Microstructure of siliconized layer on AISI-304 stainless steel

The microstructure of siliconizing layer obtained by pack cementation on an AISI-304 stainless steel was investigated by means of field emission scanning electronic microscopy.The experimental results reveal that the thickness of the siliconized layer reaches over 60μm when siliconizing is performed at 1050℃ for 6h.The siliconized layer consists of the outer high-silicon layer and the inner α-phase diffused layer.The different morphology of spinodal-like microstructure is observed for the α-phase in the diffused layer,which becomes finer from the surface to the inner part of the layer,and changes from the crossed weaving pattern,orthogonal plates to short intersected rods.Orderly transformed microstructure is also observed in the middle of the diffused layer,and below it nanometer-sized crystalline microstructure appears.EDS results indicate that the microstructure of the pack cementation siliconizing layer is closely related to the gradient of silicon concentration.