Sulfide-oxide corrosion has a negative impact on the life of aircraft engine parts, weakening the crack resistance of the surface layer of the material. The surface acquires a layered structure consisting of oxide layers and a sulfide sublayer, in which residual stresses occur; the material near the surface is depleted by alloying elements. To describe this process, a previously constructed related model is used that describes the mutual diffusion of alloy components and aggressive media, their chemical reactions, swelling deformations that create stresses, and plastic deformations that promote their relaxation. A one-dimensional problem for a half-space is considered, the stress-strain state of which satisfies certain constraints simplifying numerical calculation. The solution of the complete system of related equations is implemented in the application package COMSOL Multiphysics. The process of oxidation and sulfide-oxide corrosion of heat-resistant steel is calculated. Profiles of the mass fractions of metal components, aggressive substances, and corrosion products, as well as profiles of intrinsic deformations and residual stresses, were obtained. The results show the formation of several diffusion zones: zones of oxides, sulfides, and intermediate zones. A uniform distribution of metal components is observed in the zones of oxides and sulfide. Two modes of corrosion have been identified, in which its rate is controlled by the kinetics of chemical reactions or the kinetics of mutual diffusion. The first mode is short-lived and determines the rate of formation of the layered structure. The second mode is responsible for advancing the corrosion layers deep into the metal and is key for predicting the growth of corrosion layers. In the latter, tensile plastic deformations and compressive residual stresses are formed. In the material under the corrosion layer, the residual stresses are tensile, which can cause the formation and growth of surface microcracks and subsequent destruction.

high-temperature corrosion, model, calculation, interdiffusion, stresses, elastoplasticity, chemical reactions, coupled processes