Influence of Plasma Electrolytic Polishing Conditions on Surface Roughness of Steel

Anodic polishing of St45 medium carbon steel (0.45 wt % C) and 12Cr18Ni10Ti austenitic stainless steel in aqueous electrolytes based on ammonium chloride or ammonium sulfate is studied under conditions of natural or force convection. Surface roughness, weight loss of the samples and the current resulted from polishing are measured. A possibility of plasma electrolytic polishing using a setup for the anodic thermal chemical treatment of compounds with a longitudinal electrolyte flow is shown. Polishing regimes are found to decrease the initial surface roughness of the steels from R-a = 1.0 to 0.19-0.22 mu m in 5 minutes at a sample weight loss 0.5-0.7 mg/s. The minimal surface roughness is obtained using a 3% solution of ammonium chloride at a flow rate of 0.8 L/min, voltage of 300 V, and electrolyte temperature of 80 degrees C.