Local plastic strain evolution in a high strength dual-phase steel

Ghadbeigi, Hassan; Pinna, C.; Celotto, S.; Yates, J. R.

doi:10.1016/j.msea.2010.04.052

Cited by 236 publications

(132 citation statements)

References 9 publications

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“…In order to investigate the reliability of local strain maps determined with the DIC technique, an in-situ tensile testing procedure developed by the authors [31] has been used. The microtensile specimen, Fig.…”

Section: Methodsmentioning

confidence: 99%

Quantitative Strain Analysis of the Large Deformation at the Scale of Microstructure: Comparison between Digital Image Correlation and Microgrid Techniques

2012

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A comparative study has been carried out to assess the accuracy of the Digital Image Correlation (DIC) technique for the quantification of large strains in the microstructure of a Interstitial Free (IF) steel used in automotive applications. A microgrid technique has been used in this study in order to validate independently the strain measurements obtained with DIC. Microgrids with a pitch of 5 microns were printed on the etched microstructure of the IF steel to measure the local in-plane strain distribution during a tensile test carried out in a Scanning Electron Microscope (SEM). The progressive deformation of the microstructure with microgrids has been recorded throughout the test as a sequence of micrographs and subsequently processed using DIC to quantify the distribution of local strain values. Strain maps obtained with the two techniques have been compared in order to assess the accuracy of the DIC measurements obtained using the natural patterns of the revealed microstructure in the SEM micrographs. Although results obtained with the two techniques are qualitatively similar, therefore demonstrating the reliability of DIC applied to microstructures, even after large deformations in excess of 0.7. However, an average error of about 16% was found in the strain values calculated using DIC.

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Section: Methodsmentioning

confidence: 99%

Quantitative Strain Analysis of the Large Deformation at the Scale of Microstructure: Comparison between Digital Image Correlation and Microgrid Techniques

2012

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“…Recently, it has been demonstrated that direct information on strain partitioning can be obtained using in-situ mechanical testing setups, which enable microstructural imaging during deformation and follow-up microscopic-digital image correlation (lDIC) analysis (Kang et al, 2007;Tasan et al, 2010;Ghadbeigi et al, 2010Ghadbeigi et al, , 2013Kapp et al, 2011;Joo et al, 2013;Marteau et al, 2013;Han et al, 2013). Kang et al (2007) have shown that strain partitioning between ferrite and martensite can be significantly decreased by a tempering treatment, leading to an increase in the critical damage nucleation strain.…”

Section: Introductionmentioning

confidence: 99%

“…Tasan et al (2010) demonstrated that the detrimental influence of microstructural banding strongly depends on the continuity of the band, as well as its morphology and the mechanical character of the phase that composes the band. Ghadbeigi et al (2010) have presented a quantitative analysis of critical strain levels for different damage nucleation mechanisms in a DP1000 microstructure (Ghadbeigi et al, 2010). Local strains well above 100% are reported for damage incidents within ferrite and at martensite-ferrite phase boundaries.…”

Section: Introductionmentioning

confidence: 99%

Strain localization and damage in dual phase steels investigated by coupled in-situ deformation experiments and crystal plasticity simulations

Taşan

Hoefnagels

Diehl

et al. 2014

International Journal of Plasticity

429

176

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a b s t r a c tFerritic-martensitic dual phase (DP) steels deform spatially in a highly heterogeneous manner, i.e. with strong strain and stress partitioning at the micro-scale. Such heterogeneity in local strain evolution leads in turn to a spatially heterogeneous damage distribution, and thus, plays an important role in the process of damage inheritance and fracture. To understand and improve DP steels, it is important to identify connections between the observed strain and damage heterogeneity and the underlying microstructural parameters, e.g. ferrite grain size, martensite distribution, martensite fraction, etc. In this work we pursue this aim by conducting in-situ deformation experiments on two different DP steel grades, employing two different microscopic-digital image correlation (lDIC) techniques to achieve microstructural strain maps of representative statistics and high-resolution. The resulting local strain maps are analyzed in connection to the observed damage incidents (identified by image post-processing) and to local stress maps (obtained from crystal plasticity (CP) simulations of the same microstructural area). The results reveal that plasticity is typically initiated within ''hot zones'' with larger ferritic grains and lower local martensite fraction. With increasing global deformation, damage incidents are most often observed in the boundary of such highly plastified zones. High-resolution lDIC and the corresponding CP simulations reveal the importance of martensite dispersion: zones with bulky martensite are more susceptible to macroscopic localization before the full strain hardening capacity of the material is consumed. Overall, the presented joint analysis establishes an integrated computational materials engineering (ICME) approach for designing advanced DP steels.

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“…The martensite cracking was found to be more frequent in a coarse martensite microstructure [5,7]. The martensite failure may occur due to : i) decohesion of prior austenite grain boundaries [8,9], ii) fracture of martensite islands due to crack initiation [10] and iii) decohesion at the ferrite-martensite interface [11]. These mechanisms have been determined from post-mortem microstructural investigations, therefore the onset of damage initiation has not been accurately identified.…”

Section: Introductionmentioning

confidence: 99%

“…The micro-scale deformation of materials has been mainly studied through the observation of microstructural evolution using different techniques including insitu mechanical testing combined with strain measurements at a microscopic scale [9,[13][14][15][16][17].…”

Section: Introductionmentioning

confidence: 99%