Mapping the parent austenite orientation reconstructed from the orientation of martensite by EBSD and its application to ausformed martensite

Miyamoto, Gorō; Iwata, Naomichi; Takayama, Naoki; Furuhara, Tadashi

doi:10.1016/j.actamat.2010.08.001

Cited by 247 publications

(132 citation statements)

References 16 publications

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“…The [14]. Therefore, it is possible to identify the crystallographic orientation of γ grain based on EBSD analysis of the martensite structure [15,16]. According to the K-S relationship [14], 24 different variants of martensite are possible to form in a γ grain.…”

Section: Crystallographic Relationship Between Dendrite and As-cast γmentioning

confidence: 99%

Transition of solidification mode and the as-cast γ grain structure in hyperperitectic carbon steels

2012

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Formation processes of as-cast γ grain structures during casting of hyperperitectic carbon steels with 0.15-0.45 mass% carbon concentrations have been studied by means of a rapid unidirectional solidification technique. In steels with 0.15-0.41 mass% carbon concentrations, coarse columnar γ grains (CCG) with a minor axis diameter of 1-3mm developed along the direction of temperature gradient. In a steel with 0.38 mass% carbon, importantly, columnar γ grains (CG) whose minor axis diameter is less than 500 μm form before the formation of CCG and the grain structure discontinuously changes from CG to CCG. The fraction of CG region increases with increase in the carbon concentration. In the samples with the carbon concentration higher than 0.43 mass%, the as-cast structure consists of CG over almost the entire ingots. Analyses on a relation between γ grain and dendrite structures and their crystallographic orientations indicate that the formation of CG originates from the primary solidification of γ phase instead of δ phase. This is supported by numerical analysis on the dendrite growths.

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Section: Crystallographic Relationship Between Dendrite and As-cast γmentioning

confidence: 99%

Transition of solidification mode and the as-cast γ grain structure in hyperperitectic carbon steels

2012

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“…The basic analytical method is borrowed from the PTMC, 14 which provides the equation for the unextended cone based on B. On this cone, usually two equivalent solutions for the possible invariant normal can be derived using Equation (1). As shown in Figure 5b, numerous O-line interfaces can be determined for a specific invariant normal.…”

Section: /2′mentioning

confidence: 99%

“…Experimental characterisation of crystallographic information has been facilitated by advances in electron microscopy, especially the development of the electron backscatter diffraction technique. [1][2][3] Computer simulations of microstructures generated from solid-state phase transformations have also achieved a certain degree of success. [4][5][6][7][8] The orientations of the predicted faceted interfaces are a key parameter that can be used to check whether a simulated morphology actually resembles what is observed in a real material.…”

Section: Introductionmentioning

confidence: 99%

Faceted interfaces: a key feature to quantitative understanding of transformation morphology

Zhang

Dai

2016

npj Comput Mater

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Faceted interfaces are a typical key feature of the morphology of many microstructures generated from solid-state phase transformations. Interpretation, prediction and simulation of this faceted morphology remain a challenge, especially for systems where irrational orientation relationships (ORs) between two phases and irrational interface orientations (IOs) are preferred. In terms of structural singularities, this work suggests an integrated framework, which possibly encompasses all candidates of faceted interfaces. The structural singularities are identified from a matching pattern, a dislocation structure and/or a ledge structure. The resultant singular interfaces have discrete IOs, described with low-index g's (rational orientations) and/or Δg's (either rational or irrational orientations). Various existing models are grouped according to their determined results regarding the OR and IO, and the links between the models are clarified in the integrated framework. Elimination of defect types as far as possible in a dominant singular interface often exerts a central restriction on the OR. An irrational IO is usually due to the elimination of dislocations in one direction, i.e., an O-line interface. Analytical methods using both three-dimensional and two-dimensional models for quantitative determinations of O-line interfaces are reviewed, and a detailed example showing the calculation for an irrational interface is given. The association between structural singularities and local energy minima is verified by atomistic calculations of interfacial energies in fcc/bcc alloys where it is found that the calculated equilibrium cross-sections are in a good agreement with observations from selected alloys.

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“…In the reconstruction program developed in the previous study, 19) an α orientation map measured by EBSD at a certain step size is analyzed. The measured data set of α orientations in a small mesh, of which edge length is L1, are here represented by the orientation matrix, M (2) where N is the number of data in a single mesh.…”

Section: Reconstruction Proceduresmentioning

confidence: 99%

“…They assume a rational orientation relationship (OR) between the parent and product phases, such as Kurdjumov-Sachs or Nishiyama-Wasserman relationships for fcc to bcc transformation, then calculate the orientation of the parent phase. In contrast, the present authors 19) have recently developed a new program to reconstruct a γ orientation map based on an orientation map of bcc martensite, in which an OR between γ and martensite is assumed to have non-parallel relations in close-packed planes and directions. 20) The same program was applied to ausformed martensite, and a deformed γ structure was successfully visualized.…”

Section: Introductionmentioning

confidence: 99%

Reconstruction of Parent Austenite Grain Structure Based on Crystal Orientation Map of Bainite with and without Ausforming

et al. 2011

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By using a reconstruction program recently developed by the present authors, the parent austenite grain structure is reconstructed from the crystal orientation map of bainite structure. Local austenite orientation can be reconstructed from non-ausformed bainite structure with errors of 1.7° and 1.0° at spatial resolutions of 5 and 20 μ m respectively. The angle of errors is further reduced to be less than 0.5° when an analysis area is extended to a whole austenite grain. Application of the reconstruction program to the bainite structure transformed from deformed austenite has clarified that the variation in grain shape and deformation texture of parent austenite can be well reconstructed.

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Mapping the parent austenite orientation reconstructed from the orientation of martensite by EBSD and its application to ausformed martensite

Cited by 247 publications

References 16 publications

Transition of solidification mode and the as-cast γ grain structure in hyperperitectic carbon steels

Transition of solidification mode and the as-cast γ grain structure in hyperperitectic carbon steels

Faceted interfaces: a key feature to quantitative understanding of transformation morphology

Reconstruction of Parent Austenite Grain Structure Based on Crystal Orientation Map of Bainite with and without Ausforming

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