摘要
采用维氏硬度(HV)、电导率测试(EC)、扫描电镜(SEM)、透射电镜(TEM)、室温拉伸、冲击韧性实验研究预时效对7020铝合金组织与性能的影响。研究结果表明:合金经470℃固溶1 h后进行65℃预时效处理,与直接双级时效对比,合金的拉伸性能随预时效时间的延长而逐渐上升;65℃/168 h+90℃/8 h+160℃/26 h的抗拉强度为355.9 MPa,屈服强度为290.5 MPa,伸长率为16.3%,维氏硬度为120.9,电导率为22.4 MS/m;直接双级时效时,抗拉强度为320.4 MPa,屈服强度为256.7 MPa,伸长率为17.6%;维氏硬度为103.5,电导率为21.9 MS/m;合金经470℃固溶1 h后进行65℃预时效处理时,沿挤压方向和垂直挤压方向冲击吸收功分别为52.1 J和45.9 J;直接双级时效时,沿挤压方向和垂直挤压方向冲击吸收功分别为43.5 J和38.8 J;时效析出相随预时效时间的延长在晶内、晶界越来越细小弥散,晶界析出相断续分布。
The effects of pre-ageing treatment on the mechanical properties of 7020 aluminum alloy were investigated by means of Vickers hardness（HV）, electrical conductivity measurement（EC）, scanning electron microscopy（SEM）, transmission electron microscopy（TEM）, tensile test and impact toughness tests. The results show that after 470 ℃/1 h solution treatment followed by pre-aging at 65 ℃, the mechanical properties of investigated alloy＇s increase with the increase of the pre-aging time, while impact energy increases at first and then decreases. Compared to the direct two-stage aging at 65 ℃/168 h＋90 ℃/8 h＋160 ℃/26 h, the tensile strength, yield strength and elongation are 355.9 MPa, 290.5 MPa and 16.3%, respectively; the Vickers hardness is 120.9, and conductivity is 22.4 MS/m. However, for direct two-stage aging, the tensile strength, yield strength and elongation are 320.4 MPa, 256.7 MPa and 17.6%, respectively; Vickers hardness is 104.7, and conductivity is 21.9 MS/m. For 470 ℃/1 h solution treatment followed by pre-aging at 65 ℃, impact energy along the direction of extrusion and perpendicular to that are 52.1 J and 45.9 J, respectively, and for the direct two-stage aging, impact energy along the direction of extrusion and perpendicular to that are 43.5 J and 38.8 J, respectively. The distribution of precipitates inside the grains and at the grain boundaries are more finely dispersed within the extension of pre-aging time. Precipitates at the grain boundaries are discontinuous.
出处
《中南大学学报（自然科学版）》
EI
CAS
CSCD
北大核心
2017年第3期578-584,共7页
Journal of Central South University:Science and Technology
基金
国家重点研发计划项目(2016YFB0300901)~~
关键词
7020铝合金
预时效
拉伸性能
冲击韧性
显微组织
7020 aluminum alloy
pre-aging
tensile properties
impact toughness
microstructure
