Additive Manufacturing: Mechanisms and Mitigation of Aqueous Corrosion and High-temperature Oxidation: Corrosion Assessment of Additively Manufactured Parts II
Program Organizers: Amir Mostafaei, Illinois Institute of Technology; Yashar Behnamian, University of Alberta; Bryan Webler, Carnegie Mellon University
Wednesday 2:00 PM
October 20, 2021
Room: A112
Location: Greater Columbus Convention Center
2:00 PM
Influence of Heat Treatment on Electrochemical Behavior of Additively Manufactured 7050 Aluminum Alloy: Rupesh Rajendran1; Kevin Chasse2; Preet Singh1; 1Georgia Institute of Technology; 2Northrop Grumman Mission Systems
The benefits of additive manufacturing process when combined with high-strength and light-weight properties, makes the 7xxx series aluminum alloys promising candidates for the aerospace industry. However, limited work exists to understand the effect of post-processing treatments like artificial ageing on their microstructure and corrosion behavior. This work aims to understand differences in microstructure and the resulting electrochemical response of additively manufactured Al 7050 alloys fabricated via Selective Laser Melting(SLM), as a result of varying ageing durations. Microstructure of differently heat-treated SLM Al 7050 alloy was characterized by optical and scanning electron microscopy. General electrochemical behavior was studied using potentiodynamic polarization and electrochemical impedance spectroscopy techniques. Equivalent wrought alloy samples were also tested under similar heat-treated conditions for comparison. The results showed that SLM alloys have less corrosion susceptibility, in general, compared with its analogous wrought 7050 alloys. The effects of underaging and overaging on the pitting behavior is also discussed.
2:30 PM
Electrochemical Behavior of Additively-manufactured Steels: Mohammad Jamalkhani1; Amir Mostafaei1; 1Illinois Institute of Technology
Compared to fusion-based additive manufacturing (AM) such as laser powder bed fusion (L-PBF), binder jet printing (BJP), aka a non-beam-based process, utilizes a powder feedstock and an inkjet printhead to shape metal powders into preforms that are then processed in a furnace to reach near-full density. Based on the AM processing, as-fabricated parts show different microstructures in which columnar grain structures with fine solidification cells are common in L-PBF steels, while fine equiaxed grains with some annealing twins are seen in BJP steels. Here, corrosion behavior of AM fabricated steels will be studied. Surface topography, porosity, surface oxide composition, and electrochemical characteristics, including pitting corrosion, dynamic polarization, and electrochemical impedance spectroscopy are investigated at room temperature in different electrolytes. Results are compared to corrosion behavior of wrought and cast steel alloys. The nature of passive film structure and its impact on the corrosion resistance of AM fabricated parts are discussed.
3:00 PM
Corrosion Behavior of Additively Manufactured Parts Made Using Non-spherical Ti-6Al-4V Powder in 3.5 wt% NaCl Solution: Sourabh Bagi1; Muktesh Paliwal2; Anthony Rollett3; Amir Mostafaei1; 1Illinois Institute of Technology; 2Kymera International - Reading Alloys; 3Carnegie Mellon University
In powder bed additive manufacturing, feedstock and processing affect final microstructure and properties of 3D-printed parts. While numerous studies have evaluated 3D-printing of spherical powder, very limited research has been carried out on the processing of the non-spherical feedstock. This study is targeted specifically to the use of non-spherical, HDH (Hydride-DeHydride), Ti-6Al-4V powders in the L-PBF process. Two different post-heat treatments including hot isostatic pressing and solution treatment are applied. The microstructures, potentiodynamic curves, and electrochemical impedance spectroscopy methods are characterized for L-PBF processed and post-treated HDH Ti-6Al-4V specimens. Though as-built part exhibit anisotropic microstructure (i.e., lamellar α + acicular α’ + β phases) and corrosion behavior compared to ASTM standard wrought Ti-6Al-4V, post processings results in homogenized grain structures and enhanced corrosion behavior. Constituent phases, grain size, and morphology directly determine the corrosion resistance of the resulting parts.
3:30 PM Break
3:50 PM
Laser Shock Peening Effect on 5xxx Sensitization and Exfoliation of 5XXX series Aluminum Alloys: Saba N. Esmaeely1; Allison Akman2; Gabriella Marino1; Jenifer Locke1; 1The Ohio State University; 2Naval Surface Warfare Center,
Laser shock peening (LSP), has been shown useful in mitigating corrosion degradation in some materials. As the laser pulse interacts with the water and opaque layer, a plasma is produced. Shock waves are generated as a result of the plasma being confined in water, which causes plastic deformation and compressive residual stresses on the alloy surface. It is generally thought that the LSP induced compressive residual stress affect the formation and growth of the passive film and local surface chemistry concentrations just below the surface to improve the corrosion resistance. In recent years, LSP research has investigated different aluminum alloys; however, the focus has revolved around improvements in corrosion resistance, fatigue life, mechanical performance, while the effect on 5xxx series sensitization remains uncertain. The current study aims at investigating how effectively LSP mitigates exfoliation and corrosion in sensitized Al-Mg Al alloys and if this effectiveness varies with product thickness.
4:20 PM
Corrosion Behavior of Laser Powder Bed Fusion Processed Ti-6Al-4V in Different Electrolytes: Melody Delpazir1; Muktesh Paliwal2; Marcella Vaicik1; Amir Mostafaei1; 1Illinois Institute of Technology; 2Kymera International - Reading Alloys
Cost-effective Ti-6Al-4V biomaterial powder with non-spherical morphology is produced by Hydride-Dehydride (HDH) method and processed by laser powder bed fusion (L-PBF) for biomedical implant purposes. It is generally recognized that corrosion behavior is negatively affected by heterogeneous microstructure and defects. Thus, it is needed to conduct a systematic study on the role of processing parameters and post processing heat treatments on microstructure, which can enhance our understanding on possible defect formation in micro and macro scale and their impact on corrosion resistance. Thus, corrosion behavior is investigated in different electrolytes (e.g., dulbecco's modified eagle medium (DMEM) and phosphate buffered saline (PBS)), coupled with optical and scanning electron microscopy observations to understand role of the material’s microstructure and phase formation (such as α, α’, β) on dissolution of alloying elements in contact with cells and physiological solutions present in tissues. Results indicate potential application of non-spherical material for fabrication of bio-implants.