The formation of a boronised layer on aluminised steel and surface corrosion behaviours

摘要

Boron-aluminised layers were formed on plain carbon steels Q235 (1020), 45 (1045), and alloyed steel GCrl5 (E52100) by dipping them in a molten aluminium bath at 720℃ and then diffused plus boronised at 950℃ for six hours. The microstructures of the layers were then studied with an optical microscope, SEM, and XRD and the oxidation, hot-corrosion, and abrasion resistance behviours were examined. The microstructures of the boronised layer on aluminised steel were similar to the simplex boronised steels. The XRD analysis results indicated that there existed Fe_2B, Fe_2AlB_2 and Fe_2Al_5 in the layer. The results of the high temperature oxidation showed that the aluminium hot-dipped layers had good oxidation-resisting abilities at 950℃, but the complex boronised layer was not able to resist at the same temperature. The cyclic oxidization tests showed that both layers had the same anti-oxidization levels at 650℃, and were superior to the untreated steels; they also presented good anti-corrosion ability in salt-coated oxidization tests. Under dry abrasive conditions, wear resistance of the complex boronised layer was superior to the aluminium hot-dipped layer.