Steel Surface Modification by Cathodic Carburizing and Anodic Polishing under Conditions of Electrolytic Plasma

Abstract

Low-carbon steel (Type 20) is subjected to cathodic carburizing followed by quenching and anodic plasma electrolytic polishing. The structure of the surface layer and its elemental composition are established, and the microhardness distribution within the surface layer, as well as its surface roughness, are measured. The microhardness of the surface layer exceeds 900 HV after carburizing at 900°C for 20 min in a solution containing ammonium chloride and glycerol. It is established that an increase in the surface roughness Ra to 9 μm after cathodic carburizing is related to the formation and destruction of an outer oxide layer. It is shown that the surface roughness can be reduced to 3.5 μm by anodic polishing in a 3% solution of ammonium chloride for 180 s.