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— | tutorials:t20 [2020/08/13 14:54] – [T20: Simulating grain growth] pwarczok | ||
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+ | ===== T20: Simulating grain growth ===== | ||
+ | //This tutorial was tested on\\ | ||
+ | MatCalc version 6.03 rel 1.000\\ | ||
+ | license: free\\ | ||
+ | database: mc_fe.tdb; mc_fe.ddb// | ||
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+ | ==== Complimentary files ==== | ||
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+ | Click {{: | ||
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+ | ==== Contents ==== | ||
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+ | * Single-class model for grain growth | ||
+ | * Solute drag effect on grain growth | ||
+ | * Pinning of grain of grain boundary by precipitates | ||
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+ | ===== Setting up the system ===== | ||
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+ | From the database mc_fe.tdb, select Fe, Nb and C as elements and the phase FCC_A1 phase. Read in the mobility database mc_fe.ddb. Set the system composition to 0.1 wt.% C and 0.04 wt.% Nb. Create a precipitation domain named ' | ||
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+ | ===== Grain growth of pure Fe-matrix ===== | ||
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+ | The simplest possible scenario for grain growth will be considered first: a single-phase, | ||
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+ | In **' | ||
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+ | {{: | ||
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+ | Next, in the **'MS Evolution' | ||
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+ | {{: | ||
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+ | Using **Calc > precipitation kinetics**, set up an isothermal simulation with an end-time of 3600 s (1 hour) and a temperature of 900°C. Click on **' | ||
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+ | Create a plot of type ' | ||
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+ | Label the existing series as **' | ||
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+ | {{: | ||
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+ | Clearly, the temperature increases the growth rate. A curious MatCalc user is encouraged to check if changing Nb and C contents to negligible values, like 1e-10 wt.%, gives the same output. | ||
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+ | ===== Grain growth of supersaturated Fe-matrix - solute drag effect ===== | ||
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+ | In this tutorial, the effect of solutes atom on the grain growth will be implemented in the framework proposed by Cahn. In this approach, the energies describing the interaction of grain boundary with the solute atoms are used. Open the **' | ||
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+ | {{: | ||
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+ | For a better overview, remove the series representing 1000 and 1100°C from the plot. Setup again the isothermal simulation for 3600 s at 900°C. Start the simulation and plot the grain diameter series next to the existing one. | ||
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+ | {{: | ||
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+ | One can notice, that the simulated solute drag effect of Nb atoms slowed down the growth rate and the final grain diameter after 1 hour is expected to be around 170 micrometers - almost a half of the grain size for the pure iron matrix simulated previously. | ||
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+ | ===== Grain growth in presence of precipitates - grain boundary pinning ===== | ||
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+ | The final simulation demonstrates the effect of the precipitates on the grain growth. | ||
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+ | {{: | ||
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+ | Once again, setup the isothermal simulation for 3600 s at 900°C and plot the grain diameter of austenite when the calculation is completed. | ||
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+ | {{: | ||
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+ | A further decrease of the grain rate can be observed, once the precipitate phase is present. On the first sight, one might get an impression that the effect of the precipitates is not that big. However, it must be remarked that the precipitates were created in this simulation and phase fraction of these has a minor value of almost 4e-6 after one hour, compared to around 4e-4 in equilibrium at this temperature. The difference in the grain sizes gets more and more significant, | ||
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+ | ===== Subsequent articles ===== | ||
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+ | Go to the [[: |