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임창동,신광선,이재철 대한금속재료학회 1999 대한금속재료학회 학술대회 개요집 Vol.1999 No.1
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임창동,유봉선,서영명 대한금속·재료학회 2009 METALS AND MATERIALS International Vol.15 No.4
The effect of the reduction ratio per pass on the microstructural evolution of an AZ31 gravity cast plate during hot rolling was evaluated systematically. {1012} extension twinning was observed in large grains after an earlier rolling pass, but it disappeared upon a subsequent rolling pass due to the reorientation of the grains in an unfavorable direction caused by repetitive rolling. The finer grains were newly formed at the boundaries of the original large grains and twin boundaries by dynamic recrystallization. The grain size distribution was changed from a bimodal distribution upon a small total reduction to a homogeneous distribution upon a large total reduction due to the formation of finer grains that continued at the grain boundaries of large grains by repetitive hot rolling. The size and distribution of the grains were affected not only by the reduction ratio per pass but also by the total reduction (number of rolling passes). The effect of the reduction ratio per pass on the microstructural evolution of an AZ31 gravity cast plate during hot rolling was evaluated systematically. {1012} extension twinning was observed in large grains after an earlier rolling pass, but it disappeared upon a subsequent rolling pass due to the reorientation of the grains in an unfavorable direction caused by repetitive rolling. The finer grains were newly formed at the boundaries of the original large grains and twin boundaries by dynamic recrystallization. The grain size distribution was changed from a bimodal distribution upon a small total reduction to a homogeneous distribution upon a large total reduction due to the formation of finer grains that continued at the grain boundaries of large grains by repetitive hot rolling. The size and distribution of the grains were affected not only by the reduction ratio per pass but also by the total reduction (number of rolling passes).
균질화처리한 AZ31-xCa(x=0~2.0 wt.%) 중력 주조재의 열간압연 특성
임창동,유봉선,김수현,이진수,김완철 대한금속재료학회 2004 대한금속·재료학회지 Vol.42 No.6
The effects of homogenization on hot rolling properties of gravity cast AZ31-xCa (x=0-2.0 wt.%) alloys were evaluated by examination of surfaces and microstructures of sheets. The side cracking during hot rolling was decreased by homogenization through the elimination of local inhomogeneity and solution of brittle precipitate into matrix. The coarse grains in raw materials were changed to fine grains with the average particle size of 5-10 μm by repeated hot rolling through the dynamic recrystallization. A deformation twinning was more favorably formed in the hot-rolled sheets after homogenization. It is considered that the grains grow and the precipitates are solved into the matrix during homogenization heat treatment, which results in the increased possibility of formation of deformation twinning during hot rolling. (Received March 29, 2004)