Abstract

An experimental study has been carried out on the surface characteristics of hot-dip aluminized (HDA) C45 carbon steel. The coated specimens were also tested thrice by cycling heat between the ambient temperature and 700°C inside an electrical resistance furnace. Both the as-coated and the oxidized samples were analyzed by scanning electron microscopy, energy dispersive spectrometry, and elemental mapping. Microstructural features and other important characteristics (compositional changes, chemical elemental distributions, growth of the intermetallic phases, the formation of micro-voids, etc.) were investigated. Under the high temperature tested conditions, the HDA coated C45 carbon steel close-to-surface top-layer almost entirely converted to iron-aluminum intermetallics, with Fe to Al atomic ratios of 1 to 2 corresponding to the phases FeAl and FeAl₂. However, the innermost intermetallic phase (FeAl) formed between the finger-like structure and the steel substrate appeared quite compact and sound (without voids, micro-crack, and internal iron oxide scale), which is a convincing sign and an experimental proof of a high chemical and mechanical stability of such type of surface coatings. The results confirm that even inexpensive carbon steel, if properly aluminized, can provide sufficient protection against excessive oxide scale formation in the air at high temperatures.

中文翻译：

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热浸镀铝C45碳钢在空气中循环加热前后的表征

摘要

对热浸镀铝 (HDA) C45 碳钢的表面特性进行了实验研究。通过在电阻炉内在环境温度和 700°C 之间循环加热，还对涂层试样进行了三次测试。通过扫描电子显微镜、能量色散光谱法和元素图分析涂层样品和氧化样品。研究了微观结构特征和其他重要特征（成分变化、化学元素分布、金属间相的生长、微孔洞的形成等）。在高温测试条件下，HDA 涂层 C45 碳钢接近表面的顶层几乎完全转化为铁铝金属间化合物，₂ . 然而，在指状结构和钢基体之间形成的最里面的金属间相（FeAl）看起来非常致密和完好（没有空隙、微裂纹和内部氧化铁皮），这是一个令人信服的迹象和实验证明。这种类型的表面涂层具有很高的化学和机械稳定性。结果证实，即使是廉价的碳钢，如果适当镀铝，也可以提供足够的保护，防止高温下空气中形成过多的氧化皮。