magistrsko delo
Gregor Hvala (Avtor), Maja Vončina (Mentor)

Povzetek

Aluminijevi livarski zlitini AlSi10Mg in AlSi12 sta v livarstvu zelo pogosto uporabljeni v avtomobilski industriji. Lije se ju s tehnologijo tlačnega litja. Na trgu so prisotne tako primarne kot sekundarne/reciklirane aluminijeve zlitine, ki se razlikujejo v ceni in kakovosti. Ker obstajajo določene razlike v kakovosti teh zlitin, je bila v tem delu opravljena analiza vpliva kakovosti zlitine na strjevanje, mikrostrukturo in mehanske lastnosti. Primerjava omenjenih lastnosti je potekala v litem stanju in v toplotno obdelanem stanju. Vpliv kakovosti zlitine na strjevanje je bil analiziran z enostavno termično analizo in diferenčno vrstično kalorimetrijo. Glavne mehanske lastnosti, ki so bile analizirane, so natezna trdnost, meja plastičnosti, raztezek in trdota. Predhodne raziskave kažejo, da imajo reciklirane zlitine okoli 10–15 % nižje trdnostne lastnosti zaradi vsebnosti večjega deleža nečistoč, med katere velja izpostaviti predvsem železo, kateremu se je v sekundarnih zlitinah težko izogniti. Tvori namreč intermetalne faze, ki negativno vplivajo na mehanske lastnosti. Mikrostrukturne razlike so bile analizirane z uporabo svetlobnega mikroskopa. Medsebojno smo primerjali zlitini AlSi10Mg in AlSi12 z njunima izvedenkama izdelanima iz sekundarnih surovin (AlSi10Mg(Fe) in AlSi12(Fe)), z večjim deležem železa, ki slabša mehanske lastnosti. V zlitinah se njegov vpliv kompenzira z manganom, ki omogoča, da se namesto ostrih iglic ß-Al5FeSi tvori bolj zaželena, zaobljena Fe-faza ?-Al15(Fe,Mn)3Si2 v obliki kitajske pisave. Pri zlitini AlSi10Mg je pokazano, da ima razmerje Mn:Fe izrazit vpliv na mehanske lastnosti, magnezij pa med toplotno obdelavo izločevalno utrjuje aluminijevo matrico, kar bistveno zvišuje mehanske lastnosti. Zlitina AlSi12 pa ni izločevalno utrjevalna, zato se po toplotni obdelavi mehanske lastnosti bistveno ne izboljšajo.

Ključne besede

kakovost zlitine;livarske zlitine;strjevanje;mikrostruktura;mehanske lastnosti;

Podatki

Jezik: Slovenski jezik
Leto izida:
Tipologija: 2.09 - Magistrsko delo
Organizacija: UL NTF - Naravoslovnotehniška fakulteta
Založnik: [G. Hvala]
UDK: 669
COBISS: 67164163 Povezava se bo odprla v novem oknu
Št. ogledov: 395
Št. prenosov: 106
Ocena: 0 (0 glasov)
Metapodatki: JSON JSON-RDF JSON-LD TURTLE N-TRIPLES XML RDFA MICRODATA DC-XML DC-RDF RDF

Ostali podatki

Sekundarni jezik: Angleški jezik
Sekundarni naslov: influence of input material on solidification, microstructure and mechanical properties of AlSi12 and AlSi10Mg alloys
Sekundarni povzetek: Aluminium casting alloys AlSi10Mg and AlSi12 are frequently used in the automotive industry (in casting applications). There are both: primary as well as secondary/recycled aluminium alloys on the market, that vary in price and quality. As there are certain differences in the quality of these alloys, an analysis about the influence of quality on solidification, microstructure and mechanical properties was implemented in this research work. The comparison of the mentioned properties took place in the as-cast state and the heat treated state. The influence of alloy quality on solidification was analyzed by simple thermal analysis and differential scanning calorimetry. The basic mechanical properties analyzed were tensile strength, yield strength, elongation and hardness. Preliminary research determined that recycled alloys have around 10–15% lower strength properties due to higher share of iron, which is challenging to avoid in secondary alloys. It forms intermetallic phases that negatively affect the mechanical properties. Microstructural differences were analyzed using an optical microscope. AlSi10Mg and AlSi12 alloys with their derivatives made of secondary aluminium (AlSi10Mg(Fe) and AlSi12(Fe)) were compared, which contain a higher proportion of iron, which impairs mechanical properties. In alloys, its effect is compensated by manganese, which allows the formation of a more desirable, rounded Fe-phase α-Al15(Fe,Mn)3Si2 in the form of Chinese script instead of sharp β-Al5FeSi needles. In the case of the AlSi10Mg alloy, the Mn:Fe ratio has been shown to have a pronounced effect on the mechanical properties, while magnesium hardens the aluminium matrix during heat treatment, which significantly increases the mechanical properties. However, the AlSi12 alloy is not a precipitation hardenable alloy, so the mechanical properties do not improve significantly after heat treatment.
Sekundarne ključne besede: alloy quality;casting alloys;solidification;microstructure;mechanical properties;
Vrsta dela (COBISS): Magistrsko delo/naloga
Študijski program: 0
Komentar na gradivo: Univ. v Ljubljani, Naravoslovnotehniška fak., Oddelek za materiale in metalurgijo
Strani: XVII, 61 f.
ID: 13028200