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master's thesis
Usporedba mikrostrukture i tvrdoće čelika Hardox 450 i čelika XAR 450
Zagreb: University of Zagreb, Faculty of Mechanical Engineering and Naval Architecture, 2022. urn:nbn:hr:235:483273
Stojaković, Mario
University of Zagreb
Faculty of Mechanical Engineering and Naval Architecture

Institutional repository: Repository of Faculty of Mechanical Engineering and Naval Architecture University of Zagreb

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Stojaković, M. (2022). Usporedba mikrostrukture i tvrdoće čelika Hardox 450 i čelika XAR 450 (Master's thesis). Zagreb: University of Zagreb, Faculty of Mechanical Engineering and Naval Architecture. Retrieved from https://urn.nsk.hr/urn:nbn:hr:235:483273

Stojaković, Mario. "Usporedba mikrostrukture i tvrdoće čelika Hardox 450 i čelika XAR 450." Master's thesis, University of Zagreb, Faculty of Mechanical Engineering and Naval Architecture, 2022. https://urn.nsk.hr/urn:nbn:hr:235:483273

Stojaković, Mario. "Usporedba mikrostrukture i tvrdoće čelika Hardox 450 i čelika XAR 450." Master's thesis, University of Zagreb, Faculty of Mechanical Engineering and Naval Architecture, 2022. https://urn.nsk.hr/urn:nbn:hr:235:483273

Stojaković, M. (2022). 'Usporedba mikrostrukture i tvrdoće čelika Hardox 450 i čelika XAR 450', Master's thesis, University of Zagreb, Faculty of Mechanical Engineering and Naval Architecture, accessed 20 December 2024, https://urn.nsk.hr/urn:nbn:hr:235:483273

Stojaković M. Usporedba mikrostrukture i tvrdoće čelika Hardox 450 i čelika XAR 450 [Master's thesis]. Zagreb: University of Zagreb, Faculty of Mechanical Engineering and Naval Architecture; 2022 [cited 2024 December 20] Available at: https://urn.nsk.hr/urn:nbn:hr:235:483273

M. Stojaković, "Usporedba mikrostrukture i tvrdoće čelika Hardox 450 i čelika XAR 450", Master's thesis, University of Zagreb, Faculty of Mechanical Engineering and Naval Architecture, Zagreb, 2022. Available at: https://urn.nsk.hr/urn:nbn:hr:235:483273

Metadata
TitleUsporedba mikrostrukture i tvrdoće čelika Hardox 450 i čelika XAR 450
Title (english)Comparison of the microstructure and hardness of Hardox 450 and XAR 450 steels
AuthorMario Stojaković
MentorVera Rede (mentor)
GranterUniversity of Zagreb
Faculty of Mechanical Engineering and Naval Architecture
Zagreb
Defense date and country2022-12-15, Croatia
Scientific / art field,
discipline and subdiscipline		TECHNICAL SCIENCES
Mechanical Engineering
Abstract
Cilj ovoga diplomskog rada bio je analizirati i usporediti kemijski sastav, mikrostrukturu te mikrotvrdoću i makrotvrdoću dvaju konstrukcijskih čelika otpornih na trošenje: čelika Hardox 450 i čelika XAR 450. Utvrđeno je da su oba čelika niskougljična. Čelik Hardox 450 sadrži više ugljika, oko 0,14 %C. U čeliku XAR 450 ima oko 0,08 %C, ali sadrži tri puta viši udio karbidotvornih legirnih elemenata (Cr i Mo). Mikrostruktura obaju čelika je slična i sastoji se od niskougljičnog martenzita. Zbog visoke tvrdoće moguće je da u strukturi postoji i određena količina precipitiranih karbida, ali njih je teško uočiti na svjetlosnom mikroskopu. Tvrdoće HV1, HV0,5 i HV0,2 podjednake su za oba čelika i iznose oko 500 HV. Tvrdoće obaju čelika podjednake su i kod nižih opterećenja, a iznose 547 HV0,05 odnosno oko 620 HV0,02. Porastom opterećenja pri mjerenju smanjuju se vrijednosti tvrdoće do opterećenja od 4,91 N (HV0,5) nakon čega tvrdoća ostaje konstantna. Smanjenjem opterećenja pri mjerenju tvrdoće povećavaju se rasipanja vrijednosti, što je posljedica nehomogenosti u mikrostrukturi i mogućih nepreciznijih očitanja sitnijih otisaka kod najnižih opterećenja. Veća rasipanja prisutna su kod čelika XAR 450 pa su i vrijednosti standardne devijacije te koeficijenata varijacije više.
Abstract (english)
The aim of this thesis was to analyze and compare the chemical composition, microstructure, microhardness, and macro hardness of two wear-resistant structural steels: Hardox 450 steel and XAR 450 steel. Both steels were found to be low in carbon. Hardox 450 steel contains more carbon, about 0.14 %C. In XAR 450 steel, there is about 0.08% C, but it contains three times the proportion of carbideforming alloying elements (Cr and Mo). The microstructure of both steels is similar and consists of low-carbon martensite. Due to the high hardness, it is possible that there is a certain amount of precipitated carbides in the structure, but they are difficult to see under a light microscope. The hardness HV1, HV0.5, and HV0.2 are equal for both steels and around 500 HV. The hardness of both steels is equal even at lower loads, exactly 547 HV0.05 and around 620 HV0.02. As the measurement load increases, the hardness values decrease up to a load of 4.91 N (HV0.5), after which the hardness remains constant. By reducing the load when measuring the hardness, the dispersion of values increases, which is a consequence of inhomogeneity in the microstructure and possible less precise measurement of smaller prints at the lowest loads. Larger dispersions of values are present in XAR 450 steel, so the values of standard deviation and coefficient of variation are also higher.
Keywords
Keywords (english)
Languagecroatian
URN:NBNurn:nbn:hr:235:483273
Study programmeTitle: Mechanical Engineering; specializations in: Design, Process and Energy Engineering, Production Engineering, Engineering Modelling and Computer Simulation, Marine Engineering, Industrial Engineering and Management, Materials Engineering, Mechatronics and Robotics, Autonomous Systems
Course: Materials Engineering
Study programme type: university
Study level: graduate
Academic / professional title: magistar/magistra inženjer/inženjerka strojarstva (magistar/magistra inženjer/inženjerka strojarstva)
Type of resourceText
File originBorn digital
Access conditionsOpen access
Terms of useLicence In copyright icon
Created on2022-11-30 13:02:12