ECAP对A390铝合金显微组织和拉伸性能的影响（英文）

Effect of ECAP on microstructure and tensile properties of A390 aluminum alloy

研究等径角挤压(ECAP) A390铝合金的抗拉强度和伸长率,揭示其显微组织和拉伸性能之间的关系。采用光学显微镜(OM)、扫描电镜(SEM)和能谱仪(EDS)对样品的显微组织进行分析。力学性能测试结果表明,经过3道次挤压后,材料的极限抗拉强度(UTS)从铸态的142 MPa提高到275 MPa。与铸态样品相比,当ECAP道次增加到4时,材料的伸长率显著提高。研究发现,随着ECAP道次的增加,材料的强度和伸长率提高,这是因为颗粒的均匀分布、颗粒尺寸的减小和空位的消除,尤其是与原始硅颗粒相邻的空位的消除。断口分析结果表明,当ECAP的道次增加到4时,在合金中形成均匀的圆形韧窝,合金断裂机理由铸态时的脆性断裂转变为韧性断裂。

The purpose of the present research is to determine the tensile strength and elongation of the A390 alloy processed by ECAP and to reveal the relationship between the microstructure and tensile properties. Optical microscopy (OM), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were used for microstructural analysis of the samples. The results of the mechanical testing showed that the ultimate tensile strength (UTS) increased from 142 MPa for the as-cast sample to 275 MPa for the sample after the third ECAP pass. Increasing the ECAP passes up to 4 led to a remarkable enhancement of elongation compared with the as-cast sample. It was found that the improvement of strength and ductility of A390 alloy with increasing the number of ECAP passes was attributed to the homogenous distribution of particles, reduction of particle size, and elimination of voids especially adjacent to the primary silicon particles. The results of fractography demonstrated that when the number of ECAP passes increased to 4, the uniform round dimples formed and the relatively brittle as-cast sample transformed to a ductile alloy.