Joint Characteristics and Corrosion Properties of Bypass-Current Double-Sided Arc-Welded Aluminum 6061 Alloy with Al-Si Filler Metal

doi:10.1007/s40195-016-0394-1

Abstract

Abstract:

Sheets of aluminum 6061 alloy were welded using bypass-current double-sided arc welding with Al-Si filler wire to investigate the effect of Al-Si intermetallic compounds on the microstructure, microhardness and corrosion behavior of weld joint. Experimental results indicated that the Al_4.5FeSi phase in the topside of the weld joint was finer than that in the backside and newly formed phase of Al_0.5Fe₃Si_0.5 was observed in the backside. The formation of reinforcing phases of Al-Fe-Si in the weld improved the microhardness of the weld by about 18%. The corrosion resistance of the weld zone was greater than that of the base metal, while the corrosion current displayed opposite, and the corrosion resistance of the weld region was better than that of the base metal.

Key words: Bypass-current, double-sided, arc, welding, Aluminum, 6061, alloy, Joint, characteristics, Interface, analysis, Microhardness, Corrosion, behavior

Yu-Gang Miao, Ben-Shun Zhang, Bin-Tao Wu, Xiao-Xiao Wang, Guang-Yu Chen, Duan-Feng Han. Joint Characteristics and Corrosion Properties of Bypass-Current Double-Sided Arc-Welded Aluminum 6061 Alloy with Al-Si Filler Metal[J]. Acta Metallurgica Sinica (English Letters), 2016, 29(4): 360-366.

Figures/Tables 13

Table 1 Chemical composition of aluminum 6061 alloy and 4043 filler metal (in wt%)

Material	Si	Fe	Mg	Cu	Zn	Mn	Cr	Ti	Al
6061 Alloy	0.4-0.8	0.7	0.8-1.2	0.15-0.4	0.25	0.15	0.04-0.35	0.15	Bal.
Filler metal	4.5-6.0	0.8	0.05	0.3	0.1	0.05	-	-	Bal.

Fig. 1 Schematic diagram of BC-DSAW process

Table 2 Welding parameters used for current study

Welding parameter	Value and unit
Main current	130 A
Main arc voltage	22 V
Flow rate of argon in MIG torch	15 L/min
Bypass current	30 A
Flow rate of argon in bypass TIG torch	5 L/min
Flow rate of argon in backside TIG torch	5 L/min
Welding speed	11.2 mm/s
Distance between filler wire and bypass tungsten	3 mm
Distance contact tip to workpiece	12 mm
Distance backside electrode to workpiece	3 mm
Distance bypass electrode to workpiece	6 mm
Angle between bypass electrode and filler wire	45°

Fig. 2 Appearance of aluminum alloy joint made by BC-DSAW: a topside; b backside

Fig. 3 Cross sections of BC-MIG and BC-DSAW: a morphology of BC-MIG; b distribution of arc energy by BC-MIG;c morphology of BC-DSAW; d distribution of arc energy for BC-DSAW

Fig. 4 Microstructures of different regions of weld joint as marked by A, B, C, D and E in Fig. 3c: a region A; bregion B; c region C; d region D; e region E

Fig. 5 XRD patterns for different weld zones: a upper region; b lower region

Fig. 6 Microhardness for different welding zones: a along base metal to weld zone; b along top to root of weld zone

Fig. 7 Cyclic polarization cures of weld zone and base metal in 0.5 wt% NaCl solution at (25 ± 1) °C

Table 3 Electrochemical parameters derived from potentiodynamic polarization plots of Fig. 7

Corrosion zone	E _vs.SCE (mV)	i _corr (μA/cm²)
Base metal	-741	0.2407
Weld zone	-597	0.1862

Fig. 8 Schematic diagram of Si, Al and Cl particles positions in 0.5 wt% NaCl solution

Fig. 9 Nyquist diagram for weld zone and base metal in 0.5 wt% NaCl solution at (25 ± 1) °C

Fig. 10 Polarization resistance value of weld zone and base metal from EIS simulation

References 21

[1]	V. Fahimpour, S.K. Sadrnezhaad, F. Karimzadeh, Mater. Des.39, 329(2012)
[2]	M. Jariyaboon, A.J. Davenport, R. Ambat, B.J. Connolly, S.W.Williams, D.A. Price, Corros. Sci. 49, 877(2007)
[3]	J.Q. Li, P. Xiao, J. Eur. Ceram. Soc. 22, 1225(2002)
[4]	J. Zhang, D.C. Weckman, Y. Zhou, Weld. J. 87, 18(2008)
[5]	A. Kumar, S. Sundarrajan, Int. J. Adv. Manuf. Technol. 42, 118(2009)
[6]	Y.M. Zhang, S.B. Zhang, Weld. J. 77, 57(1998)
[7]	Y.G. Miao, X.F. Xu, B.T. Wu, J. Mater. Process. Technol. 214,1590(2014)
[8]	J. Corral, E.A. Trillo, Y. Li, L.E. Murr, J. Mater. Sci. Lett. 19,2117 (2000)
[9]	D.A. Wadeson, X. Zhou, G.E. Thompson, P. Skeldon, L. Djapic Oosterkamp, G. Scamans, Corros. Sci. 48, 887(2006)
[10]	W. Dai, S.H. Xue, J.Y. Lou, S.Q. Wang, Mater. Trans. 53, 1638(2012)
[11]	L.C. Tsao, T.C. Tsai, C.S. Wu, H.T. Chuang, J. Mater. Eng.Perform. 10, 705709(2001)
[12]	K. El-Menshawy, A.W.A. Corros. Sci. 54, 167(2012)
[13]	A.G. Rao, V.A. Katkar, G. Gunasekaran, V.P. Deshmukh, N.Prabhu, B.P. Kashyap, Corros. Sci. 83, 198(2014)
[14]	Y.G. Miao, B.T. Wu, X.F. Xu, D.F. Han, Acta Metall. Sin.(Engl. Lett.) 27, 1038(2014)
[15]	K.H. Li, Y.M. Zhang, Weld. J. 87, 11(2008)
[16]	E. Orgis, A. Wahlen, H. Luchinger, P.J. Uggowitzer, J. Light Met. 2, 263(2002)
[17]	A.F. Norman, V. Drazhner, P.B. Prangnell, Mater. Sci. Eng. A 259, 53 (1999)
[18]	M.G. Li, D.Q. Sun, X.M. Qiu, D.X. Sun, S.Q. Yin, Mater. Sci.Eng. A 424, 17 (2006)
[19]	S.Y. Chang, L.C. Tsao, T.Y. Li, T.H. Chuang, J. Alloys Compd.488, 174(2009)
[20]	G.L. Song, M.H. Liu, Corros. Sci. 72, 73(2013)
[21]	C.H. Tang, F.T. Cheng, H.C. Man, Mater. Sci. Eng. A 373, 195 (2004)