چكيده به لاتين
In this study, the impact of hot ECAP passes and heat treatment on the microstructure and tensile properties of an Al-8%Mg binary alloy was examined. The alloy was produced through a casting process, and the hot ECAP operation was conducted at a temperature of 200°C with a strain rate of 0.0003 s⁻¹, resulting in the production of 1-pass (1p), 3-pass (3p), and 5-pass (5p) samples. Subsequently, mechanical testing and microstructural analysis were performed, including microhardness measurements, tensile testing, metallographic analysis, and SEM and EDS evaluations on all samples (1p, 3p, and 5p). The findings revealed that as the number of hot ECAP passes increased, the Ultimate Tensile Strength (UTS) of the samples significantly improved, reaching up to 235 MPa, 262 MPa, and 272 MPa, with elongation values rising to 28%, 32%, and 35%, respectively. Additionally, with the increase in the number of passes, the hardness of the samples increased to 75 HV, 80 HV, and 83 HV, respectively. During high-temperature deformation, the samples underwent artificial aging, leading to the formation of Al3Mg2 precipitates within the matrix. With additional ECAP passes, the amount of these precipitates further increased.
Following this, the ECAPed samples underwent annealing at temperatures of 150°C and 250°C for 30 minutes and were subsequently quenched in water. After annealing at 150°C, the 1-pass sample experienced recovery, which increased its elongation to 35%. The hardness of the samples after annealing at 150°C did not exhibit significant changes. In contrast, at 250°C, the 1-pass sample underwent recrystallization. Furthermore, due to the low amount of Al3Mg2 and the depletion of Mg from the supersaturated solid solution during annealing at this temperature, the elongation of the 1-pass sample decreased to 16%. However, due to the substantial presence of Al3Mg2 in the 3-pass and 5-pass samples, no noticeable changes in UTS and elongation occurred, and these samples maintained good thermal stability at these temperatures (264 MPa and 263 MPa with 30% and 33% elongation after annealing at 150°C, and 264 MPa and 257 MPa with 31% and 35% elongation after annealing at 250°C, respectively). The hardness of all samples stabilized at around 81 HV after annealing at 250°C.
