A Study on the Surface Characteristics of Dual Phase Steel by Electron Backscatter Diffraction (EBSD) Technique

Jeong, Bong-Yong; Ryou, Min; Lee, Chongmu

doi:10.4313/teem.2014.15.1.20

Cited by 6 publications

(2 citation statements)

References 30 publications

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“…Comparing the two images, it shows that grains (or particles) with a darker contrast in the IQ map consistently have a darker contrast in the SPM scan as well. Dark contrast in the IQ map is an indication that the quality of the EBSD pattern obtained at that location is of lower quality (lesser contrast in the diffraction pattern) (Wu et al, 2005; Wright & Nowell, 2006; Jeong, 2014). The opposite holds for lighter contrast.…”

Section: Resultsmentioning

confidence: 99%

Phase Identification of Dual-Phase (DP980) Steels by Electron Backscatter Diffraction and Nanoindentation Techniques

2016

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Phase identification of multi-phase materials provides essential information relating the material to its mechanical properties. In this study we selected DP980, a type of dual-phase steel, to investigate the content of martensite and ferrite grains. A combination of advanced techniques was used to provide detailed and precise information of the microstructure. Scanning and transmission electron microscopy were used to provide observations of the sample surface at different scales. Martensite and ferrite phases of DP980 were further identified and characterized using electron backscatter diffraction and scanning probe microscopy. Results obtained with nanoindentation tests confirmed that the differences in nanohardness values in single-phase grains are martensite and ferrite with different surface heights shown by scanning probe microscopy. The similarity shown in the image quality map and scanning probe microscopy proves that a large fraction of martensite can be distinguished in this undeformed material using image quality parameters obtained during electron backscatter diffraction imaging.

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Section: Resultsmentioning

confidence: 99%

Phase Identification of Dual-Phase (DP980) Steels by Electron Backscatter Diffraction and Nanoindentation Techniques

2016

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“…Based there on [96] show the correlation of low image-quality values to the occurrence of martensite, see also [99]. This is used by several contributions to analyze volume fraction, morphology, and distribution of the martensitic inclusion phase of DP steels, see, e.g., [35,36,97,98,100]. For the improvement in the representativity of the EBSD measurement especially the phase fraction determination [21] propose a new EBSD scanning scheme with a two-step size movement of the electron beam.…”

Section: Introductionmentioning

confidence: 99%

Computational modeling of dual-phase steels based on representative three-dimensional microstructures obtained from EBSD data

et al. 2015

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The microstructure of dual-phase steels consisting of a ferrite matrix with embedded martensite inclusions is the main contributor to the mechanical properties such as high ultimate tensile strength, high work hardening rate, and good ductility. Due to the composite structure and the wide field of applications of this steel type, a wide interest exists in corresponding virtual computational experiments. For a reliable modeling, the microstructure should be included. For that reason, in this paper we follow a computational strategy based on the definition of a representative volume element (RVE). These RVEs will be constructed by a set of tomographic measurements and mechanical tests. In order to arrive at more efficient numerical schemes, we also construct statistically similar RVEs, which are characterized by a lower complexity compared with the real microstructure but which represent the overall material behavior accurately. In addition to the morphology of the microstructure, the austenite-martensite transformation during the steel production has a relevant influence on the mechanical properties and is considered in this contribution. This transformation induces a volume expansion of the martensite phase. A further effect is determined in nanoindentation test, where it turns out that the hardness in the ferrite phase increases exponentially when approaching the martensitic inclusion. To capture these gradient properties in the computational model, the volumetric expansion is applied to the martensite phase, and the arising equivalent plastic strain distribution in the ferrite phase serves as basis for a locally graded modification of the ferritic yield curve. Good accordance of the model considering the gradient yield behavior in the ferrite phase is observed in the numerical simulations with experimental data.Keywords Reconstruction of microstructure · Dual-phase steel · RVE · Microheterogeneous materials · EBSD-FIB · SSRVE · Volume expansion of martensite · Multiscale simulations

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Heterogeneous Strain Distribution and Saturation of Geometrically Necessary Dislocations in a Ferritic–Pearlitic Steel during Lubricated Sliding

et al. 2018

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The microstructural evolution of ferritic-pearlitic steel is studied during unidirectional sliding under boundary lubrication using a ball-on-flat configuration. Dislocation activity as a function of distance to surface is determined using orientation gradients by electron backscatter diffraction in logarithmic intervals up to one million of sliding cycles. The orientation gradient results show the formation of geometrically necessary dislocations and low-angle grain boundaries, followed by a consolidation of those grain boundaries as nanocrystalline grains. The density of geometrically necessary dislocations and low-angle grain boundaries is observed to reach a steady state after around 100 000 cycles. Plastic strain is not homogeneously distributed within both material phases, that is, ferrite and pearlite. Most of the plastic deformation is carried by the ferritic phase. The heterogeneous strain distribution between the ferritic and the pearlitic phase observed in the electron backscatter diffraction measurements is attributed to stress incompatibilities at the grain boundaries.

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A Study on the Surface Characteristics of Dual Phase Steel by Electron Backscatter Diffraction (EBSD) Technique

Cited by 6 publications

References 30 publications

Phase Identification of Dual-Phase (DP980) Steels by Electron Backscatter Diffraction and Nanoindentation Techniques

Phase Identification of Dual-Phase (DP980) Steels by Electron Backscatter Diffraction and Nanoindentation Techniques

Computational modeling of dual-phase steels based on representative three-dimensional microstructures obtained from EBSD data

Heterogeneous Strain Distribution and Saturation of Geometrically Necessary Dislocations in a Ferritic–Pearlitic Steel during Lubricated Sliding

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