A fully coupled chemo-mechanical cohesive zone model for oxygen embrittlement of nickel-based superalloys

Auth, Kim Louisa; Brouzoulis, Jim; Ekh, Magnus

doi:10.1016/j.jmps.2022.104880

Cited by 15 publications

(20 citation statements)

References 26 publications

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“…The free energy per unit area for the chemo-mechanically coupled interface material model Ψ Γ s is given by Auth et al 8 as…”

Section: Chemo-mechanically Coupled Free Energymentioning

confidence: 99%

“…2,7 Additionally it has been observed that the crack growth rate increases for increasing stress intensity factors for intergranular crack growth. 2,5,7 A numerical modeling framework for describing the interaction of oxygen diffusion and mechanical material degradation has been suggested in Auth et al 8 The framework includes a fully chemo-mechanically coupled cohesive law, describing the acceleration of mechanical degradation by the presence of oxygen as well as the acceleration of oxygen transport by the mechanical stress state. However, it does not yet provide a complete set-up for simulating crack propagation through polycrystals in a physically realistic manner.…”

Section: Introductionmentioning

confidence: 99%

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Modeling of environmentally assisted intergranular crack propagation in polycrystals

Auth,

Brouzoulis,

Ekh

2023

Numerical Meth Engineering

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Polycrystalline nickel‐based superalloys experience accelerated intergranular crack growth when exposed to dwell times in oxygen‐rich environments and a combination of high temperature and tensile mechanical loading. Increasing crack growth rates are observed for increasing amounts of environmental oxygen in a certain oxygen concentration range, while below and above that range crack growth rates remain approximately constant. A fully coupled chemo‐mechanical modeling framework accounting for the degradation of grain boundaries by oxygen has been presented by the authors. In this work, we expand the framework by a moving boundary condition to capture a realistic oxygen flux in grain boundary cracks for both edge cracks connected to the environment and interior cracks. In numerical simulation results, the behavior of the moving boundary condition is shown for intergranular crack propagation through a polycrystal subjected to cyclic loading. Finally, the capabilities of the modeling framework to qualitatively predict the dependence of the average crack growth rate on the environmental oxygen content, load level, and dwell time are evaluated and it is shown that predictions qualitatively agree with experimental observations for intergranular fracture.

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“…The free energy per unit area for the chemo-mechanically coupled interface material model Ψ Γ s is given by Auth et al 8 as…”

Section: Chemo-mechanically Coupled Free Energymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Modeling of environmentally assisted intergranular crack propagation in polycrystals

Auth,

Brouzoulis,

Ekh

2023

Numerical Meth Engineering

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“…[80,228,255,256] Some local mechanical properties are reported for γ 0 precipitates, intragranular carbides, or the δ-phase in superalloys, [257][258][259][260] and are invaluable for precise mechanical modeling. [261][262][263] Quantitative experimental methods [72,157,158,[264][265][266][267] and data analysis approaches [88,89,184,268] exist for GB segregation. However, little to no quantitative information is reported for the local composition of phase boundaries in the proximity of GBs.…”

Section: Processability and Propertiesmentioning

confidence: 99%

Review of Microstructure–Mechanical Property Relationships in Cast and Wrought Ni‐Based Superalloys with Boron, Carbon, and Zirconium Microalloying Additions

et al. 2022

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Cast and wrought Ni‐based superalloys are materials of choice for harsh high‐temperature environments of aircraft engines and gas turbines. Their compositional complexity requires sophisticated thermo‐mechanical processing. A typical microstructure consists of a polycrystalline γ‐matrix, strengthening Ni3(Al,Ti) γ′ precipitates, carbides (MC, M6C, and M23C6), borides (M2B, M3B2, and M5B3), and other inclusions. Microalloying additions of B, C, and Zr commonly improve high‐temperature strength and creep resistance, although excessive additions are detrimental. Grain boundary (GB) segregation may improve cohesion and displace embrittling impurities. Finely dispersed carbides and borides are desired to control grain size via GB pinning. However, excessive decoration of GBs may lead to failure during processing and in‐service. Hence, a systematic review on the roles of B, C, and Zr in cast and wrought Ni‐based superalloys is required. The current state of knowledge on GB segregation and precipitation is reviewed. Experimental and modeling results are compared across various processing steps. The impact of GB precipitation on mechanical properties is most well researched. Co‐precipitation in proximity to GBs interacting with local microstructure evolution and mechanical properties remains less explored. Addressing these gaps in knowledge allows a more complete understanding of processing–microstructure–properties relationships in advanced cast and wrought Ni‐based superalloys.

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“…Chemo-mechanics problems have gained increasing attention in the past decades, as a more refined understanding of processes in man-made and natural materials as well as living tissue can only be obtained by incorporation of mechanical and chemical loading conditions and their mutual interactions. Research in various fields of chemo-mechanics have emerged and are concerned for example with the coupling of deformation and diffusion in gels [18,19,28,42,58], the prediction of the transition from pitting corrosion to crack formation in metals [17,20], hydrogen diffusion [22,55] and embrittlement [1,4,45], functional degradation in Li-ion batteries [53,54], chemical reaction-induced degradation of concrete [52,64], diffusion mediated tumor growth [29,65], or modeling of lithium-ion batteries [51].…”

Section: Introductionmentioning

confidence: 99%

“…Fig 4. One eighth of the cube domain, highlighted in dark gray, with edge length L = 1 mm employed in the parallel scalability study…”

mentioning

confidence: 99%

Monolithic parallel overlapping Schwarz methods in fully-coupled nonlinear chemo-mechanics problems

et al. 2023

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We consider the swelling of hydrogels as an example of a chemo-mechanical problem with strong coupling between the mechanical balance relations and the mass diffusion. The problem is cast into a minimization formulation using a time-explicit approach for the dependency of the dissipation potential on the deformation and the swelling volume fraction to obtain symmetric matrices, which are typically better suited for iterative solvers. The MPI-parallel implementation uses the software libraries deal.II, p4est and FROSch (Fast of Robust Overlapping Schwarz). FROSch is part of the Trilinos library and is used in fully algebraic mode, i.e., the preconditioner is constructed from the monolithic system matrix without making explicit use of the problem structure. Strong and weak parallel scalability is studied using up to 512 cores, considering the standard GDSW (Generalized Dryja-Smith-Widlund) coarse space and the newer coarse space with reduced dimension. The FROSch solver is applicable to the coupled problems within in the range of processor cores considered here, although numerical scalablity cannot be expected (and is not observed) for the fully algebraic mode. In our strong scalability study, the average number of Krylov iterations per Newton iteration is higher by a factor of up to six compared to a linear elasticity problem. However, making mild use of the problem structure in the preconditioner, this number can be reduced to a factor of two and, importantly, also numerical scalability can then be achieved experimentally. Nevertheless, the fully algebraic mode is still preferable since a faster time to solution is achieved.

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A fully coupled chemo-mechanical cohesive zone model for oxygen embrittlement of nickel-based superalloys

Cited by 15 publications

References 26 publications

Modeling of environmentally assisted intergranular crack propagation in polycrystals

Modeling of environmentally assisted intergranular crack propagation in polycrystals

Review of Microstructure–Mechanical Property Relationships in Cast and Wrought Ni‐Based Superalloys with Boron, Carbon, and Zirconium Microalloying Additions

Monolithic parallel overlapping Schwarz methods in fully-coupled nonlinear chemo-mechanics problems

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