EFFECT OF CHANGES IN TENSILE PROPERTIES DUE TO COLD BENDING ON LARGE DEFORMATION BEHAVIOR OF HIGH-GRADE COLD BEND PIPE

摘要

The large deformation behavior of cold bend was experimentally and analytically investigated. Full-scale large deformation experiments were conducted on two API X80 grade cold bends with a bending angle of approximately 9 degrees for both closing and opening modes. Finite element (FE) analyses were also conducted to simulate the large deformation behavior by considering the distribution of tensile properties after the cold bending process. The results of the simulation were in good agreement with the large deformation experiments. The deformability of cold bend in the opening mode was greater than that in the closing mode. Changes in the tensile properties due to the cold bending process had a large influence on the deformability of cold bend. In particular, distribution of the part with work hardening after the cold bending process had large effect on the deformability in the closing mode.