Tag Archives: quenching

1033–1040 A. Kešner,, R. Chotěborský and M. Linda
Determining the specific heat capacity and thermal conductivity for adjusting boundary conditions of FEM model
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Determining the specific heat capacity and thermal conductivity for adjusting boundary conditions of FEM model

A. Kešner¹,*, R. Chotěborský¹ and M. Linda²

¹ Department of Material Science and Manufacturing Technology Faculty of
Engineering, Czech University of Life Sciences Prague, Kamýcká 129, CZ165 21 Prague – Suchdol, Czech Republic
² Department of Electrical Engineering and Automation, Faculty of Engineering, Czech University of Life Sciences Prague, Kamýcká 129, CZ165 21 Prague – Suchdol, Czech Republic
*Correspondence: kesner@tf.czu.cz

Abstract:

One of modern way of the heat treatment process of agricultural tools such as chisels or tines is FEM modelling. FEM models needs the accurate boundary conditions for successful solution. Specific heat capacity and thermal conductivity are important parameters for the design of the physical properties of heat treatment. These parameters are used for the formation of the temperature field during the cooling process at the heat treatment. More accurate parameters allow you to better estimate the final microstructure in the entire cross-section of the material. Specific heat capacity and thermal conductivity are known from material sheets, but they are stated as constant values. This is the reason why this work is focused on the determination of specific heat capacity and thermal conductivity of steel during the quenching. For the experiment in this work was chosen material 25CrMo4. The values of specific heat capacity and thermal conductivity were determined by comparing the experimentally measured cooling curves and cooling curves generated by the mathematical model. The dependences of specific heat capacity and thermal conductivity were compared in temperature, so that the relationships of cooling curves were statistically significant under alfa level 0.05.

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1004–1014 A. Kešner, R. Chotěborský and M. Linda
Determination of the heat flux of steel for the heat treatment model of agricultural tools
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Determination of the heat flux of steel for the heat treatment model of agricultural tools

A. Kešner¹*, R. Chotěborský¹ and M. Linda²

¹Department of Material Science and Manufacturing Technology Faculty of Engineering, Czech University of Life Sciences Prague, Kamýcká 129, CZ 165 21 Prague – Suchdol, Czech Republic
²Department of Electrical Engineering and Automation, Faculty of Engineering, Czech University of Life Sciences Prague, Kamýcká 129, CZ 165 21 Prague – Suchdol, Czech Republic;
*Correspondence: kesner@tf.czu.cz

Abstract:

 Chisels and tines for agricultural machinery are mechanically worn. Mechanical wear depends on the microstructure of the material. The desired microstructure of the material, specifically steel is obtained by heat treatment. Microstructure after heat treatment can be determined in two ways. The first one is the experimental determination, which is timeconsuming and not economically efficient. The second is to build the thermal model during the heat treatment. Microstructure is affected during the heat flux during heat treatment. This research was focused on the boundary conditions of the model heat flux during quenching. The heat flux was measured during quenching with solid cylindrical samples (ø25–50 mm) by means of two thermocouples. The first temperature was measured in the axis of the sample and the second temperature was measured near the sample surface. The results of the heat flux were appointed to the model and experimentally verified. In this way it is possible to construct a model of tines and chisels for agricultural machine, which shows the progress of the heat flux during quenching.

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