Complex Boronized Layer on the Hot-dip Aluminized Steels and Its Surface Performances

摘要

Plain carbon steels were dipped in molten aluminum bath at 720℃ ± 5℃ and diffused for 1, 2.5 and 6 hours respectively and then boronized at 950℃ for 6 hours. The oxidation, hot-corrosion and abrasion resistance behavior were examined. The experimental results showed the compounds of the aluminized layer, from the surface to the matrix, were composed of Fe_2Al_5 ( η -phase ), Fe_3Al ( β_1-phase ) and α phase. The microstructure of aluminized plus complex boronized were similar to that simplex boronized. The XRD analysis results indicated that there existed Fe_2B, Fe_2AlB_2 and Fe_2Al_5 in this kind of layer. The simplex aluminized layers still remained bright gray appearance when oxidized at 950℃, but complex boronized layer was not able to resist oxidization at the temperature. Both the layers of complex boronized and aluminized had the same anti-oxidization level in the circulative oxidization tests, and also good anti-corrosion ability in molten salt medium. Under dry abrasive conditions, wear resistance of complex boronized layer was superior to the aluminized layer.