Abstract: Through adding a certain amount of rare earth SmCl₃ to the aluminium infiltrant and using low temperature powder-embedded aluminizing method, the P92 steel was aluminized at different temperatures and time. The morphology of the aluminized layer was observed by using OM and SEM, the element distribution in cross-section and phase structure of the aluminized layer were analyzed by means of EDS and XRD, respectively, and the microhardness of the aluminized layer was measured by microhardness tester. The results show that after aluminizing at 550 ℃ for 6, 8, 10 h, respectively, no aluminizing layer is found on the surface of the P92 steel. After aluminizing at 750 ℃ for 10 h, the aluminized layer has defects like being loose and porous, whereas the quality of the aluminized layer is better at 650 ℃, with no shrinking pore cracks or other defects. After aluminizing at 650 ℃ for 6, 8, 10 h, respectively, the average thicknesses of the aluminizing layers are 27, 30, 31 μm, respectively. The hardness of the aluminized layer is approximately 260 HV0.025 higher than the average hardness of the P92 steel substrate. After aluminizing at 650 ℃, the surface phase of the P92 steel is AlFe₃ and AlCrFe₂, and after aluminizing at 750 ℃, it is AlFe.

Key words: P92 steel, rare earth SmCl₃, aluminizing process