镁合金塑性加工技术发展及应用

Development and Application of Plastic Processing Technologies of Magnesium Alloys

我国是世界上镁资源最为丰富的国家,镁及镁合金具有质轻、比强度高、阻尼减振、电磁屏蔽性能优良、储能特性好等优点,是最有潜力的轻量化材料之一,其推广应用对节能减排和能源转型战略具有重要意义。但镁合金具有密排六方晶体结构,塑性变形能力较差。如何改善镁合金的塑性变形能力是扩大镁合金应用的瓶颈问题之一。本文综述了10多年来,世界各国在改善镁合金塑性、提升镁合金塑性变形能力等方面所做的大量工作,及在镁合金塑性加工技术等方面取得的重要进展。发展了"固溶强化增塑"新型镁合金设计理论和"熔体变温自纯化"等关键制备技术,形成了一批高塑性变形镁合金材料和牌号,其中杂质Fe含量可降到10×10^(-6)以下,超高塑性镁合金延伸率可达到60%以上,超高强度(抗拉强度大于550 MPa)镁合金延伸率可以达到10%以上;开发了非对称挤压、非对称轧制、非对称改性、往复循环多道次镦挤开坯技术、扩收控制大比率锻造技术、挤锻复合成形技术等一批镁合金新型塑性加工技术。这些合金和技术使变形镁合金基面织构显著弱化,明显提高了变形镁合金板材、管型材和锻件的塑性成形能力和制品质量,产品成本大幅度降低,在板材、管型材和锻件制备加工中实现了成功应用。

China has the most abundant magnesium resources in the world.Magnesium and its alloys have the advantages of low density,high specific strength,good damping property,and exceptional electromagnetic-shielding and energy-storage characteristics.They are one of the most promising lightweight materials.The enhanced applications of magnesium alloys can save energy and reduce emissions and are significant to the new Chinese energy strategy.However,magnesium alloys have a hexagonal close-packed structure and exhibit relatively low ductility.A bottleneck in expanding the application of magnesium alloys is improving the ductility of magnesium alloys.For more than ten years,efforts have been made to improve the ductility and plastic deformation ability.Progress has been made in plasticprocessing technologies of magnesium alloys.The novel alloy design theory"solid solution strengthening and ductilizing"and advanced preparation technologies such as"melt self-purification through varying temperature"have been established.Series of new magnesium alloys with good ductility and corresponding alloy grades have been developed,where the impurity content of iron can be reduced to below 10×10^(-6);the elongation was more than 60%for ultrahigh plasticity magnesium alloys and is above 10%for the ultrahigh-strength magnesium alloys(UTS>550 MPa).New plastic-processing technologies,such as asymmetric extrusion,asymmetric rolling,asymmetric modification,cyclical multipass upsetting and squeezing,expansion control large ratio forging,and extrusion and forging composite forming,have been developed.These newly developed magnesium alloys and processing technologies weaken the basal texture in wrought magnesium alloys,improving the formability of sheets,tubes,profiles,and forgings and their product quality and reducing their product cost.These technologies have been successfully applied in the processing of magnesium sheets,pipe profiles,and forgings.