A Study on the Phase Formation and Physical Characteristics of Hot-Dip Aluminized Coating at 750 °C

• Published in: Metallography, microstructure, and analysis microstructure, and analysis, 2021-12, Vol.10 (6), p.823-838
• Main Authors: Dey, Partha Pratim, Modak, Pranabananda, Chakrabarti, Debalay, Banerjee, P. S, Ghosh, Manojit
• Format: Article
• Language: English
• Subjects: Aluminum base alloys; Characterization and Evaluation of Materials; Chemical composition; Chemistry and Materials Science; Crystallography; Electron backscatter diffraction; Electron probe microanalysis; Emission analysis; Glow discharges; Hot dip aluminizing; Immersion coating; Intermetallic compounds; Interstitial free steels; Iron; Magnesium compounds; Materials Science; Metal silicides; Metallic Materials; Nanotechnology; Optical emission spectroscopy; Physical properties; Scanning electron microscopy; Silicon compounds; Silicon substrates; Spectrum analysis; Structural Materials; Surfaces and Interfaces; Technical Article; Thin Films; X-ray diffraction
• ISSN: 2192-9262; 2192-9270
• DOI: 10.1007/s13632-021-00800-3

In this research, microstructure and crystallographic features of different phases generated on interstitial free steel hot dipped in Al-6.9Si-1.4Mg alloy melt was examined. Bath temperature was 750 °C for 0.5, 1, 3 and 6 min dipping. A combined arrangement of scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and electron backscatter diffraction was used for phase identification. Results indicated that aluminized layer comprised of outer Al-Si alloy top-coat, thin FeAl 3  layer and a thick Fe 2 Al 5  layer in contact with steel substrate. Ternary Fe-Al-Si intermetallic compounds of Al 2 FeSi ( τ 3 ) and Al 3 FeSi 2  ( τ 4 ) were also identified. Elemental mapping, chemical composition analysis and in-depth composition profile of elements were done by electron probe microanalysis and glow discharge optical emission spectroscopy (GDOES). XRD study confirmed elemental silicon (Si) and magnesium (Mg) in the form of Mg 2 Si. SEM-EDS and GDOES studies confirm a sudden rise in Si at% at the top and in the intermetallic layer, which was attributed to the existence of Si-bearing phases or elemental pro-eutectic Si. The formability of the coated sheet was assessed by bending the samples at 180° to investigate the peeling-off of the outer coating layer from the steel surface.