镁铝层合板波纹辊轧制复合机理研究

Light metal Mg, Al and its alloys are widely used in aerospace, electronics, energy and other high-tech fields. The property advantages of the two metal such as corrosion resistance, oxidation, light weight, high specific strength can be obtained by solid-phase connection of Mg and Al. A new rolling technology is proposed based on the corrugated roll, the scheme of “corrugated roll + flat roll” is used in rough rolling and the scheme of normal flat roll is used in finish rolling. By studying the metal plastic forming process in corrugated roll gap and hot behavior, analyzing the influence relationship between the metallurgical bonding and plate shape of Mg-Al laminates and parameters such as corrugation curve, thickness ratio, rolling pass, forming temperature, reduction rate and deformation rate, to establish the theoretical model of relationship between the laminates structure and rolling conditions, to clarify the microstructure evolution rule during rolling and subsequent heat treatment, to reveal the relationship between the interface strength and the mechanical properties and the metallographic structure, to establish the forming theory and method of Mg-Al laminates based on the corrugated roll, which can improve the interface strength by 15%~25%, reduce the curvature more than 80%, reduce the joint interface residual stress more than 80%, and lay the scientific foundation for developing high quality, low cost manufacturing process of Mg-Al laminates.

轻金属镁、铝及其合金是航空航天、电子、能源等高新技术领域中广泛应用的金属。将镁和铝固相连接成复合结构，可以发挥两种金属的性能优势，获得耐腐蚀、抗氧化、轻质、比强度高的复合材料。本项目基于波纹型轧辊，提出一种镁铝层合板新型轧制方法，粗轧时采用“波纹辊+平辊”的方案，精轧时上下辊均采用平辊。通过研究镁铝两金属在波纹辊缝中的塑性成形过程及热行为，分析波纹曲线、厚度配比、轧制道次、成形温度、压下率、变形速率等参数与镁铝层合板冶金结合及板形的影响关系，建立描述层合板结构与复合轧制条件关系的理论模型，阐明微观组织结构在轧制及后续热处理过程中的演变规律，揭示层界面结合强度和层合板力学性能与组织结构之间的内在联系，形成完善的镁铝层合板波纹轧制成形理论和方法，提高结合界面连接强度15%~25%，减小瓢曲度80%以上，消除结合界面残余应力80%以上，为开发出高品质、低成本的镁铝层合板制备工艺奠定科学基础。

镁/铝层合板因其强度高、耐腐蚀性强、质轻等优势被广泛应用于船舶制造、航空航天和国防军工等领域。传统爆炸复合和轧制复合工艺存在高污染、工艺复杂、板形质量差、结合强度低、残余应力大等问题，本项目提出一种基于波纹型轧辊的波-平轧制复合新技术，粗轧时采用“波纹辊+平辊”的方案，精轧时上下辊均采用平辊。该技术通过波纹型轧辊引入周期性阶跃载荷，细化基体和界面晶粒尺寸，可以在小压下和低温情况下实现复合板的高质量结合。本项目通过有限元模拟建立了波纹辊轧制和传统平轧模型，分析了两种工艺条件下轧制变形区应力场、应变场与温度场发分布规律，并与层合板的微观组织演变规律进行联系，进而分析了波-平轧制变形区内金属变形行为、流动规律及微观组织演变过程。通过分析波纹轧与传统平轧变形区内的应力结果，以及波纹轧辊特殊辊形曲线对轧制变形区内层合板前滑区和后滑区分布状态的影响，发现波纹轧搓轧区在数量以及长度上均大于传统平轧，这有利于促进结合界面硬化层与氧化层的破裂，同时波纹轧也能增大结合界面处的压应力峰值，促进异种金属间的结合。另外，采用波纹轧制在轧制温度250℃和37.5%压下率的条件下实现镁板和铝板的轧制复合，而相同压下率条件下，采用传统平轧实现双金属轧制复合的临界温度为300~350℃。波纹轧制镁/铝层合板的抗拉强度在轧制温度为350℃时达到峰值310 MPa。传统平轧层合板抗拉强度低于波纹轧制层合板，伸长率则略高于波纹轧制层合板。波-平镁/铝层合板在轧制温度为350℃时综合力学性能达到最佳，最大拉伸应力为384 MPa，延伸率为15.52%。根据轧制应力应变、显微组织、界面分离形貌等模拟和实验结果分析，提出波纹型轧辊提高镁、铝双金属结合效率和结合治疗的原因在于波峰和波谷处存在应力和应变的周期性变化，局部强应力和剪切变形促使待复合表面出现大量裂纹并暴露内层新鲜金属，促进了界面金属的嵌入能力。本项目可为异种金属复合板高效轧制复合提供理论指导和技术支撑，进一步推动高品质金属复合板的制备和应用。