Utjecaj modifikacije eutektika na mikrostrukturu i mehanička svojstva AlSi12 legure

master's thesis

• Title (english): Influence of modification of eutectic on microstructure and mechanical properties of AlSi12 alloy
• Author: Alan Mirić
• Mentor: Branko Bauer (mentor)
• Granter: University of Zagreb; Faculty of Mechanical Engineering and Naval Architecture; Zagreb
• Defense date and country: 2021-07-14, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Metallurgy; Physical Metallurgy

Abstract

Lijevanje je jedan od najstarijih procesa oblikovanja metala, a nekada je to bila umjetnost koja se čuvala kao čuvana tajna među obiteljima. Događaji u drugoj polovici prošlog stoljeća podigli su proces lijevanja od umjetnosti do znanosti. Kako bi ostala konkurentna na današnjem tržištu moderna ljevaonica mora u potpunosti iskoristiti sve prilike koje joj pruža moderna tehnologija. Ona omogućava detaljniju, bržu i raniju analizu problema u dizajnu odljevka i uljevnog sustava, omogućujući tako bolje donošenje odluka o poboljšanju samog dizajna i kvalitete. Stoga su troškovi i rizici svedeni na minimum.
U teorijskom dijelu kratko je opisan uvod u lijevanje, objašnjena je svrha pripreme i obrade taline kao i rezultat njihovog utjecaja na svojstva odljevka. Također su objašnjena svojstva aluminijskih legura sa detaljnijim opisom AlSi12 legure.
U drugom dijelu diplomskog rada je proveden eksperiment u Ljevaonici Bujan d.o.o. Istražen je utjecaj modifikacije eutektika AlSi12 legure dodavanjem natrija te je promatrano slabljenje djelovanja natrija s vremenom. Uzorci taline iz peći uzimani su u razmacima približno deset minuta. Napravljena je toplinska analiza svake taline, zatim analiza kemijskog sastava, analiza mikrostrukture i statički vlačni pokus.
Prema dobivenim rezultatima zaključeno je kako je utjecaj natrija nestao 23 minute nakon obrade taline te sukladno tome se vidi nestajanje vlaknastog silicija te ponovna pojava igličastoj silicija u mikrostrukturi eutektika.

Abstract (english)

Metal casting is one of the oldest metal shaping processes and it used to be an art that was kept as a secret among families. Events in the second half of past century elevated the casting process from art to science. In order to remain competitive in today's market, modern foundries must take full advantage of all of the opportunities that modern technology has to offer. It enables a more detailed and a faster analysis of design problems, thus enabling better decision-making to improve the design and quality itself. Therefore, costs and risks are minimized.
In this thesis, the influence of modifications of the eutectic of AlSi12 alloy by the addition of sodium was investigated as well as the influence of the cooling rate of the casting on the mechanical and metallurgical properties.
In the second part of the thesis, an experiment in the Ljevaonica Bujan d.o.o. was conducted. The influence of modifications of eutectic AlSi12 alloys by the addition of sodium was investigated and the weakening of sodium action with time was observed. Melting samples from the furnace were taken at intervals of approximately ten minutes. Thermal analysis of each melt was performed, followed by an analysis of chemical composition, microstructure and and a static tensile strenght experiment.
According to the obtained results, it was concluded that the influence of sodium disappeared 23 minutes after the melt treatment, and accordingly the disappearance of fibrous silicon and the reappearance of needle silicon in the microstructure of eutectic can be seen.

• Keywords: lijevanje; Al-Si legure; eutektik; modifikacija
• Keywords (english): casting; Al-Si alloys; eutectic; modification
• Language: croatian
• URN:NBN: urn:nbn:hr:235:440893
• 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: 2021-07-09 13:48:09