激光叠焊铝/钢组合点阵结构面芯异质接头微观组织调控与失效机理

Lattice truss structures composed of steel plates and aluminum cores have many advantages including light weight, high strength and toughness, good structure efficiency, the integration of multiple functions and better energy absorption than the structures fabricated by single material, which are excellent structures for the key structural components of the oncoming good shock resistance and explosion-proof armored vehicles. The core issue of restricting large-scale application for aluminum/steel lattice truss structures is that the brittle compound layers at the interface of dissimilar joints induce the failure between the face sheets and truss cores. Laser lap welding with adding the interlayer is proposed to manufacture aluminum/steel lattice truss structures. The main research includes two parts. Firstly, the influences of welding parameters and alloy elements of the interlayer on microstructure of dissimilar joints for aluminum/steel lattice truss structures are researched. Microstructure regulation and interfacial reaction mechanisms of dissimilar joints are revealed. Secondly, the influences of the microstructure in dissimilar joints on the failure of aluminum/steel lattice truss structures are studied base on the results of lateral compression and three-point bending tests. The mechanisms on the cracking initiation, propagation and failure processes of dissimilar joints for aluminum/steel lattice truss structures are clarified. The links among welding parameters, microstructure and failure mechanisms are established. The manufacturing method and failure theories of aluminum/steel lattice truss structures are enriched by our results, which provide theoretical guidance and technical supports for the practical application.

铝/钢异种金属组合的点阵结构，具有轻质、高强、高韧、优良的结构效率、多功能一体化和比单一材料的结构更好的吸能特性等优点，是新一代高性能抗冲击、防爆装甲车关键部件使用的理想结构。制约铝/钢组合点阵结构可靠服役的核心问题是面芯异质接头存在脆性界面化合物层，容易引起面芯连接失效。提出添加中间层的激光叠焊制备工艺，其关键在于研究面芯异质接头微观组织调控和连接失效机理。主要研究内容包括：一、研究激光焊接参数和中间层合金元素对面芯异质接头微观组织的影响，揭示面芯异质接头微观组织调控与界面反应机理；二、基于侧压试验和三点弯曲试验研究铝/钢组合点阵结构异质接头微观组织对面芯连接失效的影响，探究面芯异质接头裂纹的萌生、扩展与失效渐进演化机理，建立焊接参数、微观组织与连接失效的内在联系。研究成果将丰富点阵结构的制备方法和失效的基本理论，并为其实际应用提供理论指导和技术支撑。

铝/钢异种金属组合的点阵结构，具有轻质、高强、高韧、优良的结构效率、多功能一体化和比单一材料的结构更好的吸能特性等优点，是新一代高性能抗冲击、防爆装甲车关键部件使用的理想结构。制约铝/钢组合点阵结构可靠服役的核心问题是面芯异质接头存在脆性界面化合物层，容易引起面芯连接失效。项目提出添加中间层的激光叠焊制备工艺，主要研究结果如下：研究焊接参数（激光功率、焊接速度、离焦量、中间层成分和厚度等）对铝/钢点阵结构面芯异质焊缝成形的影响；分析了激光焊接参数对铝/钢组合点阵结构面芯异质接头微观特征以及界面层的影响，基于添加Ni箔、Cu箔和Ni+Cu中间层的钢/铝激光焊接头微观组织分析，表明中间层的添加会改变金属间化合物的相组成，减少脆性金属间化合物的生成。进一步研究不同厚度中间层对铝/钢异种金属激光焊接界面的影响，揭示铝/钢组合点阵结构面芯异质接头微观组织调控与界面反应机理；并结合剪切试验获得了与中间层成分和厚度匹配的铝/钢点阵结构制备工艺。研究铝/钢组合点阵结构的力学行为和承载能力，通过改变面板厚度、芯子厚度和芯子高度，分析了在弯曲载荷下结构的变形特征，揭示了结构尺寸对铝/钢组合点阵结构承载能力和稳定性的影响规律；建立铝/钢组合点阵结构平压试验和三点弯曲过程的有限元模型，研究了组合型式对铝/钢组合点阵结构的变形和承载能力的影响，揭示铝/钢组合点阵结构承载下的渐进过程及规律。项目研究成果为点阵结构的制备及工程应用提供理论指导和技术支撑。