1、上海交通大学 硕士学位论文 汽车用铝合金焊接工艺的研究 姓名：杨淑芳 申请学位级别：硕士 专业：材料加工工程 指导教师：楼松年 20040101 6061 FISCO 6061 6061 6061 X EDX 6061 6061 6061 3A21 4043 6061 TIG MIG 6061 6061 6061 6061 6061 TIG MIG TIG MIG - - 6061 6061 9 13mm 6061 RESEARCH ABOUT THE WELDING TECHNOLOGY OF AUTOMOTIVE ALUMINIUM ALLOYS ABSTRACT The weldabil
2、ity of automotive aluminum alloys is not very good and deficiencies (such as porosity, hot cracking) often occur during welding. Therefore, the article explored the welding technology of 6061 aluminum alloy that is often used in car body. This research provides experiment data for the application of
3、 aluminum alloys in automotive industry. The work also has important practical value to the further use of aluminum alloys that will make automotive lighter. The weldability of 6061 alloy was examined by means of FISCO to test welding crack susceptibility and tests of porosity sensibility. The weldi
4、ng technology of 6061 was studied to get suitable welding parameters. The mechanical properties of 6061 welded joint were also tested. In order to make further research of the different performance between welded joint and base metal of 6061 alloy, the microstructure characteristics and point compon
5、ent of butt joint of 6061 alloy were studied by means of advanced test methods including optics microscope and energy dispersive X -ray microanalysis (EDX). Furthermore, the article also covered research of effects about different welding processes and parameters on 6061 alloy bead sizes. The analys
6、is results indicate that 6061 alloy is characterized by the sensibility of crystal crack and hydrogen porosity. Under the same condition, 6061 alloy is more susceptible to hot cracking than 3A21 alloy. While 4043 welding wire was used as the filler metal, low crack susceptibility was achieved and ho
7、t crack only emerged in arc crater. Crater crack appeared both longitudinal and horizontal. As far as 6061 alloys porosity susceptibility is concerned, influencing factors include welding m ethods, relative humidity of the environment, surface state of test plate, composition of shielding gas and we
8、lding variables. There were three main types of porosity in welded joint, i.e. porosity of chains, intensive porosity and single porosity. It was found that to strictly control sources of moisture could effectively reduce the amount of porosity in the weld. In addition, 6061 alloys porosity suscepti
9、bility could be reduced by use of suitable welding variables and adding gas with oxidizability to the shielding atmosphere. The result of welding procedures test shows that welding parameters have great effect on weld shape. And hybrid welding of laser and electric arc can allow the weld with larger
10、 penetration and width compared to that seam welded by single welding method (such as TIG, MIG and YAG laser). So it is proved that the hybrid welding process is ideal. The study of microstructure and properties of 6061 welding joint indicates that hardness, tensile strength and plasticity of the jo
11、int are lower than the relevant properties of base metal and the weakest point of welded joint is in the soften zone of HAZ, 913mm away from the weld center. It is formed due to the overaging of the main strengthening phase particle, which aggregates and coarsens during the influence of welding heat
12、. After some extent of natural seasoning, tensile strength and plasticity of the joint are restored. KEY WORDS automotive, 6061 alloy, hot cracking, porosity, welding technology, microstructure - 1 - 1.1 1 2 35 6 101 60% 47% A8 15 1 1 1 1 (mm) (kg) (mm) (kg) (%) 0.75 8.50 1.00 3.90 54 0.75 10.47 1.0
13、0 4.50 54 2 10% 6% 8% 1.1 50% 3 60 - 2 - Fig.1.1 Relationship between Fuel Consumption and Gross Vehicle Weight 1.2 1.2.1 1896 11 30 12 1 2 60 20 ModelT 2030 360 Tarus - 3 - 12 13 1 3 1 2 1 3 14 1995 ArgentoVivo 1995 91kg 1240kg Ford 182kg 1270kg GM EV-1 CheryslerNeonLite 284kg 3 1996 CHerysler 408k
14、g 21% 6022-T6 AIX 97 1997 CevCherysler 97 1998 FordP2000 135.6kg 52.7% 32.8% 22.8% 1.2 12 610 100 45 100 35 50 30 1985 78 20 50 80 90 + + + - + + - 4 - 44 65 81 55 100 1317 Fig.1.2 Application of Aluminum to Passenger Cars in the U.S. as of 1996 18 20 1.3 Audi A8 Audi A2 NSX Insight 80% 1999 A2 2010
15、 158kg 1995 72 Fig.1.3 Track Records and Forecast of the Amount of Aluminum Used for A Passenger Car in Japan U.S.and Europe 80 - 5 - 80 110kg CA141 25kg NJ130 134 20kg EQ140 17kg 1.2.2 2000 Al-Cu-Mg 5000 Al-Mg 6000 Al-Mg-Si 1216 2000 5000 6000 Al-Mg-Si Al-Mg-Si T6 200 360MPa Al-Cu-Mg Al-Zn-Mg Al-Cu
16、-Mg Al-Zn -Mg Al-Cu-Mg Al-Zn -Mg Al-Mg-Si 6000 Mg 2 Si 6000 1 Al-Mg-Si Al-Mg-Si Mg 2 Si Mg 2 Si Mg Si 1.73 1 Mg 2 Si Mg 2 Si Mg 2 Si Mg 2 Si .Si 1.4 Mn -AlFeSi -AlFeSi Mg 2 Si 0.1 m Mg .Si - 6 - Fig.1.4 The Influence of Mg 2 Si and Excess Si on The Tensile Strength ex 1-Si, ex=0.2 2-Si, ex=0.15 3-Si, ex=0.10 4 -Si, ex=0.05 2 Al-Mg-Si Al-Mg-Si 1 4 1 4 MPa MPa % MPa 6005A 265 235 810 - 6005 265 235 810 205 T5 6063 186 145 12 117 6005A 290 270 810 - 6005 290 250 810 - 6063 241 214 12 152 T6 6061 310 276 17 207 260 310MPa Al-Mg-Si 6005 6005A 6061 6061 1.3 - 7 - 1.3.1 2025 1 5 1 5
