2 results
Search Results
Now showing 1 - 2 of 2
Article Citation - WoS: 6Citation - Scopus: 7Role of Metal Quality and Porosity Formation in Low Pressure Die Casting of A356: Experimental Observations(Polska Akad Nauk, Polish Acad Sciences, 2021) Gursoy, O.; Nordmak, A.; Syvertsen, F.; Colak, M.; Tur, K.; Dispinar, D.Porosity is one of the major problems in casting operations and there are several discussions in the literature about the porosity formation in aluminum castings. Bifilms are the defects that are introduced into the melt by turbulence. They can be detected with reduced pressure test and presented numerically by measuring bifilm index. The measure of bifilm index is the sum of total oxide length given in millimeters from the cross-section of reduced pressure test sample solidified under 0.01 MPa. In this work, low pressure die casting (LPDC) unit was built in an attempt to enhance the producibility rate. The unit consists of a pump housing that was placed inside the melt in the melting furnace where the pressure was applied instead of the whole melt surface. It was observed that the melt quality of A356 alloy was deteriorated over time which had led to higher porosity. This was attributed to the increased oxide thickness of the bifilm by the consumption of air in between the folded oxides. A relationship was found between bifilm index and pore formation.Article Citation - WoS: 7Citation - Scopus: 8Evolution of Aluminium Melt Quality of A356 After Several Recycling(Polska Akad Nauk, Polish Acad Sciences, 2020) Gursoy, O.; Erzi, E.; Tur, K.; Dispinar, D.Recyclability is one of the great features of aluminium and its alloys. However, it has been typically considered that the secondary aluminium quality is low and bad. This is only because aluminium is so sensitive to turbulence. Uncontrolled transfer and handling of the liquid aluminium results in formation of double oxide defects known as bifilms. Bifilms are detrimental defects. They form porosity and deteriorate the properties. The detection and quantification of bifilms in liquid aluminium can be carried out by bifilm index measured in millimetres as an indication of melt cleanliness using Reduced Pressure Test (RPT). In this work, recycling efficiency and quality change of A356 alloy with various Ti additions have been investigated. The charge was recycled three times and change in bifilm index and bifilm number was evaluated. It was found that when high amount of Ti grain refiner was added, the melt quality was increased due to sedimentation of bifilms with Ti. When low amount of Ti is added, the melt quality was degraded.
