Abstract: Through studying the coupling between stress evolvement and reversely bending behaviour during roller leveling process, it is demonstrated that the bending history of the section needs to be taken into account during the analysis of continuous recurvate process. With the application of elastic-plastic theory, a numerical solution has been established to describe the continuous recurvate process precisely considering the section deformation history. With this solution, the stress evolvement and its affect to the M-C curve are studied detailedly during the straightening process under small deformation procedure. It is found that the deformation history has a non-negligible effect on the bending characteristics of the section in reversely bending, and the difference of bending characteristics will make the M-C curve of the different section under the same process conditions not converged. In the roller leveling process, although the beam goes through the same device, the sections with different initial curvatures will possess different deformation history and different bending characteristics, which eventually results in that the range of the residual curvature of beam can not gradually reduce with the increase of the number of reverse bending as expected. This theoretically explains why the small deformation procedure shows poor performance at the production site.

Key words: Bending, Elastoplasticity, Straightening, Stress analysis