磁场处理对高强度钢拼焊板冲压性能的影响机制研究

The application of high strength steel tailor-welded blanks (TWBs) is an important approach to the target of automotive lightweight. The key technical problem in the application of lightweight high strength steel is to enhance the stamping performances of high strength steel TWBs. In this project, the stamping performances of high strength steel TWBs are improved by using magnetic treatment. By theoretical analyses, experimental tests and finite element simulations, and by macro and micro examinations, the microstructure evolvement model of high strength steel TWBs being exposed to a magnetic field is built, the relationships between stamping performances, mechanical properties and microstructures of high strength steel TWBs are expatiated, the mechanism of stamping performance improvement of high strength steel TWBs is revealed, the coordinated controlling method of the formability and springback of high strength steel TWBs that subjected to magnetic treatment is established, and finally the design method of stamping process of high strength steel TWBs, based on magnetic treatment, is achieved. By performing this project, the stamping performances of high strength steel TWBs are enhanced by using magnetic treatment rather than only by optimization of stamping process parameters in traditional method, and the entire process is analysed by considering the interactions of macro and micro deformations rather than by only considering macro ones. Furthermore, this project has both academic and practical significance for establishing the scientific theory of magnetic treatment technology, which can be used to high strength steel TWBs, as well as for improving the application of high strength steel TWBs in lightweight automotive parts.

高强度钢拼焊板冲压技术是实现汽车轻量化目标的重要途径，提高高强度钢拼焊板冲压性能是轻量化高强度钢应用发展亟待解决的关键技术问题。本项目拟利用磁场处理提升高强度钢拼焊板冲压性能。通过理论研究、实验测试和有限元模拟，宏微观分析相结合，建立高强度钢拼焊板磁场处理微观组织演化模型，阐明磁场作用下高强度钢拼焊板冲压性能与其宏观力学性能、微观组织演变之间的内在联系，揭示磁场处理提升高强度钢拼焊板冲压性能的机制，建立磁场处理高强度钢拼焊板成形极限和回弹协调控制方法，形成基于磁场处理的高强度钢拼焊板冲压技术设计方法。本项目研究将高强度钢拼焊板冲压性能的提升，从传统上单纯依赖冲压工艺优化，拓展到借助外磁场处理技术来实现；从考虑宏观塑性成形推进到综合分析宏、微观变形相互作用，对于形成高强度钢拼焊板冲压性能磁场处理技术工程科学理论，促进高强度钢拼焊板在轻量化汽车零部件中的应用具有重要的学术价值和现实意义。

针对高强度钢拼焊板冲压性能较差技术难题，本项目提出借助外磁场处理提升高强度钢拼焊板冲压性能新技术，并开展了相应的基础理论研究。基于电磁场、温度场、塑性力学和相变理论，建立了高强钢拼焊板焊接/磁处理/冲压力学模型与有限元模型，研究了磁场对高强钢拼焊板等材料微观组织、力学性能、成形性能和服役性能的影响规律，揭示了磁处理提升材料组织性能的内在机理，为高强钢拼焊板、轴承钢等的先进磁处理工艺应用提供了科学依据和技术方法。. 首先开发了高强钢拼焊板磁处理装备实验平台，研究了磁场参数对材料磁感应强度、磁力线分布的影响规律。针对高强钢拼焊板、轴承钢等试验材料，开展了物理力学性能参数测定和材料模型表征；建立由高斯面热源和圆柱体热源构成的面体组合热源模型，并通过BP神经网络与遗传算法GA对进行参数优化，实现了对激光焊接温度场和应力应变场的精确模拟。在此基础上，建立了高强钢拼焊板焊接/磁处理/冲压物理力学模型与有限元模型，研究了磁处理对材料微观组织、残余应力、力学性能、成形性能和服役性能的影响规律，通过磁畴演化和位错演化机制揭示了磁处理提升材料组织性能的内在机理。. 在项目研究中共发表标注基金号的论文9篇，其中SCI索引论文4篇，EI索引5篇，中文核心论文3篇，国内外会议论文2篇。培养磁场处理技术相关方向硕士、博士研究生3人。申请中国发明专利4项，其中授权2项。参加国际学术会议3次、国内学术会议2次。. 通过本项目的研究，探索了借助外磁场处理提升高强度钢拼焊板冲压性能新技术，研究了磁场作用下高强钢拼焊板组织性能的变化规律和内在机理。在本项目研究成果基础上，拓展了研究材料和成形工艺，实现了基础理论及前沿技术的拓展与创新。本项目对于提高高强钢拼焊板在轻量化车身上的应用程度和磁处理技术水平具有重要的学术价值和实际意义。