Cost-effective lightweight complex-shaped structural components made of magnesium: A hybrid manufacturing paradigm

汽车工业正在经历一个重大转变，在车辆设计考虑中使用轻质材料，以提高燃料/动力经济性。镁（Mg）具有低密度、约为铝的三分之二的密度、高比强度和良好的疲劳性能，近年来受到了极大的关注。然而，由于镁在室温下的有限成形性，其在汽车结构部件中的应用受到限制。铸造和锻造已被考虑用于制造疲劳关键部件，如转向和悬架部件。铸造能够以相对低的成本制造复杂形状，但可能导致缺陷和差的机械性能。另一方面，锻造提供了优异的机械性能，但限于简单的形状，或者需要在阶段之间进行飞边修整的多阶段锻造。为了充分利用铸造的成本效益和锻造零件的上级材料性能，本研究提出了一种新型的混合铸造后锻造镁合金。在这种独特的方法中，零件首先铸造成具有工程材料分布的最佳中间形状，然后在接近再结晶温度下锻造成最终形状。本研究的总体目标是发展一个科学的理解的影响的初始材料分布和性能的铸造过程中的微观组织和织构的演变及其最终性能。这项研究将开发用于制造汽车应用的镁复杂形状结构部件的科学知识和技术。

Automotive industries are going through a major shift in using lightweight materials in vehicle design considerations to improve fuel/power economy. Magnesium (Mg) with low density, approximately two-thirds as dense as aluminum, high specific strength, and good fatigue properties, has received significant attention in the recent years. However, due to limited formability of Mg at room temperature, its application to automotive structural components has been limited. Casting and forging have been considered for manufacturing of fatigue-critical parts such as steering and suspension components. Casting enables manufacturing of complex shape at relatively low cost but can result in defects and poor mechanical properties. On the other hand, forging provides excellent mechanical properties but is limited to simple shapes, or requires multiple stage forging with flash trimming in between stages. To leverage the cost-effectiveness of casting and superior material properties of forged parts, a novel hybrid cast followed by forging of Mg alloys is proposed in this research. In this unique method the part is first cast to an optimum intermediate shape with engineered material distribution and then forged into its final shape at near re-crystallization temperature. The overall objective of this research is to develop a scientific understanding of the impact of the initial material distribution and properties of cast on the microstructure and texture evolution during the forging process and its final properties. This research will develop the scientific knowledge and enabling technologies that will be used to manufacture Mg complex-shaped structural parts for automotive applications.