THE MICROSTRUCTURE - MECHANICAL PROPERTIES INTERRELATIONSHIP IN A357-T6 CAST ALUMINUM ALLOYS (SOLUTION, PREMIUM QUALITY)

Aluminum alloy A357 castings are commonly treated to the T6 temper prior to service. Because of this solution heat treatment and artificial aging sequence, the mechanical properties are enhanced. The purposes of this research are to study the kinetics of the solution heat treatment and to relate the accompanying microstructural changes to mechanical properties.;The kinetics of the solution heat treatment were monitored through the morphological changes of the silicon-rich structures as a function of solution heat treatment time and the coarsening process. The kinetic results indicate that the size parameters of the silicon-rich structures are the best microstructural predictors of ultimate strengths and uniform elongations for unmodified A357 alloys. Similarly, the density parameters are the best predictors for these two mechanical properties in modified, grain-refined A357 alloys.