高性能铝锂合金挤压型材形性协调控制基础科学问题与关键技术研究

Aluminum-lithium (Al-Li) alloy extrusion profiles have important application in the field of aerospace. Many fundamental scientific problems need to be researched to achieve the coordinative control of shape and performance for Al-Li alloy profiles. This project plans to study the new principles and methods of precise extrusion manufacturing of Al-Li alloy profiles, such as the stringer, integral panel and hollow profiles used for aircraft fuselage and wings. The Al-Li alloys billets fabricated by spray forming and casting are used as extrusion billets, respectively. In this project, the flow behavior of Al-Li alloys and their microstructural evolution rules will be studied. The effect of extrusion die structure and process parameters on the shape, microstructure and properties of the profiles will be researched, and the optimization design methods of extrusion process and die parameters will be revealed. The influence of the homogenization process of ingot and the strengthening and toughening process of profiles on their microstructure and mechanical properties will be investigated, and the formation mechanism of anisotropy of Al-Li alloy profiles will be revealed. The physical mechanism of solid state welding process, interface structure and its evolution during porthole die extrusion will be studied, and a new welding quality prediction model that can couple the material flow behavior, solid state welding process and the evolution of microstructure will be established. Finally, the theory and technology of the coordination control of shape and performance for Al-Li alloy profiles will be established, and the typical Al-Li alloy profiles used in aerospace field will be manufactured. The implementation of this project has great significance to break through the extrusion technology of Al-Li alloy profiles, and to promote the development of plastic processing discipline and aerospace industry.

铝锂合金型材在航空航天领域具有重要用途，实现铝锂合金型材成形成性协调控制面临诸多基础科学问题的挑战。本项目针对飞机机身与机翼长桁件、整体壁板和空心型材构件，以喷射成形和铸态铝锂合金为挤压材料，研究铝锂合金型材精确挤压成形成性一体化制造的新原理和新方法。研究铝锂合金材料热流变行为，揭示其微观组织演变规律；研究模具与工艺参数对型材形状、微观组织及性能的影响规律，建立挤压工艺与模具参数优化设计方法；研究锭坯均质化和型材强韧化对组织和力学性能影响规律，揭示铝锂合金型材各向异性形成机制；研究铝锂合金型材挤压焊合行为、界面结构及演变的物理机制，创建能够耦合材料流动行为-固态焊合过程-微观组织演变的焊合质量预测模型。形成铝锂合金型材成形成性协调控制理论与技术，实现航空用典型铝锂合金型材构件的成形制造。项目实施对于突破铝锂合金型材挤压技术，促进我国塑性加工学科和航空航天领域的发展具有重要意义。

铝(锂)合金等轻量化构件具有重要应用前景，型材挤压面临材料热变形行为、本构模型、微观组织演变、分流焊合机制、模具设计制造等科学技术问题挑战，本项目建立了铸态2196和喷射态2195铝锂合金热成形精确本构模型和型材韧性开裂预测准则及挤压极限图，确定了合金的热变形工艺区间（铸态2196：460-520℃、0.01-1s-1；喷射态2195：475-525℃、0.1-1s-1），为确定合理挤压工艺参数提供了理论模型。建立了锭坯均匀化第二相溶解与溶质元素扩散动力学模型，揭示了铝锂合金型材力学性能各向异性产生机制，确定了型材强韧化最优热处理工艺参数，提出了重固溶再时效和预变形再时效的热处理方法，提高了型材力学和耐腐蚀性能及各项同性性能。阐明了型材分流挤压界面焊合行为、焊合物理机制，建立了评估焊合质量的一种焊合能指数模型及界面结合率的定量表征方法，提出了一种抑制分流挤压焊合区晶粒异常长大的时效前退火处理工艺；发明了多种挤压模具结构及多轴差速挤压弯曲一体化成形技术；建立了多腔壁板型材挤压模具优化设计方法，开发了多种铝(锂)合金型材挤压模及成形工艺，解决了型材扭拧变形、焊合线偏移、内筋波浪或尺寸不足等问题，提高了型材组织和力学性能。挤压出飞机、导弹、舰船用典型铝锂合金型材，开发出民机上长桁、下长桁、一号肋及XX型号航天飞航产品三段舱体用铝合金型材产品、变频模块散热用铝合金基板型材产品及航空用铝合金大型薄壁筒、飞机轮毂、高速列车轴箱体及汽车轮毂等构件，项目成果还应用于复兴号和600公里磁悬浮高速列车车体型材的研制，所研制的有关构件已成功应用或交付，并取得了明显的经济、社会和军事效益。. 本项目执行期间，发表论文44篇，其中SCI收录43篇，他引492次。获发明专利26件、实用新型专利3件，申请发明专利9件（含1件美国专利）。获省科技进步二等奖1项、省高校科技一等奖1项，在科研育人方面获省教学成果二等奖1项。已培养毕业博士生5名和硕士生5名，其中1名博士学位论文获上银优秀机械博士论文佳作奖和省优秀博士学位论文奖，2名团队成员获国家级人才支持、5人次获省级人才支持。

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