Effects of Surface Microstructure and Chemical Compositions of Steels on Formation of Fe-Zn Compounds during Continuous Galvanizing

Nishimoto, Akihiko; Inagaki, Jun-ichi; Nakaoka, Kazuhide

doi:10.2355/isijinternational1966.26.807

Cited by 28 publications

(17 citation statements)

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“…This observation suggests that the formation of at the coating-steel interface differs from grain boundThe Al content in the coating overlay is lowest at 0.15 pct melt Al level on both the IF and the LC steels. As ary nucleation of outbursts reported by Nishimoto et al [4] Fig. 10-Composition maps for a cross section of IF steel hot dipped in 0.18 pct Al zinc melt.…”

Section: Stem Microanalysis Of Coatings For Al and Fe Distributionsmentioning

confidence: 94%

“…While Hertveldt et al [9] zinc during continuous galvanizing has been investigated by determined that the inhibition layer is composed of a zinca number of researchers. Nishimoto et al [4] concluded that bearing FeAl or FeAl 2 compound, Guttmann, et al [10] indicarbon and phosphorous in solution in steel inhibited the cated that the inhibition layer is comprised of Fe 2 Al 5 with formation of zinc-iron alloy outbursts in the coating. Saito a high zinc content.…”

Section: Introductionmentioning

confidence: 99%

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Distribution of aluminum in hot-dip galvanized coatings

Furdanowicz¹,

Shastry²

1999

Metall Mater Trans A

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Hot-dip galvanized panels of low-carbon (LC) and interstitial-free (IF) steels were produced in a laboratory simulator with an average coating mass of 60 g/m 2 . Three pot aluminum levels were used, viz., 0.10 pct (by wt), 0.15 pct, and 0.18 pct. Metallography, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) were used to characterize coating and base steel microstructures. Wet chemical analysis and scanning transmission electron microscopy (STEM) were employed for compositional analyses. The aluminum content of the melt was found to be the predominant factor influencing the distribution of Al in the coating. At 0.18 pct melt aluminum, Al is partitioned between the aluminide inhibition layer at the coating-steel interface (ϳ80 pct) and the zinc overlay (ϳ20 pct). At 0.15 pct, it is partitioned among the aluminide layer (ϳ75 pct to 80 pct), zinc-iron (FeZn 13 , ) intermetallic layer (ϳ5 pct to 15 pct), and the coating overlay (ϳ10 pct). At 0.10 pct, the aluminum is divided almost equally between the overlay and the zinc-iron intermetallics. At the two lower aluminum levels is the distribution marginally influenced by the steel grade. The was found to not preferentially nucleate at the ferrite grain boundaries. When both the aluminide and occurred at the coating-steel interface, the particles appeared near discontinuities and thinner regions in the aluminide layer. The coating, relative to the melt, is enriched in aluminum because of its concentration in the aluminide and in the zinc-iron intermetallics. This enrichment increases with melt aluminum through an increase in the aluminum content of the aluminide layer and not of its thickness. In addition, a few tens-of-nanometers-thick layer enriched in aluminum, oxygen, and iron is observed on the outer surface of all coatings. The aluminum content in this layer also increases with an increase in the melt aluminum, but it contributes negligibly to the coating's content because of its extreme thinness.

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Section: Stem Microanalysis Of Coatings For Al and Fe Distributionsmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

Distribution of aluminum in hot-dip galvanized coatings

Furdanowicz¹,

Shastry²

1999

Metall Mater Trans A

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“…Better knowledge of the phase make-up of the coatings and of its effect on formability is therefore required to optimize these coatings. The nature and the distribution of the intermetallics depend mainly on the steel substrate chemistry and different parameters of the galvannealing process (bath and annealing temperatures, annealing time, A1 bath content, etc., Fader1 et al, 1992;L'Ecuyer et al, 1992;Nishimoto et al, 1986).…”

Section: Introductionmentioning

confidence: 99%

Development and application of a dry ultramicrotomy technique for the preparation of galvanneal sheet coatings

Barreto

Veillette

L’Éspérance

1995

Microscopy Res & Technique

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The formability of galvanneal steel sheets used in the automotive industry is influenced by the presence and distribution of brittle and difficult to distinguish Zn-Fe intermetallics in the coating. Characterization of these intermetallics requires a high spatial resolution technique such as analytical transmission electron microscopy (ATEM). Sample preparation by ion milling is impossible due to iron redeposition, and traditional ultramicrotomy using water affects the coating chemistry. A technique based on dry ultramicrotomy has therefore been developed. To optimize the technique, different parameters (knife angle, cutting medium, thickness setting on the ultramicrotome, cutting speed) have been investigated for the preparation of galvanneal coatings and pure A1 sections. Results show that dry cutting does not affect the coating chemistry but shortens the life of the knife. Knife quality (cleanliness, sharpness and absence of defects) is a major factor to obtain good dry sections. The best results for the more ductile pure A1 are obtained with a 35 degrees knife whilst for the harder galvanneal coating it is recommended to use a 55 degrees knife. These results suggest that the sectioning mechanism for the harder material involves more a cleavage-fracture mechanism whilst a greater amount of shear is involved when sectioning relatively ductile A1. The optimum parameters for sectioning galvanneal coatings are established and results obtained by parallel electron energy loss spectrum imaging and energy dispersive X-ray spectrometry in the TEM are given. This study shows that with a good control of all the sectioning parameters it is possible to obtain good sections repeatedly and rapidly.

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“…2,4) Inagaki et al 2) observed a thick Fe2Al5Znx layer in the coatings produced with a 0.15 wt% bath aluminum as compared with the coatings produced with a 0.13 wt% bath aluminum. This intermetallic layer acts as a barrier for FeZn diffusion and inhibits the formation of ζ-phase and δ-phase.…”

Section: Introductionmentioning

confidence: 99%

“…It has been shown by multiple researchers that these alloying elements affect the steel/zinc interaction. Inagaki et al, 2) Nishimoto et al, 4) Lin et al 5) showed that phosphorus and carbon can segregate to the surface and grain boundaries and inhibit the outburst reaction and slows down the formation of Fe-Zn intermetallic compounds. Rangarajan et al 6) found carbon and phosphorus segregation in extra low carbon steels and rephosphorized steels, respectively.…”

Section: Introductionmentioning

confidence: 99%

Influence of Substrate Molybdenum on Galvannealing Kinetics of an Advanced High Strength Steel

2014

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Advanced high strength steels (AHSS) are used for car body applications in the automotive industry to improve passenger safety, improve fuel efficiency and to lower harmful carbon emissions. Galvannealed AHSS are used to provide corrosion protection. AHSS are alloyed with several elements such as Mn, Si, Al, P, Mo, etc. to achieve better mechanical properties. However, the knowledge of the effects of Mo on galvannealing behavior is limited. This investigation was conducted to study the influence of molybdenum in steel on galvannealing kinetics. Five dual-phase steels with Mo varying from 0 wt% to 0.4 wt% were used for this study. The results showed a delay in the galvannealing kinetics with an increase in the steel molybdenum content. No obvious improvement in the coating appearance was observed with increasing molybdenum.

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Effects of Surface Microstructure and Chemical Compositions of Steels on Formation of Fe-Zn Compounds during Continuous Galvanizing

Cited by 28 publications

References 0 publications

Distribution of aluminum in hot-dip galvanized coatings

Distribution of aluminum in hot-dip galvanized coatings

Development and application of a dry ultramicrotomy technique for the preparation of galvanneal sheet coatings

Influence of Substrate Molybdenum on Galvannealing Kinetics of an Advanced High Strength Steel

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