Growth of intermetallic layer in the aluminide mild steel during hot-dipping

Cheng, Wei-Jen; Wang, Chaur-Jeng

doi:10.1016/j.surfcoat.2009.09.061

Cited by 155 publications

(76 citation statements)

References 15 publications

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“…It has been shown that a continuous growth occurs in the [001] direction due to such a vacancy. In addition, Cheng and Wang conducted a pure Al hot-dip experiment at 700 • C for 180 s [19]. Here, the η phase shows heterogeneous growth in the [001] direction in the a-ferrite, and thus grows like a tongue.…”

Section: Discussionmentioning

confidence: 99%

Study on the Formation of Reaction Phase to Si Addition in Boron Steel Hot-Dipped in Al–7Ni Alloy

et al. 2017

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Abstract:In order to reduce the intermetallic compounds formed during the application of an Al-7Ni wt % hot-dip multifunctional coating on boron steel, developed for Tailor Welded Blanks (TWB) and hot stamping, 2-6 wt % Si was added to the coating to change the reaction layer. The coating was run at 690 • C for 120 s. Al 9 FeNi phases were formed on the steel interface, Fe 2 Al 5 was formed on the steel, FeAl 3 was generated between the existing layers, and flake-type Al 2 Fe 3 Si 3 was formed in the Fe 2 Al 5 phase, depending on the Si content. In addition, as Si was added to the coating, the thickness of the Fe 2 Al 5 phase decreased and the thickness of the Al 9 FeNi phase and Al 2 Fe 3 Si 3 increased. The decrease in the thickness of the Fe 2 Al 5 phase was mainly due to the effect of the Si solid solution and the Al 2 Fe 3 Si 3 formation in the Fe 2 Al 5 phase. The reason for the growth of Al 9 FeNi is that the higher the Si content in the coating, the more the erosion of the interface of the steel material due to the coating solution. Therefore, the outflow of Fe into the coating liquid increased.

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Section: Discussionmentioning

confidence: 99%

Study on the Formation of Reaction Phase to Si Addition in Boron Steel Hot-Dipped in Al–7Ni Alloy

et al. 2017

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“…Reaction layers or reaction phases have been studied for a long time in the diffusion reaction or coating process of Fe and pure Al [22][23][24], Fe and Al alloys [25,26], steel and pure Al [27][28][29][30][31], and steel and Al alloys [32,33]. The reaction layers formed in these studies were classified into the following three types: (1) Al/FeAl 3 (θ)/Fe 2 Al 5 (η)/Fe [22][23][24]33] where the intermetallic layer is composed of an outer minor FeAl 3 (θ) layer and an inner major 11 maintaining the dipping temperature.…”

Section: Discussionmentioning

confidence: 99%

Identification of Intermetallic Compounds and Its Formation Mechanism in Boron Steel Hot-Dipped in Al-7 wt.% Mn Alloy

et al. 2017

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Abstract:In laser welding and hot stamping Al-Si-coated boron steel, there is a problem that the strength of the joint is lowered due to ferrite formation in the fusion zone. The purpose of this study is to develop an Al-7 wt.% Mn hot-dip coating in which Mn, an austenite stabilizing element, replaces the ferrite stabilizing element Si. The nucleation and formation mechanism of the reaction layer was studied in detail by varying the dipping time between 0 and 120 s at 773 • C. The microstructure and phase constitution of the reaction layer were investigated by various observational methods. Phase formation is discussed using a phase diagram calculated by Thermo-Calc TM . Under a 30 s hot-dipping process, no reaction occurred due to the formation of a Fe 3 O 4 layer on the steel surface. The Fe 3 O 4 layer decomposed by a reduction reaction with Al-Mn molten alloy, constituent elements of steel dissolved into a liquid, and the reaction-layer nucleus was formed toward the liquid phase. A coated layer consists of a solidified layer of Al and Al 6 Mn and a reactive layer formed beneath it. The reaction layer is formed mainly by inter-diffusion of Al and Fe in the solid state, which is arranged on the steel in the order of Al 11 Mn 4 → FeAl 3 (θ) → Fe 2 Al 5 (η) phases, and the Fe 3 AlC (κ) in several nm bands formed at the interface between the η-phase and steel.

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“…EDS and XRD analyses show that the major phase is Fe3Al with Cr-contents of around 10.21 (at.%) for the specimen oxidized at 1000 °C after 250 cycles, see Figure 3b and 4b. As mentioned above, the crack perpendicular to the surface of the specimen in the aluminide layer growing through surface allows oxygen to reach the inner interface of the scale via crack network [14,15]. Figure 3 and 5 show cross-sectional micrographs and the corresponding EDS line profiles of elements of oxide and aluminide layer formed after oxidation at 1000 °C and 900 °C.…”

Section: Degradation Of the Aluminide Layermentioning

confidence: 94%

Degradation of Aluminide Layers During Cyclic Oxidation of Ferritic 430 Stainless Steel

Badaruddin¹

2011

jtm

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In order to increase the performance of the preferred Ferritic 430 SS for manufacturing automobile and motor-cycle exhaust systems. The aluminizing coating on the surface of bare steel was applied by hot-dipping method in a molten pure aluminum. The high temperature oxidation of the aluminized steel was cyclically studied at 900 °C and 1000 °C in static air. The degradation of intermetallic layers during cyclic oxidation were analyzed by means of X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS). The crack perpendicular to the specimen surface rapidly propagated through the FeAl and Fe3Al layers due to a thermal expansion mismatch upon cooling to room temperature. The accumulation of voids generated crack at the interface between the aluminide layer and the steel substrate. Oxygen is allowed to penetrate into the aluminide layer crack, rapidly forming alumina oxide and closing the crack. Some of the aluminide layers peeled off due to this rapid growth. Thus, the protective Al2O3 layer degraded and later, the substrate was oxidized subsequently to form iron-rich oxide (Fe2O3) at 1000 °C.

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Growth of intermetallic layer in the aluminide mild steel during hot-dipping

Cited by 155 publications

References 15 publications

Study on the Formation of Reaction Phase to Si Addition in Boron Steel Hot-Dipped in Al–7Ni Alloy

Study on the Formation of Reaction Phase to Si Addition in Boron Steel Hot-Dipped in Al–7Ni Alloy

Identification of Intermetallic Compounds and Its Formation Mechanism in Boron Steel Hot-Dipped in Al-7 wt.% Mn Alloy

Degradation of Aluminide Layers During Cyclic Oxidation of Ferritic 430 Stainless Steel

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