Cyclic and isothermal oxidation behaviors of first and fourth-generation superalloys AM1 and MCNG were investigated to evaluate the ability of the scratch test to quantify the adhesion of multi-layered oxide scales. Effects of sulfur content and of scale thickness were studied independently. Available models lead to large discrepancies in the calculated work of adhesion values with the evaluation of the residual stress being the largest source of error. Nevertheless, models can assess the effect of sulfur content and the scratch test can be used to correlate the long-term cyclic oxidation behavior and the adhesion of oxide scales.

International audienceThis work focuses on the effect of alloyed sulphur as MnS inclusions in austenitic stainless steels. AISI 304L and AISI 303 were oxidized at 1000 degrees C in synthetic air. The high sulphur grade, AISI 303, presents a breakaway oxidation with formation of nodules with an inner part composed of alternated layers of Fe-rich and Cr-rich oxides. During oxidation, MnS inclusions near the metal/oxide interface are partially dissociated. Manganese is incorporated in the oxide. The sulphur is trapped in Cr,Mn-oxysulphide aggregates which formation leads to a local decrease of the Cr concentration and consequently to the formation of non-protective Fe-rich oxide

International audienceTwo austenitic stainless steels, AISI 304L and AISI 303, were submitted to cyclic oxidation and to static mechanical loading after isothermal oxidation at 1000 degrees C. Alloy 303 contains ten times more S than 304L and some Mn addition. During the steel process, it formed manganese sulfides that lead to the formation of a less resistant oxide scale. Both alloys showed similar behavior during thermal cycling but breakaway oxidation and intensive spallation occurred much sooner for alloy 303 than for alloy 304L. A correlation could be drawn between tensile test on preoxidized samples, isothermal and cyclic oxidation. (C) 2015 Elsevier Ltd. All rights reserved