Effect of Sr-Ti-B and T6 Heat Treatment on Microstructure and Mechanical Properties of Sand Cast A360 Alloy

The effect the additions of Sr, Ti, B, and subsequent T6 heat treatment on the microstructure and mechanical properties of sand cast A360 alloy were investigated. The samples were produced by sand casting at 720 degrees C temperature. Strontium additions of 141, 441, and 767 ppm were performed on samples to examine the effect of the modifier element. Moreover, Al-5Ti-B master alloy was added to the alloy as a grain refiner. The samples were solution treated at 540 degrees C for 1 h, and T6 treatment was carried out at different temperatures and times to determine the best heat treatment condition. Tensile and hardness tests were applied to the samples for investigation of the mechanical properties. Moreover, the quality index was calculated for the whole effect of both the modifier element and T6 treatment. The highest tensile properties were achieved from the sample doped by 141 ppm strontium, and the higher content of strontium led to a decrease in mechanical properties. The best Ultimate Tensile Strength (UTS) of the heat-treated samples (doped 144 ppm strontium) was achieved under the heat treatment conditions applied at 180 degrees for 4 hours. For the untreated/heat-treated samples, the best UTS and EL% (Elongation) values were 199,4/284.6 MPa and 4%/3.7%, respectively.