High-Rate Pulsed Galvanostatic Anodic Dissolution of Chromium−Nickel Steels in Electrolytes for Electrochemical Machining: The Role of Surface Temperature

Abstract

A pulsed galvanostatic anodic dissolution of chromium−nickel steels (types Kh18N10 (Cr18Ni10) and KhN35VT (CrNi35WT)) under the conditions of electrochemical machining is studied in chloride, nitrate, and mixed chloride−nitrate electrolytes at current densities up to 100 A/cm2. In all the considered solutions (except for the dissolution of CrNi35WT in chloride solutions), for relative pulse durations s ≥ 2 (duty cycle D ≤ 50%), the faradaic rate of dissolution reaches a limiting value of ~0.18 mg/C, irrespective of pulse duration (from 20 μs to 2 ms), which translates into the current efficiencies of alloy dissolution of 50 and 68% for the Cr18Ni10 and CrNi35WT alloys, respectively. Using direct current for processing (i.e., s < 2) boosts the current efficiency, and the rise in surface temperature is crucial to this effect.