Modeling the Creep Rupture of Tensile Rods in an Aggressive Medium with Account of a Variable Diffusion Coefficient

The creep rupture of a long rod subjected to tension in an aggressive medium is considered. Using a diffusion equation where the diffusion coefficient D is a monotonically decreasing function of concentration c of the medium, the diffusion penetration of elements of the aggressive medium into the material of the rod is modeled. On the border between the rod and external medium, a condition of mass transfer is assumed. The approximate method put forward for solving the diffusion equation is based on the introduction of a diffusion front. Two stages of the diffusion process are considered: penetration of the front and saturation. A comparison between solutions of the diffusion equation for proposed D(c) functions is performed. The influence of D(c) on the creep rupture of a tensile rod is evaluated using the Rabotnov kinetic theory of creep and creep rupture.