Tag Archives: hardness

758-768 A. Kešner, R. Chotěborský, M. Linda and M. Hromasová
Using the FEM model for design the heat treatment of an agricultural tools
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Using the FEM model for design the heat treatment of an agricultural tools

A. Kešner¹*, R. Chotěborský¹, M. Linda² and M. Hromasová²

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

Abstract:

Agricultural tools need mechanical properties such as abrasive wear, hardness and toughness. These mechanical properties are achieved by choosing a suitable steel and subsequent heat treatment of the steel. Phases of the microstructure affects the final steel properties. The phase composition in the steel is influenced with the designing of the heat treatment. 25CrMo4 steel was investigated for the production of agricultural tools. The heat treatments ware designed for different cooling conditions. The salt bath was used to cooling as a medium with subsequent cooling on the water or in the air. The FEM method was used to designing the heat treatment conditions. The Johnson-Mehl-Avrami-Kolmogorov equation and the Koistinen-Marburger equations were used to prediction the microstructure phases. The microstructures were verified with experimental measurements. The ASTM G65 method was using for abrasion resistance tests. The results show that this procedure can be used to designing parameters of heat treatment of agricultural tools.

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1078–1087 M. Müller and R. Chotěborský
Impact strength behaviour of structural adhesives
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Impact strength behaviour of structural adhesives

M. Müller* and R. Chotěborský

Department of Material Science and Manufacturing Technology, Faculty of
Engineering, Czech University of Life Sciences, Kamýcká 129, CZ 165 21 Prague,
Czech Republic
*Correspondence: muller@tf.czu.cz

Abstract:

A cohesive force at an adhesive bond is one of the limit for a strength of an adhesive bonding. This study is focused on an impact force of an adhesive. Samples without a notch were cast in the casting mould at a laboratory temperature with a normal pressure. The instrumentation microcharpy test equipment was used for the evaluation of the impact force. The samples were tempered at a laboratory temperature, 40 °C and 60 °C. Results showed that the temperature of the specimens influenced the impact strength, the toughness and the maximum deformation of the adhesives. Higher temperature decreased the impact force but it increased the toughness. The hardness Shore D of commercial filled two-component epoxies is comparable. A nonhomogeneity of adhesives distinguished for a porosity was found by the investigation of a fracture surface.

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