Failure analysis of cast open-cell iron based foams from the submicron to the macro-scale

开孔泡沫钢是很有前途的冲击吸收应用候选材料。它们通常价格低廉，密度低，与泡沫铝相比，它们结合了更高的强度和高的延展性和韧性。然而，以前的工作几乎总是专注于闭孔和开孔泡沫铝。由于铝合金的变形和失效行为与钢相比有很大的不同，而且由于支柱尺寸小和浇注条件不同，关于散装钢的知识不能简单地转移到泡沫钢上，泡沫钢的进一步发展依赖于对这些泡沫钢microstructure/mechanical-property-relationships的更好的了解。因此，在本研究中，我们计划通过结合泡沫的力学测试和单个抽出的支柱的2D显微镜和3D断层成像方法，研究一种新型铸钢泡沫及其支柱在不同长度尺度(从亚微米到厘米)上的力学行为和微观结构。将所得结果与前人对奥氏体钢泡沫的研究结果进行比较，得出不同组织与泡沫性能之间的关系。将整合不同长度尺度上支柱组织和力学性能之间的关系，并将其用于建议对泡沫钢的组织和生产工艺进行可能的改进。

Open cell steel foams are promising candidates for impact absorbing applications. They are generally inexpensive, possess a low density, and, as compared to aluminium foams, they combine a higher strength with high ductility and toughness. Former work, nevertheless, nearly always focuses on closed- and open-cell aluminium foams. As aluminium alloys have a profoundly different deformation and failure behaviour as compared to steels, and because the knowledge on bulk steel cannot simply be transferred to foams because of the small size of the struts and the different casting conditions, further development of steel foams relies on improved knowledge on the microstructure/mechanical-property-relationships of these foams. In this study, we therefore plan to investigate the mechanical behaviour and the microstructure of a novel cast steel foam and its struts on different length-scales from the sub-µm to cm range, by combination of mechanical testing of foams and single, extracted struts with 2D microscopy and 3D tomography methods. The results will be compared with those from former work on austenitic steel foams, and correlations between the different microstructures and the foam properties will be deduced. The relationships between the strut microstructure and the mechanical properties on the different length-scales will be integrated and used to suggest possible improvements in the microstructure and the production process of steel foams.