Towards the microstructure design of DP steels: A generic size-sensitive mean-field mechanical model

Allain, Sébastien; Bouaziz, Olivier; Pushkareva, Irina; Scott, Colin

doi:10.1016/j.msea.2015.04.017

Cited by 42 publications

(37 citation statements)

References 55 publications

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“…The latter becomes dominant in DP steels containing high martensite fractions where the mean carbon content in martensite < 0.5 wt.%. 14) A high dispersion was observed in both the uniform and total elongations of asquenched samples, nevertheless a clear trend of decreasing UE with increasing martensite content was found (Fig. 4) in agreement with other published data.…”

Section: Tensile Properties Of As-quenched Samplessupporting

confidence: 91%

“…It has been observed that the earliest interface voids tend to nucleate at high values of local ferrite strains (ε n > 0.2). 14,36) It is reasonable to propose that at this point the flow stress in martensite is nearly constant and that of ferrite is only slowly increasing. Where Hv m and Hv α are the martensite and ferrite hardness values.…”

Section: Modelling Interface Decohesion In Dp Steelsmentioning

confidence: 99%

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Relationship between Microstructure, Mechanical Properties and Damage Mechanisms in High Martensite Fraction Dual Phase Steels

Pushkareva

Allain²,

Scott

et al. 2015

ISIJ International

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Section: Tensile Properties Of As-quenched Samplessupporting

confidence: 91%

Section: Modelling Interface Decohesion In Dp Steelsmentioning

confidence: 99%

Relationship between Microstructure, Mechanical Properties and Damage Mechanisms in High Martensite Fraction Dual Phase Steels

Pushkareva

Allain²,

Scott

et al. 2015

ISIJ International

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“…The 50% α + 50% α' material obtained after a 2 h treatment at 920°C followed by water quenching exhibits a remarkable work-hardening, which induces a desirable increase in both ultimate tensile strength and uniform strain ( Table 2). As reported for other heterogeneous materials, such as dual-phase (DP) steels [37][38][39] and ferrite-pearlite steels [40], the origin of this work-hardening can be attributed to the presence of a mechanical contrast between the two phases. Indeed, when deforming such a composite microstructure, the softest phase is the first to deform plastically, while the hardest remain elastic.…”

Section: Modeling the Work-hardening Behavior Of Multiphase Microstrumentioning

confidence: 59%

“…Beyond its simplicity, the main advantage of the iso-work assumption is also the absence of calibration parameters. The iso-work model has been successfully applied to heterogeneous steel microstructures, such as Ferrite-Martensite Dual-Phase [40] or Ferrite-Pearlite steels [39].…”

Section: Modeling the Work-hardening Behavior Of Multiphase Microstrumentioning

confidence: 99%

Micromechanical behavior and thermal stability of a dual-phase α+α’ titanium alloy produced by additive manufacturing

et al. 2019

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In order to improve the tensile properties of additively manufactured Ti 6Al 4V parts, specific heat treatments have been developed. Previous work demonstrated that a sub-transus thermal treatment at 920°C followed by water quenching generates a dual-phase α+α′ microstructure with a high work-hardening capacity inducing a desirable increase in both strength and ductility. The present study investigates the micromechanical behavior of this α+α′ material as well as the thermal stability of the metastable α' martensite. To that end, annealing of the α+α′ microstructure is performed and the resulting microstructural evolution is analyzed, along with its impact on the tensile properties. A deeper understanding of the micromechanics of the multiphase microstructure both before and after annealing is achieved by performing in-situ tensile testing within a SEM, together with digital image correlation for full-field local strain measurements. This approach allows the strain partitioning to be quantified at a microscale and highlights a significant mechanical contrast between the two phases. In the α+α′ microstructure, the α′ phase is softer than the α phase, which is confirmed by nanoindentation measurements. Partial decomposition of the martensite during annealing induces a substantial hardening of the α′ phase, which is attributed to fine-scale precipitation and solution strengthening. A scale transition model based on the iso-work assumption and describing the macroscopic tensile behavior of the material depending on the individual mechanical behavior of each phase is also proposed. This model enables to provide insights into the underlying deformation and work-hardening mechanisms.

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“…As already mentioned, another important component in the processing of DP steels is the bake hardening (BH) [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] step, which includes cold working followed by aging heat treatment. This step is known to impart DP steels with a characteristic property known as continuous yielding, which is generally attributed to the production and pinning of dislocations in the ferrite component, especially in the vicinity of ferrite/martensite interfaces [1,[7][8][9][10][11][12][13][14]16,18,19,22,28,[30][31][32][33][34]. The discussion above points out the difficulties encountered in the optimization of the processing of DP steels to meet the desired combination of properties [1,35,36].…”

Section: Introductionmentioning

confidence: 99%

New Insights into the Microstructural Changes During the Processing of Dual-Phase Steels from Multiresolution Spherical Indentation Stress–Strain Protocols

Khosravani

Caliendo

Kalidindi

2019

Metals

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In this study, recently established multiresolution spherical indentation stress-strain protocols have been employed to derive new insights into the microstructural changes that occur during the processing of dual-phase (DP) steels. This is accomplished by utilizing indenter tips of different radii such that the mechanical responses can be evaluated both at the macroscale (reflecting the bulk properties of the sample) and at the microscale (reflecting the properties of the constituent phases). More specifically, nine different thermo-mechanical processing conditions involving different combinations of intercritical annealing temperatures and bake hardening after different amounts of cold work were studied. In addition to demonstrating the tremendous benefits of the indentation protocols for evaluating the variations within each sample and between the samples at different material length scales in a high throughput manner, the measurements provided several new insights into the microstructural changes occurring in the alloys during their processing. In particular, the indentation measurements indicated that the strength of the martensite phase reduces by about 37% when quenched from 810 • C compared to being quenched from 750 • C, while the strength of the ferrite phase remains about the same. In addition, during the 10% thickness reduction and bake hardening steps, the strength of the martensite phase shows a small decrease due to tempering, while the strength of the ferrite increases by about 50% by static aging.

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Towards the microstructure design of DP steels: A generic size-sensitive mean-field mechanical model

Cited by 42 publications

References 55 publications

Relationship between Microstructure, Mechanical Properties and Damage Mechanisms in High Martensite Fraction Dual Phase Steels

Relationship between Microstructure, Mechanical Properties and Damage Mechanisms in High Martensite Fraction Dual Phase Steels

Micromechanical behavior and thermal stability of a dual-phase α+α’ titanium alloy produced by additive manufacturing

New Insights into the Microstructural Changes During the Processing of Dual-Phase Steels from Multiresolution Spherical Indentation Stress–Strain Protocols

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