摘要
7050铝合金厚板是飞机的主体结构材料,其高向性能大的差异是材料应用的技术瓶颈.为寻求减小材料高向性能差异的技术途径,通过金相显微镜、扫描电镜、X射线衍射、常温拉伸实验,对比研究了单级、双级固溶处理对200 mm厚7050铝合金超厚板高向组织与力学性能的影响.研究表明:在热轧态板材中,1/4厚层与中心层含有大量粗大S相与Al7Cu2Fe相;单级固溶处理所得的厚板中仍有很多未溶的第二相,时效后抗拉强度在1/4厚层最低,强度沿板材厚度方向先降低后升高再降低;双级固溶处理后大量AlZnMgCu相与S相的溶解使各厚度层的第二相百分数均显著下降,其中1/4厚层的第二相百分数由2.45%下降到0.51%,时效后的抗拉强度达到561 MPa,比单级固溶提高了12.5%;双级固溶处理后板材的中心层抗拉强度最低.双级固溶提高了厚板的整体力学性能,同时高向性能差异减小.
To decrease the difference of the properties along the normal direction of 7050 aluminum alloy plates with heavy thickness,the effects of single-step,double-step solution treatment were investigated on the microstructures and mechanical properties of 7050 aluminum alloy plate with thickness of 200 mm comparatively.Optical microscopy,scanning electron microscopy,energy disperse X-ray spectroscopy and tensile test were used to analyze the microstructures and mechanical properties of the plate.The results show that considerably coarse S and Al7Cu2Fe phase particles are observed at 1/4 thickness and core locations of the rolled plate.After single-step solution treatment,most second phase particles are still distributed along the normal direction of the plate,and the tensile strength of the aged plate markedly decreases first and then increases,finally decreases again.And the lowest strength exhibits at 1/4 layer of the plate.After double-step solution treatment,most AlZnMgCu and S phases are dissolved,the volume fraction of the second phase particles decreases significantly at the 1/4 thick layer from 2.45% to 0.51%,and compared with single-step solution treatment,the tensile strength increases to 561 MPa by 12.5% and the lowest strength exhibits at the core of the plate.Double-step solution treatment not only increases the mechanical properties,but also reduces the difference of the properties along the thickness of the plate.
出处
《材料科学与工艺》
EI
CAS
CSCD
北大核心
2013年第2期20-26,共7页
Materials Science and Technology
基金
国家重点基础研究发展计划资助项目(2012CB619501)
关键词
7050铝合金
超厚板
双级固溶
第二相
力学性能
7050 aluminum alloy
heavy thickness plate
solution treatment
second phases
mechanical properties
