20.500.12556/RUL-183946 Vpliv temperature toplotne obdelave jekla Ck45 na mehanske lastnosti Influence of heat treatment temperature on the mechanical properties of Ck45 steel Problem predstavljajo visoke cene jekel z natančno določenimi lastnostmi. Ta problem lahko naslovimo z uporabo cenovno dostopnejših jekel, ki jim s skrbno načrtovano toplotno obdelavo izboljšamo mehanske in fizikalne lastnosti, tako da ustrezajo zahtevani aplikaciji. Diplomsko delo obravnava toplotno obdelavo jekla Ck45. Preizkušance smo kalili v dveh različnih kalilnih medijih in jih nato popuščali pri določenih temperaturah. Sledila je analiza, ki je zajemala merjenje trdote, udarne žilavosti in zaostalih napetosti. Na koncu smo z mikroskopom preučili površine lomnih mest in analizirali mikrostrukturo toplotno obdelanih vzorcev. Ugotovili smo, da je za doseganje optimalnih mehanskih lastnosti jekla ključno pravilno izbrati kalilni medij. Pomembno vlogo za želene mehanske lastnosti ima tudi temperatura popuščanja. Ugotovili smo, da najboljše ravnovesje med trdoto in žilavostjo dosežemo z zaporedjem postopkov kaljenja in popuščanja pri 500 °C. Aljaž Levstek 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 konstrukcijska jekla Ck45 toplotne obdelave kaljenja popuščanja trdote žilavosti zaostale napetosti construction steel Ck45 heat treatment hardening tempering hardeness toughness residual stresses true false false [A. Levstek] Slovenski jezik Angleški jezik Diplomsko delo/naloga 2026-06-23 08:30:38 2026-06-23 08:30:49 2026-07-02 09:01:50 0000-00-00 00:00:00 2026 0 Ljubljana 0 XXII, 60 str. 0000-00-00 NiDoloceno NiDoloceno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 621.785.616:536.4:620.17(043.2) 285788 283335939 47048.pdf 47048.pdf 1 ABEAF90652D9CE24EB2F0D0B04ECB915 b6b9236693df587a93bd103425ff25270c127cbaa7fceee7f49a2862717b09a8 037f5036-6ecd-11f1-9b0d-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=236282 Fakulteta za strojništvo 0 0 0