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
In this project we study the development of a maraging steel alloy consisting of Fe, Ni and Al, that shows pronounced response to the intrinsic heat treatment imposed during Laser Additive Manufacturing (LAM). Without any further heat treatment, it was possible to produce a maraging steel that is intrinsically precipitation strengthened by an…
The aim of the current study is to investigate electrochemical corrosion mechanisms by examining the metal-liquid nanointerfaces. To achieve this, corrosive fluids will be strategically trapped within metal structures using novel additive micro fabrication techniques. Subsequently, the nanointerfaces will be analyzed using cryo-atom probe…
TiAl-based alloys currently mature into application. Sufficient strength at high temperatures and ductility at ambient temperatures are crucial issues for these novel light-weight materials. By generation of two-phase lamellar TiAl + Ti3Al microstructures, these issues can be successfully solved. Because oxidation resistance at high temperatures is…
We plan to investigate the rate-dependent tensile properties of 2D materials such as metal thin films and PbMoO4 (PMO) films by using a combination of a novel plan-view FIB based sample lift out method and a MEMS based in situ tensile testing platform inside a TEM.