Production of AlSi5Cu3Mg alloy by gravity casting method, and metallurgical and mechanical characterization after heat treatment

Aluminum is one of the most widely used non-ferrous metals in the industry. Advantages such as lightness, appearance, reproducibility, physical and mechanical properties, and corrosion resistance compared to other metals make aluminum and its alloys prominent in the industry. According to the European Aluminum Association data, the transport sector is the largest sector for aluminum products in Europe and represents almost 40% of the sector. The lightness of aluminum reduces the weight of many vehicles, from passenger aircraft to cars, increases fuel efficiency and reduces CO2 emissions. Most of the aluminum powertrain components (80-85%) are cast parts produced with different casting technologies. Casting alloys generally have concentrations of up to 20% of magnesium and copper alloys, mainly silicon. [1] It is possible to increase the mechanical properties by heat treatments applied to aluminum alloys. In this study, AlSi5Cu3Mg alloy which is used in the automotive industry will be used. This alloy is mainly used in the manufacture of mechanical components, cylinder heads, the engine industry, and hydraulic components. It is aimed to determine the necessary process conditions in order to keep the product quality at the highest level by examining the effect of casting temperature, solution and artificial aging times on the mechanical strength and microstructure of the material on the parts that will be produced by AlSi5Cu3Mg aluminum alloy gravity casting method. The Si content of AlSi5Cu3Mg alloy used for this study was kept in the range of 4.5-7%. Chemical analysis and X-Ray analysis in the scope of non-destructive testing was applied to the samples produced by casting AlSi5Cu3Mg alloy at three different casting temperatures. Samples with suitable X-Ray analysis results waited in two different periods at a constant solution temperature (495 °C) for 4 and 8 hours, then received quenching process and kept at a constant artificial age hardening temperature (170 °C) for 6, 7, 8, 9 and 10 hours. In addition to the samples obtained by artificial aging, a group of samples was left to natural aging for 6 days after the solution process and necessary tests were performed. Tensile test, hardness test, and microstructure analysis were performed for the analysis of 36 groups of samples obtained in accordance with the 36 parameters created under the above conditions. Besides, JMatPro (Java-based Material XI Properties) simulation software was used to estimate at which rate and at which temperature the formation and transformation of the phases occurred depending on the heat treatment conditions of AlSi5Cu3Mg alloy. As a result, when the samples produced at casting temperatures of 710 °C, 715 °C and 720 °C, taken to the solution in 2 different periods (4 and 8 hours), and aged for 5 different periods (6, 7, 8, 9 and 10 hours) at 170 °C were examined, the sample with the highest strength was obtained with a casting temperature of 715 °C, 4 hours of solution at 495 °C and an aging time of 10 hours at 170 °C. When mechanical results are compared, the contribution of T4 heat treatment to tensile strength is less than that of T6 heat treatment. According to the test results, the tensile strength of T6 treated samples is 14.30% higher than that of T4 treated samples. Likewise, the % elongation amounts of the samples treated with T6 are higher than the samples treated with T4 treatment. When the microstructure images were compared, it was seen that the precipitates could not be distributed homogeneously in the structure after the T4 process and that the precipitates were homogeneously distributed after the T6 process.