Micromechanical modeling of dual phase steels

Al-Abbasi, F.M.; Nemes, J. A.

doi:10.1016/j.ijmecsci.2003.10.007

Cited by 137 publications

(51 citation statements)

References 70 publications

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“…Note that, with a small volume fraction of martensite phase, it is difficult for the martensite phase to experience plastic deformation. [35] Therefore, the initial yield strength of the martensite phase does not seem to affect the UTS and UTS strain noticeably for the current RVE. Table IV lists the predicted failure modes for the DP 780 under tensile loading for the different mechanical properties of the martensite phase.…”

Section: A Stress-vs-strain Curvesmentioning

confidence: 67%

“…To this end, micromechanical finite element models have been used to understand the local mechanics and mechanisms governing the macroscopic behavior of heterogeneous materials. [34][35][36][37][38][39] These models provided some good information on the overall behavior of the heterogeneous materials based on the known properties of their constituents and the detailed interactions among them. Still, most of the studies did not consider the ultimate ductile failure of DP steels, and only a few examined the failure of these complex steels by developing phenomenological failure criteria for prescribed failure mode and intentional critical loading planes.…”

Section: Introductionmentioning

confidence: 99%

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Influence of Martensite Mechanical Properties on Failure Mode and Ductility of Dual-Phase Steels

Choi

Liu

et al. 2009

Metall Mater Trans A

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The effects of the mechanical properties of the martensite phase on the failure mode and ductility of dual-phase (DP) steels are investigated using a micromechanics-based finite element method. Actual microstructures of DP steels obtained from scanning electron microscopy (SEM) are used as representative volume elements (RVEs) in the finite element calculations. Ductile failure of the RVE is predicted as plastic strain localization during the deformation process. Systematic computations are conducted on the RVE to quantitatively evaluate the influence of the martensite mechanical properties and volume fraction on the macroscopic mechanical properties of DP steels. These properties include the ultimate tensile strength (UTS), ultimate ductility, and failure modes. The computational results show that, as the strength and volume fraction of the martensite phase increase, the UTS of DP steels increases, but the UTS strain and failure strain decrease. In addition, shear-dominant failure modes usually develop for DP steels with lower martensite strengths, whereas split failure modes typically develop for DP steels with higher martensite strengths. The methodology and data presented in this article can be used to tailor DP steel design for its intended purposes and desired properties.

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Section: A Stress-vs-strain Curvesmentioning

confidence: 67%

Section: Introductionmentioning

confidence: 99%

Influence of Martensite Mechanical Properties on Failure Mode and Ductility of Dual-Phase Steels

Choi

Liu

et al. 2009

Metall Mater Trans A

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“…Compared to the high-strength low-alloy (HSLA) steels, the DP steels exhibit a higher ultimate strength, higher work hardening rate, and elimination of yield point elongation with a considerable increase in ductility and formability. [1] In fact, the mechanical behavior of DP steels has been widely studied in the past years, [2][3][4] including the influence of the volume fraction (V m ) of the harder phase (martensite) on the yield and ultimate strengths. It was already established that during deformation the strain may be transferred into the martensite islands, after the ferrite matrix is excessively strained, and the shearing of the interface between the martensite and ferrite occurred in DP steels with a high value of V m .…”

Section: Introductionmentioning

confidence: 99%

Stress and Strain Partitioning of Ferrite and Martensite during Deformation

Cong

Jia

et al. 2009

Metall Mater Trans A

106

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The direct measurement of the stress or strain partitioning during deformation in the materials, consisting of two phases with the same crystallographic structure and different microstructures, is still difficult so far. This is due to the fact that no effective characterization tool is available with the ability to distinguish the local strain and stress at microscale level. In this article, we studied the micromechanical behavior of ferrite/martensite dual-phase (DP) alloys using the in-situ high-energy X-ray diffraction (HEXRD) technique. We established a new method to separate the stress and strain in the ferrite and martensite during loading. Although the ferrite and martensite exhibit the same crystal structure with similar lattice parameters, the dependence of (200) lattice strains on the applied stress is obviously different for each phase. A visco-plastic self-consistent (VPSC) model, which can simulate the micromechanical behavior of two-phase materials, was used to construct the respective constitutive laws for both phases from the experimental lattice strains and to fit the macro-stress-strain curve. The material parameters for each phase extracted from our experiments and simulations could be used for designing other DP alloys and optimizing some complex industrial processes.

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“…23) This difference in the local flow behavior due to microstructural aspects can then cause void formation to initiate from decohesion of atomic bonds at the interface between the matrix and inclusion or second phase particle. Support for crack initiation and propagation at the nonmetallic inclusions and stringers sites was given in the work of Vora and Polonis 24) that found the particles to be weakly bonded to the matrix and elongated in the direction of material flow.…”

Section: Resultsmentioning

confidence: 99%

Characterization of Internal Voids and Cracks in Cold Heading of Dual Phase Steel

2005

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In this work, the mechanism of void and microcrack formation along the adiabatic shear bands (ASB) was studied for processing dual phase steel by cold heading. Experimental investigation along with finite element simulation has confirmed that this mechanism depends on two types of instabilities, namely geometrical and thermal instabilities. The geometric instability occurs in the presence of second phase particles (inclusions) and in relation to the material flow orientation, whilst the thermal softening arises due to the localized plastic deformation inside the ASB. Progressive deformation was observed to cause the elongation of voids in the direction of shearing that formed microcracks in the ASB of the cold headed specimen. In addition, transformed bands were observed in the highly deformed zones as a result of the temperature in the ASB exceeding the Ac 3 transformation temperature 847°C. The superposition of the location of the ASB region containing the voids and micro-cracks with the phase transformation zone indicates that the development of optimized processing conditions is particularly critical for preventing fracture during cold heading of dual phase steels.KEY WORDS: dual phase steel; cold heading; adiabatic shear bands; voids; cracks; inclusions.rials. However, most of the plastic work (90-95 %) is converted into heat causing a local temperature increase and a flow stress decrease. Thus, a competing mechanism between the work hardening and the thermal softening commences and continues in the deformation zone. As the work hardening mechanism dominates over the thermal softening at the beginning, an increase in the flow stress occurs and with continuing deformation, the thermal softening mechanism can progressively dominate over work hardening increases, which then triggers unstable deformation. This instability condition will force the deformation to localize into a narrower band that through further localization can lead to final failure. 4)There are two types of ASBs, namely the deformed adiabatic shear bands (DASBs) and the transformed adiabatic shear bands (TASBs). DASBs occur in materials that do not undergo phase transformation, or when the local increased temperature in the band is not high enough to cause phase transformation. The damage and fracture process in DASBs involves a number of metallurgical events involving different steps between void nucleation and crack propagation. The initial phase of damage coincides with void nucleation at inclusion edges or at grain boundaries due to the interaction of local stresses and dislocations phenomena. The damage in the material is then driven by the accumulated plastic strain and affected by the stress triaxiality. 5) Moreover, deformation under compressive loads shows that when there is compressive (negative) stress triaxiality, the formability is greater than in the tensile loading state, i.e. positive stress triaxiality.6) It is therefore a competition between the stress triaxiality levels reached in the specimen and the high plastic strains, w...

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Micromechanical modeling of dual phase steels

Cited by 137 publications

References 70 publications

Influence of Martensite Mechanical Properties on Failure Mode and Ductility of Dual-Phase Steels

Influence of Martensite Mechanical Properties on Failure Mode and Ductility of Dual-Phase Steels

Stress and Strain Partitioning of Ferrite and Martensite during Deformation

Characterization of Internal Voids and Cracks in Cold Heading of Dual Phase Steel

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