentially corroded and the have a significant affect on IGC rate.