Plastic strain of the bimetal tube subjected to inner pressure

The problem of deformation of a two-layer (bimetallic) thick tube under inner pressure is considered. A dependence of critical load from physical and geometrical properties of the product at which plastic flow is occurred at the beginning of either inner or outer layer is derived. The relations for the semi-analytical solution of the problem of irreversible deformation of a two-layer pipe under the influence of internal pressure are derived. A special case of deformation of a bimetallic pipe made of 09G2C steel with an internal plating layer made of corrosion-resistant 13XFA steel at various thicknesses is considered. The calculation of the autofrettage process was performed in order to improve the operational properties of the product. Conclusions about the choice of the optimal (in terms of strength properties) thickness of the cladding layer, based on the physical parameters of the materials used and the geometric dimensions of the product are drawn.