Optimization of stirring parameters on the rheocast microstructure and mechanical properties of aluminum alloy ADC12

Abstract

This paper presents an experimental design approach for the optimization process parameters for the aluminum solid alloy casting of ADC12 alloys. To achieve this goal, the stirring time parameter and stirring speed are selected and two levels of this parameter are considered. Design of expert (DOE) of tests was used for experimental design and analysis of results. The aluminum ADC12 slurry is stirred by a mechanical stirrer (straight plate stirrer models) at 610C with a variation of speed 250, 300, 350 rpm for 20, 40, 60 seconds. Furthermore, the aluminum slurry of ADC12 is poured on a metal mold with temperature 600C. The microstructure characteristics were examined by direct observation using optical microscopy, secondary α-Al phase dendrite arm spacing and shape factor were identified. The mechanical properties were investigated by the hardness test and tensile test. The microstructure and mechanical properties of aluminum alloys ADC12 made with semi-solid rheocasting casting technology using several parameters stirring have been studied, and the results obtained can be synergized as follows. The highest mechanical properties (Hardness 122,5 HB, Tensile strength 238.2 N / mm2) occur at 300 rpm stirring speed and 20 seconds stirring time. Secondary Dendrite Arm Spacing (SDAS) lowest occurred at 25 rpm stirring speed and 20 seconds stirring time of 13.93 μm. The highest shape factor occurs at 300 rpm stirrer spin and 20 seconds stirring time of 0.47. The optimal stirring parameters recommended for producing a hardness response of 122,071 HRC, tensile strength 236,271 N / mm2, Shape Factor (SF) 0.38994, and Secondary Dendrite Arm Spacing (SDAS) are 317 rpm (stirring speed) and 20 seconds (stirring time).