| STS403 stainless steel substrate was treated by duplex treatment of chromizing and boronizing. Metallographic cross sections of the treated specimens were consisted of duplex layer, layer, Cr diffusion layer, and matrix. Microstructures of duplex layer and others layers formed on STS403 were examined by OM, SEM, EDS, XRD and surface properties of duplex layer were evaluated by micro-vickers hardness tester, wear tester and corrosion tester. From the XRD analysis of the duplex layer, various phases such as FeB, Fe₂B, CrB were identified. The results from EDS analysis showed that intermedium layer contained much more Cr than any other layers. The activation energy for the diffusion of boron in the chromium diffusion layer in the duplex treated STS403 steel was calculated to be approximately 220 kJ/mole, which was higher than the diffusional activation energy of boron in the STS403 steel, 160 kJ/mole. Microhardness of duplex layer was measured to be approximately Hv1800-2000 (50 gf). On high temperature wear testing at 600℃, duplex treated specimen exhibited an excellent wear resistance, showing that the wear volume of the duplex treated specimen was approximately five times smaller than that of untreated specimen. From the result of anodic polarization curves in 1M, H₂SO₄ solution, duplex treated specimen showed an excellent corrosion resistance than the specimen treated by boronizing only. |
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