High-temperature Oxidation of Hot-dip Aluminized 2.25Cr-1Mo Steel |
Muhammad Ali Abro1, Junhee Hahn2, Dong Bok Lee3 |
1Department of Mechanical Engineering, Mehran University of Engineering and Technology, SZAB Campus, 2Center for Energy Materials Metrology, Korea Research Institute of Standards and Science, Daejon 34113, Republic of Korea 3School of Advanced Materials Science & Engineering, Sungkyunkwan University, Suwon 16419, Republic of Korea |
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Received: 8 January 2018; Accepted: 19 February 2018. Published online: 8 May 2018. |
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ABSTRACT |
When 2.25Cr-1Mo steel was hot-dip aluminized, a coating consisting of (Al-rich topcoat)/(Al13Fe4 layer)/(Al5Fe2 layer) formed. With increment of oxidation temperature, the transform of Al→Al13Fe4→Al5Fe2→AlFe→AlFe3→α-Fe(Al)→α-Fe occurred through interdiffusion between the coating and the substrate as follows. The oxidation at 700 oC changed the coating to (α-Al2O3 scale)/(α-Al2O3, Al13Fe4, Al5Fe2)-mixed layer)/(Al5Fe2 layer)/(AlFe layer)/(AlFe3 layer)/(α-Fe(Al) layer). The oxidation at 800 oC changed the coating to (α-Al2O3 scale)/((α-Al2O3, Al5Fe2)-mixed layer)/(Al5Fe2 layer)/(AlFe layer)/(AlFe3 layer)/(α-Fe(Al) layer). The oxidation at 900 oC changed the coating to (α-Al2O3 scale)/((α-Al2O3, AlFe)-mixed layer)/(AlFe layer)/(AlFe3 layer)/(α-Fe(Al) layer). The oxidation at 1000 oC changed the coating to ((α-Al2O3, Fe2O3)-mixed layer))/(AlFe3 layer)/(α-Fe(Al) layer). |
Keywords:
hot dipping, aluminizing, P22 steel, oxidation |
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