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Xhoffer, C.; Dillen, H.; Cooman, Bruno C. De; Hubin, Annick

doi:10.1023/a:1003435824284

Cited by 25 publications

(17 citation statements)

References 8 publications

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“…The galvannealed coating consistently showed more positive potential values than did the galvanized coating due to its content of iron, an element with a nobler thermodynamic standard electrochemical potential. While the curve corresponding to the galvanized coating presented a single and well defined plateau at 1.0 V, the curve for the galvannealed coating presented three potential plateaus, two of them well defined at )0.91 V and )0.75 V and a short broad one at )0.82 V. These results are in close agreement with those previously reported [5][6][7][8][9][10][11]. Based on these studies, the plateau observed at )1.0 V can be attributed to the g phase, corresponding to the Zn layers, while those observed at )0.91 V, )0.82 V and )0.75 V can be ascribed, respectively, to the n, d, and G Zn-Fe intermetallic phases.…”

Section: Corrosion Testssupporting

confidence: 92%

“…Galvannealed coatings, which are produced by rapid annealing of galvanized steel at temperatures ranging from 490°C to 540°C, consist of several zinc-iron intermetallic phases: the f, the d and the G phases [1][2][3]. Due to its superior properties, galvannealed steel has been increasingly used in the automotive industry and interest in understanding its corrosion behavior has grown [4][5][6][7][8][9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, the passivation process for both zinc-rich n and d phases is diffusion-controlled over the range of pH 9-14 [6]. The electrochemical stripping technique has been used to characterize the Zn-Fe intermetallic phases present in galvannealed coatings [7][8][9][10][11] and in synthesized alloys [9]. Fabri-Miranda et al [12], who studied the corrosion of galvannealed steel exposed to an industrial environment for a year, concluded that the corrosion process was associated with the presence of depressions in the external coating surface related to the presence of n and d Zn-Fe intermetallic phases.…”

Section: Introductionmentioning

confidence: 99%

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Evaluation of the corrosion behavior of galvannealed steel in chloride aqueous solution and in tropical marine environment

Silva

Costa

Mattos³

et al. 2005

J Appl Electrochem

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An investigation was made into the corrosion behavior of commercial galvannealed steel in 10 )2 mol dm )3 NaCl aqueous solutions and in a tropical marine environment, using scanning electron microscopy (SEM), galvanostatic electrochemical stripping (GES), potentiodynamic linear polarization (PLP), and electrochemical impedance spectroscopy (EIS) techniques and open circuit measurements (E oc ). For purposes of comparison, a commercial galvanized steel was also subjected to similar corrosion tests. GES and SEM techniques allowed for the identification of f, d and G intermetallic phases and revealed cracks in the galvannealed steel. The PLP, EIS and E oc results indicated that the galvannealed coating was more corrosion resistant than galvanized coating in an aqueous medium, but that their corrosion behaviors were similar in the marine environment. The corrosion behavior of the galvannealed steel was affected by the evolution of the cracking process in the Zn-Fe layer due to the dissolution of zinc-rich phases, while the galvanized steel displayed generalized corrosion in the aqueous medium and localized corrosion in the marine environment.

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Section: Corrosion Testssupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Evaluation of the corrosion behavior of galvannealed steel in chloride aqueous solution and in tropical marine environment

Silva

Costa

Mattos³

et al. 2005

J Appl Electrochem

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“…Other researchers have. 19) According to Marder,17) the cracks form in the delta phase, but can also extend to the zeta and gamma phases. Figure 2(c) shows the presence of cracks in coating layers for samples heat treated at 520°C for 135 s. Compared to the situation in Figs.…”

Section: Flds Of the Steelsmentioning

confidence: 99%

Effect of Heat Treatment on Formability of Hot-dip Galvanized Low Carbon Steel Sheet

Azadeh

Toroghinejad

2009

ISIJ Int.

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Fig. 1. One series of galvannealed samples after stretching. Strain Distribution ProfilesThe major and minor diameters of the ellipses in the longitudinal direction and the corresponding distances of the ellipses from the pole were measured. From these data, strain distribution profiles were drawn by plotting the distance from the pole on the abscissa and the corresponding major and minor strains on the ordinate. FractographyThe fractured surfaces were studied using a scanning electron microscopy. The specimens were cut close to the region of the fracture. The fracture cross sections were cleaned with alcohol before study. The nature of fracture was analyzed from the features of the fracture to study the relationship between the features and the formability parameters. Results and Discussion Coating LayersThe experimental results of galvanized coating microstructure examined using SEM, EDS semi-quantity analysis, XRD patterns, and liner analysis of coating sections revealed that the coating microstructure consisted of z (Zn-4.2%Fe) and h (Zn-1.1%Fe) layers on steel surface (Fig 2(a)). The surface of the galvanized samples had shiny spangles but then changed to matt with no spangles. Figures 2(b), 2(c) show the section and the microstructure of galvanized samples and those annealed at 520°C and for varying durations. The apparent surface of coating at 120 s was silvery and bright without spangles but at 135 s, it turned gray and matt. Considering EDS semi-quantity analysis and XRD patterns, the galvannealed coating at 120 s consisted of G, d, z, and h layers while at 135 s, it only contained G and d layers. It can be seen in Fig. 2(c) that cracks initiated and propagated along the d phase. FLDs of the SteelsThe formability limit diagrams for the galvanized and galvannealed steels under investigation are presented in Fig. 3. The diagrams are similar in shape (V-shaped). The vertical and horizontal axes in these diagrams represent the percentages of maximum strain and minimum strain, respectively. The strains were measured for the necked ellipses and around the fracture area. That is why the forming limit diagrams were drawn under the obtained points.On the FLDs, the regions corresponding to the negative minor strain (tension-compression region) and the positive minor strain (tension-tension region) are not symmetrical. Thus, in the tension-compression region, the slope of the forming limit curve is higher and the safe zone is wider than those of the tension-tension region. It is clear from Fig. 3 that the level of forming limit diagrams and the major strains decrease with increasing heat treatment time at a constant temperature. The lowest limit strain of a FLD, which corresponds to 0 % minor strain, is known as the plain strain (FLD 0 ). Since failure appearing in cold-formed parts under pressed conditions often occurs in this state, the value for FLD 0 represents the most critical strain state on the FLD. High values of FLD 0 mean better formability. 18)FLD 0 values for galvanized and annealed samples are pre...

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“…The embrittlement of the coating mainly depends on the iron content and distribution of different Fe-Zn intermetallic phases. [4][5][6] Several efforts have been made to correlate the microstructure of galvannealed coatings to their performance, especially the coating formability during press forming operations. [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] Most of the work has been carried out using galvanizing and galvannealing simulators, where the growth of the coating takes place under fully controlled experimental conditions.…”

Section: Introductionmentioning

confidence: 99%

Structural and Textural Characterization of the Substrate and Coated Layer in an Industrial Galvannealed Interstitial-Free Steel

Chakraborty

Ray

Sangal

2008

Metall Mater Trans A

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An attempt has been made to characterize the microstructural and textural aspects of the substrate and the coated layer on industrially produced galvannealed interstitial-free (IF) steel. A number of experimental techniques were used for this purpose. The major part of the coating was found to be made up of the d layer, favorable for good formability. The texture of the substrate steel contained a sharp c component, which imparts high deep drawability. The offbasal texture {01.3} uv:w h i of the coating was also beneficial for this purpose. The favorable microstructural and textural characteristics led to satisfactory powdering resistance to the coated material.

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Untitled

Cited by 25 publications

References 8 publications

Evaluation of the corrosion behavior of galvannealed steel in chloride aqueous solution and in tropical marine environment

Evaluation of the corrosion behavior of galvannealed steel in chloride aqueous solution and in tropical marine environment

Effect of Heat Treatment on Formability of Hot-dip Galvanized Low Carbon Steel Sheet

Structural and Textural Characterization of the Substrate and Coated Layer in an Industrial Galvannealed Interstitial-Free Steel

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