Please wait a minute...
Acta Metall Sin  2017, Vol. 53 Issue (12): 1651-1658    DOI: 10.11900/0412.1961.2017.00025
Orginal Article Current Issue | Archive | Adv Search |
Microstructures and Mechanical Properties of Thin Plate Aluminium Alloy Joint Prepared by High Rotational Speed Friction Stir Welding
Fenjun LIU1,2, Li FU1,3,4(), Haiyan CHEN1,3,4
1 School of Materials Science and Engineering, Northwestern Polytechnical University, Xi'an 710072, China
2 College of Energy Engineering, Yulin University, Yulin 719000, China
3 State Key Laboratory of Solidification, Northwestern Polytechnical University, Xi'an 710072, China
4 Shaanxi Key Laboratory of Friction Welding Technologies, Northwestern Polytechnical University, Xi'an 710072, China
Download:  HTML  PDF(9228KB) 
Export:  BibTeX | EndNote (RIS)      

Aluminium alloys were widely applied in rail transit, ships and aerospace owing to their unique properties, such as low density, high strength and stiffness, outstanding corrosion resistance and low temperature performance. As a type of structure material, aluminium alloy joining was inevitable. However, these alloys were often considered very difficult to weld using traditional fusion welding technique since the welding seams were often accompanied with metallurgical defects, large deformation and stress. Friction stir welding (FSW), an innovative solid-state welding technology invented at the welding institute (TWI), was seen by designers as an effective joining methods in welding aluminium alloys due to low heat input, small stress-strain and environment friendly. In this work, 0.8 mm thick plate of 6061-T6 aluminium alloy was successfully welded by use of high rotational speed fiction stir welding technology. The microstructure and mechanical property of the butt joints prepared by high rotational speed friction stir welding were analysed in detail. The results show that the well surface topography and excellent bonding interface existed in the nugget zone (NZ) were observed. Both of the microhardness of the weld seam was lower than that of the substrate. The lowest microhardness of the butt joints located between the thermo-mechanically affected zone (TMAZ) and heat affected zone (HAZ). Compared with the conventional rotational speed, the number of β-Mg2Si, Al2CuMg and Al8Fe2Si precipitated phases existed in the NZ was more, which made the microhardness in the NZ improved significantly. The rod-shaped precipitates (Mg2Si) have the greatest influence on the microhardness. The excellent mechanical properties were obtained at the rotational speed of 8000 r/min and welding speed of 1500 mm/min. The maximum tensile strength was 301.8 MPa, which was 85.8% of the as-received 6061-T6 (351.7 MPa). And the toughness-brittleness fracture mode appeared.

Key words:  thin plate 6061-T6 aluminium alloy      high rotational speed      friction stir welding (FSW)      microstructure      tensile property     
Received:  19 January 2017     
ZTFLH:  TG146.2  
Fund: Supported by National Natural Science Foundation of China (No.51575450), Key Areas of Innovation Team in Shaanxi Province (No.2014KCT-12), Natural Science Foundation of Shaanxi Province (No.S2016-YFJZ0164), Research Fund of the State Key Laboratory of Solidification (NWPU) (No.127-QP-2015)

Cite this article: 

Fenjun LIU, Li FU, Haiyan CHEN. Microstructures and Mechanical Properties of Thin Plate Aluminium Alloy Joint Prepared by High Rotational Speed Friction Stir Welding. Acta Metall Sin, 2017, 53(12): 1651-1658.

URL:     OR

Fig.1  Schematic of 6061-T6 friction stir welding (FSW) device (a), pin tool (b) and tensile specimen (c) (RS—retreating side, AS—advancing side, unit: mm)
Fig.2  Surface morphologies of 6061-T6 FSW joints obtained at rotational speeds of 2000 r/min (a) and 8000 r/min (b)
Fig.3  Morphologies of 6061-T6 FSW joints obtained at rotational speeds of 2000 r/min (a) and 8000 r/min (b) (BM—base material, HAZ—heat affected zone, TMAZ—thermo-mechanical affected zone, NZ—nugget zone)
Fig.4  Microstructures of 6061-T6 FSW joints corresponding to areas of HAZ (a, d), TMAZ (b, e), and NZ (c, f) at 2000 r/min (a~c) and 8000 r/min (d~f)
Fig.5  Bright field TEM images of precipitated phases morphology and distribution of HAZ (a, c) and NZ (b, d) obtained at 2000 r/min (a, b) and 8000 r/min (c, d), respectively
Fig.6  Grain morphology maps of 6061-T6 FSW joints corresponding to Fig.3b(a) region 1 (NZ) (b) region 2 (TMAZ) (c) region 3 (HAZ)
Fig.7  Fraction of different grain type in 6061-T6 FSW joints corresponding to Fig.6
Fig.8  Microhardness distributions of 6061-T6 FSW joints along the transverse to the weld center
Fig.9  EBSD grain-boundary maps showing the grain structure in the NZ of 6061-T6 FSW joint obtained at 8000 r/min
ω / (rmin-1) v / (mmmin-1) σUTS / MPa σYS / MPa δ / %
0 0 351.7 296.8 21.50
2000 300 239.0 179.2 4.80
7000 1500 289.4 207.8 4.88
8000 1500 301.8 216.6 5.39
9000 1500 300.8 213.0 5.44
10000 1500 292.6 205.7 5.31
11000 1500 292.2 201.8 5.49
Table 1  Tensile properties of 6061-T6 and FSW butt joints with different rotational speeds
Fig.10  Fractographies of 6061-T6 FSW joint obtained at 8000 r/min after tensile test (a) and magnified morphologies of area A in Fig.10a (b) (Inset shows the fracture position)
[1] Rhodes C G, Mahoney M W, Bingel W H, et al.Effects of friction stir welding on microstructure of 7075 aluminum[J]. Scr. Mater., 1997, 36: 69
[2] Da Silvada A A M, Arruti E, Janeiro G, et al. Material flow and mechanical behaviour of dissimilar AA2024-T3 and AA7075-T6 aluminium alloys friction stir welds[J]. Mater. Des., 2011, 32: 2021
[3] Mishra R S, Ma Z Y.Friction stir welding and processing[J]. Mater. Sci. Eng., 2005, R50: 1
[4] Threadgill P L, Leonard A J, Shercliff H R, et al.Friction stir welding of aluminium alloys[J]. Int. Mater. Rev., 2009, 54: 49
[5] Nandan R, DebRoy T, Bhadeshia H K D H. Recent advances in friction stir welding—Process, weldment structure and properties[J]. Prog. Mater. Sci., 2008, 53: 980
[6] Wang T, Zou Y, Matsuda K.Micro-structure and micro-textural studies of friction stir welded AA6061-T6 subjected to different rotation speeds[J]. Mater. Des., 2016, 90: 13
[7] Liu F C, Ma Z Y.Influence of tool dimension and welding parameters on microstructure and mechanical properties of friction stir welded 6061-T651 aluminum alloy[J]. Metall. Mater. Trans., 2008, 39A: 2378
[8] Guo J F, Chen H C, Sun C N, et al.Friction stir welding of dissimilar materials between AA6061 and AA7075 Al alloys effects of process parameters[J]. Mater. Des., 2014, 56: 185
[9] Liu H J, Hou J C, Guo H.Effect of welding speed on microstructure and mechanical properties of self-reacting friction stir welded 6061-T6 aluminum alloy[J]. Mater. Des., 2013, 50: 872
[10] He C, Liu Y J, Dong J F, et al.Through thickness property variations in friction stir welded AA6061 joint fatigued in very high cycle fatigue regime[J]. Int. J. Fatigue, 2016, 82: 379
[11] Rodrigues D M, Loureiro A, Leitao C, et al.Influence of friction stir welding parameters on the microstructural and mechanical properties of AA 6016-T4 thin welds[J]. Mater. Des., 2009, 30: 1913
[12] Galvao I, Leitao C, Loureiro A, et al.Friction stir welding of very thin plates[J]. Soldag. Insp. Sao. Paulo., 2012, 17: 2
[13] Leal R M, Leit?o C, Loureiro A, et al.Material flow in heterogeneous friction stir welding of thin aluminium sheets: Effect of shoulder geometry[J]. Mater. Sci. Eng., 2008, A498: 384
[14] Scialpi A, De Filippis L A C, Cavaliere P. Influence of shoulder geometry on microstructure and mechanical properties of friction stir welded 6082 aluminium alloy[J]. Mater. Des., 2007, 28: 1124
[15] De Giorgi M, Scialpi A, Panella F W, et al.Effect of shoulder geometry on residual stress and fatigue properties of AA6082 FSW joints[J]. J. Mech. Sci. Technol., 2009, 23: 26
[16] Scialpi A, De Giorgi M, De Filippis L A C, et al. Mechanical analysis of ultra-thin friction stir welding joined sheets with dissimilar and similar materials[J]. Mater. Des., 2008, 29: 928
[17] Murr L E, Liu G, McClure J C. A TEM study of precipitation and related microstructures in friction-stir-welded 6061 aluminium[J]. J. Mater. Sci., 1998, 33: 1243
[18] Zhao H H, Feng X S, Xiong Y Y, et al.Microstructure and properties of micro friction stir welded joint of Al-alloy ultra thin plate with zero tilt angle[J]. Trans. China Weld. Inst., 2014, 35(7): 47(赵慧慧, 封小松, 熊艳艳等. 铝合金超薄板无倾角微搅拌摩擦焊接头组织性能[J]. 焊接学报, 2014, 35(7): 47)
[19] Schmidt H, Hattel J, Wert J.An analytical model for the heat generation in friction stir welding[J]. Model. Simul. Mater. Sci. Eng., 2004, 12: 143
[20] Schmidt H B, Hattel J H.Thermal modelling of friction stir welding[J]. Scr. Mater., 2008, 58: 332
[21] Chen H Y, Fu Li, Liang P.Microstructure, texture and mechanical properties of friction stir welded butt joints of 2A97 Al-Li alloy ultra-thin sheets[J]. J. Alloys Compd., 2017, 692: 155
[22] Malopheyev S, Vysotskiy I, Kulitskity V, et al.Optimization of processing-microstructure-properties relationship in friction-stir welded 6061-T6 aluminum alloy[J]. Mater. Sci. Eng., 2016, A662: 136
[23] Liu F J, Fu L, Zhang W Y, et al.Interface structure and mechanical pro-perties of friction stir welding joint of 2099-T83/2060-T8 dissimilar Al-Li alloys[J]. Acta Metall. Sin., 2015, 51: 281(刘奋军, 傅莉, 张纹源等. 2099-T83/2060-T8异质Al-Li合金搅拌摩擦焊搭接界面结构与力学性能[J]. 金属学报, 2015, 51: 281)
[24] Sato Y S, Kokawa H, Enomoto M, et al.Microstructural evolution of 6063 aluminum during friction-stir welding[J]. Metall. Mater. Trans., 1999, 30A: 2429
[25] Sato Y S, Urata M, Kokawa H, et al.Hall-Petch relationship in friction stir welds of equal channel angular-pressed aluminium alloys[J]. Mater. Sci. Eng., 2003, A354: 298
[26] Sattari S, Bisadi H, Sajed M.Mechanical properties and temperature distributions of thin friction stir welded sheets of AA5083[J]. Int. J. Mech. Appl., 2012, 2: 1
[1] GENG Yaoxiang, FAN Shimin, JIAN Jianglin, XU Shu, ZHANG Zhijie, JU Hongbo, YU Lihua, XU Junhua. Mechanical Properties of AlSiMg Alloy Specifically Designed for Selective Laser Melting[J]. 金属学报, 2020, 56(6): 821-830.
[2] HUANG Yuan, DU Jinlong, WANG Zumin. Progress in Research on the Alloying of Binary Immiscible Metals[J]. 金属学报, 2020, 56(6): 801-820.
[3] YU Jiaying, WANG Hua, ZHENG Weisen, HE Yanlin, WU Yurui, LI Lin. Effect of the Interface Microstructure of Hot-Dip Galvanizing High-Strength Automobile Steel on Its Tensile Fracture Behaviors[J]. 金属学报, 2020, 56(6): 863-873.
[4] YU Chenfan, ZHAO Congcong, ZHANG Zhefeng, LIU Wei. Tensile Properties of Selective Laser Melted 316L Stainless Steel[J]. 金属学报, 2020, 56(5): 683-692.
[5] ZHAO Yanchun, MAO Xuejing, LI Wensheng, SUN Hao, LI Chunling, ZHAO Pengbiao, KOU Shengzhong, Liaw Peter K.. Microstructure and Corrosion Behavior of Fe-15Mn-5Si-14Cr-0.2C Amorphous Steel[J]. 金属学报, 2020, 56(5): 715-722.
[6] LI Yuancai, JIANG Wugui, ZHOU Yu. Effect of Nanopores on Tensile Properties of Single Crystal/Polycrystalline Nickel Composites[J]. 金属学报, 2020, 56(5): 776-784.
[7] LIU Zhenpeng, YAN Zhiqiao, CHEN Feng, WANG Shuncheng, LONG Ying, WU Yixiong. Fabrication and Performance Characterization of Cu-10Sn-xNi Alloy for Diamond Tools[J]. 金属学报, 2020, 56(5): 760-768.
[8] LI Xiucheng,SUN Mingyu,ZHAO Jingxiao,WANG Xuelin,SHANG Chengjia. Quantitative Crystallographic Characterization of Boundaries in Ferrite-Bainite/Martensite Dual-Phase Steels[J]. 金属学报, 2020, 56(4): 653-660.
[9] YANG Ke,SHI Xianbo,YAN Wei,ZENG Yunpeng,SHAN Yiyin,REN Yi. Novel Cu-Bearing Pipeline Steels: A New Strategy to Improve Resistance to Microbiologically Influenced Corrosion for Pipeline Steels[J]. 金属学报, 2020, 56(4): 385-399.
[10] QIAN Yue,SUN Rongrong,ZHANG Wenhuai,YAO Meiyi,ZHANG Jinlong,ZHOU Bangxin,QIU Yunlong,YANG Jian,CHENG Guoguang,DONG Jianxin. Effect of Nb on Microstructure and Corrosion Resistance of Fe22Cr5Al3Mo Alloy[J]. 金属学报, 2020, 56(3): 321-332.
[11] XIAO Hong,XU Pengpeng,QI Zichen,WU Zonghe,ZHAO Yunpeng. Preparation of Steel/Aluminum Laminated Composites by Differential Temperature Rolling with Induction Heating[J]. 金属学报, 2020, 56(2): 231-239.
[12] CHENG Chao,CHEN Zhiyong,QIN Xushan,LIU Jianrong,WANG Qingjiang. Microstructure, Texture and Mechanical Property ofTA32 Titanium Alloy Thick Plate[J]. 金属学报, 2020, 56(2): 193-202.
[13] WANG Xi,LIU Renci,CAO Ruxin,JIA Qing,CUI Yuyou,YANG Rui. Effect of Cooling Rate on Boride and Room Temperature Tensile Properties of β-Solidifying γ-TiAl Alloys[J]. 金属学报, 2020, 56(2): 203-211.
[14] DENG Congkun,JIANG Hongxiang,ZHAO Jiuzhou,HE Jie,ZHAO Lei. Study on the Solidification of Ag-Ni Monotectic Alloy[J]. 金属学报, 2020, 56(2): 212-220.
[15] WANG Tao,WAN Zhipeng,LI Zhao,LI Peihuan,LI Xinxu,WEI Kang,ZHANG Yong. Effect of Heat Treatment Parameters on Microstructure and Hot Workability of As-Cast Fine Grain Ingot of GH4720Li Alloy[J]. 金属学报, 2020, 56(2): 182-192.
No Suggested Reading articles found!