旋转摩擦焊接头界面结构不均匀特征与力学性能的相关性研究

During rotary friction welding, the radial gradient heat generation and uneven deformation will result in inhomogeneous interface structure in joint. Especially for the dissimilar metals joint, asymmetric deformation turns much severer. These defects have been bottlenecks, limiting the application of rotary friction welding technique in manufacturing key parts for engine industries. Through systematically investigating the effect of inhomogeneous interface structure on mechanical properties of rotary friction welded joint, the joint interface structure could be optimized and the asymmetric deformation could be diminished. This proposal will combine experimental research and theoretical analysis to reveal the uneven feature and its characterization of interface in homogeneous metals joint, and analyze the effect of inhomogeneous interface structure on mechanical properties. Then the mapping relation model of "process parameters → interface structure → mechanical properties" will be built for optimizing the interface structure and guiding the selection of process parameters. Based on the research results from homogeneous metals joint interface, this proposal will design a novel joint structure, in which the hard metal can be plasticized by the friction with itself and then the viscoplastic metal initiates to rub the soft base metal. Finally, sound and strong joint between hard and soft substrates could be achieved by rotary friction diffusion welding and friction fusion welding processes. The research results will enrich the fundamentals of process theory on rotary friction welding and achieve customized manufacture process based on the product requirements of structure and function. It will further expand the application scope of rotary friction welding in dissimilar materials.

旋转摩擦焊过程中接头径向产热和变形不均会导致界面结构不均匀，尤其对于异质组配接头，不对称变形更加严重，已成为制约该方法应用于发动机等领域关键构件制造的瓶颈。通过系统研究旋转摩擦焊接头界面结构不均匀特征与力学性能的相关性，有望优化接头界面结构，减小接头不对称变形。本项目结合工艺试验及理论分析，解析典型同质材料组配接头界面结构的不均匀特征及其表征，并开展界面结构不均匀特征和力学性能相关性的系统研究，构建“工艺参数→界面结构→力学性能”的映射关系模型，反向优化界面结构，指导工艺参数制定。基于同质组配接头界面结构研究成果，设计新型接头形式，通过硬侧金属预摩擦所形成的高温粘塑性金属摩擦锻压软侧金属，制造软硬异质组配旋转摩擦扩散焊和摩擦熔焊优质高强接头。项目研究成果将丰富旋转摩擦焊工艺基础理论，实现基于构件结构和功能需求的定制化工艺设计，并拓展旋转摩擦焊在异质组配接头制造领域的应用范围。

旋转摩擦焊方法已广泛应用于一般性工业领域，但由于旋转摩擦焊过程中接头径向产热和变形不均会导致界面结构不均匀，尤其对于异质组配接头，不对称变形更加严重，破坏了接头结构的完整性并降低了接头服役寿命，成为制约该方法在要求高质量、高可靠性领域关键构件中应用的瓶颈。为了优化接头界面结构、减小不对称变形进而获得可靠连接的完整性构件，本项目选取发动机等领域关键构件中广泛应用的铝合金、钛合金、不锈钢和铜合金等典型材料，总结提出了同质组配和仅单侧变形、两侧同时变形的软硬异质组配等三种类型接头的划分依据，通过优化工艺参数获得了三种类型界面结构的稳定无缺陷接头，提取晶粒尺寸、强化相分布、金属间化合物厚度、织构、微区应变等组织参量表征了接头界面组织结构的不均匀特征，揭示了界面径向先升后降热力耦合梯度产热和不均匀组织结构之间的相关性。创新设计了沿径向局部切片以及逐层减薄的取样方式，系统测试并表征了接头的拉伸、冲击、硬度分布、电阻率等性能，得出旋转摩擦焊接头力学性能高度依赖于界面不均匀组织结构以及测试试样尺寸。在此基础上，针对钛/钢和铝/钢两类软硬异质组配接头，分别开发出了硬侧金属发生充分塑性变形的旋转摩擦扩散焊和旋转摩擦熔焊新工艺，实现了软硬异质组配接头界面组织结构逆向设计和力学性能调控，最后对比得出了热处理可有效降低界面组织不均匀性并提升接头综合性能。项目研究成果丰富了旋转摩擦焊工艺基础理论，实现了基于构件结构和功能需求的定制化工艺设计，为制定旋转摩擦焊接头力学性能测试试样尺寸标准提供了数据保障，将有力推动和拓展旋转摩擦焊在异质组配接头制造领域的应用范围。完成项目期间，已发表SCI刊源论文16篇（含已录用1篇），EI刊源论文14篇，第一作者SCI刊源论文8篇。授权发明专利1项，实质审查中2项，参会交流11次，培养硕士研究生7名（已答辩毕业3名）。晋升副教授职称2人。