Investigation of the Corrosion Behaviour of Welded Area of Austenitic Stainless Steels under Stress

Abstract

The corrosion behavior of austenitic stainless steel was investigated under both static and dynamic conditions. In this study, corrosion behavior of welded and unwelded austenitic stainless steels, SS304, SS310, SS316 were investigated using three different stirring speeds; 100, 200, 350 rpm and were subjected to two different corrosive environments; seawater (3.5% NaCl), and acidic ferric chloride (FeClᴣ). The rate of corrosion was measured using spectrophotometry. The microstructure was examined using optical microscopy. Experimental results indicated that the highest corrosion rate was observed in acidic ferric chloride, 8.56 mg. min -1 .cm -2 for SS304 at 350 rpm speed (high mechanical stress condition), compared to seawater under the same conditions, 7.96×10 -4 mg. min -1 .cm -2 . Welded stainless steel area were highly sensitive to the corrosive environment as a result of the increasing thermal stresses in both the weld zone and the heat affected zone (HAZ). Also, the corrosion rate was found to increase with increasing the stirring speed due to its effect on the mass transfer and mechanical stresses.