Journal ArticleDOI
Combined effect of special grain boundaries and grain boundary carbides on IGSCC of Ni–16Cr–9Fe–xC alloys
TLDR
In this article, an intergranular stress corrosion cracking (IGSCC) was investigated using interrupted constant extension rate tensile tests in a primary water environment at 360°C, where thermal-mechanical treatments were used to increase the fraction of special boundaries from approximately 20-25% to between 30 and 40%.Abstract:
Susceptibility to intergranular stress corrosion cracking in Ni–16Cr–9Fe– x C alloys in 360°C primary water is reduced with increasing fraction of special grain boundaries, i.e. coincident site lattice boundaries (CSLB) and low angle boundaries, and grain boundary carbides. Intergranular stress corrosion cracking (IGSCC) was investigated using interrupted constant extension rate tensile tests in a primary water environment at 360°C. Thermal–mechanical treatments were used to increase the fraction of special boundaries from approximately 20–25% to between 30 and 40%. In a carbon-doped heat, further heat treating was used to precipitate grain boundary carbides preferentially on high-angle boundaries (HAB). Orientation imaging microscopy was used to determine the relative grain misorientations and scanning electron microscopy (SEM) was used to identify specific grain boundaries after each interruption. After each strain increment, the same regions in each sample were examined for cracking. Results showed that irrespective of the microstructure condition, CSLBs always cracked less than HABs. Results also showed that IGSCC is reduced with increasing solution carbon content, and for the same amount of carbon in solution, the addition of grain boundary carbides reduced IGSCC still further. The best microstructure was the one consisting of an enhanced CSLB fraction and chromium carbides precipitated preferentially on high-angle boundaries.read more
Citations
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Journal ArticleDOI
Twinning-related grain boundary engineering
TL;DR: In this article, the fundamental concepts of grain boundary engineering (GBE) accompanied by a critical appraisal of GBE investigations are reported, and several variants on processing route schedules to produce successfully a GBE microstructure with improved properties.
Journal ArticleDOI
Grain boundary engineering: historical perspective and future prospects
Tadao Watanabe,Tadao Watanabe +1 more
TL;DR: A brief introduction of the historical background of grain boundary engineering for structural and functional polycrystalline materials is presented in this article, where a new approach in terms of the grain boundary and interface engineering is discussed for the design and development of high performance materials with desirable bulk properties.
Journal ArticleDOI
Analysis of grain boundary networks and their evolution during grain boundary engineering
TL;DR: In this article, the authors describe a technique for the quantitative experimental study of grain boundary network topology, with an emphasis on the connectivity of special and random grain boundaries, and show that the special grain boundary fraction is a poor predictor of network topologies, but that the higher order correlation derived from triple junction distributions can successfully describe the length scales of random boundary clusters.
Journal ArticleDOI
On the relationship between grain boundary connectivity, coincident site lattice boundaries, and intergranular stress corrosion cracking
TL;DR: In this article, a stochastic model is presented for easily and accurately determining the proportion of neutral-twins, which do not disrupt connectivity in the network of random boundaries based on the relative frequency of twin-variant boundaries (i.e. Σ9s and Σ27s) in the microstructure.
Journal ArticleDOI
Connectivity and percolation in simulated grain-boundary networks
TL;DR: In this paper, a Monte Carlo method is used to construct physically realistic networks composed of high-angle grain boundaries that are susceptible to intergranular attack, as well as twin-variant boundary that are damage resistant.
References
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Journal ArticleDOI
The structure of high-angle grain boundaries
TL;DR: In this paper, a superimposed dislocation network is proposed for the cubic system, which is a natural extension of previous dislocation models and models based on coincidence relationships, and explains many of the observed properties of grain boundaries.
Journal ArticleDOI
Mechanism of twinning-induced grain boundary engineering in low stacking-fault energy materials
TL;DR: In this article, the role of annealing twinning in low stacking-fault energy (SFE) materials as a means to achieve this aim has been satisfactorily explained.
Journal ArticleDOI
A TEM investigation of M23C6 carbide precipitation behaviour on varying grain boundary misorientations in 304 stainless steels
E. A. Trillo,L. E Murr +1 more
TL;DR: In this article, transmission electron microscopy (TEM) along with electrochemical potentiokinetic reactivation (EPR) testing was performed on different grades of 304 stainless steel to assess the sensitization and precipitation behavior on different grain boundary misorientations.
Journal ArticleDOI
A thermodynamic and kinetic basis for understanding chromium depletion in Ni-Cr-Fe alloys
Gary S. Was,R. M. Kruger +1 more
TL;DR: In this article, a thermodynamic and kinetic model was constructed to describe the development of the chromium depleted zone in Ni-Cr-Fe alloys heated in the range 773-1173 K.
Journal ArticleDOI
Structure-dependent intergranular oxidation in Ni–Fe polycrystalline alloy
TL;DR: In this paper, the effect of grain-boundary character on intergranular oxidation has been investigated in a Ni-40 at.c.%Fe polycrystalline alloy, and a difference in the extent of intergranularity oxidation between coincidence site lattice (hereafter denoted as CSL) boundaries and random boundaries was observed.
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