Determination Of The Effect Of Cooling Rate And Strontium Amount On Eutectic Si Modification Performance Of A356 Alloy Via Casting Simulation

Abstract

It is well-known that strontium addition into molten metal as a eutectic modifier increases the elongation and toughness values of the cast parts by refining the eutectic phases. However, when over-modification occurs, porosity increases due to some unwanted physical and chemical reactions that develop within the structure. On the other hand, it has been seen that high cooling rates tend to reduce the porosity of the alloy, decrease grain size and secondary dendrite arm spacing and refine eutectic silicon phase on Al-Si casting alloys. Within the scope of this project, it is aimed to investigate the effects of the cooling rate of cast part and the addition amount of strontium on the silicon modification behavior of Al A356 (AlSi7Mg) alloy parts using casting simulation environment. In order to examine the effect of strontium addition, 150, 250, 350 and 450 parts per million of strontium additions were chosen based on thermodynamic calculations. After the casting session of each Al A356 composition with different strontium amount by using special designed 5-spoke mold on casting simulation, thermal analysis was done by obtained thermocouple data from casting part’s each spoke. Obtained thermal analysis data was interpreted with the casting simulation outputs. Within all aspects, the 150 parts per million strontium addition on Al A356 alloy has been identified as the most useful simulation model in terms of casting performance.