Usporedba mikrostrukture i svojstava dvaju konstrukcijskih čelika otpornih na trošenje

master's thesis

• Title (english): Comparison of microstructure and properties of two wear resistance structural steels
• Author: Helena Lukšić
• Mentor: Vera Rede (mentor)
• Granter: University of Zagreb; Faculty of Mechanical Engineering and Naval Architecture; Zagreb
• Defense date and country: 2021-12-16, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Mechanical Engineering

Abstract

Cilj ovoga diplomskoga rada bio je odrediti i usporediti mikrostrukturu, tvrdoću i otpornost na
abrazijsko trošenje dvaju konstrukcijskih čelika poboljšane otpornosti na abrazijski
mehanizam trošenja – čelika Hardox 450 i čelika XAR 450. Ispitivanje otpornosti na abraziju
provedeno je standardnom metodom „suhi pijesak – gumeni kotač“ te na uređaju Taber
abrader.
Oba čelika imaju sličnu homogenu sitnozrnatu martenzitnu mikrostrukturu.
Kod obaju čelika dobivene su podjednake vrijednosti tvrdoće HV2 u svim karakterističnim
presjecima ploče. Vrijednosti tvrdoća HV0,2 i HV1 nešto su više od vrijednosti tvrdoće HV2,
no puno veća su i rasipanja rezultata.
Ispitivanje otpornosti na abraziju metodom „suhi pijesak – gumeni kotač“ pokazuje da čelik
Hardox 450, u odnosu na čelik XAR 450, ima manji gubitak volumena za oko 8 %, ali
rasipanja rezultata kod ovog čelika su puno veća nego kod čelika XAR 450.
Pri ispitivanju otpornosti na abraziju na uređaju Taber abrader, oba čelika pokazala su vrlo
sličnu otpornost. Također, kod obaju čelika može se uočiti fenomen „kritične veličine
abrazivnog zrna“. Kritična veličina abrazivnog zrna slična je kod oba čelika i nalazi se između
21,8 μm i 30,2 μm.

Abstract (english)

The aim of this master's thesis was to determine and compare microstructure, hardness and resistance to abrasion wear of two structural steels of improved resistance to the abrasion wear mechanism – the Hardox 450 steel and the XAR 450 steel. The abrasion resistance test was carried out using the standard "dry sand – rubber wheel" method and on the Taber abrader.
Both steels have a similar homogeneous fine-grained martensitic microstructure.
In both steels, equal values of HV2 hardness were obtained in all characteristic sections of the plate. The hardness values of HV0.2 and HV1 were slightly higher than the value of HV2 hardness, but the scattering of results was much higher.
Abrasion resistance testing using the "dry sand - rubber wheel" method shows that the Hardox 450 steel, compared to the XAR 450 steel, has a lower volume loss of about 8 %, but the scattering of results in this steel was much higher than in steel XAR 450.
When testing abrasive wear resistance on the Taber abrader, both steels showed very similar resistance. Also, in both steels, the phenomenon of "critical size of abrasive grain" can be observed. The critical size of the abrasive grain is similar in both steels and is located between 21.8 μm and 30.2 μm.

• Keywords: konstrukcijski čelici; otpornost na abrazijsko trošenje; tvrdoća
• Keywords (english): structural steels; abrasion wear resistance; hardness
• Language: croatian
• URN:NBN: urn:nbn:hr:235:350847
• Study programme: Title: Mechanical Engineering; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra inženjer/inženjerka strojarstva (magistar/magistra inženjer/inženjerka strojarstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2021-12-13 20:07:03