Effect of Ultrasonic Impact on the Microstructure of Welded Joint of 2195 Al-Li Alloy

doi:10.1007/s40195-016-0396-z

Abstract

Abstract:

It is known that an ultrasonic impact during tungsten inert gas welding can refine the grains and improve the mechanical properties of the welded joints of aluminum alloys. However, the influence mechanism of the ultrasonic impact on the microstructures is still unclear. In this research, the effects of the mechanical and ultrasonic impact on the microstructures of the welded joint of 2195 Al-Li alloy are analyzed. It is found that the mechanical impact could not refine the grains, but the ultrasonic impact could refine the grains. The grains become smaller in the weld center with an increase in the ultrasonic amplitude. Possible mechanisms for the grain refinement are discussed. The results show that the small temperature gradient promotes formation of the equiaxed grain and the cavitation promotes heterogeneous nucleation.

Key words: Ultrasound, TIG, welding, Microstructure, Al-Li, alloy

Qi-Hao Chen, San-Bao Lin, Chun-Li Yang, Cheng-Lei Fan. Effect of Ultrasonic Impact on the Microstructure of Welded Joint of 2195 Al-Li Alloy[J]. Acta Metallurgica Sinica (English Letters), 2016, 29(4): 367-372.

Figures/Tables 8

Fig. 1 Schematic of the experimental setup

Table 1 Parameters of the welding power source

EN (A)	EP (A)	Duty cycle (%)	Frequency (Hz)
100	53	75	100

Table 2 Chemical compositions of 2195 Al-Li alloy and 1060 aluminum alloy (wt%)

Material	Cu	Li	Ag	Zr	Ti	Fe	Si	Mn	V	Mg	Zn	Al
2195	4.02	1.00	0.40	0.11	0.068	0.16	0.03	0	0	0	0	Bal.
1060	0.05	0	0	0	0.03	0.35	0.25	0.03	0.05	0.03	0.05	Bal.

Fig. 2 Microstructures of the welded joint: a original TIG, b mechanical impact, and c ultrasonic impact

Fig. 3 Effect of the ultrasonic amplitude on the grain refinement in the weld center a 7.5 µm, b 8.1 µm, and c8.81 µm

Fig. 4 Macrostructures observed by optical microscopy (OM) at the a fusion zone without the ultrasonic impact, bweld center without the ultrasonic impact, c fusion zone with the ultrasonic impact, d weld center with the ultrasonic impact

Fig. 5 Temperature distribution in the weld pool

Fig. 6 Microstructures of a longitudinal section

References 18

[1]	A.E. Hughes, R.J. Taylor, B.R.W. Surf. Interface Anal.25, 223(1997)
[2]	H.R. Kotadia, A. Das, E. Doernberg, R. Schmid-Fetzer, Mater.Chem. Phys. 131, 241(2011)
[3]	S.L. Zhang, Y.T. Zhao, X.N. Cheng, G. Chen, Q.X. Dai, J.Alloys Compd. 470, 168(2009)
[4]	L.H. Zhang, Y. Jun, X.M. Zhang, J. Cent, South Univ. Technol.17, 431(2010)
[5]	H. Puga, S. Costa, J. Barbos, S. Ribeiro, M. Prokic, J. Mater.Process. Technol. 211, 1729(2011)
[6]	M. Qian, A. Ramirez, A. Das, J. Cryst. Growth 311, 3708 (2009)
[7]	L.B. He, P. Yang, L.M. Li, M.S. Wu, Ultrasonics 54, 2178(2014)
[8]	Q.J. Sun, S.B. Lin, C.L. Yang, G.Q. Zhao, Sci. Technol. Weld.Join. 14, 765(2009)
[9]	W.L. Dai, Mater. Lett. 57, 2447(2003)
[10]	H.T. Qu, Harbin Institute of Technology, 2014 (in Chinese)
[11]	Y. Cui, C.L. Xu, Q. Han, Adv. Eng. Mater. 9, 161(2007)
[12]	L. Nastac, ISIJ Int. 54, 1830(2014)
[13]	J.W. Li, T. Momono, Y. Fu, J. Zheng, Y. Tayu, Trans. Nonferrous Met. Soc. China 17, 691 (2007)
[14]	A. Ramirez, Q. Ma, B. Davis, T. Wilks, D.H. Stjohn, Scr. Mater.59, 19(2008)
[15]	T.V. Atamanenko, D.G. Eskin, L. Zhang, L. Katgerman, Metall.Mater. Trans. A 41, 2056 (2010)
[16]	G.I. Eskin, Amsterdam, 1998)
[17]	Y. Tsunekawa, H. Suzuki, Y. Genma, Mater. Des. 22, 467(2001)
[18]	G. Wang, M.S. Dargusch, M. Qian, D.G. Eskin, D.H. Stjohn, J.Cryst. Growth 408, 119 (2014)