Coefficient of thermal expansion in austenite transformation

solid-solid phase transformations, influence of stresses and strains
Shenyz
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Joined: Mon Jul 25, 2016 4:33 pm
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Coefficient of thermal expansion in austenite transformation

Postby Shenyz » Tue Oct 10, 2017 4:37 pm

Hello, I would like to ask a question, I want to simulate the process of austenite to ferrite transformation, in the simulation of the coupling of the stress, so in the material data for elasticity recommendations plate need to fill the austenite thermal expansion coefficient .
The coefficient of thermal expansion is defined as the ratio of the length of a solid matter to a length at 20 ° C (ie, a standard laboratory environment) when the temperature changes by 1 degree Celsius. Now we will record the length of the material at 20 ℃ as L0.
For the thermal expansion coefficient of austenite, I collected the experimental data from the literature, L0 is the length of the material at 20 ℃, but this time the material is all ferrite, so I would like to ask, the program in this The corresponding L0 of the thermal expansion coefficient of the austenite to be filled is the length of the ferrite at 20C or the length of the austenite at20 ℃?

Bernd
Posts: 803
Joined: Mon Jun 23, 2008 9:29 pm

Re: Coefficient of thermal expansion in austenite transformation

Postby Bernd » Tue Oct 10, 2017 4:58 pm

Dear Shenyz,

The definition of the coefficient of thermal expansion does not need a reference temperature. Instead, molar volume and thermal expansion of each phase should be determined at the temperature at which they exist in your simulation. Of course, experimental values are also only available at temperatures where the corresponding phases exist.
In case your simulation spans a temperature range where molar volume and the thermal expansion coefficient are changing significantly, you can input the T-dependent molar volume as a table, and MICRESS will calculate the thermal expansion coefficient automatically from the table (keyword "from_file").
Alternatively, in case you use a thermodynamic database with description of volumes like TCFE8, you can take the molar volume directly from the database without need of searching for literature values, and thermal expansion coefficient are also be calculated automatically (keyword "database").

Best wishes
Bernd


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