| Abstract Scope |
Manufacturing a line pipe includes complex forming steps: decoiling, leveling, and roll forming. The mechanical properties of final formed pipe are evaluated from samples taken out of the pipe, which needs additional bending deformations for standard tensile tests. In this process, materials are subject to complex deformation paths, represented by cyclic bending superimposed with tensile deformation. The material under loading path changes exhibits anisotropic hardening like Bauschinger effect and transient response, and what’s more they are orientation dependent. Therefore, understanding the evolution of mechanical properties of pipe steels during the forming process is important to design coil strength targeting the final pipe strength. In this study, a distortional anisotropic hardening model, which captures the Bauschinger and cross-hardening/softening effects, is applied to predict the mechanical responses under multiple deformation paths. Specifically, identification of model parameters, finite element modeling, and quantitative validations by predicting proof strength after pipe forming are presented. |