The Efficacy of a Chelating Agent-Based Oxide Remover to Clean Corrosion Products from Ferrous Fracture Surfaces
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TECHNICAL ARTICLE—PEER-REVIEWED
The Efficacy of a Chelating Agent-Based Oxide Remover to Clean Corrosion Products from Ferrous Fracture Surfaces Aphrodite Strifas . Michael K. Budinski . Edward Komarnicki . Nancy B. McAtee . Matthew Fox . Erik Mueller . Frank Zakar
Submitted: 22 August 2019 Ó This is a U.S. government work and its text is not subject to copyright protection in the United States; however, its text may be subject to foreign copyright protection 2019
Abstract Challenges exist when cleaning fracture surfaces to reveal fractographic features without damaging the fracture surfaces further. This technical paper will compare the efficacy of cleaning ferrous-based fracture surfaces with a chelating stripping agent versus inhibited acid solutions. The chelating stripping agent used in this study was commercially available Evapo-Rust. The inhibited acid solutions used in this study were ASTM G1 C.3.1 solution and ASTM G1 C.3.5 solution. In this study, metallographically prepared samples of annealed type 8620 steel were immersed in the ASTM G1 C.3.1 solution, ASTM G1 C.3.5 solution, and Evapo-Rust for different times under inactive and ultrasonic conditions. The extent of damage to the polished surfaces was qualitatively examined using various types of optical microscopy. The sample damage was visually compared to a baseline sample etched with 2% natal. The indices used to qualify the extent of damage were the existence of pits and microstructural etching. It was found that a chelating agent-based oxide remover causes less etching and pitting on metallographically prepared annealed type 8620 steel samples than inhibited acid solutions. Keywords Corrosion Ultrasonic Steel microstructure Pitting Optical microscopy Microstructure
A. Strifas (&) M. Fox E. Mueller F. Zakar Alexandria, USA M. K. Budinski E. Komarnicki National Transportation Safety Board, Washington, DC, USA N. B. McAtee Washington, USA
Introduction Examination of metallic fracture surfaces to understand the mode of fracture is frequently an important aspect of the component failure analysis process, and the practice has been used to make significant strides in understanding the micromechanisms of fracture since the advent of electron microscopy [1]. Because fractures often occur under adverse conditions such as corrosive environments, there has always been a challenge in cleaning fracture surfaces to reveal fractographic features while avoiding further fracture surface damage. There are numerous articles on the cleaning of fracture surfaces for fractographic examination that discuss each step of the process and how to preserve surface deposits using sequential peelings of acetate tape prior to bulk removal of the adherent corrosion product layer [2–5]. The corrosion product layers on fracture surfaces can reveal much about the history of environmental exposure on the failed component. Characterizing and sequentially removing deposits on the fracture surface is one of the most critical steps in mechanical failure analysis, and
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