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材料研究学报  2021, Vol. 35 Issue (7): 543-552    DOI: 10.11901/1005.3093.2020.227
  研究论文 本期目录 | 过刊浏览 |
焊后时效对7046铝合金搅拌摩擦焊接头力学性能的影响
廖泽鑫1,2, 李承波1,2,3, 刘胜胆1,2,4(), 唐建国1,2,4, 黄传演3, 朱贤燕3
1.中南大学材料科学与工程学院 长沙 410083
2.中南大学 有色金属材料科学与工程教育部重点实验室 长沙 410083
3.广东和胜工业铝材股份有限公司 中山 528463
4.中南大学 有色金属先进结构材料与制造协同创新中心 长沙 410083
Effect of Post Aging on Mechanical Properties of Friction Stir Welded 7046 Aluminum Alloy
LIAO Zexin1,2, LI Chengbo1,2,3, LIU Shengdan1,2,4(), TANG Jianguo1,2,4, HUANG Chuanyan3, ZHU Xianyan3
1.School of Materials Science and Engineering, Central South University, Changsha 410083, China
2.Key Laboratory of Nonferrous Metal Materials Science and Engineering, Ministry of Education, Central South University, Changsha 410083, China
3.Guangdong Hoshion Industrial Aluminum Co. Ltd. , Zhongshan 528463, China
4.Nonferrous Metal Oriented Advanced Structural Materials and Manufacturing Cooperative Innovation Center, Central South University, Changsha 410083, China
引用本文:

廖泽鑫, 李承波, 刘胜胆, 唐建国, 黄传演, 朱贤燕. 焊后时效对7046铝合金搅拌摩擦焊接头力学性能的影响[J]. 材料研究学报, 2021, 35(7): 543-552.
Zexin LIAO, Chengbo LI, Shengdan LIU, Jianguo TANG, Chuanyan HUANG, Xianyan ZHU. Effect of Post Aging on Mechanical Properties of Friction Stir Welded 7046 Aluminum Alloy[J]. Chinese Journal of Materials Research, 2021, 35(7): 543-552.

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摘要: 

对厚度为3.5 mm的7046铝合金挤压板材进行搅拌摩擦焊接并对焊接接头进行人工时效,研究了焊后时效对接头力学性能的影响。结果表明,焊接接头时效前的硬度分布大致呈“W”形,抗拉强度为406.5 MPa,焊接系数为0.8,拉伸时在后退侧热影响区与热机影响区的过渡位置出现断裂,此处的硬度值最低,断裂面上有大量的韧窝;进行120℃×24 h时效后,接头的热影响区、热机影响区和焊核区的硬度都显著提高,母材区的硬度变化不大,硬度分布大致呈“一”形,抗拉强度大幅度提高到490 MPa,焊接系数达到0.96,拉伸时在焊核区中心断裂,断裂面有大量的沿晶裂纹。时效后接头区域的晶内GPI区转变成具有更好强化效果的η′亚稳相,使接头的硬度和强度提高;与其它区域相比,焊核区中晶界η相的分布更连续,晶界处无沉淀析出带的体积分数更大,因此容易成为拉伸时的断裂位置。

关键词 金属材料7046铝合金搅拌摩擦焊接焊后时效微观组织力学性能    
Abstract

Extruded sheets of 7046 aluminum alloy of 3.5 mm in thickness were subjected to friction stir welding (FSW) and then post aging treatment. The hardness profile of the FSW joint exhibits a "W" shape and the ultimate tensile strength is 406.5 MPa with a welding coefficient of 0.8. During tensile test fracture appears at the minimum hardness zone, which is the transition area between the heat affected zone (HAZ) and the thermal-mechanically affected zone (TMAZ) on the retreating side. There are a lot of dimples on the fracture surface. After aging at 120℃ for 24 h there is little change in the hardness of the base metal (BM) but the hardness of the HAZ, TMAZ and nugget zone (NZ) increase apparently, which is more or less the same as that of the BM. The ultimate tensile strength increases significantly up to about 490MPa with the welding coefficient increasing to about 0.96. Fracture appears at the NZ and there are a lot of intergranular cracks on the fracture surface. After aging, the GPI zones within grains of the FSW joint transform into η' metastable phase with better strengthening effect, leading to higher hardness and strength. η phase tends to be more continuous at grain boundaries and there is a higher volume fraction of precipitates free zones near grain boundaries in the NZ than other regions, therefore, fracture tends to occur in the NZ during tensile test.

Key wordsmetallic materials    7046 aluminum alloy    friction stir welding    post weld aging    microstructure    mechanical properties
收稿日期: 2020-06-13     
ZTFLH:  TG457.14  
基金资助:国家重点研发计划(2016YFB0300901);广东省中山市科技局重大专项(2016A1001)
作者简介: 廖泽鑫,男,1996年生,硕士
ZnMgCuZrTiFeSiAl
6.441.410.270.150.020.110.07Bal.
表1  7046铝合金的化学成分

Rotation speed

/r·min-1

Welding speed

/mm·min-1

Pin

diameter/mm

Pin

depth/mm

Shoulder diameter/mm

Plunge depth

/mm

Tilt angle

160040032.8120.22.5
表2  搅拌摩擦焊接参数
图1  硬度测试和室温拉伸试样的取样示意图
图2  FSW接头横截面的宏观形貌
图3  FSW接头母材区、热影响区和热机影响区的金相照片
图4  FSW焊接接头焊核区和轴肩影响区的金相照片
图5  FSW接头不同区域的透射电镜照片和对应的选区衍射花样
SamplesFSW jointFSW joint after ageing
BMHAZNZBMHAZNZ
Size of η phase55.2±9.281.4±13.232.1±7.058.4±6.179.9±11.736.7±8.3
Interparticle spacing79.3±11.2236.3±22.4-84.5±7.8223.9±30.6-
PFZ width42.3±2.7--43.7±4.337.4±4.136.5±3.1
表3  焊接接头不同区域的晶界析出相尺寸、间距和PFZ宽度 (nm)
图6  AG-FSW接头不同区域的透射电镜照片和对应的选区衍射花样
图7  焊接接头的硬度曲线
SamplesRp0.2/MPaRm/MPaA/%

Rp0.2

efficiency

Rm

efficiency

A

efficiency

Fracture

location

BM476.0±3.5507.7±4.29.0±1.1----
FSW joint289.5±6.2406.5±5.86.2±0.60.610.800.69HAZ/TMAZ
AG-FSW joint457.2±8.4490.0±5.12.5±0.80.960.960.28NZ
表4  母材和焊接接头的室温拉伸性能
图8  室温拉伸后接头断口的金相照片
图9  室温拉伸后接头断口的扫描电镜照片
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