Shear pipe effects and dynamic shear-strain localization in martensitic steels

Hatem, Tarek M.; Zikry, M. A.

doi:10.1016/j.actamat.2009.06.028

Cited by 29 publications

(11 citation statements)

References 37 publications

(54 reference statements)

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“…10b and d). This special configuration aligns the slip-systems with the maximum resolved shear-stress direction with the long direction of the blocks, and when combined with the low angle boundaries between blocks, acts as shear pipes for the localization of dislocation-densities and shear strains; more details for shear pipes effect is presented by Hatem and Zikry (2009c).…”

Section: Article In Pressmentioning

confidence: 99%

“…To address these limitations and to obtain greater predictive capabilities, we have extended the dislocation-density based crystalline models proposed by Zikry and Kao (1996), Ashmawi and Zikry (2000) and Hatem and Zikry (2009a, 2009b, 2009c to investigate dynamic shear-strain localization in lath martensite steels. Within those formulations, we account for martensitic transformations and parent austenite crystalline orientations for an accurate OR description of lath microstructure.…”

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confidence: 99%

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Dynamic shear–strain localization and inclusion effects in lath martensitic steels subjected to high pressure loads

Hatem

Zikry

2010

Journal of the Mechanics and Physics of Solids

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Section: Article In Pressmentioning

confidence: 99%

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confidence: 99%

Dynamic shear–strain localization and inclusion effects in lath martensitic steels subjected to high pressure loads

Hatem

Zikry

2010

Journal of the Mechanics and Physics of Solids

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“…To characterize martensitic microstructure, we will follow the characterization scheme of Morito et al (2003), which has been used by Hatem and Zikry (2009). We designate a block as a group of laths with approximately the same values of low angle misorientations, and a packet as a collection of blocks with the same habit plane.…”

Section: Martensitic Microstructural Representationmentioning

confidence: 99%

Microstructural modeling of crack nucleation and propagation in high strength martensitic steels

Zikry

2014

International Journal of Solids and Structures

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a b s t r a c tA dislocation-density based multiple-slip crystalline plasticity formulation, a dislocation-density grain boundary (GB) interaction scheme, and an overlapping fracture method were used to investigate crack nucleation and propagation in martensitic steel with retained austenite for both quasi-static and dynamic loading conditions. The formulation accounts for variant morphologies, orientation relationships, and retained austenite that are uniquely inherent to lath martensitic microstructures. The interrelated effects of dislocation-density evolution ahead of crack front and the variant distribution of martensitic blocks on crack nucleation and propagation are investigated. It is shown that dislocation-density generation ahead of crack front can induce dislocation-density accumulations and plastic deformation that can blunt crack propagation. These predictions indicate that variant distribution of martensitic blocks can be optimized to mitigate and potentially inhibit material failure.

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“…In the present study, microtensile testing was employed to characterise the mechanical response of each phase in a bainite/martensite structure. Additionally, numerical analysis with crystal plasticity finite element method (CPFEM) was performed to elucidate the microscopic mechanism of the experimentally observed deformation behaviour.The CPFEM analyses have helped in understanding plastic behaviours, 14,15) and studies on dual-phase steels successfully reproduced the observed deformation and fracture behaviours. 16,17) However, few studies have applied CPFEM to bainite/martensite dual-phase-structured steel.…”

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“…The CPFEM analyses have helped in understanding plastic behaviours, 14,15) and studies on dual-phase steels successfully reproduced the observed deformation and fracture behaviours. 16,17) However, few studies have applied CPFEM to bainite/martensite dual-phase-structured steel.…”

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Micro-tensile Behaviour of Low-alloy Steel with Bainite/martensite Microstructure

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Micro-tensile testing and numerical analysis using a crystal plasticity finite element method (CPFEM) were employed to elucidate the deformation behaviour of bainite/martensite structures of a low-alloy steel. The bainite single-phase specimens exhibited habit-plane-orientation-dependent yielding, similar to the martensite single-phase specimens. In the bainite/martensite dual-phase specimen, deformation concentrated in the bainite region oriented favourably for in-habit-plane slip, leading to low-ductility fracture. With consideration of the habit-plane-orientation-dependent yielding, the present CPFEM analysis successfully reproduced the anisotropic plastic deformation behaviour of the single-phase steels observed in the experiments. The numerical results for the bainite/martensite specimen showed slip localization in the bainite region and stress concentration near the interphase boundary. This suggests that the interphase boundary can be a site for the fracture origin.KEY WORDS: micromechanical characterisation; bainite; martensite-austenite constituent; crystal plasticity finite element analysis; plastic anisotropy; habit plane.tensitic phases hinders the understanding of the mechanical response of each phase.Mine et al. have analysed the mechanical characteristics of the microconstituents in the single-phase lath martensite structure of a low-alloy steel using micro-tensile testing.12) This study revealed that lath martensite structures with single packets exhibited moderate ductility and that the plastic deformation behaviour depended on the habitplane orientation relative to the loading direction. Thus, micro-tensile testing allows for the analysis of deformation behaviour on the microstructural scale. In addition, a microtensile test study by Ogata et al. indicated that pre-strained ferrite/martensite dual-phase steel was embrittled by ultra grain refinement in the ferrite region, rather than by cracking in the martensite region.13) This finding suggested that martensite was not always the main cause of embrittlement in high-strength steels. In the present study, microtensile testing was employed to characterise the mechanical response of each phase in a bainite/martensite structure. Additionally, numerical analysis with crystal plasticity finite element method (CPFEM) was performed to elucidate the microscopic mechanism of the experimentally observed deformation behaviour.The CPFEM analyses have helped in understanding plastic behaviours, 14,15) and studies on dual-phase steels successfully reproduced the observed deformation and fracture behaviours. 16,17) However, few studies have applied CPFEM to bainite/martensite dual-phase-structured steel. Therefore, in the present study, we confirm the applicability of a simple CPFEM with linear hardening laws to the deforma- ISIJ International, Vol. 56 (2016), No. 12tion behaviour of the bainite and martensite single-phase structures. Furthermore, by using the material parameters identified in the analyses of single-phase structures, the analysis of the bainit...

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Shear pipe effects and dynamic shear-strain localization in martensitic steels

Cited by 29 publications

References 37 publications

Dynamic shear–strain localization and inclusion effects in lath martensitic steels subjected to high pressure loads

Dynamic shear–strain localization and inclusion effects in lath martensitic steels subjected to high pressure loads

Microstructural modeling of crack nucleation and propagation in high strength martensitic steels

Micro-tensile Behaviour of Low-alloy Steel with Bainite/martensite Microstructure

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