Electrochemical Dissolution Behavior of Nickel-Based Hastelloy X Superalloy at Low Current Densities

Abstract

Electrochemical machining (ECM) is a proven processing technique for fabricating difficultto-cut nickel-based superalloys with complex shapes using the principle of anodic dissolution. However, the metallic surface is susceptible to stray corrosion under conditions of low current density, which increases the difficulty of using ECM on nickel-based superalloy such as Hastelloy X (HX). In this study the electrochemical dissolution behavior of wrought HX at low current density was systematically analyzed. The results revealed that M 23 C 6 carbides were irregularly distributed on the grain boundaries. The polarization curves and open-circuit potential measurements showed that an appropriate temperature (35 • C) and concentration (10 wt.%) aided in the formation of efficient and stable dissolution in NaNO 3 solution. The findings also revealed that selective corrosion occurred preferentially on the grain boundary or near the M 23 C 6 precipitations after passivation film polarization. After careful investigation of the different-stage dissolution microstructures and the solid black block-shape products, M 23 C 6 precipitation was found to play a key role in the dissolution of HX alloy at low current density. A qualitative model was established to demonstrate the electrochemical dissolution behavior of wrought HX alloy in NaNO 3 solution. This model offers a new insight into the suppression of stray corrosion of Ni-based superalloys in aerospace applications.

Optimization of process parameters in micro electrochemical machining using TOPSIS technique with Analytical Hierarchy Process (AHP)

“…It is critical to machine hard, composite, ceramic, and complicated materials without changing their surface topography in production features. According to the literature research, among the numerous nontraditional milling processes, the micro-electrochemical machining process plays a significant role in machining Hastelloy C-276 [1,2]. It is a very accurate machining process that can perform machining on any type of conductive workpiece [3].…”

Modeling and Prediction of Water-Jet-Guided Laser Cutting Depth for Inconel 718 Material Using Response Surface Methodology

“…Moreover, in a high-temperature environment, the material has a chemical reaction tendency caused by the cutting force, and the surface finish after processing is poor [ 4 ]. At present, some traditional non-contact processing methods are used to process Inconel 718, such as electric discharge machining (EDM), electrochemical machining (ECM), and laser beam machining (LBM), which can bring high machining efficiency at a reasonable cost [ 5 , 6 , 7 ].…”

Transient simulation of electrochemical machining processes for manufacturing of surface structures in high‐strength materials

“…As ECM bypasses these limitations, its implementation for the machining of nickel‐based alloys has been studied extensively in the past. Their dissolution characteristics have been described over a wide range of current densities 8,9 . This data have been applied for the design of both shaping 10 and finishing 11 processes of Inconel parts.…”

“…Their dissolution characteristics have been described over a wide range of current densities. 8,9 This data have been applied for the design of both shaping 10 and finishing 11 processes of Inconel parts.…”