The Effect of Water Mist Cooling of Casting Die on the Solidification, Microstructure and Properties of AlSi20 Alloy

Abstract

Unmodified AlSi20 alloy were casted at the research station, allowing for sequential multipoint cooling using a dedicated computer-controlled program. This method allows for the formation of the microstructure of hypereutectic AlSi20 alloy and also increases hardness. Primary silicon dendrites were found in the microstructure of cooled samples. Based on these dendrites, the formation of primary silicon particles is explained. Cooling of casting die with a water mist stream causes changes in solidification, which leads to expansion of the boundary layer with columnar crystals and shrinkage of the core zone with equiaxed crystals. It also causes more regular hardness distribution around pre-eutectic Si crystals, which can lead to tensile strength and machinability improvement.

Analysis of Crystallization Process of Intensive Cooled AlSi20CuNiCoMg Alloy

“…The metallic sampler was cooled with water mist delivered by hose of cooling circuit (Fig. 4 point 9) and produced in the device (1,2). At the end, the water mist stream is emitted by cylindrical nozzle towards the external surface of sampler.…”

“…The work is a part of studies on the application of water mist system for multipoint sequential cooling of casting die to produce high strength castings [1,2]. These studies reflect world trends in the research of intensive cooling, rapid crystallization, forming of microstructure and properties of aluminum alloys, magnesium and multi-alloyed alloys.…”

Evaluation of Thermal Conditions at Cast-Die Casting Mold Interface

“…Individual parameters and their values are listed in Table 2. To determine the heat dissipated by the cast according to the relation [Klobčar 2008, Majernik 2019, Wladysiak 2017, Yu 2016. To determine the amount of the heat dissipated by cooling of the cast according to it should be noted that each part of the cast will cool under different conditions.…”

Possibility of Utilization of Gate Geometry to Modify the Mechanical and Structural Properties of Castings on the Al-Si Basis

“…Solidification speed significantly influences the formation of microstructural defects and the mechanical properties of the final product. Except for the aforementioned, the conditions of solidification could affect the morphology and amount of externally solidified crystals (ESC) or cold flakes within the casting [5,6]. Cooling speed thus significantly influences the structure improvement and the volume ratio of the porosity within the casting.…”