５０５２アルミニウム合金厚板の圧延中のポロシティ粗大化現象

Abstract

The changes of pore in DC slab, after homogenized and after rolling were systematically investigated. It was found that pore size and number in the slab after the homogenization generally increased, and over 150 μm in size of the pore near the center of slab were observed. The pore size in the center of thick plate rapidly increase after rolling, and they grow as a double in comparison with the pore size after the homogenization. In this study, to understand the change of pore size during manufacture processing of thick plate, FEM modeling of the rolling process was performed for explaining why the pore become coarse during hot rolling process. From the contrast of FEM results and measurement results of the pore, the pore coarsening phenomenon of 5052 aluminum alloy thick plate in the rolling procedure was clarified. Main conclusions are shown below. (1) The FEM results show that the pressure by the roll affects only the thick plate surface and show that there is a negative pressure (tension) taking place in the center of plate when the rolling reduction is small. Therefore, it is supposed the pore size near the center increase by the tension force. (2) It is considered that stress ratio of the thick plate (rolling direction component/directional component) can be used as one of the criteria of the porosity coarsening during rolling process.