چكيده به لاتين
In this study, the effect of friction stirring process conditions on the microstructure and mechanical properties of ZA27 alloy was investigated. The parameters of this study were the percentage of copper in the alloy, the rotation speed of the tool, the traverse speed, and the number of passes that were examined. First, due to changes in mechanical properties due to changes in the percentage of copper in the alloy, three alloys with different percentages of copper (0, 2, and 4) were used and the feasibility of the friction stirring process on these alloys was investigated. By performing preliminary experiments and using Taguchi experiment design, a range of tool rotation speed and traverse speed was obtained, which is 600 rpm, 750 rpm, and 950 rpm for tool rotation speed and traverse speed 50 mm/min, 65mm/min, and 80 mm/min. In this range of tool rotation speed and traverse speed, a frictional stirring process was performed on all three alloys. In addition to the tool rotation speed and traverse speed, the number of passes parameter was also examined, and up to two passes of friction stirring process was performed on the alloys. Metallographic experiments, then light microscopy and scanning electron microscopy were used to identify and examine the microstructure, and tensile and microhardness tests were used to investigate the mechanical properties of the samples. According to the test results, the optimal rotation speed was 600 rpm and the optimum advance speed was 50 mm/min, 65 mm/min, and 2 passes were obtained for all three alloys. The dendritic structure of cast alloys underwent severe changes after friction stirring and was accompanied by a decrease in grain size. In all copper-free specimens, the yield strength after friction stirring decreased from 245 MPa to 160 MPa, and the percentage of elongation before failure in this alloy increased 7 times. However, the yield strength in the alloy with 2% copper increased from about 283 MPa to 300 MPa, and in the alloy with 4% copper from 278 MPa to 318 MPa, and in all alloys the percentage increase in length before failure increased significantly. The hardness in the mixing region was reduced by at least 20% in all three alloys.
