Development of Warm Forging Method for Magnesium Alloy

A new warm forging method for magnesium alloys is proposed by taking their material properties into consideration. Since the ductility of Mg alloys is low at room temperature, the forging operation is conducted in the temperature range of 200-400°C. In the warm forging of Mg alloys, the billet is easily cooled down in the die cavity before the onset of forging due to high thermal conductivity. This problem is solved by heating the billet with high-temperature tools. Since the flow stress of Mg alloys exhibits a significant work softening phenomenon, a very high load tends to appear at the beginning of the forging process. In order to reduce the peak forging load, a new concept of billet shape is proposed; the shape is so chosen that pre-straining is caused without restraining the flow in the early stage of the process and then die filling is attained with a low flow stress. In this study, the proposed warm forging method is confirmed to be valid through finite element simulation and experiment using a servo-controlled press.