چكيده به لاتين
In this research, the effect of hot ECAP passes and heat treatment on microstructure and tensile properties of Al-4%Mg binary alloy was investigated. This alloy was produced through casting and hot ECAP process was done at 200°C with strain rate of 0.0003 s-1 and 1p (1-pass ECAP), 3p and 5p samples were produced. After that, mechanical tests and microstructural investigation include microhardness, tensile test, metallographic test, SEM and EDS analysis on 1p, 3p and 5p samples were performed. It was shown that with increment in number of hot ECAP passes, Ultimate Tensile Strength (UTS) of samples respectfully increased up to 235MPa, 262MPa and 272MPa and elongation were increased up to 28%, 32% and 35% respectfully. Also, with increment in number of passes, hardness of samples was increased up to 75Hv, 80HV and 83HV respectfully. During deformation at high temperature, samples were artificially aged. As a result of it, Al3Mg2 precipitate was made in matrix in a way that with increase in number of passes, the amount of this precipitate was also increased. Afterward, the ECAPed samples were annealed at 150°C and 250° in 30 min and quenched at water. At 150°C, 1p samples experienced recovery and the elongation of it increased up to 35%. The hardness of samples after annealing at 150°C didn’t experiences a considerable change. At 250°C, 1p sample went through recrystallization. Moreover, low amount of Al3Mg2 and Mg depletion from super saturated solid solution due to the annealing at this temperature, elongation of 1p sample was decreased up to 16%. However, 3p and 5p samples due to the high amount of Al3Mg2 because of hot deformation did not went through changes in UTS and elongation and showed decent thermal stability at these temperatures (264MPa and 263MPa with 30% and 33% elongation after annealing at 150°C, 264MPa and 257MPa with 31% and 35% elongation after annealing at 250°C respectively). The hardness of samples became same with the value of 81HV after annealing at 250°C.
