Characterization of the Fe-Al Interfacial Layer in a Commercial Hot-dip Galvanized Coating.

McDevitt, Erin; Morimoto, Yasuhide; Meshii, M.

doi:10.2355/isijinternational.37.776

Cited by 56 publications

(37 citation statements)

References 2 publications

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“…The Fe dissolution process would therefore be blocked on those zones were Fe 2 Al 5 Zn x has nucleated while it would proceed in the adjoining areas leading to the observed "holes" which would be then occupied by the subsequent nucleation of the δ phase. The reason why metastable Fe 2 Al 5 Zn x nucleates at the steel/liquid Zn interface, instead of stable δ, is likely due to epitaxic relationships between Fe 2 Al 5 Zn x and the ferrite, already reported by different authors [5,6,16].…”

Section: Discussionmentioning

confidence: 93%

Nature of the inhibition layer in GA baths

Alvarez

Bertrand

Mataigne

et al. 2014

Metall. Res. Technol.

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-The nature of the intermetallic layer which forms on the steel surface during immersion in typical galvanizing baths for galvannealed (GA) sheets production has been investigated on two commercial Titanium-stabilized Interstitial-Free (Ti-IF) steel substrates galvanized in baths with different Al contents. Results from this study show that in both cases the inhibition layer is biphasic and composed of a very thin Al-rich phase layer, identified as Fe 2 Al 5 Zn x , and a thicker Zn-rich phase layer on top of it, identified as δ. Experimental results also show that the Fe 2 Al 5 Zn x phase layer becomes discontinuous when decreasing the bath Al content. Discussions about the mechanisms of formation and the final microstructure of this inhibiting layer are also tackled in this paper by means of the Al-Fe-Zn ternary phase diagram at 460 • C and assumptions to justify any deviation from thermodynamic equilibrium are as well proposed.

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Section: Discussionmentioning

confidence: 93%

Nature of the inhibition layer in GA baths

Alvarez

Bertrand

Mataigne

et al. 2014

Metall. Res. Technol.

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“…To obtain high-quality coatings, some alloy elements are added to the zinc bath. [1][2][3][4][5][6][7][8][9][10][11][12] Aluminum is one of the most important elements in galvanizing. Virtually all galvanizing baths contain aluminum.…”

Section: Introductionmentioning

confidence: 99%

Phase Equilibria of the Al-Co-Zn System at 450 °C

Zhao

Yin

et al. 2011

J. Phase Equilib. Diffus.

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The 450°C isothermal section of the Al-Co-Zn ternary system was determined experimentally by means of scanning electronic microscopy coupled with wave dispersive x-ray spectroscopy, and x-ray powder diffraction. Nine three-phase regions have been confirmed experimentally. The liquid phase is in equilibrium with all Al-Co compounds except Al 3 Co. The maximum solubility of Zn in AlCo, Al 5 Co 2 , Al 9 Co 2 and Al 13 Co 4 is 8. 76, 18.14, 1.24, 8.97 at.%, respectively. The Al solubility in the Co-Zn compounds (c 2 , c 1 , c, b 1 ) is very small, no more than 0.14, 0.28, 0.32, and 0.62 at.%, respectively. No true ternary compound was found in the present study.

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“…It has shown that inhibition layer consists of Fe 2 Al 5 (orthorhombic) and Fe 3 Al (DO 3 ) particles and retards the formation of the Fe-Zn intermetallic. 11,12) Harvey and Mercer showed by transmission electron microscopy that inhibition layer is composed mostly of Fe 2 Al 5 particles containing 10-15 wt% Zn. 13) Morimoto et al investigated the crystallographic relationship between steel substrate and Fe 2 Al 5 on various steel and concluded that the chemical composition of steel substrate affects the microstructure of inhibition layer.…”

Section: Introductionmentioning

confidence: 99%

“…13) Morimoto et al investigated the crystallographic relationship between steel substrate and Fe 2 Al 5 on various steel and concluded that the chemical composition of steel substrate affects the microstructure of inhibition layer. 11,12) In particular, an addition of P in Ti-added interstitial free (IF) steel favored the formation of the thick Fe 2 Al 5 layer and retarded the Fe-Zn reaction.…”

Section: Introductionmentioning

confidence: 99%

Correlation between the Microstructure of Galvannealed Coatings and the Defoliation during Press Forming

Hong

2005

ISIJ Int.

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The defoliation properties of galvannealed coating, so-called powdering and flaking, in a commercial continuous galvanizing line were investigated by scanning electron microscopy, X-ray diffraction, a roughness profiler and deep drawing test. Both aluminum content in molten zinc and galvannealing temperature were found to be critical factors controlling the microstructure and mechanical properties of galvannealed coatings. Below 0.135 wt% Al, the coating surface was composed of a mixture of granular d 1p and columnar z phases, while, above 0.155 wt% Al, the coating surface contained the mixture of granular d 1p and pan-cake d 1k phases. The appearance of brittle d 1k phase approximately 10 mm in size can account for the high amount of defoliation during deep drawing test. The formation of relatively ductile z phase and thin G phase contributes to improve the press formability. The optimization of the surface microstructure controlling the ratio of granular d 1p and columnar z phases was important to reduce the powdering.KEY WORDS: galvannealing; powdering; flaking; Al content; Fe-Zn intermetallics. Experimental ProceduresThe GA coatings investigated in the present study were prepared from the industrial CGL equipped with extensive strip cleaning section, all radiant tube annealing furnaces, pre-melting and two pots zinc system and induction-type galvannealing furnace. 15) The cleaning section contains serials of aqueous alkaline dipping tank, abrasive brushing machine, pickling and electrolytic cleaning tank. Table 1 shows the chemical compositions of the TiϩNb-added IF steel sheets used in present study, where a small amount of carbon and nitrogen were precipitated as TiC, NbC and TiN nano-particles while steel sheets were elongated. The GA coatings were produced at galvannealing temperatures between 480 and 620°C with a line speed of approximately 80-100 m/min. Al content in the zinc bath was varied between 0.125 and 0.165 wt% and the zinc bath temperature was between 448 and 457°C. More than 100 samples for automotive panels with 0.6-1.0 mm thick and the coating weight of 45-60 g/m 2 per each side were prepared. Al content in zinc bath and Fe, Zn and Al compositions of GA coating were analyzed by inductively coupled plasma (ICP) method. The plan-view and cross-sectional microstructures were investigated using a Cambridge SEM combined with an energy dispersive X-ray spectroscopy (EDS). To reveal the precise thickness of G layer, GA coating was mounted in the plastic mold, polished and, finally, etched using the 1 % HCl solution for 40 s. Deep drawing and U-bend tests were adopted for clarifying the correlation between the microstructure and defoliation of GA coating. Figure 1 shows the schematic illustration of (a) deep drawing dies and (b) the photographs of deformed sample. The amount of powdering was evaluated as difference in the weight of the sample before and after deep drawing test. On the other hand, the correlation between GA coating microstructure and flaking properties was characterized by the U-ben...

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Characterization of the Fe-Al Interfacial Layer in a Commercial Hot-dip Galvanized Coating.

Cited by 56 publications

References 2 publications

Nature of the inhibition layer in GA baths

Nature of the inhibition layer in GA baths

Phase Equilibria of the Al-Co-Zn System at 450 °C

Correlation between the Microstructure of Galvannealed Coatings and the Defoliation during Press Forming

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