Semi-solid state forming process (SS) is a technology that, due its benefits, is a reality for automotive industry applications, especially for aluminum silicon alloys. In this forming process, one of the most important aspects is alloy rheological behavior because it directly affects the flux condition and mechanical properties of tixoformed parts. An empiric way for measuring this parameter is the fluidity test. The aim of this work was to study the influence of waiting time on the fluidity of an A356 alloy in a semi-solid state. Samples were heated until partial melting at 590ºC, followed by waiting times of 10min and 30min. The alloy was injected into a long and continuous channel. The results obtained were discussed using pre-existent theories for semi-solid state systems with coexisting solid and liquid phases. Some microstructural parameters were measured to explain theobserved phenomena. The degree of fluidity of A356 alloy is strongly affected by waiting time.
A356; tixoforming; semi-solid; rheoloy; fluidity
