Continuous Fabrication Process of Grain Controlled Aluminum Material for Rheology Forming and Its Microstructural Evaluation

摘要

In rheo forming process, slurry making is very important factor because the microstructure of slurry affects the quality of final products. Therefore, to control the microstructure of slurry, slurry making by new rheo die casting was studied. To continuously fabricate grain controlled material, cup was cleaned and heated up to about 200 ℃ to prevent the abrupt decrease of molten metal and transferred to the slurry making machine. In slurry making machine, molten metal was poured into a preheated cup and the initial temperature was about 650 ℃ .The used material, in this experiments, was A3 5 6 aluminum alloy. In the 4 cooling stages, a respective air cooling time was changed from 5 sec to 60 sec to make slurry temperature below 600 ℃. High frequency induction heating was given during about 55 seconds. After these processes, grain controlled aluminum material was made. In new rheocasting method, processes parameters are degree of overheat in molten metal, cooling condition, high frequency induction heating condition and cup temperature. Microstructures according to these parameters were observed. By image analysis, solid fraction, equivalent diameter and roundness of grain were investigated and discussed. Finally, to find out mechanical properties of grain controlled aluminum part by rheo die casting, tensile tests were carried out to the T6 heat treatment.