Magnesium Technology 2024: Corrosion and Coatings
Sponsored by: TMS Light Metals Division, TMS: Magnesium Committee
Program Organizers: Aeriel Murphy-Leonard, Ohio State University; Steven Barela, Terves, Inc; Neale Neelameggham, IND LLC; Victoria Miller, University of Florida; Domonkos Tolnai, Institute of Metallic Biomaterials, Helmholtz-Zentrum Hereon
Monday 8:30 AM
March 4, 2024
Room: Windermere Y-3
Location: Hyatt
Session Chair: Aeriel Leonard, The Ohio State University; Domonkos Tolnai, Helmholtz-Zentrum Hereon
8:30 AM Introductory Comments
8:50 AM Keynote
Different Analytical Methods to Determine the Influence of Pitting on the Residual Performance of Mg Alloys as Implant Materials: Petra Maier1; 1University of Applied Sciences Stralsund
Mg-alloys are prone to pitting due to their non-uniform protective corrosion layers, which can lead to an increase in stress intensity based on the notch effect, pit-to-crack transition and thus premature failure. A small set of analytical methods to determine the extent of pitting and its effect on the resulting residual strength is presented. Micrographs, 3D-microscopy or 3D-analysis using CT are used to determine the amount and geometry of pitting - each with advantages and disadvantages. The influence of the corrosion pits on the mechanical properties is tested by static, quasi-static and cyclic test methods: by tensile, flexural or fatigue testing - either after corrosion or overlapping. Knowledge about the critical pit is of general interest. Stress corrosion is discussed by applying static tests like C-ring testing, which also plays a role in slow strain rate tensile tests and stress corrosion cracking is more or less influenced by corrosion pits.
9:30 AM
Dissolution Rate Change of Dissolving Magnesium in a Deoxygenated Environment: Timothy Dunne1; Lei Zhao1; Jiaxiang Ren1; Peng Cheng1; Yu Liu1; 1CNPC USA Corp
Dissolvable magnesium in frac plugs must maintain integrity for the duration of the operation and dissolve fully thereafter. Lab generated dissolution estimates are often much shorter than what is measured in the field. This study compared standard water bath corrosion testing to autoclaves with and without a nitrogen purge at 95°C 1 wt% KCl. The water bath test dissolution rate fell within the range of the unpurged autoclave. There was a substantial decrease in the dissolution rate of the autoclave where the nitrogen was used for purging entrapped air. The reduced dissolution rate of the material in the purged autoclave appears to be representative of the deoxygenated downhole environment. The possible reasons of the dissolution rate reduction of magnesium in the deoxygenated environment will be explained and modelled in the paper. The study will demonstrate to industry that testing needs re-envisioned and faster dissolving materials used in field.
9:50 AM
Improved Formability and Corrosion Resistance of Pure Magnesium by Parts-per-million-level Addition of Copper and Calcium: Mingzhe Bian1; Isao Nakatsugawa1; Xinsheng Huang1; Yasumasa Chino1; 1National Institute of Advanced Industrial Science and Technology
Poor cold formability, poor corrosion resistance and high cost of alloying elements are longstanding barriers to the widespread use of Mg. In this talk, we report that both the room-temperature (RT) stretch formability and corrosion resistance of the commercially used pure Mg could be significantly improved by adding trace amounts of Cu and Ca. The significant enhancement in the RT stretch formability is associated with the weakened basal texture and refined microstructure, whereas the substantial improvement in the corrosion resistance is related to the strong Fe-removal ability induced mainly by Ca addition and formation of a protective surface film enriched with Cu and Ca. Owing to the trace amounts of the alloying elements, the resultant alloy also showed excellent thermal conductivity, which was almost two times higher than that of the most commonly used Mg alloy (AZ31). These findings are expected to stimulate the development of high-performance Mg alloys.
10:10 AM Break
10:30 AM Invited
Evaluation of Corrosion Performance of Friction Stir Processed Magnesium Alloys Using Multimodal Analysis Across Length Scales: Sridhar Niverty1; Shuai Tan1; Venkateshkumar Prabhakaran1; Piyush Upadhyay1; Hrishikesh Das1; Rajib Kalsar1; David Garcia1; Mageshwari Komarasamy1; Glenn Grant1; Darrell Herling1; Vineet Joshi1; 1PNNL
Friction Stir Processing (FSP) homogenizes and refines the microstructure through severe plastic deformation. Previous studies have demonstrated that the processed zone is more corrosion resistant as compared to the base Mg alloy. However, the corrosion behavior of the microstructure immediately adjacent to the processed zone, and how it affects the base material under corrosive environments has received little attention. In this study, we have used a multimodal corrosion measurement system to investigate the corrosion behavior of the surface and cross-section of FSP AZ31 and AZ91 Mg alloy plates by imaging the sample, acquiring electrochemical data, and collecting evolved hydrogen. Additionally, Scanning Electrochemical Cell Microscopy (SECCM) was employed to study variation in localized corrosion behavior from the base metal into the stir zone from the advancing and retreating sides. Microscopy was employed to identify the microstructural cause for the enhanced susceptibility to corrosion in the heat affected zone and base material.
10:55 AM
Corrosion Rates by Immersion and Calorimetry on the Example of Extruded Mg10Gd(1Nd)1La: Petra Maier1; Benjamin Clausius1; Thea-Simone Tegtmeier1; Lars Wadsö2; Dmytro Orlov2; 1University of Applied Sciences Stralsund; 2Lund University
This study is a follow-up investigation of the influence of the alloying elements Nd and La on the corrosion by immersion of an extruded and heat-treated Mg10Gd. The previous study made clear that the age-hardened condition has the lowest corrosion rate but high pitting corrosion susceptibility. The extruded Mg10Gd(1Nd)1La shows the lowest pitting factors based on severe corrosion. In this study, the corrosion morphology and corrosion rates are discussed based on calorimetric data and 3D-analysis by µCT and compared to the results from the immersion tests. Thermal power and enthalpy readings from the isothermal calorimetry offer information on the reaction kinetics. The corrosion rate values are discussed based on the evaluation method – in general agreement alloying with Nd reduces the corrosion rate. The pitting factor is found to be very dependent on the reference average penetration: weight or volume loss, or evaluation by 3D volume or by 2D cross-sections.