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In this study, different melt treatment operations were evaluated and compared to end product's scrap rate using bifilm index (BI) method. Results clearly show that degassing with finer gas bubbles increases cleaning performance for the removal of any type of bifilms in the melt. BI method is a reliable and quick way to determine melt quality at any given time during casting process which is found to have a direct correlation with rejection rate. [ABSTRACT FROM AUTHOR]

Corrosion behavior of A356 aluminum alloy with different grain refiners was evaluated. For this purpose, the Sr-modified A356 alloy was grain refined with Al5Ti1B and Al3B, and then, the corrosion characteristics were determined. For the mechanical properties, impact and Vickers hardness tests were carried out. To determine the corrosion behavior, both the electrochemical impedance spectroscopy technique and by potentiodynamic polarization plots were carried out in a 3.5 wt.% NaCl solution at 25 °C. The corrosion resistance of A356 alloy was dramatically improved in sequence with the following modifications compared to the unmodified castings: Sr, Ti and B additions. This situation applies to both different cooling rates, namely die and sand casting. The increase in corrosion rate was more than 80% for all alterations of the microstructure. Additionally, charge transfer resistance was increased ten times in die cast samples, while this value was 2.5 for sand cast samples compared to the unmodified alloy. It is important to note that sand casting of the unmodified alloy was improved four times with regard to the die cast unmodified A356. [ABSTRACT FROM AUTHOR]

Aluminium and its alloys have been widely used in the automotive industry for some time and A356 is one of the most popular aluminium alloys today in the sector. It contains approximately 7 wt.% Si and 0.3 wt.% Mg. Due to the defects that may be present in the cast parts, expected mechanical properties may not be reached and this alloy may perform in service under its potential. In a low pressure die casting, several precautions have to be taken in order to produce high quality and defect-free castings. Temperature of casting and the schemical composition of the melt is recorded continuously. Die temperature, pressure levels and their durations are optimized; degassing and fluxing operations are performed. Yet, regardless of the precautions, there could still be rejected parts. It is becoming clear that a good quality raw material is one of the most underrated points of the industry and that the starting material has a great effect on the final product and it should be taken in to account more seriously. Therefore, regarding the first rule of Campbell's 10 Rules of Casting, in this study, the quality of the starting material of supply chains for a wheel manufacturer was investigated. Chemical compositions were compared, fluidity tests, mechanical tests and bifilm indexes of these various sources and ingots were measured and a final quality index was proposed to create a reference for the quantification of quality of supplier's ingots. This new index was compared with the rejection rates. [ABSTRACT FROM AUTHOR]