Влияние размера зерна подложки на механические характеристики материала с пористым керамическим покрытием

Abstract

In this work we numerically investigate the deformation and fracture in a material with a porous ceramic coating and a polycrystalline steel substrate. The internal structure of the porous coating and microstructure of the substrate is accounted for explicitly in the calculations. To describe an internal geometry of the composite, we introduce a curvilinear mesh generation algorithm. To generate the polycrystalline structure of the substrate we use the cellular automata method with original modifications introduced. The steel substrate exhibits an elastic-plastic behavior, while the ceramic coating is elastic-brittle. To account for the grain size effect on the initial yield stress we use the Hall - Petch relationship. The boundary-value problem in the plane strain formulation is solved numerically by the finite difference method. Numerical investigations on uniaxial tension, compression, and surface loading of two-dimensional specimens are conducted. Four samples investigated are characterized by an average substrate grain size of 2, 5, 15 and 30 ?m. The complex stressstrain state taking place in loaded composite is analyzed. In the case of tension or compression, cracks are shown to originate in the local regions experiencing tensile loading. The influence of the substrate grain size on the fracture behavior of the composite is examined.