Influence of grain boundaries on short crack growth behaviour of IGSCC

Kamaya, Masayuki

doi:10.1111/j.1460-2695.2004.00799.x

Cited by 20 publications

(17 citation statements)

References 11 publications

(26 reference statements)

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“…Such stress field due to inhomogeneity plays a critical role in the initiation and growth behavior of microstructurally-small-crack (Kamaya and Kitamura, 2004). For example, in intergranular stress corrosion cracking (SCC) of nickel alloy in high-temperature water, the initiation of a crack, which the size is about one grain boundary length, greatly depends on inclination of grain boundary to the tensile axis (Kamaya, 2004). Cracks tend to be initiated easily at grain boundaries which inclination is perpendicular to tensile axis.…”

Section: Introductionmentioning

confidence: 99%

Three-dimensional local stress analysis on grain boundaries in polycrystalline material

Kamaya¹,

Kawamura

Kitamura

2007

International Journal of Solids and Structures

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In order to understand the initiation behavior of microstructurally small cracks in a stress corrosion cracking condition, it is important to know the tensile normal stress acting on the grain boundary (normal GB stress). The local stress in a polycrystalline body is enhanced by the inhomogeneity which stems from the shape and orientation of each grain. The stress in a three-dimensional polycrystalline body consisting of 100 grains with random orientation, under a remote uniform tensile stress condition, is evaluated by the finite element method. It was revealed that the local stress on the polycrystalline body is inhomogeneous under uniform applied stress and becomes large at those grain boundaries that are perpendicular to the load axis, though there is large fluctuation. It was also shown that the normal GB stress tends to be large near the triple points due to the deformation constraint caused by adjacent grains. Finally, the maximum stress on the surface of a large component caused by the inhomogeneity was evaluated by using Gumbel statistics.

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Section: Introductionmentioning

confidence: 99%

Three-dimensional local stress analysis on grain boundaries in polycrystalline material

Kamaya¹,

Kawamura

Kitamura

2007

International Journal of Solids and Structures

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“…Several techniques have been developed and used for studying the crack initiation and propagation in heterogeneous or polycrystalline microstructures. Kamaya [39] employed the body force method for investigating 2D intergranular stress corrosion cracking. Sukumar et al [40] studied the competition between inter-and transgranular crack growth in 2D polycrystalline brittle microstructure by using the extended FEM.…”

Section: Introductionmentioning

confidence: 99%

A three-dimensional cohesive-frictional grain-boundary micromechanical model for intergranular degradation and failure in polycrystalline materials

Benedetti

Aliabadi

2013

Computer Methods in Applied Mechanics and Engineering

116

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In this study, a novel three-dimensional micro-mechanical crystal-level model for the analysis of intergranular degradation and failure in polycrystalline materials is presented. The polycrystalline microstructures are generated as Voronoi tessellations, that are able to retain the main statistical features of polycrystalline aggregates. The formulation is based on a grain-boundary integral representation of the elastic problem for the aggregate crystals, that are modeled as threedimensional anisotropic elastic domains with random orientation in the three-dimensional space. The boundary integral representation involves only intergranular variables, namely interface displacement discontinuities and interface tractions, that play an important role in the micromechanics of polycrystals. The integrity of the aggregate is restored by enforcing suitable interface conditions, at the interface between adjacent grains. The onset and evolution of damage at the grain boundaries is modeled using an extrinsic non-potential irreversible cohesive linear law, able to address mixed-mode failure conditions. The derivation of the traction-separation law and its relation with potential-based laws is discussed. Upon interface failure, a non-linear frictional contact analysis is used, to address separation, sliding or sticking between micro-crack surfaces. To avoid a sudden transition between cohesive and contact laws, when interface failure happens under compressive loading conditions, the concept of cohesive-frictional law is introduced, to model the smooth onset of friction during the mode II decohesion process. The incrementaliterative algorithm for tracking the degradation and micro-cracking evolution is presented and discussed. Several numerical tests on pseudo-and fully three-dimensional polycrystalline microstructures have been performed. The influence of several intergranular parameters, such as cohesive strength, fracture toughness and friction, on the microcracking patterns and on the aggregate response of the polycrystals has been analyzed. The tests have demonstrated the capability of the formulation to track the nucleation, evolution and coalescence of multiple damage and cracks, under either tensile or compressive loads.

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“…As shown in Fig. 4(b), grains in the body were generated by Voronoi tessellation explained in the following: [15][16][17] (1) Nuclei are located at random positions in the body.…”

Section: Review Of Experimental Resultsmentioning

confidence: 99%

Angular Distribution of Slip Steps by Three-Dimensional Polycrystalline Model for Stainless Steel

Kamaya¹,

Fukuya²,

Kitamura

2009

Journal of Nuclear Science and Technology

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Localized deformation plays an important role in the initiation of irradiation-assisted stress corrosion cracking, and it can be characterized by the spacing and inclination of slip steps observed on the surface. In order to examine the contribution of mechanical factors (stress) to slipping, the angular distribution of slip steps was evaluated by using a three-dimensional polycrystalline model generated by Voronoi tessellation. An elastic finite element analysis was performed to derive the resolved shear stress (RSS) acting on each slip system. Random crystallographic orientations assigned to each grain caused the microstructural inhomogeneity of local stress due to anisotropic elastic properties. The angular distribution obtained was compared with the experimental results observed in irradiated and deformed stainless steel. It was shown that mechanical factors dominate the slipping behavior of the irradiated stainless steel and that not only RSS but also normal stress acting on the slip plane affects the crystallographic slip. The angular distribution was also evaluated from the maximum Schmid factor of individual grains, in which the inhomogeneous local stress was not taken into account. The angular distributions obtained using RSS and the Schmid factor were almost the same. This suggests that the inhomogeneity of local stress negligibly affects the angular distribution of slip steps, although the change in the local stress in the polycrystalline material is significant.

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Influence of grain boundaries on short crack growth behaviour of IGSCC

Cited by 20 publications

References 11 publications

Three-dimensional local stress analysis on grain boundaries in polycrystalline material

Three-dimensional local stress analysis on grain boundaries in polycrystalline material

A three-dimensional cohesive-frictional grain-boundary micromechanical model for intergranular degradation and failure in polycrystalline materials

Angular Distribution of Slip Steps by Three-Dimensional Polycrystalline Model for Stainless Steel

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