不锈钢-碳钢层合板带冷轧复合、减薄冷轧和矫直过程的板形与界面力学行为

The bonding interface quality and flatness control are the key issues in metal clad sheet production, also they are the core problems for cold rolling cladding, cold reduction rolling and straightening for stainless-carbon steel clad sheet. This project intends to research and use bonding force and bonding degree to identify bonding state of the clad interface based on the theory of metallurgical bonding formation by interfacial atomic diffusion. The effect of the cold rolling progress on the surface dispersion and cracking, the no-sliding contact of body material, and interfacial atomic activation and diffusion to form metallurgical bonding are studied. The bonding mechanism and condition of cold clad rolling are studied. Then the composite criterion of cold clad rolling is established. The mechanical model of cold rolling-cladding is established including the microscopic elastoplastic contact of rough surface, flatness , residual stress, and the multi-scale simulation model and solving method. The interface mechanical behavior, interface bonding state, deformation compatibility of components, flatness and residual stress are analyzed. Based on the theory of crack and hole, the characterization of the bonding layer is developed, besides, the geometric, mechanical models and the models of damage and hardening of the bonding layer are established. The evolution laws of bonding layer state, interface residual stress and flatness in thinning rolling and straightening progress for clad rolling are studied. The rolling tests of clad sheet are carried out to verify the results of analytical and numerical model. The feasible technology of cold rolling cladding, cold reduction rolling and straightening for stainless-carbon steel sheet are researched.

界面结合状态与板形控制是金属层合板带制备的关键，也是不锈钢-碳钢层合板带冷轧复合、减薄冷轧与矫直能否实现的核心问题。项目拟基于界面原子扩散形成冶金结合的原理，研究使用结合力与结合度表征轧制复合界面结合状态；研究冷轧工艺对于表面层分散破裂、本体材料物理不滑动接触、界面原子激活并扩散、形成冶金结合的影响规律和冷轧复合的结合机制与结合条件，建立冷轧复合的结合判据；建立涉及粗糙表面弹塑性接触细观界面和板形及残余应力的冷轧复合力学模型和跨尺度仿真模型及求解方法，研究界面力学行为与结合状态、组元间变形协调与板形及残余应力；应用裂纹及空洞理论建立结合层的表征方法与几何及力学模型以及结合层的损伤模型与强化模型，研究层合板减薄轧制与矫直过程中结合层状态、界面残余应力和板形的演变规律，开展层合板轧制试验，验证解析和数值计算结果，研究不锈钢-碳钢层合板带冷轧复合可行工艺与轧制复合板带减薄冷轧和矫直的可行工艺。

热轧复合是目前制备不锈钢-碳钢金属层合板带的主要方法，但能否实现温轧复合甚至冷轧复合，以及层合板减薄轧制、矫直还是值得研究的问题。本课题采用模拟实验、数值仿真、理论分析的方法，研究了轧制复合界面结合规律、界面层的表征调控，及层合板轧制矫直过程中板形演变规律。提出了实现不锈钢-碳钢温轧复合的可行工艺、界面层的调控技术以及减薄轧制矫直过程中改善板形的可行对策。主要成果包括：建立了基于Fick第二定律的界面元素扩散浓度的关系模型、界面结合强度的关系模型、以及基于表面粗糙峰弹-塑性接触变形的界面复合率模型；建立了304不锈钢/Q235碳钢轧制复合分子动力学模型，提出利用晶格常数一致性和晶格保持度作为评价势函数适用性的指标，分析不锈钢-碳钢轧制复合微观变形机理；建立了轧制过程中双金属层合板翘曲（C翘、L翘、反向C翘）解析计算力学模型，获得了厚度方向不均匀延伸与板形翘曲之间的定量关系，揭示了金属层合板产生板形翘曲缺陷的力学根源及金属层合板板形翘曲缺陷演变的影响因素及规律，提出改善翘曲缺陷的工艺对策；建立了金属层合板瓢曲变形板形缺陷产生全过程数值模型，分析了金属层合板瓢曲变形的力学机理及屈曲临界条件的影响规律；开展相应工业实验及应用研究，提出实现不锈钢-碳钢温轧复合的工艺对策；提出层合板界面层表征方法和指标，得到了再加工过程中界面层复合质量的演变规律；实验研究了不锈钢-碳钢层合板的组织热稳定性与高温力学性能，明确高温条件下界面层的生长规律并提出通过热处理调控界面层性能的工艺措施；建立了双金属本体+界面层三元结构的有限元模型，研究获得减薄轧制和矫直过程中板形、残余应力以及界面结合强度的影响规律，并提出相应的工艺改进对策。部分成果应用于坤泰镕创和博特复合材料公司的冷轧复合设备设计与工艺技术开发，协助试生产出了多种类型的不锈钢、碳钢、铜、铝等双金属和三层金属冷轧复合产品，创造了一定的经济和社会效益。