Journal article
Microstructure and residual elastic strain at graphite nodules in ductile cast iron analyzed by synchrotron X-ray microdiffraction
Manufacturing Engineering, Department of Mechanical Engineering, Technical University of Denmark1
Department of Mechanical Engineering, Technical University of Denmark2
Composite Mechanics and Structures, Department of Wind Energy, Technical University of Denmark3
Department of Wind Energy, Technical University of Denmark4
Oak Ridge National Laboratory5
Argonne National Laboratory6
Villum Center for Advanced Structural and Material Testing, Centers, Technical University of Denmark7
The microstructure and residual elastic strain at graphite nodules (GNs) in ductile cast iron produced using either a fast or slow cooling rate have been characterized using synchrotron 3D X-ray Laue microdiffraction. The results show that thermal stress is introduced during cooling and that part of this stress is relaxed by plastic deformation of the polycrystalline ferrite matrix.
It is found that the plastic deformation is accommodated by the formation of dislocations and dislocation boundaries, which are organized in a cell structure. The dislocation density quantified based on the microstructure is most pronounced at the GN/matrix interface around small GNs in the fast cooled sample.
Residual elastic strain is also present, which is mainly compressive with a maximum of 6.0-9.9 × 10-4 near the GNs. Gradients of plastic deformation and elastic strain field around the GNs are observed. The results document for the first time that both the elastic strain field and the plastic strain field averaged over the grains around the GNs is approximately scaling with GN size and not affected by the cooling rate.
The experimental data are compared with simulations by a finite element method, and agreement and disagreement are discussed in detail.
Language: | English |
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Year: | 2019 |
Pages: | 221-230 |
ISSN: | 18732453 and 13596454 |
Types: | Journal article |
DOI: | 10.1016/j.actamat.2019.01.038 |
ORCIDs: | Zhang, Y. B. , Andriollo, T. , Fæster, S. , Tiedje, N. , Hattel, J. and Juul Jensen, D. |