Mikrostruktura i svojstva nodularnog lijeva legiranog silicijem i molibdenom

master's thesis

• Title (english): Microstructure and properties of ductile iron alloyed with silicon and molybdenum
• Author: Fabijan Kumer
• Mentor: Zoran Glavaš (mentor)
• Committee member: Ivan Jandrlić (predsjednik povjerenstva)
• Committee member: Zoran Glavaš (član povjerenstva)
• Committee member: Martina Lovrenić-Jugović (član povjerenstva)
• Granter: University of Zagreb; Faculty of Metallurgy; Sisak
• Defense date and country: 2019-07-26, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Metallurgy

Abstract

U ovom diplomskom radu analizirana je mikrostruktura i ispitana su vlačna
svojstva, tvrdoća, žilavost i otpornost na oksidaciju na 850 °C nodularnih ljevova legiranih
sa 4,28, 4,49 i 4,81 mas. % Si i 0,6 mas. % Mo. Pored toga, ispitana je otpornost na
oksidaciju na 850 °C feritnog nodularnog lijeva sa 2,11 mas. % Si i od feritno-perlitnog
nodularnog lijeva sa 3 mas. % Si. U analiziranim SiMo nodularnim ljevovima grafitne
čestice imaju nodularni oblik. Metalna osnova sastoji se od ferita i malog udjela
globularnog perlita koji je izlučen po granicama feritnih zrna i okružuje karbide
molibdena. S porastom udjela silicija povećava se granica razvlačenja, vlačna čvrstoća,
omjer Rp0,2/Rm i tvrdoća, a smanjuje istezanje i žilavost SiMo nodularnih ljevova jer se
povećava intenzitet očvršćivanja ferita. Karbidi molibdena negativno utječu na istezanje i
žilavost SiMo nodularnog lijeva. Analizirani SiMo nodularni ljevovi imaju znatno bolju
otpornost na oksidaciju na 850 °C od feritnog nodularnog lijeva sa 2,11 mas. % Si i od
feritno-perlitnog nodularnog lijeva sa 3 mas. % Si. Otpornost na oksidaciju nodularnog
lijeva povećava se s porastom udjela silicija.

Abstract (english)

This graduate thesis analyses the microstructure, tensile properties, hardness, toughness
and oxidation resistance at 850 ° C of ductile irons alloyed with 4.28, 4.49 and 4.81 wt. %
Si and 0.6 wt. % Mo. In addition, oxidation resistance at 850 ° C of ferritic ductile iron
containing 2.11 wt. % Si and ferritic-pearlitic ductile iron containing 3 wt. % Si was also
examined. In the analysed SiMo ductile irons, the graphite particles have a nodular shape.
The metallic matrix is composed of ferrite and a small share of globular pearlite which is
present on the grain boundaries of ferrite and surrounds the molybdenum carbides. With
the increase in silicon content, yield strength, tensile strength, ratio Rp0,2/Rm and hardness
increases, and the elongation and toughness of SiMo ductile irons decreases due to increase
in intensity of strengthening of ferrite. Molybdenum carbides negatively affect elongation
and toughness of SiMo ductile irons. Analysed SiMo ductile irons have a much better
oxidation resistance at 850 ° C than the ferritic ductile iron containing 2.11 wt. % Si and
from the ferritic-pearlitic ductile iron containing 3 wt. % Si. The oxidation resistance of
ductile iron increases with increasing silicon content.

• Keywords: SiMo nodularni lijev; mikrostruktura; mehanička svojstva; otpornost na oksidaciju
• Keywords (english): SiMo ductile iron; microstructure; mechanical properties; oxidation resistance
• Language: croatian
• URN:NBN: urn:nbn:hr:115:833718
• Study programme: Title: Graduate study program Metallurgy; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra inženjer/inženjerka metalurgije (magistar/magistra inženjer/inženjerka metalurgije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2019-08-28 06:10:02