Analysis of Localized Plastic Strain in Heterogeneous Cast Iron Microstructures Using 3D Finite Element Simulations

Abstract

The design and production of light structures in cast iron with high static and fatigue performance is of major interest in e.g. the automotive area. Since the casting process inevitably leads to heterogeneous solidification conditions and variations in microstructural features and material properties, the effects on multiple scale levels needs to be considered in the determination of the local fatigue performance. In the current work, microstructural features of different cast irons are captured by use of micro X-ray tomography, and 3D finite element models generated. The details of the 3D microstructure differ from the commonly used 2D representations in that the actual geometry is captured and that there is not a need to compensate for 3D-effects. The first objective with the present study is to try and highlight certain aspects at the micro scale that might be the underlying cause of fatigue crack initiation, and ultimately crack propagation, under fatigue loading for cast iron alloys. The second objective is to incorporate the gained knowledge about the microstructural behavior into multi-scale simulations at a structural length scale, including the local damage level obtained in the heterogeneous structure subjected to fatigue load.

Probing the structure and mechanical properties of the graphite nodules in ductile cast irons via nano-indentation

“…19 Figure 10 compares the pattern of recorded experimentally to that predicted by the alignment function, equation (9), assuming that the geometrical parameters determined in the previous paragraph apply. Good agreement can be observed along the s-axis as well as along the t-axis.…”

“…Comparison between the pattern predicted by the alignment function, equation(9), and the experimental data in terms of maximum indenter penetration. (a) Indents along the s-axis, (b) indents along the t-axis.…”

“…(b) Pattern along the t-axis. Effect of the uncertainty on the and parameters on the pattern predicted by the alignment function, equation(9). (a) Effect of uncertainty on the pattern along the s-axis.…”

Recent trends in X‐ray‐based characterization of nodular cast iron

“…However, it is foreseen that image analysis techniques, possibly supported by machine learning, might solve this issue in the future. In fact, contrast‐enhancing techniques based on image analysis have already been applied to distinguish the pearlite from the ferrite in DI with ferritic–pearlitic matrix 60 …”

Uncovering the local inelastic interactions during manufacture of ductile cast iron: How the substructure of the graphite particles can induce residual stress concentrations in the matrix

“…The consequence is that the fracture process of SGI can hardly be explained on the basis of standard theoretical models which consider the material as homogeneous (Dong et al, 1997) (Berdin et al, 2001). Prompted by the recent progress in advanced characterization techniques such as micro X-ray tomography, which allows unprecedented insight into the morphology and distribution of the microstructural phases, more advanced models which take into account the local interactions arising between the different microstructural elements are now emerging, whose development is a current research area (Costa et al, 2010) (Collini and Pirondi, 2014) (Hütter et al, 2015b) (Salomonsson and Olofsson, 2017) (Fernandino et al, 2017).…”