Environmentally Assisted Cracking: Theory and Practice: On-Demand Oral Presentations
Sponsored by: TMS Structural Materials Division, TMS: Corrosion and Environmental Effects Committee
Program Organizers: Bai Cui, University of Nebraska Lincoln; Raul Rebak, GE Global Research; Srujan Rokkam, Advanced Cooling Technologies, Inc.; Jenifer Locke, Ohio State University
Monday 8:00 AM
March 14, 2022
Room: Corrosion
Location: On-Demand Room
Multiscale Modeling of Fatigue Crack Growth and Environmental Effects: Ting Zhu1; 1Georgia Institute of Technology
Hydrogen embrittlement of metallic materials is widely observed, but remains a challenge for predictive computational modeling. This talk is focused on an ongoing effort toward the multiscale modeling of hydrogen-mediated fatigue crack growth in austenitic stainless steel. An interatomic potential of the Fe-Ni-Cr-H alloy system was developed to enable the atomistic simulations of hydrogen and dislocation interactions in stainless steel. A cyclic crystal plasticity model was formulated with guidance from the atomistic reaction pathway modeling of dislocation mobility. Our crystal plasticity finite element simulations revealed the effect of crystal-level plastic deformation on fatigue crack growth. Further challenges and opportunities on predictive multiscale modeling of hydrogen embrittlement will be discussed.
Recent Progress on Modeling Corrosion Damage with Peridynamics: Florin Bobaru1; 1University of Nebraska-Lincoln
Peridynamics uses an integral approach for representing damage and other discontinuous phenomena, including the autonomous evolution of interfaces in corrosion problems. This type of computational modeling has shown surprisingly accurate simulations of physical realities like dynamic brittle fracture, impact fragmentation, pitting corrosion, SCC. In this talk will give an account on recent progress of peridynamic modeling of corrosion processes and corrosion-induced damage, and their validation against experimental results ([1-2]). Examples include: pitting corrosion and lacy covers, pit merger, crevice corrosion, galvanic corrosion, corrosion in polycrystals, stress-dependent corrosion, and coupled corrosion-fracture. I will also discuss some recent results on fast convolution-based methods for efficiently computing peridynamic models with hundreds/thousands of pits. References [1] S. Jafarzadeh, Z. Chen, and F. Bobaru, (2019). Computational modeling of pitting corrosion. Corrosion Reviews 37(5), 419-439.[2] Z. Chen, S. Jafarzadeh, J. Zhao, F. Bobaru, (2021). Journal of the Mechanics and Physics of Solids 146, 104203.
Environmentally Assisted Cracking Research for Current and Advanced Nuclear Structural Materials: Rongjie Song1; Michael McMurtrey1; Boopathy Kombaiah1; Drew Johnson1; Michael Heighes1; Peng Xu1; Colin Judge1; 1Idaho National Laboratory
Understanding environmentally assisted cracking is an important aspect of nuclear materials research, as it provides information about failure mechanisms that lead to safety concerns or shutdowns. Idaho National Laboratory has ongoing research to understand how materials behave in the harsh nuclear environments for both the current fleet of light water reactors, as well as advanced reactors, where materials are exposed to more extreme environments. Corrosion and cracking of current materials, advanced materials, and materials formed through advanced manufacturing techniques are being examined, with particular interest in irradiation effects on corrosion and cracking, as well as the effects of environmental impurities. Testing, such as stress corrosion cracking, corrosion fatigue, and in-situ crack growth measurements, as well as a suite of characterization tools, including electron microscopy techniques and x-ray computed tomography, are being utilized to better understand the material response, limitations, and cracking mechanisms to ensure safe and reliable nuclear plants.
Stress Corrosion Cracking Behavior of Mg-Al-Zn Alloys in Humid Air: Toshiaki Manaka1; 1National Institute of Technology(KOSEN), Niihama College)
Magnesium alloys have been known to be susceptible to stress corrosion cracking(SCC), which is based on hydrogen embrittlement. In the present study, the SCC behavior of Mg-Al-Zn alloys with different amounts of Al was investigated by slow strain rate tensile testing at room temperature in two environments: humid air(HA) with relative humidity of 90% or above and dry nitrogen gas (DNG) atmosphere with relative humidity of 5% or less. The elongation of the specimens in HA was smaller than that in DNG. SEM observation revealed that fracture surfaces were covered with fine dimples in DNG, while quasi-cleavage fracture without corrosion product was observed near the specimen surface in HA. It is assumed that hydrogen atoms invaded into the specimen by reaction between water vapor and magnesium surface, and caused the degradation of ductility, resulting in hydrogen embrittlement.
Cold Spray Process to Combat Potential Stress Corrosion Cracking in Used Nuclear Fuel Storage Stainless Steel Canisters: Nicholas Pocquette1; Hwasung Yeom1; Hemant Agiwal1; William Bowman1; Kenneth Ross2; John Kessler3; Gary Cannell4; Frank Pfefferkorn1; Kumar Sridharan1; 1University of Wisconsin-Madison; 2Pacific Northwest National Laboratory; 3J Kessler and Associates; 4Fluor Corporation
Cold Spray technology has been investigated as a method for the repair and mitigation of chloride induced stress corrosion cracking (CISCC) in 304L and 316L stainless steel canisters used to store spent nuclear fuel in dry cask storage systems (DCSS). The cold spray process is powder-based, solid-state method for producing high-density coatings and deposits. The compressive residual stresses and fine grain structure of the coatings is expected to mitigate the initiation and growth of CISCC. The substrates in this study were 304L and 316L and coating materials were 304L, 316L and nickel. The cold spray coatings were deposited on flat and curved geometry samples. The CISCC mechanism in the cold spray deposits were examined using the boiling MgCl2 tests and compared to that of the uncoated samples. Electrochemical corrosion studies were conducted to characterize pitting behavior and stability of the surface passivation layer, phenomena that contribute to initiation of CISCC.
Mitigation of Stress Corrosion Cracking in Al-Mg via Laser Shock Peening: Eric Dau1; Matthew McMahon1; 1Naval Surface Warfare Center, Carderock Division
Al-Mg alloys such as AA5083 and AA5456 continue to be utilized in marine construction due to their good weldability and high strength-to-weight ratio. However, sensitization continues to be a challenge at intermediate temperatures due to the high corrosivity of the intergranular β phase, which enables stress corrosion cracking (SCC) and promotes premature failure in service. Previous work demonstrated that laser shock peening (LSP) is a promising residual stress impingement technique that has the ability to mitigate SCC by reducing the effective stress. The present work seeks to further understand the mechanism through which LSP mitigates through-thickness SCC when the compressive residual stress layer only partially penetrates through the material thickness. The incidence of crack tunneling will be evaluated in detail due to the deleterious impact this phenomenon would have on thin aluminum sheet. This evaluation will elucidate the strengths and weaknesses of LSP for SCC mitigation in aggressive seawater exposure.
Capturing the Effect of Environment and Electrochemistry on Crack Growth of Metals and Alloys Using Density Functional Theory: Christopher Taylor1; 1DNV
Predicting the effect of variations in environmental conditions, such as temperature, pH, electrochemical potential and chloride concentration, among others, on static and/or dynamic crack growth rates of alloys is extremely challenging due to the complexity of the processes occurring at the interface and the near-surface regions of both the environment and material that contribute to changes in crack growth rate. Using density functional theory, we can probe the nature of hypothetical intermediates and transition states that are significant to processes like proton or water reduction, oxygen reduction, hydrogen adsorption/absorption, and oxide formation. An approach based on an underlying database of DFT calculations on reference alloy systems was developed to predict the dominant surface chemical processes on a freshly exposed crack surface, as a function of near-surface environment. The findings of this approach applied to a range of materials will be presented.
New Insights into the Impact of Hydrogen on Monotonic/Cyclic Plasticity in Nickel Single Crystal Based on Nanoindentation Investigation: Siva Prasad Murugan1; Abdelali Oudriss1; Guillaume Hachet1; Xavier Feaugas1; 1La Rochelle University
The impact of hydrogen on the monotonic and cyclic plasticity of <001> oriented nickel single crystal was investigated using nanoindentation. Static and dynamic nanoindentations were performed on undeformed and pre-strained samples with and without hydrogen. The indented surfaces were analyzed by SEM-FIB, EBSD, and TEM to characterize the development of dislocation structures and any other defects and hence to establish the hydrogen-plasticity correlation near the surface. Hydrogen-induced impacts on maximum shear stress to activate dislocations, hardness, and elastic modulus were observed in the static nanoindentation experiment. The long-range internal stresses developed in the hydrogen charged samples during the dynamic nanoindentation were compared to the results of TEM (dislocation density) and cyclic micro-tensile test (effective and back stresses). A competition between cyclic hardening/softening was observed with and without hydrogen, attributed to the hydrogen-induced differences in the development of dislocation structures and subsequent internal stresses.
Ab Initio Study of Hydrogen Embrittlement in Binary Nickel Alloys: Aman Prasad1; Ranim Mohamad1; Frédéric Christien2; Franck Tancret1; Isabelle Braems1; 1Université de Nantes, Institut des Matériaux de Nantes – Jean Rouxel (IMN), CNRS UMR 6502, 2 rue de la Houssinière, BP 32229, 44322 Nantes Cedex 3, France; 2Mines Saint-Etienne, Univ Lyon, CNRS, UMR 5307 LGF, Centre SMS, F - 42023 Saint-Etienne France
In presence of hydrogen nickel alloys undergo a ductile-to-brittle transition. A novel nano inverse hydrogen-enhanced decohesion (HEDE) mechanism which takes into account both the influence of hydrogen on cohesion and dislocation emission proposes that for pure Ni this transition occurs in presence of H due to lowering of the stress intensity factor for cleavage (KIc) below the stress intensity factor for ductile dislocation emission and crack blunting (KIe) [Tehranchi et. al. (2020)]. The approach is here extended to binary nickel alloys (with V, Mo, Co, Nb, Ti, W, Fe, Cr) to investigate the influence of alloying elements on HEDE and, in future, to design alloys with reduced hydrogen embrittlement. First-principles calculations were performed to calculate KIe and KIc as a function of solute concentration. Further the critical concentration of H required for each alloy to undergo a ductile-to-brittle transition is calculated and described as a function of the solute nature.
Environmental Creep Behavior of a 9Cr Martensitic Steel in CO2 and Air: Richard Oleksak1; Kyle Rozman1; Jeffrey Hawk1; Ömer Doğan1; 1National Energy Technology Laboratory
Future supercritical CO2 (sCO2) power systems require structural alloys which are resistant to creep in CO2-rich environments. Herein we studied the environmental degradation of a 9Cr martensitic steel during creep testing in 1 bar of flowing CO2 or air at 650 °C. We found that CO2 caused a clear reduction in creep strength relative to air, which was associated with an increased depth of cracking initiated in the oxide scale. Microstructural analyses revealed this cracking was caused by a sub-surface zone of coarsened metal carbides resulting from carbon uptake during the CO2 exposure. The existence of this brittle carburized zone, and its subsequent oxidation behavior, facilitated and perpetuated the propagation of cracks initiated in the oxide scale. This work indicates that creep-oxidation interactions represent an important materials consideration for sCO2 power cycles and confirms that limiting steel carburization is critical for reducing long-term degradation in these environments.
In Situ Experiments to Reveal Coupling Between Stress and Hydrogen on Stress Corrosion Cracking of Fe-based Alloys: Arun Devaraj1; Dallin Barton1; Tingkun Liu1; Sten Lambeets1; Cheng-Han Li1; Mark Wirth1; Daniel Perea1; Matthew Olszta1; Jinhui Tao1; Tianyi Li2; Yang Ren2; Shuang Li1; Chongmin Wang1; 1Pacific Northwest National Laboratory; 2argonne national laboratory
When stainless steel is subjected simultaneously to an applied tensile stress and a corrosive, high-temperature aqueous medium, the individual and combined interactions of hydrogen and oxygen with the alloy microstructure are thought to lead to intergranular stress corrosion cracking (SCC), however a nano to atomic scale mechanistic understanding of these interactions are only beginning to emerge. Using novel in situ experiments in transmission electron microscopy, atom probe tomography, atomic force microscopy and synchrotron high-energy x-ray diffraction, we develop a multiscale understanding of this mechanochemical coupling during SCC of Fe-Cr-Ni model alloys. We reveal the structure and composition of oxide layers, the difficult to map hydrogen segregation at the oxide-metal interfaces and grain boundaries, and deformation-induced defects. These experiments ultimately aim to provide a scientific basis for tailoring the microstructure of metallic alloys to enhance the resistance to stress corrosion cracking and hydrogen embrittlement when used in nuclear and automotive applications.
Effect of Irradiation on the Cracking Behavior of Stainless Steels in Light Water Reactor Environment: Yiren Chen1; Bogdan Alexandreanu1; Appajosula Rao2; 1Argonne National Laboratory; 2Nuclear regulatory commission
The core internal components of light water reactors (LWRs) made of austenitic stainless steels are crucial for the safe and economic operation of nuclear power reactors. Subject to the harsh service environment inside the reactor core, a wide range of degradation processes can take place in reactor metals, leading to deteriorated service performance and reduced operational lifetime. To assure the long-term availability of LWRs, the extent of material degradation must be evaluated carefully. In this work, the cracking behavior of stainless steels was investigated with neutron-irradiated materials. Crack growth tests were performed in simulated LWR coolant, and the crack propagation rates of irradiated specimens were measured under cyclic and constant loads at different doses and stress intensity factors. The degree of irradiation embrittlement was also evaluated with J-R curve tests at several doses. The effect of irradiation on the cracking behavior of stainless steels in LWR environment was discussed.
Effects of Test Orientation on Environmentally-assisted Cracking of 5xxx Series Aluminum Alloys: Yang Liu1; John Lewandowski1; 1Case Western Reserve University
5xxx series Aluminum-Magnesium alloys are solid solution strengthened by Mg and used in a variety of applications due to their good strength, weldability and corrosion resistance. However, thermal exposures for sufficient time may sensitize the material to corrosion and/or environmentally-assisted cracking (EAC) via the precipitation of Mg-rich phases at grain boundaries. In this work, the effects of sensitization treatments on EAC have been determined for laboratory-sensitized 5xxx alloys. Fracture toughness tests were conducted in humid air and/or 0.6M NaCl solution on laboratory-sensitized alloys both in Longitudinal-Transverse (L-T) direction and Short-Transverse (S-T) direction, including experiments on thinner (e.g. 6mm-thick) plate. Changes in crack growth response due to laboratory-sensitization will be presented along with SEM fractography.
Stress Corrosion Cracking Study of Fe39Mn20Co20Cr15Si5Al1 (at.%) Compositionally Complex Alloy in 3.5 wt.% NaCl Salt Solution: Pranshul Varshney1; Nilesh Kumar1; 1University of Alabama-Tusaloosa
The combined effect of stress and corrosive environment may cause premature failure in engineering materials due to stress corrosion cracking (SCC) phenomenon. Compositionally complex alloys (CCAs) possess promising mechanical properties but their SCC behavior is not known. In this work, slow strain rate tensile (SSRT) test at strain rates of 10-6 to 10-4 s-1 using smooth dog-bone shaped tensile specimens was conducted on transformation induced plasticity Fe39Mn20Co20Cr15Si5Al1 (at.%) CCA in 3.5 wt.% NaCl solution at room temperature to study SCC characteristics. Advanced analytical tools including x-ray photoelectron spectroscopy and transmission electron microscopy were used to characterize microstructure of the alloy before and after SCC. The preliminary results showed non-monotonic variation in ductility with decrease in strain rates. Further analysis of SSRT data obtained at different strain rates and post-deformation microstructure including identification of corrosion product(s) and passivation film is in progress and will be discussed during presentation.