The finite-element method (FEM) has been used to numerically investigate the effect of work roll configuration on the leveling effectiveness of tail-up bent plates. Leveling is a process used to minimize shape defects, including flatness imperfections and uniformity of internal stresses in shape-critical applications. Leveling plays an important role in delivering the desired plate shape and meeting the required product standards. To simulate the roller leveling effectiveness of tail-up bent plates, an initially flat plate was plastically bent prior to leveling and was passed through the leveling rolls. Leveling effectiveness was estimated by the vertical displacements of tail-up bent plates with two different roll configurations. One configuration adopts a gradually increasing roll gap, while the other configuration maintains the same roll gap in the first two sets of rolls and gradually increases the roll gap for the later rolls. For comparison purposes, the entry and exit roll gaps of the two roll configurations are set to the same roll gap. To verify the accuracy of the numerical simulations, actual leveling experiments were performed using tail-up bent plates. The results show that the roll configuration significantly influences the leveling effectiveness of the tail-up bent plates. Higher leveling effectiveness is obtained for a leveling configuration that imparts more severe deformation at the earlier leveling stages. Through the analysis, the work roll configuration is determined to be essential to increase leveling effectiveness of tail-up bent plates.

Recent advances in direct laser melting (DLM) have demonstrated its great potential for manufacturing three-dimensional porous metal parts. Various combinations of powder layering and processing parameters can be set to adjust the porous properties of the final parts. This study presents the effects of powder morphologies and process parameters on porosity formation during DLM. Four types of Fe-powders composed of spherical or non-spherical particles with different sizes were experimentally investigated. Furthermore, the laser processing parameters, such as laser energy density, laser focus, and line spacing, which have a significant effect on the results, were characterized. In the case of a mixed powder composed of spherical and non-spherical powders, the packing density decreases as the non-spherical powder size increases. The porosity of the laser-melted layer increases with the degree of size misfit between the non-spherical and spherical powders. Decreased laser absorption and enlargement of the powder-depleted zone as a result of decreased packing density increases the porosity during DLM. The overall results show that the porosity of DLM parts could be actively controlled by adjusting the process parameters and powder morphologies.