轻合金挤压成形/成性一体化的研究进展

文章编号： 1007-2683（2019）05-0001-06

Abstract：Extrusion processes can exert technical characteristics and integration advantages in preparing and forming lightweight high-performance magnesium alloys. The lightweight alloy extrusion integration consisting of forming and modification emerged as the times require， and has gradually become one of the hot topics in extrusion field. The technical characteristics of above processes are that the previous independent fine grain preparation processes is skillfully integrated into the extrusion processes through optimizing extrusion dies， changing loading modes and adjusting the structure of billets， etc. The actual effects of “shapes/properties” dual control of extrusion products have been achieved in a single pass. It can be seen from the microcosm of the research overviews that compared with the conventional extrusion， its comprehensive advantages are reflected in many aspects such as reducing forming load， improving the uniformity of extrusion flow， and improving the microstructure properties of the extruded products. To solve the related basic scientific problems， it provides scientific guidance for the research and application of lightweight high-performance alloy in short process and dual control of shape/performance.

Keywords：light alloys; extrusion; shape control; performance control; microstructure

0 引 言

鋁镁合金兼具多种优异的综合性能，是航空航天、轨道交通、武器装备等领域实现轻量化的理想首选，具有广阔的发展潜力及应用前景[1-3]。传统轻合金构件成形多采用铸造工艺，但铸件材质不够致密、承载能力及制品性能存在不足之处。比较而言，塑性加工法更利于轻合金构件组织和力学性能的改善。以挤压工艺为例，成形过程中变形区内因具有三向受压应力状态和可提供较大的剪切变形量而使被加工制品获得细晶组织及优异的力学性能[4-6]，因此，该工艺逐渐成为铝镁等轻质合金构件主要的加工成形手段[7-9]。

我国铝镁资源储备非常丰富，但深加工技术的开发能力和高附加值制品的产出等方面与国外发达国家仍存在着明显差距，是长期困扰传统轻合金挤压技术快速发展及拓展应用的症结所在，更是轻合金高效精确塑性成形前沿研究领域所关注的关键基础科学问题之一[10]。

当前围绕轻合金挤压成形的相关研究工作主要集中在改性和成形两个不同层面上。前者是利用挤压工艺提供的剪切变形作为细晶改性手段来实施的[11-12]，后者则是针对半成品或成品加工成形的技术手段[13]。发展挤压成形/成性一体化技术是促进轻合金短流程深加工潜能提升的重要途径。

1 结构设计

1.1 模具结构

模具结构是决定挤出流动行为、制品组织及力学性能的重要因素之一，因此，模腔结构的精准设计显得尤为关键。XU等[14]对不同模角挤压成形制品进行了对比研究，结果表明，芯模半角为45°时获得AZ31镁合金板材内部组织较均匀，具有较弱的基面织构，屈服强度较低，但延展性较好，相对来讲，其综合性能仍为最佳。

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