Diffusion Coefficient in the Zinc Coating Shaped on the Surface of Cast Iron and Steel Alloys

Abstract

The article presents the method to assess the diffusion coefficient D in the sub-layer of intermetallic phases formed during hot-dip galvanizing “Armco” iron and ductile cast iron EN-GJS-500-7. Hot-dip galvanizing is one of the most popular forms of long-term protection of Fe-C alloys against corrosion. The process for producing a protective layer of sufficient quality is closely related to diffusion of atoms of zinc and iron. The simulation consist in performed a hot-dip galvanizing in laboratory condition above Fe-C alloys, in the Department of Engineering of Cast Alloys and Composites. Galvanizing time ranged from 15 to 300 seconds. Then metallographic specimens were prepared, intermetallic layers were measured and diffusion coefficient (D) were calculated. It was found that the diffusion coefficient obtained during hot-dip galvanizing “Armco” iron and zinc is about two orders of magnitude less than the coefficient obtained on ductile cast iron EN-GJS-500-7.

High-Temperature Behaviour of Zn-Based Galvannealed Coatings on Steel

“…Gogola et al [18] reported more specifically on the phase evaluation of galvanised coatings on a high-carbon steel with the emphasis on the coating morphology. It was interesting to find a hot-dip coating microstructure with similar features between a high-carbon steel [18] and ductile iron castings with over 3.0 wt.% of C [19,20]. However, none of the studied literature sources investigated the behaviour of Zn-based coatings on medium-to-highcarbon steels after exposure to over 600 • C.…”

Abrasion Wear Resistance of Ni - Mo Alloyed High-Chromium Cast Iron

“…Nearly all high-chromium cast iron utilized commonly in the abrasive wear conditions are the hypoeutectic alloys with the content of 10 -30% Cr and 2 -3.5% C. Their wear resistance and mechanical properties depend on the type, morphology, and volume fraction of carbides in the structure and on the matrix characteristics within which they are embedded [1,2,3,4]. The increase in the carbon and chromium contents increases the amount of the carbides, and therefore, the wear resistance improves, while toughness and the fracture resistance of castings' material are decreased.…”

“…The methods to achieve the fracture resistance can be different and, unless they are not mutually exclusive, they can be combined. The researches have indicated that to use these irons more extensively there is desired to focus on the effect of microalloying and inoculation of molten metal [1,3], possibility to modify the service properties of material using a heat treatment [1,2], and the method of hardening of the iron's matrix under the local plastic strain [1,5].…”

“…Therefore, they are finer, and irons are not so brittle. Another alternative for refining a carbide phase can be the microalloying by boron which is functioning as an inoculant during the primary crystallization [2,7]. It reduces the carbon solubility in austenite and increases the amount of the crystallization nuclei to arise the finer carbides both in as-cast state and heat treated structure.…”