Termodinamična karakterizacija zlitine AlSi12Cu1(Fe) različnih kvalitet in vpliv na končne lastnosti izdelkov : magistrsko delo

Cergol, Anej (author), Vončina, Maja (mentor), Petrič, Mitja (co-mentor)

Na kakovost končnih izdelkov vpliva mnogo dejavnikov. Eden izmed njih je livarski stroj, a kljub ustreznim livnim parametrom in pravilnemu delovanju livarskega stroja še vedno v določenih primerih ne dosegamo ustrezne kakovosti ulitkov (krčilna in plinska poroznost, nečistoče v ulitkih …). Drugi zelo pomemben dejavnik je priprava taline na litje, pri čemer morajo biti proces taljenja, razplinjevanja in transporta ustrezni. Na kakovost izdelkov pa ima velik vpliv tudi kakovost vhodnega materiala, česar analiza je bila tudi tema te magistrske naloge. Analiziran je bil vpliv kakovosti vhodnega materiala (ingotov) na kakovost ulitkov, pri čemer je prišlo do napak na ulitkih in posledično do izmeta, čeprav so bili vsi zgoraj omenjeni dejavniki (delovanje livarskega stroja in priprava taline na litje) vedno enaki. V prvem delu naloge smo spremljali proces izdelave ulitka (od pretaljevanja do končne mehanske obdelave) iz zlitine AlSi12Cu1(Fe). V primeru povečanega odstotka izmeta po končni mehanski obdelavi smo odvzeli ingot iz dobavljene zlitine, ki se je pretaljevala v tem obdobju. Na odvzetih ingotih smo analizirali stanje površine, prisotnost nečistoč na površini ingota ter v notranjosti in odstotek poroznosti. V drugem delu naloge smo analizirali vpliv kakovosti materiala na strjevanje in mikrostrukturo, ki imata neposreden vpliv na mehanske lastnosti izdelkov. Spremljali smo tudi količino nastale žlindre pri pretaljevanju. Glavni cilj naloge je bil ugotoviti, kako vpliva kakovost vhodnega materiala na pojavnost napak na končnih izdelkih. Ugotovili smo, da kakovost vhodnega materiala izrazito vpliva na celoten izkoristek (taljenja in litja) procesa izdelave določenega izdelka ter na pojavnost napak na izdelkih in posledično na izmet. Kakovost vhodnega materiala mora biti dobra in ustrezna, saj slabe kakovosti materiala med procesom taljenja ne moremo v celoti odpraviti.

• Language: Slovenian
• Keywords: zlitina AlSi12Cu1(Fe), termodinamika, strjevanje, mikrostruktura, kakovost vhodnega materiala, lastnosti izdelkov
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: NTF - Faculty of Natural Sciences and Engineering
• Place of publishing: Ljubljana
• Publisher: [A. Cergol]
• Year: 2021
• Number of pages: XVI, 62 f.
• PID: 20.500.12556/RUL-128350
• UDC: 669
• COBISS.SI-ID: 71780355
• Publication date in RUL: 09.07.2021

Secondary language

• Language: English
• Title: Thermodynamic characterization of AlSi12Cu1(Fe) alloy of different qualities and influence on final product properties : master's thesis

Abstract

The quality of the finished products is influenced by many factors. One of them is casting machine, but even in case of using appropriate casting parameters and it’s correct operation, in certain cases the appropriate quality of castings (shrinkage porosity, impurities in the castings …) is not achieved. Another very important factor influencing the quality of castings is preparation of the melt, where the melting process, degassing process, and transportation of melt to the casting machine must be appropriate. On quality of the products has a great influence also quality of the incoming material, which analysis was the topic of this master's thesis. Influence of the incoming material (ingots) quality on the quality of the castings was analyzed, whereby defects occurred in the castings and consequently the scrap, although all the above-mentioned factors (operation of the casting machine and preparation of the melt for casting) were always the same. In the first part of the thesis, the production process (from melting process to final machining process) from AlSi12Cu1(Fe) alloy. In the case of an increased scrap percentage after final machining process, the ingot from the batch that was melted in this period was taken. On seized ingots, the condition of the surface, the presence of impurities on the surface as well as inside of the sample and the percentage of porosity were analyzed. In the second part of the thesis, the influence of material quality on solidification and microstructure, which have a direct impact on the mechanical properties of the products, were analyzed. The amount of slag formed during the re-melting was also monitored. The main objective of the thesis was to determine how the quality of certain alloy batches influence the occurrence of defects in the final products. It was established, that the quality of the incoming material significantly affects the overall manufacturing efficiency (melting and casting), the occurrence of the defects in the products and consequently on the scrap rate. The quality of the incoming material must be of good and adequate, as the poor quality of the material cannot be completely corrected during the melting process.

• Keywords: alloy AlSi12Cu1(Fe), thermodynamics, solidification, microstructure, incoming material quality, product properties