Duplex Surface Treatment of Pre-Electroplating and Pulsed Nanocrystalline Plasma Electrolytic Carbonitriding of Mild Steel

Recently, new duplex surface treatments involving the use of pre-electroplating and pulsed plasma electrolytic nitrocarburizing (PPEN/C) have led to the possibility of using this material for applications usually typical for tool steels. In this work, we present results concerning the duplex treatment of pre-electroplating of Cr and PPEN/C of AISI 1020 mild steel. The samples were electroplated in a plating bath. After electroplating, the samples were nitrocarburized. The effects of time and applied voltage of PPEN/C process were discussed. The samples were characterized using scanning electron microscopy (SEM), atomic force microscopy (AFM), and microhardness testing. Electroplated layers of up to 100 μm were obtained. The subsequent PPEN/C increased the surface hardness to 1200 HV_0.2 due to the formation of nitrides and carbides. Decreasing the size of nanocrystalline carbonitrides will lead to improvement of their wear resistance significantly.