Modelling of iron dissolution during hot dip galvanising of strip steel

O’Dell, Scott; Charles, J.; Vlot, Margot; Randlè, Valerie

doi:10.1179/026708304225011289

Cited by 29 publications

(26 citation statements)

References 2 publications

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“…Bélisle et al 5) proposed that the bath temperature and Al content in zinc bath must be controlled within a close range to avoid excessive formation of intermetallics since they significantly control Fe solubility in the bath. Similar trend was predicted and also measured by McDermid et al 6,7) O'Dell et al 8) have proposed that Fe dissolution in zinc bath takes place in two stages-before and after the formation of inhibition layer. They have also derived the expression for Fe concentration in the bath, and analyzed the effects of various process parameters on Fe dissolution.…”

Section: Introductionsupporting

confidence: 73%

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Effect of Steel Composition on Iron Dissolution in Molten Zinc and Development of Fe–Zn Phases on Steel Surface

Mishra

Dutta

2007

ISIJ Int.

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The effect of steel composition on iron solubility in molten zinc and coating microstructure was studied by immersing test coupons of four different steel grades in zinc bath for 20 min at 470°C. The amount of iron dissolved in the molten zinc depends upon the steel composition. The coating was characterized by energy dispersive spectroscopy, X-ray diffraction and galvanostatic methods. The coating consists of mainly z (zeta) and d (delta) phases along with zinc layer at the top, irrespective of the steel composition. The presence of a thin layer of gamma phase has also been confirmed by XRD and galvanostatic analysis. However, the proportion and distribution of the coating phases varies with the steel chemistry.KEY WORDS: iron dissolution; hot-dip galvanizing; iron zinc alloys. ExperimentalThe iron dissolution and galvanizing experiments were carried out in an alumina crucible. Four different steel compositions (namely S 1 , S 2 , S 3 and S 4 ) were selected so that the effect of different interstitial and substitutional alloying elements like C, Si, P etc. could be examined. The details of cold rolled and annealed steel strips used in the experiments are listed in Table 1.Commercially pure zinc (800 g. of 99.99 % purity) was melted in the alumina crucible and held at 470°C for 15 min prior to each experiment to avoid any thermal gradient within the bath. Small test coupons (45ϫ40 mm 2 ) of 1 mm thick steel strips were pickled in hot HCl (15 %) for about 1 min and immediately dipped in the molten zinc for 20 min. The liquid zinc bath was stirred by the immersed sample after every 5 min (i.e. after 5, 10 and 15 min). For the entire experiment, the liquid zinc was maintained at 470°C (Ϯ5°C) in a closed chamber furnace. The dipping time was decided based on the iron saturation limit in zinc and the time required to attain that. The saturation limit of iron in molten zinc can be calculated from the following equation where [Fe] is in wt% and T is in Kelvin.The saturation limit comes to be 0.053 wt% at 470°C. The time required for saturation of molten zinc is in hours.5) The dipping time was therefore chosen such that significant iron dissolution takes place without attaining saturation in order to reveal the effects of different steel compositions. At the end of dipping i.e. after 20 min, the zinc bath was again stirred, the top dross was removed and steel test coupon was taken out of the bath quickly and air cooled. The molten zinc was cast in a sand mould. Chemical analysis of the cast zinc was carried out. This analysis has given the amount of Fe dissolved during 20 min of dipping in the molten zinc for each sample, which has been discussed in Sec. 3.1. A mixture consisting of 1 % picric acid in amyl alcohol and 1% nitric acid in amyl alcohol was used as the etchant. The micro structural and energy dispersive spectroscopy (EDS) characterization of the transverse section was carried out under scanning electron microscope (SEM) for coated samples to examine the elemental distribution across the coating. The coati...

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Section: Introductionsupporting

confidence: 73%

“…In this study, an attempt has been made to examine the effect of steel composition on iron dissolution in liquid zinc and further development of coating phases. Since iron dissolution drastically reduces with the formation of an inhibition layer, 8) no aluminum was added in the zinc bath in this study.…”

Section: Introductionmentioning

confidence: 99%

Effect of Steel Composition on Iron Dissolution in Molten Zinc and Development of Fe–Zn Phases on Steel Surface

Mishra

Dutta

2007

ISIJ Int.

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“…Disc (hereafter referred to as a counter body) of 100 mm in diameter and 10 mm thick was made of nodular grey cast iron. This material was chosen as a standard piston ring material with specification according to the ISO standard (Subclass Code MC 53) [24] and hardness of 220 HV 10 . Schematic drawing of load, pin, counter body and direction of the rotation is shown in Fig.…”

Section: Methods Of Characterizationmentioning

confidence: 99%

“…The addition of reinforcements improves the critical transition values of applied load and wear resistance compared with corresponding matrix alloy, and this improvement is achieved with the addition of up to *20 vol.% of reinforcement [10,16,17]. However, increase of the volume fraction can also provoke clustering of the particles during fabrication of the composite [17].…”

Section: Introductionmentioning

confidence: 91%

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Microstructural and Tribological Properties of A356 Al–Si Alloy Reinforced with Al2O3 Particles

et al. 2008

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In the present study, the effect of the Al 2 O 3 particles (average size of 12 lm, 3 and 10 wt.%) reinforcement on the microstructure and tribological properties of Al-Si alloy (A356) was investigated. Composites were produced by applying compocasting process. Tribological properties of unreinforced alloy and composites were studied, using pin-on-disc tribometer, under dry sliding conditions at different specific loads and sliding speed of 1 m/s. Microhardness measurements, optical microscope and scanning electron microscope were used for microstructural characterization and investigation of worn surfaces and wear debris. During compocasting of A356 alloy, a transformation from a typical dendritic primary a phase to a non-dendritic rosette-like structure occurred. Composites exhibited better wear resistance compared with unreinforced alloy. Presence of 3 wt.% Al 2 O 3 particles in the composite material affected the wear resistance only at specific loads up to 1 MPa. The wear rate of composite with 10 wt.% Al 2 O 3 particles was nearly two order of the magnitude lower than the wear rate of the matrix alloy. Dominant wear mechanism for all materials was adhesion, with others mechanisms: oxidation, abrasion and delamination as minor ones.

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Kinetics of low-temperature pack aluminide coating formation on alloy steels

Xiang

Datta

2006

Metall Mater Trans A

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Modelling of iron dissolution during hot dip galvanising of strip steel

Cited by 29 publications

References 2 publications

Effect of Steel Composition on Iron Dissolution in Molten Zinc and Development of Fe–Zn Phases on Steel Surface

Effect of Steel Composition on Iron Dissolution in Molten Zinc and Development of Fe–Zn Phases on Steel Surface

Microstructural and Tribological Properties of A356 Al–Si Alloy Reinforced with Al2O3 Particles

Kinetics of low-temperature pack aluminide coating formation on alloy steels

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