Papers by Author: Guang Ting Ma

Abstract: The distribution of residual stress in hot rolled large size H-beams is complex due to the uneven temperature distribution on the final rolling cross-sections. In this paper, 3D simulation analysis is conducted on the residual stress field of cooled large H-beams and the transformation of residual stress field during the flange cutting based on the calculations of thermo-mechanical coupling whole rolling process. There are tensile stress in the flange and web connection areas and compressive stress in web. During the flange cutting process, tensile stress increases suddenly when the kerf arrives at the flange and web connection area, resulting in the brittle fracture of the web. The method of controlling the residual stress of large H-beams is also simulated. Improvement in the distribution of residual stress is achieved through the forced cooling of the outside flange or reduction of the temperature differences on the final rolling cross-sections.

Abstract: In the H-beam rolling process, the deformations and temperature field of workpiece significantly influence the mechanical properties due to the change of product microstructure. Prediction of them is important for the groove design and passes sequences. To get the deformation behavior and the temperature field of workpiece, commercial FEM program LS-DYNA has been used to analyze the whole process of H-beam rolling. The approach is based on 3D thermal mechanical coupled finite element method. The rolling process is divided into several units for calculation. The mesh of workpiece is rebuilt in the simulation for reducing the influence of element distortion. The result shows that, the temperature at the wed to flange position maintains the highest during the whole rolling process, while area of the web the lowest. After the rolling, temperature difference is above 150K between the web’s surface and flange’s inside surface, approximate 130K on the flange’s outside surface and 200K in the cross section. The simulation results show good agreement with the measured temperature data.