Mechanical characterization and microstructure modeling of cast layered composites of aluminum/steel hybrids

本研究项目的基础是对连续复合铸造铝-钢混合动力气缸之间的结合进行研究。通过实验和模拟研究了铝/钢复合材料的基本微观力学和微观组织性能。为此，在工艺链上对连铸材料复合材料力学行为的描述正在开发中。这是基于界面区域的微观结构特性，并考虑到冶金和微观机械方面。因此，在工艺和冶金水平上优化机械性能所涉及的耗时的实验工作减少了。分析了界面微观结构，并对其力学性能进行了表征。采用了不同的机械和光学表征方法。为了描述复合区的破坏行为，在每种情况下都建立了一个模型来描述界面微观结构的形成以及变形行为。这种方法可以更详细地了解工艺参数、界面微观结构的形成和演变以及复合材料的最终力学行为之间的复杂相互作用。金相研究的结果被纳入了界面微观组织形成的模型中。由于材料复合材料的力学行为与界面微观结构密切相关，因此必须对铝/钢界面的扩散反应行为进行详细的了解。在此背景下，进一步发展了扩散反应实验，旨在隔离时间和温度的影响，以分析金属间层的动力学生长。此外，实验还对界面演化的预测模型进行了标定和验证。建立的模拟模型计算了连铸工艺参数对金属间化合物厚度增长的影响。力学研究的结果以及界面微观结构形成的结果都包含在变形行为模型中。采用推出试验和巴西试验对界面变形和断裂行为进行了分析。通过将实验确定的应变场与基于原位高速记录的数值模型相匹配，验证了潜在的弹塑性材料行为，并确定了描述金属间相和相邻结构破坏的合适预测模型。

The basis of this research project is the investigation of the bond between aluminum-steel hybrid cylinders produced by continuous composite casting. The fundamental micromechanical and microstructural properties of Aluminium/Steel hybrids are investigated experimentally and by simulation. To this end, a description of the mechanical behavior of continuous-cast material composites over the process chain is being developed. This is based on the microstructural properties of the interface area and takes metallurgical and micromechanical aspects into account. The time-consuming experimental work involved in optimizing the mechanical properties at both the process and metallurgical levels is thus reduced. The interfacial microstructures are analysed and the mechanical behavior of the hybrid is characterized. Different mechanical and optical characterization methods are used. To describe the failure behavior in the composite zone, a model is developed in each case for the formation of the interfacial microstructure as well as for the description of the deformation behavior. This approach allows a more detailed understanding of the complex interaction between the process parameters, the formation and evolution of the interfacial microstructures and the final mechanical behavior of the composite. The results of the metallurgical investigation are incorporated into the model for the formation of the interfacial microstructure. Since the mechanical behavior of the material composites is closely related to the interfacial microstructures, a detailed understanding of the diffusion-reaction behavior at the aluminium/steel interface must be generated. In this context, diffusion reaction experiments are further developed aiming at isolating the time and temperature effects to analyze the kinetic growth of the intermetallic layers. In addition, the experiments allow the calibration and validation of the predictive model for the interfacial evolution. The developed simulation model calculates the influence of the continuous casting process parameters on the intermetallic thickness growth. The results of the mechanical investigation together with the results regarding the formation of the interfacial microstructure are included in the model for the deformation behavior. The deformation and fracture behavior of the interface is analyzed using push-out and Brazilian tests. By matching experimentally determined strain fields with numerical models based on in situ high-speed recordings, both the validation of the underlying elastoplastic material behavior and the identification of suitable predictive models describing the failure of intermetallic phases and adjacent structures are performed.