Manufacturing components in light metals is becoming fundamental as well as replacing higher density materials with aluminium alloys. However, whereas productions by forging and pressing can use well-known materials (i.e. 6000, 2000 and 7000 series), thixoforming and rheoforming just employ a limited number of foundry alloys (A356 and A357), which need T4, T5, or T6 heat treatments to improve their mechanical performances, fairly modest compared with those of wrought alloys. These properties can be increased by modifying alloy composition, i.e. adding new elements and/or differently balancing those already present, and consequently inducing different behaviours to heat treatment. In this research silver was added to an AlSi alloy, together with small percentage of other precipitation hardening elements (Cu, Mg), in order to evaluate the response to heat treatment in two different cases, that is in castings characterized by dendritic rather than globular microstructure. The ageing temperatures were studied by dilatometric and calorimetric techniques varying the solution temperature (510°C and 540°C); according to the observed results, three ageing temperatures were investigated and some hardness profiles were obtained varying the soaking times.
Experimental investigation of ageing in Al-Si-Cu-Mg-Ag cast alloys
POLA, Annalisa;ROBERTI, Roberto;
2011-01-01
Abstract
Manufacturing components in light metals is becoming fundamental as well as replacing higher density materials with aluminium alloys. However, whereas productions by forging and pressing can use well-known materials (i.e. 6000, 2000 and 7000 series), thixoforming and rheoforming just employ a limited number of foundry alloys (A356 and A357), which need T4, T5, or T6 heat treatments to improve their mechanical performances, fairly modest compared with those of wrought alloys. These properties can be increased by modifying alloy composition, i.e. adding new elements and/or differently balancing those already present, and consequently inducing different behaviours to heat treatment. In this research silver was added to an AlSi alloy, together with small percentage of other precipitation hardening elements (Cu, Mg), in order to evaluate the response to heat treatment in two different cases, that is in castings characterized by dendritic rather than globular microstructure. The ageing temperatures were studied by dilatometric and calorimetric techniques varying the solution temperature (510°C and 540°C); according to the observed results, three ageing temperatures were investigated and some hardness profiles were obtained varying the soaking times.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
