ALUMINIZING OF STEEL SHEETS
MOHAMED ABD EL-RAHMAN SHADY;
Abstract
Hot-dip aluminizing is a simple process in which an aluminium coating is formed by dipping the substrate metal in a bath of molten aluminium. The process, on a continuous basis, is most economical for the production of coated sheet, wire, and strip, as well as for fabricated products made from steel or cast iron.
In this work, aluminizing of low carbon steel sheets (0.19 C) was achieved by dipping into different melt baths: AI, AI- 4%Si, -8%Si and -12%Si held at two superheat temperatures (50 and 100•C) for different periods of times (from 1 to 5 min).
The aluminized layer is normaly composed of an outer layer (aluminium layer) followed by a layer of Fe - AI intermetallic compounds with continuously decreasing aluminium content until the parent steel is reached. It was observed that the intermetallic layer thickness decreases with the addition of silicon to the aluminium bath. Also, it increases with the increase of bath temperature especially in aluminium bath. This increase is much less in case of aluminium - silicon baths. The dipping time has an effect similar to that of bath temperature. The aluminium top-coat layer, in general, decreases continuously with increasing bath temperature.
The thickness of the intermetallic layer formed during hot - dip aluminizing was found to follow the parabolic kinetic relationschip, indicating that the reaction is controlled by volume diffusion.
The dissolution of intermetallic layer was studied in case of aluminium and aluminium containing 8%Si baths. The dissolution rate was higher in the case of AI - 8%Si bath. The weight loss from the steel sheet into aluminium and AI - 8%Si baths revealed that it is larger in the case of aluminium bath compared with AI - 8%Si bath.
The intermetallic layer was analyzed by EDS analyzer. In the case of using molten aluminium bath, it consists of two zones - a thin zone of fine-crystalline FeAI3 (e phase) adjoining the aluminium layer and a thick zone of acicular crystals Fe2AI5 (TJ phase). The major phase was Fe2AI5. On the other hand, the phases formed on iron
In this work, aluminizing of low carbon steel sheets (0.19 C) was achieved by dipping into different melt baths: AI, AI- 4%Si, -8%Si and -12%Si held at two superheat temperatures (50 and 100•C) for different periods of times (from 1 to 5 min).
The aluminized layer is normaly composed of an outer layer (aluminium layer) followed by a layer of Fe - AI intermetallic compounds with continuously decreasing aluminium content until the parent steel is reached. It was observed that the intermetallic layer thickness decreases with the addition of silicon to the aluminium bath. Also, it increases with the increase of bath temperature especially in aluminium bath. This increase is much less in case of aluminium - silicon baths. The dipping time has an effect similar to that of bath temperature. The aluminium top-coat layer, in general, decreases continuously with increasing bath temperature.
The thickness of the intermetallic layer formed during hot - dip aluminizing was found to follow the parabolic kinetic relationschip, indicating that the reaction is controlled by volume diffusion.
The dissolution of intermetallic layer was studied in case of aluminium and aluminium containing 8%Si baths. The dissolution rate was higher in the case of AI - 8%Si bath. The weight loss from the steel sheet into aluminium and AI - 8%Si baths revealed that it is larger in the case of aluminium bath compared with AI - 8%Si bath.
The intermetallic layer was analyzed by EDS analyzer. In the case of using molten aluminium bath, it consists of two zones - a thin zone of fine-crystalline FeAI3 (e phase) adjoining the aluminium layer and a thick zone of acicular crystals Fe2AI5 (TJ phase). The major phase was Fe2AI5. On the other hand, the phases formed on iron
Other data
| Title | ALUMINIZING OF STEEL SHEETS | Other Titles | " تغطية ألواح الصلب بالألومنيوم “ | Authors | MOHAMED ABD EL-RAHMAN SHADY | Issue Date | 1995 |
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