In aluminium foundry, grain refinement is a fundamental treatment for obtaining good quality cast components, increasing static, dynamic and fatigue properties, reducing hot-tearing and improving the distribution of microporosity and intermetallic compounds. Nowadays, in foundry practise the refining of metal alloys is substantially carried out by means of three methods: control of heat transfer, stirring of the melt in the semisolid state and by adding Ti-B based refining agents. Nucleant particles act as heterogeneous nucleating centres in obtaining a great number of dendrites and creating the conditions for a fine and homogeneous microstructure. The present work shows the results of an experimental study designed to evaluate the effect of three different refining agents on the microstructural properties and on the parameters of the cooling curve of the A356 foundry aluminium alloy. Thermal analyses have been correlated with the microstructural data, including SDAS measurements, the average size of grains and the morphology of eutectic Si particles. A comparative study of the potential of the different refiners has been carried out, obtaining a first quantitative assessment of their performance.
Effect of different types of refinements on A356 foundry aluminium alloy: thermal and microstructural analyses
CASARI, Daniele;MERLIN, Mattia;GARAGNANI, Gian Luca
2013
Abstract
In aluminium foundry, grain refinement is a fundamental treatment for obtaining good quality cast components, increasing static, dynamic and fatigue properties, reducing hot-tearing and improving the distribution of microporosity and intermetallic compounds. Nowadays, in foundry practise the refining of metal alloys is substantially carried out by means of three methods: control of heat transfer, stirring of the melt in the semisolid state and by adding Ti-B based refining agents. Nucleant particles act as heterogeneous nucleating centres in obtaining a great number of dendrites and creating the conditions for a fine and homogeneous microstructure. The present work shows the results of an experimental study designed to evaluate the effect of three different refining agents on the microstructural properties and on the parameters of the cooling curve of the A356 foundry aluminium alloy. Thermal analyses have been correlated with the microstructural data, including SDAS measurements, the average size of grains and the morphology of eutectic Si particles. A comparative study of the potential of the different refiners has been carried out, obtaining a first quantitative assessment of their performance.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
