Strain partitioning in dual-phase steels containing tempered martensite

Han, Qihang; Asgari, Asghar; Hodgson, Peter; Stanford, Nicole

doi:10.1016/j.msea.2014.05.078

Cited by 77 publications

(18 citation statements)

References 26 publications

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“…The reduction in martensite hardness with tempering time and temperature [36] results in an increased deformation of the martensite phase and through that to the reduction of internal stress in both phases. This has been observed in strain partitioning studies by Han et al [37] and explains the significant drop in Bauschinger ratio with increasing tempering temperature shown in Figure 11b. Above 35% martensitic volume fraction there is no further increase in Bauschinger ratio ( Figure 11b).…”

Section: Bauschinger Parameterssupporting

confidence: 77%

On the Bauschinger effect in dual phase steel at high levels of strain

Weiß

Kupke

Manach

et al. 2015

Materials Science and Engineering: A

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Section: Bauschinger Parameterssupporting

confidence: 77%

On the Bauschinger effect in dual phase steel at high levels of strain

Weiß

Kupke

Manach

et al. 2015

Materials Science and Engineering: A

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“…This increasing fraction of martensite would lead to local strain re-distribution among different phases and inhibit the transformation behaviors, as suggested in previous study (Knijf et al, 2014). Previous research also suggested that the continuous deformation with proper strain and stress partitioning among different phases based on the law of mixture can still keep a hardening potential without transformation and retard the onset of strain localization (Kuang et al, 2009;Knijf et al, 2014;Bouquerel et al, 2006;Kang et al, 2007;Jacques et al, 2007;Lani et al, 2007;Han et al, 2014;Fillafer et al, 2014;Tasan et al, 2014). Of course, this hardening potential should be much weaker than the strong hardening induced by martensite transformation.…”

Section: Discussionmentioning

confidence: 79%

Dynamic shear response and evolution mechanisms of adiabatic shear band in an ultrafine-grained austenite–ferrite duplex steel

Yuan

Bian

Jiang

et al. 2015

Mechanics of Materials

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a b s t r a c tThe dynamic properties of an intercritically annealed 0.2C5Mn steel with ultrafine-grained austenite-ferrite duplex structure were studied under dynamic shear loading. The formation and evolution mechanisms of adiabatic shear band in this steel were then investigated using interrupted experiments at five different shear displacements and the subsequent microstructure observations. The dynamic shear plastic deformation of the 0.2C5Mn steel was observed to have three stages: the strong linear hardening stage followed by the plateau stage, and then the strain softening stage associated with the evolution of adiabatic shear band. High impact shear toughness was found in this 0.2C5Mn steel, which is due to the following two aspects: the strong linear strain hardening by martensite transformation at the first stage, and the suppressing for the formation of shear band by the continuous deformation in different phases through the proper stress and strain partitioning at the plateau stage. The evolution of adiabatic shear band was found to be a two-stage process, namely an initiation stage followed by a thickening stage. The shear band consists of two regions at the thickening stage: a core region and two transition layers. When the adjoining matrix is localized into the transition layers, the grains are refined along with increasing fraction of austenite phase by inverse transformation. However, when the transition layers are transformed into the core region, the fraction of austenite phase is decreased and almost disappeared due to martensite transformation again. These interesting observations in the core region and the transition layers should be attributed to the competitions of the microstructure evolutions associated with the non-uniformly distributed shear deformation and the inhomogeneous adiabatic temperature rise in the different region of shear band. The 0.2C5Mn TRIP steel reported here can be considered as an excellent candidate for energy absorbers in the automotive industry.

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“…Fig. 6(c) shows a comparison between the model predictions and experimental measurements for the yield stress and stress partitioning ratio during various tempering temperatures in DP3; the latter is defined as the ratio between the measured stress in martensite and ferrite and it has been obtained by measuring the nano-hardness distribution in both phases with micro-indentation [55]. The partitioning ratio in the model is calculated by using the martensite and ferrite strength terms in Eq.…”

Section: Resultsmentioning

confidence: 99%

“…These alloys possess good tensile strength and ductility, the former being imparted by martensite, whereas the latter is mostly controlled by the volume fraction of ferrite. The ferrite grains plastically deform earlier than the martensite grains to accommodate strain; as the stress increases, strain localisation occurs at the ferrite/martensite boundaries produced by geometrically-necessary dislocations [54]; this mechanism prevents describing the yield strength as a simple mixture rule, since strain partitioning is heterogeneous [55]. However, the partitioning behaviour in these steels is still not fully understood [56].…”

Section: Dual-phase Steelsmentioning

confidence: 99%

“…In the elastic regime upon yielding, since defining a yield criterion for dual-phase materials is complex [57,55], the offset yield point at 0.2% strain is adopted to estimate r Y for simplicity. This leads to the macroscopic elastic stress-strain response to be a linear relationship in e [30]: r ¼ r Y ðe=0:002Þ, where the 0.002 factor is the strain offset; e partitions as e ¼ ð1 À V f Þe 1 þ V f e 2 [57], where Combining the previous equations, it can be shown that the yield stress equals [57]:…”

Section: Dual-phase Steelsmentioning

confidence: 99%

See 1 more Smart Citation

A model for the microstructure behaviour and strength evolution in lath martensite

Galindo-Nava

Rivera-Dı́az-del-Castillo

2015

Acta Materialia

315

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a b s t r a c tA new model describing the microstructure and strength of lath martensite is introduced. The packet and block size were found to linearly depend on the prior-austenite grain size when introducing relevant crystallographic and geometric relationships of their hierarchical arrangements. A mechanism for the lath boundary arrangement within a block is postulated to ensure complete carbon redistribution to the lath boundaries. Accordingly, the dislocation density is obtained by considering the lattice distortion energy within a lath being equal to the strain energy of the dislocation density at the lath boundaries. Tempering effects are introduced by estimating the extent of carbon diffusing away from the lath boundaries; this mechanism relaxes the Cottrell atmospheres of lath dislocations and coarsens the boundaries. The yield stress as well as the microstructure evolution during tempering are successfully predicted by combining these results. The model is further extended to describe the yield stress in dual-phase steel microstructures by employing the iso-work principle. The model predictions are validated against experimental data in seven martensitic and five dual-phase steels, where the prior-austenite grain size, carbon content, tempering conditions and martensite volume fraction are employed as input. These results cover wide composition, initial microstructure and tempering conditions.

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Strain partitioning in dual-phase steels containing tempered martensite

Cited by 77 publications

References 26 publications

On the Bauschinger effect in dual phase steel at high levels of strain

On the Bauschinger effect in dual phase steel at high levels of strain

Dynamic shear response and evolution mechanisms of adiabatic shear band in an ultrafine-grained austenite–ferrite duplex steel

A model for the microstructure behaviour and strength evolution in lath martensite

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