Foams of Gray Cast Iron as Efficient Energy Absorption Structures: A Feasibility Study
Foams of Gray Cast Iron as Efficient Energy Absorption Structures: A Feasibility Study
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DOI：
10.1002/adem.201900080
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发表时间：
2019-04
影响因子：
3.6
通讯作者：
A. Kaya;P. Zaslansky;A. Rack;S. Fischer;C. Fleck
中科院分区：
文献类型：
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作者：
A. Kaya;P. Zaslansky;A. Rack;S. Fischer;C. Fleck
采用改进的熔模铸造工艺，以网状聚氨酯为原料，制备了灰铸铁泡沫。为了评价所生产的微观几何形状的属性，通过光学和电子显微镜在2D中以及同步加速器微计算机断层扫描在3D中研究了泡沫节段和单个支柱。机械性能通过宏观/微观机械测试和纳米压痕来确定。在灰铸铁支柱的显微组织中，观察到片状粗A型石墨颗粒和局部细过冷D型石墨颗粒。两种石墨类型的分布是不均匀的，并且可能是单个支柱的机械性能大分散的原因。高石墨含量和由此产生的支柱的脆性行为导致泡沫的应力-应变曲线中的强烈锯齿，对能量吸收产生负面影响。我们发现，与316L奥氏体钢支柱中的75%相比，能量吸收效率相对较低，低于50%。小的试样尺寸导致的尺度效应，强烈影响泡沫的机械性能。需要进一步改进灰铸铁泡沫的制造，以定制石墨分布并优化铸铁基泡沫的性能。
Gray cast iron foams, were produced using a reticulated polyurethane by using a modified investment casting process. To evaluate the attributes of the produced micro‐geometries, foam segments and single struts are investigated by light and electron microscopy in 2D, and synchrotron micro‐computed tomography in 3D. Mechanical properties are determined by macro/micro‐mechanical testing and nanoindentation. In the microstructure of the gray cast iron struts, both flake‐like coarse type A and locally fine undercooled type D graphite particles are observed. The distribution of the two graphite types is heterogeneous and is the likely cause for the large scatter of the mechanical properties of the single struts. The high graphite content and the resulting brittle behavior of the struts lead to strong serrations in the stress‐strain curve of the foams with a negative effect on energy absorption. We found a relatively low energy absorption efficiency of below 50% as compared to 75% in 316L austenitic steel struts. The small specimen size results in scale effects which strongly influence the mechanical properties of the foams. Further improvement in the fabrication of gray cast iron foams is needed to tailor graphite distributions and optimize performance of cast iron‐based foams.