Effect of salt bath nitriding process on erosion corrosion resistance of C110 steel

The C110 steel was surface-modified by salt bath nitriding at 430-640 ℃ in order to improve the corrosion and wear resistance. The effect of microstructure and nitriding temperature on erosion corrosion resistance of the nitrided layer was investigated by optical microscopy(OM),X-ray diffraction(XRD),scanning electron microscopy(SEM),and micro-hardness tester. The results show that the thickness of the nitrided layer increased with increasing nitriding temperature. The nitrided layer is consist of Fe3N and little Fe4N phases after nitriding at 430 ℃,and a small amount of the loose layer(Fe3O4) occurred in the nitrided layer at 580 ℃ and the loose layer became thicker after nitriding at 640 ℃. The surface microhardness of the samples after salt bath nitriding increased by 2-3 times than that of untreated one,and the erosion-corrosion resistance is also improved. The samples nitrided at 430 ℃ have the high microhardness and good corrosion-corrosion resistance,and the loss of mass is less than one-tenth of the untreated one. The microhardness and erosion-corrosion resistance of C110 steel decrease gradually as the temperature of nitriding increasing.