The problem arises from the high cost of steels with precisely defined properties. This issue
can be addressed by using more affordable steels whose mechanical and physical properties
can be improved through carefully planned heat treatment so that they meet the requirements
of the application.
This thesis examines the heat treatment of Ck45 steel. The specimens were quenched in two
different quenching media and then tempered at selected temperatures. The analysis included
hardness measurements, impact toughness testing, and residual stress measurements.
Finally, the fracture surfaces and the microstructure of the heat-treated samples were
examined using a microscope.
The results showed that choosing the correct quenching medium is essential for achieving
optimal mechanical properties. The tempering temperature also plays an important role in
obtaining the desired properties. We found that the best balance between hardness and
toughness is achieved with the sequence of quenching and tempering at 500 °C.
Aljaž Levstek
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