Expandable tubular technology is mainly applied in the field of oil and gas field development.Expansion cone is one of the main tools of expandable tubular technology,which is subjected to great interface stress during operation.Therefore,the rapid wear of expansion cone surface is one of the main problems restricting the development of expandable tubular technology.To investigate the surface friction and stress distribution of the expansion cone during the expansion process,the calculation models for the contact stress and friction of the expansion cone were derived based on elastic-plastic theory.The finite element method was used to simulate the expansion process of the expansion tube,and to study the changes in surface stress,contact friction stress,and expansion thrust of the expansion cone.The rationality of the finite element simulation results was verified through expansion tests.The results show that the main factors affecting the contact stress and friction of the expansion cone are the yield strength of the expansion tube and the cone angle of the expansion cone.The maximum equivalent stress of the expansion cone is concentrated at the fillet of its large radius,and the maximum friction stress is concentrated at the position of the small and large diameters of expansion cone.The expansion zone of the expansion cone only partially contacts with the inner wall of the expansion tube.The position of the small diameter of expansion cone is subjected to tensile stress,while the position of the large diameter of expansion cone is subjected to compressive stress.The maximum contact compressive stress is concentrated at the position of the large diameter of expansion cone.