프레스 포징 성형을 위한 마그네슘 박판재의 고온물성에 관한 연구
- 원문 URL
This study has been investigated the elevated temperature properties for AZ31B extruded sheet by tensile tests and computer simulation. As increasing the specimen operating temperature, strength was decreased by high temperature test and especially the discrepancy of strength decreasing was considerable at 200℃ to 250℃ The strength of longitudinal direction was superior to transversal direction by anisotropy test. At 200~350℃, the strength was lowest at an angle of 45°in extruded direction and the discrepancy of anisotropy was gradually decreased as the temperature increased. In computer simulation, the variation of sheet pre-heating temperatures, distribution of punch pressure and plastic strains during press forging of AZ31 alloy have been analyzed using an isothermal heating model, where heat transfer characteristics of the sheet and die material was counted. The plastic strain of AZ31 sheet significantly increased as the forming temperature increased from 200℃ to 300℃, which is related with the change in microstructures, such as dynamic recrystallization and additional slip system occurring during the deformation process. The foot area of boss experiences greater plastic strains especially at the region between bosses. Therefor, computer simulation analysis was useful for design concept such as optimum radius of curvature around boss and pre-heated temperature, etc.