Effects of Expansion Rate on Stress Evolution of TWIP Expandable Tubular Based on TSS Criterion

Expansion rate is key parameter to the manufacture of expandable tubular. In this paper, the effects of expansion rate on stress evolution of twinning induced plasticity (TWIP) steel expansion tubular were discussed in detail. A user subroutine UMAT using twin shear stress (TSS) yield criterion is employed to simulate the expanding process. The results show that the predicted residual stresses agree with the experiment very well. The axial expanding stress showed the layered distribution along the thickness direction and the hoop tensile stress is mainly located in the corner of expanded area. With the steady increases of expansion rate, the expanding axial, hoop and TSS stresses are all increased, and the increasing rate is decreased gradually. The residual stresses are tensile in inner surface and compressive in outer surface. Both the hoop and axial stresses are all increased with the increases of expansion rate. The suggested expansion rate should be controlled below 35%.