Observation of high-temperature phase transformation in the aluminide Cr–Mo steel using EBSD

Microstructural Changes of Al Hot-Dipped P91 Steel during High-Temperature Oxidation

“…Hot dipping formed a~20 µm-thick topcoat (spots 1-6), 15 µm-thick transient alloy layer (spots 7-10), and~35 µm-thick underlying alloy layer (spots [11][12][13][14][15][16][17][18][19] on the steel substrate (spots 20-24) (Figure 2a [4,8,13,14,18]. Hence, the Al 5 Fe 2 layer (spots [11][12][13][14][15][16][17][18][19] was thicker than the Al 13 Fe 4 layer (spots 7-10 inside the alloy layer) [10,11]. On the other hand, in the case of low-alloyed carbon steels, the characteristic finger-or tongue-like morphology that oriented along the c-axis of Al 5 Fe 2 generally developed at the coating/substrate interface [4][5][6]9,10,12,13].…”

“…Hence, the high-temperature oxidation resistance of 9Cr-1Mo steels needs to be improved through surface modification techniques. Aluminum hot-dipping is a simple, cost-effective coating technique that could form the compact, slow growing, protective alumina scale in reaction with oxygen at high temperatures [4][5][6][7][8][9][10][11][12][13][14][15]. It also improves the surface hardness by forming Al-Fe intermetallics [5,7,9,13].…”

“…Diverse aluminized coatings have been obtained by hot-dipping carbon steels in Al [5,7,12,13] and Al-Si molten baths [5,9], 5Cr-0.5Mo steels in Al [14] and Al-Si molten baths [16], and 9Cr-1Mo steels in Al-Si [17] and Al-Si-Mg molten baths [15]. They significantly enhanced the high-temperature oxidation and corrosion resistance of the underlying steels through forming α-Al 2 O 3 [5,7,9,[12][13][14]17,18], α-Al 2 O 3 + FeAl [6,15], and FeAl [16] layers. However, microstructural changes during high-temperature oxidation and the oxidation resistance of 9Cr-1Mo steels that were hot-dipped in the Al molten bath have not been adequately investigated before.…”

Corrosion of Carbon Steel with and without Aluminized Coating in (O, S, H)-containing Gases at 500-800℃

“…Such good corrosion protection was attributed to the formation of the α-Al 2 O 3 scale on the surface through the reaction of the Al-rich topcoat with the oxygen impurity in Ar/0.1%H 2 S and Ar/1%SO 2 gas. It is noted that Al readily reacts with oxygen to form the highly stable α-Al 2 O 3 at high temperatures [12,13]. In EDS line profiles shown in Figs.…”

Local strain analysis of the tertiary oxide scale formed on a hot-rolled steel strip via EBSD

“…5a. Also, the fresh steel protrudes into the oxide scale at a high deformation due to different plastic flows of the oxide scale and steel substrate [38]. Accordingly, the high intensity of local misorientation (Fig.…”