Optimizacija dodatka udrobnjevalca Nucleant 100 SP v zlitini AlSi10Mg

Pavšič, Aljaž (author), Vončina, Maja (mentor)

Pri izdelavi ulitkov iz zlitine AlSi10Mg s postopkom visokotlačnega litja se z namenom doseganja manjše velikosti kristalnih zrn in posledično boljših mehanskih lastnosti, v talino dodaja udrobnilno sredstvo na osnovi titana in bora Nucleant 100 SP. Materialu, ki je pretaljen zgolj iz ingotov, se ga dodaja v razmerju 100 g / 150 kg, v primeru, ko pa se ga pretaljuje v kombinaciji s krožnim izmetnim materialom pa se dodajanja zmanjša na 100 g / 150–200 kg, ker je v izmetu titan že prisoten. Da se za izdelavo ulitkov porabi vsa talina, ki je v dozirni peči visokotlačnega stroja, običajno traja dve uri, zato koncentracija titana oz. titanovih faz zaradi neraztopljenega udrobnilnega sredstva ali posedanja v ulitkih ni konstantna. V diplomskem delu smo se osredotočali na analizo vpliva kontaktnega časa po dodatku udrobnilnega sredstva talini in s tem na vpliv na lastnosti zlitine. Laboratorijsko simulacijo procesa smo izvedli s pomočjo gravitacijskega litja v Croning merilno celico in brez premešavanja taline. Zlitino AlSi10Mg smo stalili in sprva ulili brez dodatka Nucleant 100 SP, po dodatku le-tega pa smo talino ulili po 10, 20, 30, 60 in 120 minutah ter tako skušali modelirati in analizirati proces iz proizvodnje. Po litju in enostavni termični analizi, pri kateri smo spremljali predvsem velikost podhladitve, smo vzorce pripravili še za kemijsko analizo, z rezultati le-te smo izvedli termodinamične izračune. Izvedli smo še diferenčno vrstično kalorimetrijo, analizo mikrostrukturnih sestavin in meritev velikosti kristalnih zrn. Rezultati vseh preiskav so pokazali, da je najboljši kontaktni čas, po dodatku udrobnjevalca Nucleant 100 SP v zlitino AlSi10Mg, 20 minut, ker dosežemo najmanjšo podhladitev in najmanjše kristalno zrno ?-Al v mikrostrukturi.

• Language: Slovenian
• Keywords: zlitina AlSi10Mg, udrobnjevanje, termodinamični izračun, termična analiza, kristalna zrna, mikrostruktura
• Work type: High school thesis
• Typology: 2.11 - Undergraduate Thesis
• Organization: NTF - Faculty of Natural Sciences and Engineering
• Year: 2020
• PID: 20.500.12556/RUL-120902
• COBISS.SI-ID: 32961283
• Publication date in RUL: 26.09.2020

PAVŠIČ, Aljaž, 2020, Optimizacija dodatka udrobnjevalca Nucleant 100 SP v zlitini AlSi10Mg [online]. Bachelor’s thesis. [Accessed 8 April 2025]. Retrieved from: https://repozitorij.uni-lj.si/IzpisGradiva.php?lang=eng&id=120902

Secondary language

• Language: English
• Title: Optimization of grain-refiner Nucleant 100 SP addition in AlSi10Mg alloy

Abstract

When making castings of AlSi10Mg alloy with high pressure die casting (HPDC), grain-refiner Nucleant 100 SP, based on titanium and boron is used to achieve small grain size and consequently better mechanical properties. It is added in ratio 100 g per 150 kg when the melt is melted only from ingots but when scrap material is added this ratio decreases to 100 g per 150–200 kg of melt. To spend whole melt from dosing furnace of HPDC machine it usually takes about two hours so the concentration of titanium and it´s phases is not constant because of undissolved grain-refiner or settling. In this BSc thesis, we focused on contact time after grain-refiner addition to the melt and its impact on the properties of the alloy. We made a simulation of process by sand gravity casting in Croning measuring cell without mixing the melt. AlSi10Mg alloy was melted and first poured without the addition of Nucleant 100 SP and after the addition we poured melt after 10, 20, 30, 60 and 120 minutes of contact time and in that way tried to simulate the production process. After casting and ETA analysis, whereas mainly the undercooling size was monitored, we prepared specimens for chemical analysis from which the thermodynamic calculations were made. We also made differential scanning calorimetry (DSC) analysis, microstructure analysis, and the grain size measurement. The results of all research methods showed that the best contact time of the addition of Nucleant 100 SP in AlSi10Mg alloy is 20 minutes, when the minimum undercutting and the minimum α-Al crystal grain in the microstructure is achieved.

• Keywords: AlSi10Mg alloy, grain refinement, thermodynamic calculations, thermal analysis, crystal grains, microstructure