Study Of The Materias With Corrosion Resistance To Zinc Liqiud

Steel corrosion causes huge losses to the national economy. Hot-dip galvanizing as one of the most basic protection plays an important role in reducing such losses. In recent years, hot-dip galvanizing devices have been widely used in automobile manufacturing, construction, household appliances. However, due to corrosion in liquid zinc, apparatuses useed in the Hot-dip galvanizing line (such as Zinc pot, Submerged roll, Support roll and Bearing) are often failure in work, which hinder the further development of the hot-dip galvanizing seriously.The mechanism of liquid zinc corrosion of the steel material was investigated in the first part. On this basis, by comparing the available information in literature and phase diagrams, Fe-Al-B and Fe-Al-Si alloys were choosen as candidates for liquid zinc corrosion-resistant materials.By scanning electron microscopy (SEM) attached with energy dispersive X-ray spectroscopy (EDS), the microstructures and chemical compositions of alloy matrix and corrosion interface were investigated. The corrosion rate was determined by the weight-loss measuring and the mechanical properties of the alloys with good corrosion resistance were also tested by means of micro-pressing mark.The experimental study of Fe-Al-B alloy shows that: when Al content is less than 18 wt.%, liquid zinc corrosion-resistant of Fe-Al-B alloy change with content of B. With the increase of Al content and reducing boron content, liquid zinc corrosion resistant deteriorates. When Al content is more than 18wt.%, Al content plays the key role. When Al content lies in the range of 18wt%～27wt.%, with the increase of Al content and reducing boron content, liquid zinc corrosion-resistant increases. When Al content is more than 27wt.%, with increase of Al content, liquid zinc corrosion-resistant declines instead. When Al content is more than 24wt.%, no Borides was found in the alloys. Meanwhile, the alloys, Fe-24Al-4.2B and Fe-27Al-2.8B, both with the excellent corrosion-resistance to zinc-liquid and good toughness, can be used widely in galvanizing industry. Alloy after annealing is superior to cast alloys in liquid zinc corrosion-resistant.Results of the experimental study of Fe-Al-Si shows that: when Al content is 7%-22%wt.%, Si content is 22%-41% wt.%; the microstructure is mainly composed of FeSi,(Al,Si)₂Fe₁,(Al.,Si)₃Fe₁,(Al,Si)₅Fe₁ and (Al,Si,Nd)₂Fe₁. They have no wetting to liquid zinc, but the alloys are very brittle. With increasing silicon content in the alloy, the brittleness increases. When a small amount of the rare-earth element is added to Fe-Al-Si alloy system, the microstructure of alloy is more compact and small, toughness is greatly improved and hardness is slightly higher. The developed alloy shows good corrosion-resistance in the liquid zinc, and this work provides a theoretical basis for the further development of zinc corrosion-resistant material with better toughness.