CUI Gui-bin,JU Xin-hua,YIN Li-xin,YAN Chun-lian.Characterization of Microstructure of Hot-dip Al-Si Coating[J],50(8):375-381
Characterization of Microstructure of Hot-dip Al-Si Coating
Received:October 07, 2020  Revised:December 14, 2020
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DOI:10.16490/j.cnki.issn.1001-3660.2021.08.037
KeyWord:hot dip  Al-Si coating  phase  EBSD  Kikuchi pattern
           
AuthorInstitution
CUI Gui-bin Shougang Group Company Limited Research Institute of Technology, Beijing , China
JU Xin-hua Shougang Group Company Limited Research Institute of Technology, Beijing , China
YIN Li-xin Shougang Group Company Limited Research Institute of Technology, Beijing , China
YAN Chun-lian Shougang Group Company Limited Research Institute of Technology, Beijing , China
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Abstract:
      This paper aims to study the microstructure and phase composition of hot-dip Al-Si coating on hot-formed steel. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) were used to analyze the microstructure and composition of the surface and cross-section of the Al-Si coating; X-ray diffraction (XRD) and electron backscatter diffraction (EBSD) were used to analyze the phase composition and ratio of the Al-Si coating. The surface of the hot-dip Al-Si coating is composed of Al-rich phase, a small amount of Fe-rich phase, and high Si phase with dendritic network distribution; the cross-section of the hot-dip Al-Si coating is composed of inner and outer layers, the inner layer close to the iron matrix is an Fe-Al-Si alloy layer, and the outer layer is an Al-Si layer. Further research shows that the Al-Si layer is composed of Al-rich phase, a small amount of Fe-rich phase, and columnar distributed high Si phase; the high Si phase mainly exists at the interface between the alloy layer and the Al-Si layer and in the Al-Si layer. The phases of Al-rich phase, Fe-rich phase, high Si phase and Fe-Al-Si ternary alloy layer in the hot-dip Al-Si coating are Al, Al13Fe4, Si and Al8Fe2Si respectively. The study of high Si phase in hot-dip Al-Si coating has shown that the high-Si phase distributed at the interface between the alloy layer and the Al-Si layer can effectively hinder the growth of the coating, while the high-Si phase distributed in the Al-Si layer exists in the form of a three-dimensional network framework in space. This three-dimensional network structure as the main frame of the coating can effectively improve the strength and toughness and formability of the coating.
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