Thermal Analysis as a Microstructure Prediction Tool for A356 Aluminium Parts Solidified under Various Cooling Conditions

摘要

Thermal analysis performed with standard cups has been used since decades for melt control andrnmicrostructure prediction before casting aluminium alloys. However, obtaining a proper microstructure in a standard cuprndoes not ensure that the microstructure is correct in real parts which may solidify at very different cooling rates. For thisrnstudy, alloy A356 with different metal quality in terms of modification and grain refinement was tested. Different cooling ratesrnwere obtained by employing cylindrical test samples with various diameters cast in sand and metallic moulds. The correlationrnbetween microstructure features such as grain size, modification rate and secondary dendrite arm spacing (SDAS)rnmeasured in the standard thermal analysis cup with those obtained in the cylindrical test parts has been investigated. Thus,rnknowing the thermal modulus and the mould type it is possible to establish the required grain size and modification rate in thernstandard cup in order to get a desired structure in a real part. Corrective actions can then be taken in order to improve thernmetallurgical quality before casting the part.