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为了提高7075铝合金的力学性能,7075铝合金在350℃无润滑条件下进行了5道次的累积叠轧焊实验,通过X射线衍射(XRD)与透射电镜(TEM)分析,研究了7075铝合金在叠轧过程中微观组织的演化规律,利用室温拉伸实验,研究了叠轧道次对7075铝合金力学性能的影响规律,并且采用扫描电镜(SEM)对拉伸断口形貌进行了分析。结果表明:7075铝合金在叠轧过程中材料的组成相η相发生回溶,数量减少;微观组织经历由位错缠结/位错胞状结构向形变亚晶结构转变的过程,5道次后,形成了尺寸小于1μm的亚晶组织;材料的强度随道次的增加而增加,5道次后,其抗拉强度与屈服强度分别达到373.52,315.84 MPa,约为原始合金的1.8倍和3.2倍,同时,延伸率则随着叠轧道次的增加而下降,5道次后,延伸率仅为原始合金的1/3,并且拉伸断裂由韧性断裂转变为脆性断裂。
In order to improve the mechanical properties of 7075 aluminum alloy, the 7075 aluminum alloy has been subjected to five times of cumulative roll-bonding welding under the conditions of no lubrication at 350 ℃. The effects of 7075 aluminum alloy on the wear resistance of 7075 aluminum alloy were studied by X-ray diffraction (XRD) and transmission electron microscopy (TEM) The microstructure evolution of the alloy during the rolling process was studied. The effect of stacking pass on the mechanical properties of 7075 aluminum alloy was studied by tensile test at room temperature. The morphology of tensile fracture was analyzed by scanning electron microscope (SEM) . The results show that the phase composition of the 7075 aluminum alloy is dissolved and the number of phases is reduced during the rolling process. The microstructure undergoes the transition from dislocated tanglement / dislocation cell structure to deformable subgrain structure. After 5 passes , The subgrain structure with the size less than 1μm was formed. The strength of the material increased with the increase of the pass number. After 5 passes, the tensile strength and yield strength reached 373.52 and 315.84 MPa, respectively, which were 1.8 and 3.2 times that of the original alloy While the elongation decreases with the increase of the lamination rolling pass. After 5 passes, the elongation is only 1/3 of that of the original alloy, and the tensile fracture changes from ductile fracture to brittle fracture.