Modeling the interaction between creep deformation and scale growth process

When an alloy is oxidized (or nitrided) at high temperature with the presence of an applied stress, the scale growth rate is dependent on the magnitude and direction of the stress. Here we present a model to simulate the scale growth process under an applied bending load. This model explores the interaction between creep deformation and the scale growth process, and is able to predict the stress-driven scale growth rate, the creep response of the multilayer and the stress accumulation in the thin scale. A modest applied stress induces large stresses in the scale due to creep rate mismatch between the metal and the scale. This large stress, in turn, alters the diffusion potential governing the scale growth process, leading to a perturbation from a typical parabolic growth rate. The thin scale is also shown to influence the creep response by promoting stress redistribution in the metal–scale system.