Research On Effects Of Alloying Elements On Properties Of The Iron Base Corrosion Resisting Alloys

Hot-dip galvanizing is widely used as one of the most important methods for resisting corrosion in metal products. Due to the formidable working condition, excellent corrosion resistance to molten zinc and mechanical behavior under high temperature is required to the outer shell of internal heater used in ceramic zinc pot. At the present time, the application and generalization has been restricted for no appropriate anti-corrosion materials. In this article, effects of elements to the properties of Fe-B alloys have been studied.Based on the Fe-2.5B alloy, the elements C, Cr, Si, Mn and Nb were added. In this paper, orthogonal experimental design was used to design the component of the alloy, through fusion metallurgy, corrosion test in molten zinc and mechanical property test, the effect of alloying agents on the structure and properties was studied, and finally the optimum agents component was obtained. The microstructure, fractograph and corrosion interface were observed and analyzed by SEM, XRD and test of mechanical properties.Result showed that phase Fe2B was replaced by phase Fe3(C, B) with carbon addition, the structure of the alloy was refined, the eutectic structure became acerose and tortuous. The corrosion resistance was improved. With the increase of carbon addition, the corrosion rate and bend strength of the alloy decrease, and the hardness increase. The microcracking of Fe2B phase was inhibited with Cr element addition which improved the brittleness of the Fe-B base alloy. With the silicon addition, corrosion rate decreased but the brittleness increased.Direct-vision method was used in orthogonal experiment which indicated that carbon was the key elements. After majorization the corrosion rate was 1.0×10-3mm/h which was the maximum. A transition layer which was about 500μm was obtained in the corrosion interface. It is this transition layer that reduced the impelling of the molten zinc, therefore the corrosion resistance was improved and the shape of the sample was maintained.The corrosion behavior ofαphase and intermetallic compounds in the majorized alloy in molten zinc were different. The corrosion mechanism was changed with elements addition. Diffusion and dissolution was the main form which substituted the fracture and deviation dispersion of the intermetallic compounds. The change of the intermetallic compounds improved the transition layer. Diffusion through a corrosion transition layer is controlling the dissolution reaction.