Title Ispitivanje svojstava AlSi7Mg legure Title (english) Investigation of AlSi7Mg alloy properties Author Vanja Šuica Mentor Zdenka Zovko Brodarac (mentor)Committee member Zoran Glavaš (predsjednik povjerenstva)Committee member Zdenka Zovko Brodarac (član povjerenstva)Committee member Ljerka Slokar (član povjerenstva)Granter University of Zagreb Defense date and country 2016-09-23, Croatia Scientific / art field, TECHNICAL SCIENCES Abstract Aluminijske legure su okarakterizirane izvrsnim mehaničkim, fizikalno- kemijskim i
tehnološkim svojstvima, čime su veliku primjenu pronašle u automobilskoj industriji. U
automobile se trenutno ugrađuje oko 140 kg aluminijskih legura (glava i blok motora, nosači
ležajeva, mjenjača, naplataka i slično). Bez obzira na sve kompliciraniju geometriju dij elova i
sklopova, ta je brojka stalno u porastu, zahvaljujući inovativnim tehnologijama lijevanja. Sa
sve većim udjelom dijelova od aluminijskih legura (i ostalih lakih metala i materijala) ,
performanse, sigurnost i ekološka prihvatljivost automobila raste. Geometrija odljevka utječe
na odabir odgovarajuće legure, naknadnu obradu i zahtijevana/dobivena svojstva poput
otpornosti na koroziju, otpornost na visoke temperature, čvrstoću, tvrdoću, itd., pa se uz glavni
legirajući element Si, Al - Si legurama dodaju se i sekundarni legirajući elementi ili elementi u
tragovima poput primjerice Mg. U okviru ovog rada dokazalo se da različite brzine hlađenja i
naknadna toplinska obrada imaju značajan utjecaj na postignuta svojstva odljevaka. Razvoj
mikrostrukture i njezine značajke u različitim uvjetima skrućivanja daju uvid u vođenje procesa ,
i izrazito utječu na mehanička svojstva. Mikrostrukturna analiza ukazala je na prisu t nost
sl jedećih mikrostrukturnih konstituen ata: primarni aluminij (- Al), eutektik (- Al+β- Si),
intermetalne željezne faze Al 5FeSi i Al 8FeMg 3Si 6 te sekundarnu eutektičku fazu - Al+Mg2Si. U toplinski obrađenim uzorcima uočena je veća sklonost ka izdvajanju kompleksne
intermetalne Al 8FeMg 3Si 6 faze koja, uz precipitaciju Mg , povoljno utječe na poboljšanje
mehaničkih svojstava. Sferoidizacija primarnog aluminija, bez ob zira na pogrubljivanje, ima
pozitivan učinak na mehanička svojstva. Mikrostrukturne značajke pokazale su se kao
preliminarni pokazatelj provedenih postupaka, na osnovu kojeg je moguće predvidjeti
postignuta svojstva konačnog odljevka.
Abstract (english) Aluminium alloys are characterized by excellent mechanical, physically - chemical and
technological properties, which represent the foundation for wide application in automotive
industry . Todays’ vehicles contain around 140 kg of aluminium alloys (engine head and block, bearing support, gear box, wheels etc.). In despite of more and more compl ex geometry of parts and assembl ies, th e use is in constant growth , due to innovative casting technologies. With increasing ratio of aluminium alloys parts (and other light metals and materials), performances, safety and environmental sustainability of vehicle also increase. Casting geometry influences the selection of corresponding alloy, machining and demanded/achieved properties such as corrosion resistance; high temperature resistance, strength, hardness etc., Therefore, beside addition of main alloying element Si, also secondary alloying or trace elements such as Mg are added. Within this paper it was proven that different cooling rates and heat treatment have significant influence on achieved casting properties. The development of microstructure and its features related to different solidification conditions have indicate the process management, and particularly influence on mechanical properties. Microstructural analysis has indicated the presence of following microstructural consti tuents: primary aluminium (- Al), eutectic (-Al+β- Si), intermetallic iron phase Al 5FeSi i Al 8FeMg 3Si 6 and secondary eutectic phase -Al+Mg2Si. In heat treated samples, the higher tendency toward forming complex intermetallic Al 8FeMg 3Si 6 phase was observed, which along with Mg precipitation, affects posi tively on mechanical properties. Sph eroidi z ing of primary aluminium and its coarsening , have a positive effect on mechanical properties. Microstructural features have been imposed as a preliminary indicator of processes, and represent the base for predicti on of achieved casting properties.
Keywords
AlSi7Mg legura
mehanička svojstva
mikrostruktura
toplinska obrada
Keywords (english)
AlSi7Mg alloy
mechanical properties microstructure
heat treatment
Language croatian URN:NBN urn:nbn:hr:115:138339 Study programme Title: Graduate study program Metallurgy Type of resource Text File origin Born digital Access conditions Open access Terms of use Created on 2016-09-28 11:36:59
