Alloying Reactions and Coating Microstructure in Continuous Galvanizing and Galvannealing Process

Inagaki, Jun-ichi; Sakurai, Michitaka; Watanabe, Toyofumi

doi:10.2355/tetsutohagane1955.79.11_1273

Cited by 19 publications

(8 citation statements)

References 4 publications

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“…The retardation has been studied and possible reasons are reported. 5,6) The reasons include: (1) the formation of Si oxides on the steel substrate during a recrystallization annealing in reductive atmosphere, (2) solid solution into the Fe-Al intermetallic phase to enhance the barrier effect, and (3) solid solution into the δ 1 phase to retard the interdiffusion of Fe and Zn. The effects of Si on the retardation of the alloying reaction are, however, not fully understood because of the following reasons: (1) the alloying reaction is related to oxidation and it is difficult to distinguish the effects of Si in the two phenomena, (2) multi-elements (Fe, C, Zn and Al etc.)…”

Section: Introductionmentioning

confidence: 99%

Effects of Si Solid Solution in Fe Substrate on the Alloying Reaction between Fe Substrate and Liquid Zn

Kobayashi

2017

ISIJ Int.

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Effects of Si solid solution in Fe substrate on the formation of Fe-Zn intermetallic phase layers between the Fe(-Si) substrate and liquid Zn were investigated using a combinatorial technique. The formation of ζ-FeZn 13 layer was promoted by Si solid solution up to 2 at.% in the Fe substrate but retarded by further solution. The formation of δ 1 -FeZn 7-10 phase and Γ-Fe 3 Zn 10 phase was retarded by Si solid solution up to 10 at.%. The rate of Fe dissolution from the Fe substrate to the liquid Zn region and the Fe/Zn/Si contents in the δ 1 phase were analyzed as a function of Si content in the substrate. The results obtained suggest that the retardation of the Fe-Zn phase formation is caused by a difficulty in the nucleation of δ 1 phase at lower Si contents less than 3 at.% and by a decrease in the rate of Fe dissolution at higher Si contents.

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Section: Introductionmentioning

confidence: 99%

Effects of Si Solid Solution in Fe Substrate on the Alloying Reaction between Fe Substrate and Liquid Zn

Kobayashi

2017

ISIJ Int.

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“…[24][25][26] In the same manner, the aluminum was precipitated to the interface and the iron-zinc intermetallic compounds are hardly formed at the initial stage of the wetting in this work, as shown in 3.3.1. Although the phase of the aluminum compound at the interface was not identified in this work, it can be said the that the aspect is consistent with that in the general galvanizing process and the aluminum is assumed to be an iron-aluminum intermetallic compound from the phenomenological point of view.…”

Section: Discussionmentioning

confidence: 89%

“…This seems to indicate that the formation of iron-zinc alloy could proceed after this as in the well-known procedure in galvanizing. 24,25) It would be suggested that the diffusion manner of the droplet could be affected by such transition of reaction. Further investigation on time dependence of the interface structure would be expected to answer this question.…”

Section: Discussionmentioning

confidence: 99%

“…It is generally well known that ironaluminum intermetallic compounds are formed firstly and they inhibit the formation of the zinc-iron intermetallic compounds in the early stage of the galvanizing process. [24][25][26] Although the product at the interface was not identified in this work, it is indicated that the aluminum precipitated from the molten zinc to the interface prior to the reaction of zinc to the substrate iron in this sample. This aspect is consistent with the generally known reaction in the galvanizing process.…”

Section: Initial Contact Anglementioning

confidence: 99%

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Tailoring Model Surface and Wetting Experiment for a Fundamental Understanding of Hot-dip Galvanizing

Kawano

Renner

2011

ISIJ Int.

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The wettability of molten zinc-aluminum on a steel substrate is an important issue in the hot-dip galvanizing process for automotive applications. Especially, the effects of surface oxides have been current topics during recent years. However wetting behavior under the effects of oxide has not been well illustrated due to the complexity of the surface of actually used steel. In this work, wetting experiments using molten zinc-aluminum were applied to tailored model surfaces of iron to investigate its fundamental behavior. Well-defined aluminum oxide islands were successfully patterned on iron surfaces by physical vapor deposition with masks for this purpose. The sessile drop method with zinc-aluminum was conducted in a laboratory-made apparatus. This apparatus included a unique spin-off technique that allowed us to make an interface analysis at the early stage of wetting. The initial contact angles of the patterned samples were revealed to have followed the Cassie equation. This indicates that the wetting of zinc-aluminum on an oxide-iron system can be treated as if it is a static wetting in its initial stage, even though this system is originally considered as a reactive wetting. The molten zinc-aluminum on a patterned sample diffused into the interface between the oxide islands and the substrate in the stage after initial wetting. It is suggested that this manner of zinc-aluminum diffusion plays a key role in the reaction and formation of the interface during the hot-dip galvanizing process.

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“…Hot-dip galvanized/galvannealed steels are extensively used for steel sheets as automobile bodies because of good productivity and excellent corrosion resistance due to its sacrificial anodic effect [1]. The Fe-Zn and Fe-Albased alloying (intermetallic) phases are known to be formed as a result of the reaction between Fe in the steel substrate and Zn(Al) in the galvanizing bath during a hotdip galvanizing process and/or a subsequent annealing process [2]. Since the mechanical properties of the alloying phases and the steel substrate/coating interface highly depend on the types, morphologies and thickness of the phases formed, it is important to understand the mechanisms of the alloying reaction.…”

Section: Introductionmentioning

confidence: 99%

Effects of Si on the formation of intermetallic phases in alloying reaction between iron substrate and liquid Zn containing 0.2 wt% Al

Kobayashi

2018

SN Appl. Sci.

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The Fe-Zn and Fe-Al-based alloying phases are formed on galvanized/galvannealed steels which are extensively used as automobile bodies. This paper investigated the effects of Si on the formation of intermetallic phases in the alloying reaction between an iron substrate and liquid Zn containing 0.2 wt% Al and partitioning of Si between the phases. The addition of Si to the iron substrate was found to scarcely influence the formation and morphology of the Fe 2 Al 5 intermetallic phase layer but to reduce the amount of the δ 1-FeZn 7-10 intermetallic phase layer at the substrate/liquid interface and to disperse the phase as grains in the Zn-0.2 wt% Al coating matrix. STEM-EDS analysis demonstrates that Si partitions less into the Fe 2 Al 5 and the δ 1 phases than into the iron substrate. Enrichment of Si around an Si-depleted Fe-Zn intermetallic phase product was also observed in the beginning of the alloying reaction. The results obtained allow us to explain the effect of Si on the intermetallic phase formation in terms of a difficulty in nucleating the δ 1 phase at the substrate/liquid interface.

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Alloying Reactions and Coating Microstructure in Continuous Galvanizing and Galvannealing Process

Cited by 19 publications

References 4 publications

Effects of Si Solid Solution in Fe Substrate on the Alloying Reaction between Fe Substrate and Liquid Zn

Effects of Si Solid Solution in Fe Substrate on the Alloying Reaction between Fe Substrate and Liquid Zn

Tailoring Model Surface and Wetting Experiment for a Fundamental Understanding of Hot-dip Galvanizing

Effects of Si on the formation of intermetallic phases in alloying reaction between iron substrate and liquid Zn containing 0.2 wt% Al

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