On the role of precipitates in hydrogen trapping and hydrogen embrittlement of a nickel-based superalloy

Zhang, Zhenbo; Moore, Katie L.; McMahon, Greg; Morana, Roberto; Preuss, Michael

doi:10.1016/j.corsci.2018.10.019

Cited by 78 publications

(29 citation statements)

References 52 publications

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“…This can be fully understood now because H-assisted cracking at TBs is essentially cracking along the very adjacent DSBs. H-induced cracking along DSBs has been well recognized in Ni-based superalloys [40][41][42][43] . DSBs are the locations with high strain field and high defect density, and H tends to gather at these sites [44][45][46] .…”

Section: Discussionmentioning

confidence: 99%

“…Before charging, samples were ground and then polished in diamond suspension and colloidal silica suspension finishing with a quality for EBSD. It is known that H diffusion coefficient is very low in Ni-based superalloys 63 , and in order to introduce sufficient amount of H into the samples, the following charging protocol was used 40,43 . Cathodic charging was conducted at 80°C in a solution with NaCl (1 mol L −1 ) and distilled water.…”

Section: Methodsmentioning

confidence: 99%

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Strain localisation and failure at twin-boundary complexions in nickel-based superalloys

Zhang

Yang

et al. 2020

Nat Commun

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Twin boundaries (TBs) in Ni-based superalloys are vulnerable sites for failure in demanding environments, and a current lack of mechanistic understanding hampers the reliable lifetime prediction and performance optimisation of these alloys. Here we report the discovery of an unexpected γ″ precipitation mechanism at TBs that takes the responsibility for alloy failure in demanding environments. Using multiscale microstructural and mechanical characterisations (from millimetre down to atomic level) and DFT calculations, we demonstrate that abnormal γ″ precipitation along TBs accounts for the premature dislocation activities and pronounced strain localisation associated with TBs during mechanical loading, which serves as a precursor for crack initiation. We clarify the physical origin of the TBs-related cracking at the atomic level of γ″-strengthened Ni-based superalloys in a hydrogen containing environment, and provide practical methods to mitigate the adverse effect of TBs on the performance of these alloys.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Strain localisation and failure at twin-boundary complexions in nickel-based superalloys

Zhang

Yang

et al. 2020

Nat Commun

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“…Therefore, further studies should be focused on the influence of various microstructural factors, such as, the distance from the crack tip to GB and density of GB as well as the existence of other defects, e.g. voids [19][20][21] and inclusions [64][65][66].…”

Section: Discussionmentioning

confidence: 99%

Effect of grain boundary on the crack-tip plasticity under hydrogen environment: An atomistic study

Zhao

Zhang

2020

Journal of Applied Physics

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It has been found that the plasticity is significantly affected by the hydrogen interstitials in metallic materials. However, the underlying physics responsible for the dislocation/hydrogen interactions is still poorly understood. Using molecular dynamics simulations, we study the emission of dislocations from a crack-tip in fcc Ni single crystal and bicrystal samples under hydrogen environment. The results show that the critical Mode-I stress intensity factor (SIF) is reduced due to the presence of hydrogen, but the existence of Σ5 grain boundaries (GBs, with inclination angle ranging from 0 to π/4) almost not alter the critical Mode-I SIF for dislocation emission, compared with the single crystal cases. These findings suggest that further large-scale investigations should be conducted to study the influence of various microstructural factors, such as, the distance from the crack tip to GB and density of GB as well as the existence of other defects, e.g. voids and inclusions.

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“…Among the various methodologies that have been suggested to alleviate HE in HMnS are Al-addition [14][15][16], grain refinement [17,18], or the introduction of hydrogen traps, e.g., k-carbides [19]. However, the role of precipitates in improving hydrogen embrittlement is still a matter of discussion [20][21][22]. Recently, medium manganese steels (MMnSs) with a duplex microstructure have received significant attention due to their excellent mechanical properties and reduced production costs compared to HMnS [23][24][25][26][27].…”

Section: Introductionmentioning

confidence: 99%

Development of a Cr-Ni-V-N Medium Manganese Steel with Balanced Mechanical and Corrosion Properties

Allam

Guo

Sevsek

et al. 2019

Metals

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A novel medium manganese (MMn) steel with additions of Cr (18%), Ni (5%), V (1%), and N (0.3%) was developed in order to provide an enhanced corrosion resistance along with a superior strength–ductility balance. The laboratory melted ingots were hot rolled, cold rolled, and finally annealed at 1000 °C for 3 min. The recrystallized single-phase austenitic microstructure consisted of ultrafine grains (~1.3 µm) with a substantial amount of Cr- and V-based precipitates in a bimodal particle size distribution (100–400 nm and <20 nm). The properties of the newly developed austenitic MMn steel X20CrNiMnVN18-5-10 were compared with the standard austenitic stainless steel X5CrNi18-8 and with the austenitic twinning-induced plasticity (TWIP) steel X60MnAl17-1. With a total elongation of 45%, the MMn steel showed an increase in yield strength by 300 MPa and in tensile strength by 150 MPa in comparison to both benchmark steels. No deformation twins were observed even after fracture for the MMn steel, which emphasizes the role of the grain size and precipitation-induced change in the austenite stability in controlling the deformation mechanism. The potentio-dynamic polarization measurements in 5% NaCl revealed a very low current density value of 7.2 × 10−4 mA/cm2 compared to that of TWIP steel X60MnAl17-1 of 8.2 × 10−3 mA/cm2, but it was relatively higher than that of stainless steel X5CrNi18-8 of 2.0 × 10−4 mA/cm2. This work demonstrates that the enhanced mechanical properties of the developed MMn steel are tailored by maintaining an ultrafine grain microstructure with a significant amount of nanoprecipitates, while the high corrosion resistance in 5% NaCl solution is attributed to the high Cr and N contents as well as to the ultrafine grain size.

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On the role of precipitates in hydrogen trapping and hydrogen embrittlement of a nickel-based superalloy

Cited by 78 publications

References 52 publications

Strain localisation and failure at twin-boundary complexions in nickel-based superalloys

Strain localisation and failure at twin-boundary complexions in nickel-based superalloys

Effect of grain boundary on the crack-tip plasticity under hydrogen environment: An atomistic study

Development of a Cr-Ni-V-N Medium Manganese Steel with Balanced Mechanical and Corrosion Properties

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