This Project aims to study the variables of heat T6 appropriate to increase the hardness of aluminum semi-solid grade A356 with a total cross-sectional area of the specimen began 1x1 cm. Using stimulation techniques SIMA stress by rolling cross-section remaining 64% to be baked at a temperature of 595 ° C for 35 minutes to prepare the globular structure ball. This research is the application of experimental design full (General Full Factorial Design) for levels of factors. It consists of a variable (Variable parameters) in a melt phase two is four and six hours in the cooling medium. Water at room temperature, water temperature at 70 ° c and palm oil. The time of incubation was 0 2 4 6 10 and 12 hours of static variables (Fixed parameters) temperature in the oven, melt-phase 540 ° c Sierra and temperature curing 160 ° c Sierra will use the test. Rock Rockwell hardness testing which showed that the pieces that make up the most solid. A partially melted at a temperature of 540 ° C Sierra at 4 hours, cooling water temperature 70 ° c Sierra curing temperature of 160 ° C at 12 hours and work on the hardness. least a partially melted at a temperature of 540 ° C at 6 hours, cooling water curing temperature of 160 ° C at 0 hours, which works through the update process, the heat T6. it has a hardness greater than the initial target.