Cellular automaton model to simulate nucleation and growth of ferrite grains for low-carbon steels
- PDF / 371,990 Bytes
- 9 Pages / 612 x 792 pts (letter) Page_size
- 84 Downloads / 235 Views
B. Zhang The State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang 110006, People’s Republic of China, and College of Science, Northeastern University, Shenyang 110006, People’s Republic of China
Y.M. Wang Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, People’s Republic of China
X.H. Liu and G.D. Wang The State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang 110006, People’s Republic of China (Received 29 January 2002, accepted 3 June 2002)
A two-dimensional cellular automaton model was developed for the simulation of nucleation and growth of ferrite grains at various cooling rates in low-carbon steels. The model calculates the diffusion of the solute and temperature fields in an explicit finite method and incorporates local temperature and concentration changes into a nucleation or growth function, which is utilized by the automaton in a probabilistic fashion. The modeling provides an efficient way to understand how those physical processes dynamically progress and affect nucleation and growth of ferrite grains.
I. INTRODUCTION
Because microstructures of low-carbon steels, especially their grain sizes of ferrite, have strong influence on their mechanical properties, considerable industrial importance is placed on predicting a ␥–␣ phase transformation of steels during heat treatment. In controlled rolling, which is an optimized reheating, hot rolling, and cooling process, the chief aim is to obtain the microstructures consisting of small and uniform ferrite grains, which have favorable mechanical properties in general, and in particular yield preferable strength and toughness. In recent years, many efforts have been undertaken to understand how to obtain the refinement microstructure of ferrite grains.1–6 However, the microstructure formation in steels is not yet fully understood because of the complexity of the solid-state transformation involving the combined complex behavior of heat–mass transfer, nucleation and growth etc., in the liquid and/or solid states and their interfaces during the ␥–␣ phase transformation. Although experimental observations could qualitatively explain the microstructure formation without using modeling, quantitative understanding of this combined behavior and its dynamic dependence on temperature and composition of steels is required to control the J. Mater. Res., Vol. 17, No. 9, Sep 2002
http://journals.cambridge.org
Downloaded: 22 Mar 2015
microstructure formation and in turn, the mechanical and physical properties of products by modeling. In these modeling works, Umemoto et al. studied the effect of cooling rate and austenite grain size on the resultant ferrite grain size.1,2 Jacot and Rappaz provided a two-phase model for the prediction of microstructural evolution in an Fe–C alloy, which undergoes a diffusive phase transformation.3 However, their works could not provide an complete understanding of nucleation and growth of ferrite grains. In
Data Loading...
