摘要
采用搅拌摩擦焊对84 mm厚的6082-T4铝合金进行双面对接焊接,焊后进行人工时效(180℃×5 h)处理。研究了沿板厚方向焊接接头的微观组织与力学性能变化。结果表明:焊核区组织为细小的等轴晶粒,从表面至焊缝的中心,晶粒尺寸分别为16、13、5μm,高角度晶界所占比例分别为77.2%、76.3%、72.5%;焊核区的强化相主要为"GP区"及β″相;热机械影响区晶粒沿搅拌头旋转方向被拉长,组织中存在较高密度位错;焊缝中心层区域硬度分布呈"V"型,硬度最低值出现在双面焊重叠区,其他位置硬度曲线呈"W"型分布;正、反面两道焊缝发生断裂的位置均为TMAZ与HAZ交汇的区域,接头平均抗拉强度沿厚度方向从表面至中心分别为211、201、180 MPa,呈逐渐降低趋势;中心层抗拉强度最低,但其断裂伸长率最高,约为母材的69%;断口为大小不同的韧窝,接头表现为韧性断裂。
The double-sided of friction stir butt welding was carried out on the 6082-T4 aluminum alloys with thickness of 84 mm,and artificial aging(180 ℃×5 h)was applied after welding. The microstructure and mechanical properties of welded joints along the thickness direction were studied. The results indicate that the microstructure of the Welding Nugget Zone(WNZ)is fine equiaxed grains. From the surface of the plate to the center of welding seam,the grain sizes are 16 μm,13 μm,and 5 μm,respectively,and the proportions of high angle grain boundaries are 77.2%, 76.3%, and 72.5%, respectively. The strengthening phase of WNZ is mainly "GP zone" and β″. The grain of the Thermo-Mechanically Affected Zone(TMAZ)is elongated and there is a high density dislocation. The microhardness in the thickness direction indicates that the hardness curve of the center overlap area of the weld is "V" type,the lowest hardness value appears in the double-sided welding overlap area,while the hardness curve of the other area is "W" type,. The samples are all broken in the area where TMAZ and Heat Affected Zone(HAZ)meet.The tensile strengths from the surface to the center overlap in the thickness direction are 211 MPa,201 MPa,and 180 MPa,which gradually decrease. The center overlap zone has the lowest tensile strength,but its elongation is the highest,which is about 69% of the base metal. The fracture surfaces were distributed with dimples of different sizes,and fractures in all tensile specimens were ductile fracture.
作者
宫文彪
朱芮
郄新哲
崔恒
宫明月
GONG Wen-biao;ZHU Rui;QIE Xin-zhe;CUI Heng;GONG Ming-yue(Key Laboratory of Advanced Structural Materials,Ministry of Education,Changchun University of Technology,Changchun 130012,China;Changchun Railway Vehicles Co.Ltd.,Changchun 130062,China)
出处
《吉林大学学报（工学版）》
EI
CAS
CSCD
北大核心
2020年第2期512-519,共8页
Journal of Jilin University:Engineering and Technology Edition
基金
长春市科技创新“双十工程”项目(17SS024)
吉林省发改委产业技术研究与开发专项项目(2019C046-7).
关键词
金属材料
6082铝合金
搅拌摩擦焊
超厚板
组织
性能
metallic materials
6082 aluminum alloy
friction stir welding
ultra-thickness plate
microstructure
propertie
