Abstract
The dynamic recrystallization (DRX) simulation performance largely depends on simulated grain topological structures. However, currently solutions used different models for describing two-dimensional (2D) and three-dimensional (3D) grain size distributions. Therefore, it is necessary to develop a more universal simulation technique. A cellular automaton (CA) model combined with an optimized topology deformation technology is proposed to simulate the microstructural evolution of 42CrMo cast steel during DRX. In order to obtain values of material constants adopted in the CA model, hot deformation characteristics of 42CrMo cast steel are investigated by hot compression metallographic testing. The proposed CA model deviates in two important aspects from the regular CA model. First, an optimized grain topology deformation technology is utilized for studying the hot compression effect on the topology of grain deformation. Second, the overlapping grain topological structures are optimized by using an independent component analysis method, and the influence of various thermomechanical parameters on the nucleation process, grain growth kinetics, and mean grain sizes observed during DRX are explored. Experimental study shows that the average relative root mean square error (RRMSE) of the mean grain diameter obtained by the regular CA model is equal to 0.173, while the magnitude calculated using the proposed optimized CA model is only 0.11. This paper proposes a novel combined CA model for simulating the microstructural evolution of 42CrMo cast steel, which notably uses a ICA-based grain topology deformation method to optimize the overlapping grain topological structures in simulation.
Highlights
Grain growth and recrystallization are interactional processes depending on grain topology parameters and sizes
Due to the randomness and non-uniformity of grain orientations, simulated grain topological structures often exhibit overlapping problems, as shown in Figure 1 (the grain overlaps in the displayed three-dimensional (3D) and two-dimensional (2D) views are marked by the white circles)
3 Results and Discussion In order to verify the accuracy and reliability of the proposed DRX cellular automaton (CA) model, the flow stress curves and microstructural evolution morphology of 42CrMo cast steel are selected as verification standards representing common DRX characteristics
Summary
Grain growth and recrystallization are interactional processes depending on grain topology parameters and sizes. The described method is expected to solve overlap problems of grain topological structures in a multidimensional space [12]. A cellular automation (CA) model combined with an optimized topology deformation technology is proposed to simulate the microstructural evolution of 42CrMo cast steel during dynamic recrystallization (DRX) and solve the problem of the overlapping reduction of grain topological structures during thermomechanical processing. The above-mentioned studies were capable of solving the overlap problem of grain topological structures; they adopted different models for describing the 2D and 3D grain size distributions and could not be considered universal methods
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