This project deals with the phase quantification by nanoindentation and electron back scattered diffraction (EBSD), as well as a detailed analysis of the micromechanical compression behaviour, to understand deformation processes within an industrial produced complex bainitic microstructure.
The combination of high strength and ductility is vital for industrial products like line pipe or structural steels. Increasingly, such products are made of bainitic steels with complex microstructures [1-3]. Since such complex microstructures often consist of granular bainite and polygonal ferrite, and both phases are very difficult to distinguish under the light optical microscope, two different approaches have been applied [4-5].
As a first approach, nanoindentation tests and extreme property mapping (XPM) were used, which were additionally analysed using k-means clustering. In addition, an automatised MATLABMTEX tool was created to determine the misorientation angle within each grain, which enables the differentiation between both phases [5-7]. Furthermore, micropillar compression tests were applied on both constituents to understand the deformation process by mechanism-based models. The critical resolved shear stress (CRSS) and the corresponding activated slip systems will be used as a decisive criterion.
Subsequently, the relevant parameters to describe the representative behaviour of real microstructures can be used as an input for a computational material model to be implemented in the crystal plasticity simulation tool DAMASK [8].
This project is in cooperation and supported by Dillinger (AG der Dillinger Hüttenwerke).
Fig. 1: The granular bainite has been separated by the kernel average misorientation threshold. a) the detected granular bainite grains (the low angle grain boundaries are displayed as red lines) show also a higher kernel average misorientation compared to polygonal ferrite grains in b).
Fig. 1: The granular bainite has been separated by the kernel average misorientation threshold. a) the detected granular bainite grains (the low angle grain boundaries are displayed as red lines) show also a higher kernel average misorientation compared to polygonal ferrite grains in b).
Fig. 2: According to the crystallographic orientation of the tested grain, the slip planes are predicted for all three slip families which can be active due to the highest Schmid factor a). In comparison with a) the {112} slip plane was activated in b) during this microcompression test.
Fig. 2: According to the crystallographic orientation of the tested grain, the slip planes are predicted for all three slip families which can be active due to the highest Schmid factor a). In comparison with a) the {112} slip plane was activated in b) during this microcompression test.
Y. W. Chen et al., “Phase quantification in low carbon Nb-Mo bearing steel by electron backscatter diffraction technique coupled with kernel average misorientation
Mater. Charact., vol. 139, no. September 2017, pp. 49–58, 2018
Franz Roters, Martin Diehl, Pratheek Shanthraj, Philip Eisenlohr, Jan Christoph Reuber, Su Leen Wong, Tias Maiti, Alireza Ebrahimi, Thomas Hochrainer, Helge-Otto Fabritius, Svetoslav D. Nikolov, Martin Friák, Noriki Fujita, Nicolò Grilli, Koenraad G.F. Janssens, Nan Jia, Piet Kok, Duancheng Ma, Felix Meier, Ewald Werner, Markus Stricker, Daniel M. Weygand, and Dierk Raabe, "DAMASK – The Düsseldorf Advanced Material Simulation Kit for modeling multi-physics crystal plasticity, thermal, and damage phenomena from the single crystal up to the component scale," Computational Materials Science 158, 420-478 (2019).
International researcher team presents a novel microstructure design strategy for lean medium-manganese steels with optimized properties in the journal Science
Hydrogen is a clean energy source as its combustion yields only water and heat. However, as hydrogen prefers to accumulate in the concentrated stress region of metallic materials, a few ppm Hydrogen can already cause the unexpected sudden brittle failure, the so-called “hydrogen embrittlement”. The difficulties in directly tracking hydrogen limits…
This project with the acronym GB-CORRELATE is supported by an Advanced Grant for Gerhard Dehm by the European Research Council (ERC) and started in August 2018. The project GB-CORRELATE explores the presence and consequences of grain boundary phase transitions (often termed “complexions” in literature) in pure and alloyed Cu and Al. If grain size…
The project HyWay aims to promote the design of advanced materials that maintain outstanding mechanical properties while mitigating the impact of hydrogen by developing flexible, efficient tools for multiscale material modelling and characterization. These efficient material assessment suites integrate data-driven approaches, advanced…
The segregation of impurity elements to grain boundaries largely affects interfacial properties and is a key parameter in understanding grain boundary (GB) embrittlement. Furthermore, segregation mechanisms strongly depend on the underlying atomic structure of GBs and the type of alloying element. Here, we utilize aberration-corrected scanning…
