Interfacial bonding mechanism in Al/coated steel dissimilar refill friction stir spot welds

doi:10.1016/j.jmst.2019.01.001

Abstract

Abstract:

Defect-free dissimilar Al/zinc coated steel and Al/AlSi coated steel welds were successfully fabricated by refill friction stir spot welding. However, Al alloy and uncoated steel could not be welded under the same welding condition. Al-Zn eutectic layer formed at the Al/zinc coated steel interface showed non-uniformity in thickness and nanoscale intermetallic (IMC) produced was discontinuous. The bonding formation between the Al-Zn layer and the surrounding materials was attributed to a liquid/solid reaction mechanism. Bonding formation at Al alloy and AlSi coated steel interface was attributed to a solid/solid reaction mechanism, as the joining process did not involve with melting of base metals or AlSi coating materials. Kissing bond formed at the weld boundary acted as a crack initiation and propagation site, and the present study showed that weld strength of Al 5754/AlSi coated steel was greatly influenced by properties of original IMC layer.

Key words: Refill friction stir spot welding, Al alloy, Steel, Coated materials, Joining mechanism

Z. Shen, Y. Dingd, J. Chen, B. Shalch Amirkhiz, J.Z. Wen, L. Fu, A.P. Gerlich. Interfacial bonding mechanism in Al/coated steel dissimilar refill friction stir spot welds[J]. J. Mater. Sci. Technol., 2019, 35(6): 1027-1038.

Figures/Tables 28

Table 1 Chemical compositions of as-received materials and coated materials (wt%) [39,40].

Materials	Al	Fe	Si	Zn	Cr	Mg	Mn	B	Cu	P	Ti	C	S	Cr + Mo + Ni
Al 6022	Bal.	0.05-0.20	0.80-1.5	<0.25	0.1	0.07-0.45	0.02-0.10		0.01-0.11		<0.15
Al 5754	Bal.	0.4	0.4			2.6-3.2	0.5
DP600		Bal.	1.5				2			0.04		0.14	0.015	1
22MnB5	0.03	Bal.	0.015		0.16		2.2	0.004		0.02	0.035	0.22
Zn coating	0.3	2.0		97.7
AlSi coating	86.2	1.3	12.5

Fig. 1. Microstructure of as-received base metals: (a) Al 6022-T4, (b) Zinc coated DP600 steel and (c) AlSi coated Usibor 1500 P steel (or 22MnB5 alloy).

Fig. 2. Schematic representation of refill FSSW process: (a) surface preheating while clamping and spindles rotation, (b) sleeve plunges into the sheets while pin moves upwards, (c) tool dwells at a predetermined penetration depth, d) spindles retract back, and (e) surface dwell to flatten the weld surface.

Fig. 3. Macroscopic appearance of two unbonded two surfaces on Al and steel sides, respectively.

Fig. 4. (a) Cross section of the Al 6022/DP600 weld, (b) SEM image of magnified view of black rectangle in (a), STEM images in (c) magnified view of white rectangle in (b), (d) Al/Al-Zn layer interface, (e) Al-Zn layer/steel interface, (f) magnified view of red rectangle in (d), and (g) magnified view of blue rectangle in (e).

Table 2 EDX quantification results (wt%) indicated in Fig. 4(f) and (g).

	I	II	III	IV	V	VI	VII	VIII
Fe		0.1		0.1	37.8	1.1	100	0.6
Al	5.8	7.01	92.2	65.3	43.6	1.2		66.2
Zn	94.2	92.8	7.5	34.4	12.2	97.7		33.2
Si		0.1	0.3	0.2	6.4

Fig. 5. Hardness distribution in middle-thickness of the top Al 6022 and Al 5754.

Fig. 6. Bright field images (TEM) and the corresponding SAD patterns of selected area at (a) Al side (magnified view of yellow rectangle as shown in Fig. 4(c)), (b) Al-Zn eutectic structure and (c) zinc rich precipitate at Al-Zn grain boundary.

Fig. 7. Element maps of Fe, Al, Si and Zn in the Al-Zn layer/steel substrate interface at locations of (a) Fig. 4(e) and (b) Fig. 4(g), (c) SAD pattern of (a) region V in Fig. 4(g).

Fig. 8. Tool rotational speed, position and current during welding process.

Fig. 9. Thermal cycle at the Al 5754/AlSi coated steel interface during the joining process.

Fig. 10. (a) Optical microscope of the cross-section of Al5754/Al-Si coated weld (1.4 mm penetration depth) and magnified views of the (b) blue rectangle and (c) red rectangle in (a), (d) magnified view of red rectangle in (b).

Fig. 11. HAADF image at IMC layer/steel interface with element maps of Al, Fe and Si.

Table 3 EDX quantification results (wt%) indicated in Fig. 11(a).

	IX	X	XI	XII
Al	46.13	54.8	0.34	26.3
Fe	51.28	36.9	98.51	14
Si	2.57	8.29	1.15	59.7

Fig. 12. Bright field images (TEM) and corresponding SAD patterns of selected areas at (a) Al7Fe2Si and (b) Al5Fe2(Si).

Fig. 13. (a) Overall fracture surface of Al/zinc coated steel weld, (b) magnified view of region E in (a).

Table 4 EDX quantification results (wt%) indicated in Fig. 13.

	A	B	C	D	E	F
Fe		0.63	28.34	41.39	1.30
Al	50.88	52.89	46.10	43.85	56.06	100.00
Zn	48.94	45.83	25.05	13.49	42.43
Si	0.17	0.65	0.51	1.27	0.21

Fig. 14. Fracture path at the location of (a) brazing area, (b) sleeve stirring area and (c) pin stirring area in Fig. 13.

Table 5 EDX quantification results (wt%) indicated in Fig. 14.

`	I	II	III	IV	V	VI	VII	VIII	IX
Fe	3.13	4.74	2.91	56.41	14.57	17.26
Al	62.01	61.59	46.41	31.68	71.45	73.52	66.9	58.52	62.61
Zn	34.86	33.67	50.68	10.99	10.9	7.89	33.1	41.2	36.83
Si				0.92	3.08	1.33		0.28	0.56

Fig. 15. Effects of tool penetration depth on weld lap shear strength.

Fig. 16. Fracture surface of the Al5754/AlSi coated steel weld: (a) overall and (b) magnified view in the white rectangle in a (0.9 mm penetration, 1.42 kN).

Fig. 17. Fracture path at the location of (a) weld boundary and (b) center in Fig. 16(a).

Fig. 18. Fracture surface of the Al5754/AlSi coated steel weld: (a) overall and (b) magnified view in the white rectangle in a (1.4 mm penetration, 4.44 kN).

Fig. 19. Fracture path at the location of (a) weld boundary and (b) center in Fig. 18(a).

Table 6 EDX quantification results (wt%) indicated in Fig. 16.

Region	A	B	C	D	E	F	G	H	I
Al	53.65	95.86	95.99	92.66	93.58	92.93	95.14	93.76	95.15
Fe	38.23	1.07	0.72	0.59	1.79	0.83	1.07	0.42	0.45
Si	8.12	2.26	2.38	4.91	2.80	4.15	2.60	4.23	2.50
Mg		0.81	0.91	1.84	1.83	2.09	1.19	1.59	1.90

Table 7 EDX quantification results (wt%) indicated in Fig. 17.

	I	II	III	IV	V	VI
Al	97.52	96.74	97.34	56.32	56.70	53.20
Fe	1.64	0.69	0.29	32.13	32.31	36.21
Si	0.26	0.36		11.55	10.98	10.59
Mg	0.57	2.22	2.37

Table 8 EDX quantification results (wt%) indicated in Fig. 18.

Region	A	B	C	D	E	F	G	H	I
Al	93.5	54.0	51.7	51.7	96.7	96.4	51.9	95.0	95.8
Fe	2.8	38.2	40.6	40.5		0.1	40.9	0.6	0.6
Si	3.7	7.8	7.7	7.8	1.1	1.3	7.1	3.1	1.6
Mg					2.2	2.2	0.1	1.3	2.0

Table 9 EDX quantification results (wt%) indicated in Fig. 19.

	I	II	III	IV	V	VI
Al	94.53	93.02	96.41	54.80	54.54	54.52
Fe	3.60	4.00	2.17	32.70	33.84	33.44
Si	0.92	1.58		12.50	11.62	12.04
Mg	0.95	1.40	1.42

References

[1]	K. Martinsen, S. Hu, B. Carlson, CIRP Ann. Manuf. Technol. 64 (2) (2015) 679-699.
[2]	Y. Abe, T. Kato, K. Mori, J. Mater. Process. Technol. 177 (1) (2006) 417-421.
[3]	C.J. Lee, J.Y. Kim, S.K. Lee, D.C. Ko, B.M. Kim, J. Mech. Sci. Technol. 24 (1) (2010) 123-126.
[4]	R. Qiu, H. Shi, K. Zhang, Y. Tu, C. Iwamoto, S. Satonaka, Mater. Charact. 61 (7) (2010) 684-688.
[5]	Z. Shen, Y. Chen, M. Haghshenas, A. Gerlich, Eng. Sci. Technol. 18 (2) (2015) 270-277.
[6]	E. Taban, J.E. Gould, J.C. Lippold, Mater. Des. 31 (5) (2010) 2305-2311.
[7]	J. Chen, J. Li, B.S. Amirkhiz, J. Liang, R. Zhang, Mater. Lett. 137 (2014) 120-123.
[8]	M. Thom?, G. Wagner, B. Stra?, B. Wolter, S. Benfer, W. Fürbeth, J. Mater. Sci. Technol. 34 (2018) 163-172.
[9]	L. Agudo, D. Eyidi, C.H. Schmaranzer, E. Arenholz, N. Jank, J. Bruckner, A.R. Pyzalla, J. Mater. Sci. 42 (12) (2007) 4205-4214.
[10]	V. Patel, S. Bhole, D. Chen, Metall. Mater. Trans. A, 45 (4) (2014) 2055-2066.
[11]	E. Fereiduni, M. Movahedi, A. Kokabi, J. Mater. Process. Technol. 224 (2015) 1-10.
[12]	Y. Uematsu, T. Kakiuchi, Y. Tozaki, H. Kojin, Sci. Technol. Weld. Join. 17 (5) (2012) 348-356.
[13]	C.Y. Lee, D.H. Choi, Y.M. Yeon, S.B. Jung, Sci. Technol. Weld. Join. 14 (3) (2009) 216-220.
[14]	E. Fereiduni, M. Movahedi, A.H. Kokabi, H. Najafi, Metall. Mater. Trans. A, 48 (4) (2017) 1744-1758.
[15]	J.M. Piccini, H.G. Svoboda, Proc. Mater. Sci. 9 (2015) 504-513.
[16]	Y. Sun, H. Fujii, N. Takaki, Y. Okitsu, Mater. Des. 47 (2013) 350-357.
[17]	S. Bozzi, A. Helbert-Etter, T. Baudin, B. Criqui, J. Kerbiguet, Mater. Sci. Eng. A 527 (16) (2010) 4505-4509.
[18]	T. Liyanage, J. Kilbourne, A. Gerlich, T. North, Sci. Technol. Weld. Join. 14 (6) (2009) 500-508.
[19]	A. Da Silva, E. Aldanondo, P. Alvarez, E. Arruti, A. Echeverria, Sci. Technol. Weld. Join. 15 (8) (2010) 682-687.
[20]	Y. Chen, A. Gholinia, P. Prangnell, Mater. Chem. Phys. 134 (1) (2012) 459-463.
[21]	G. Figner, R. Vallant, T. Weinberger, H. Schrottner, H. Pasic, N. Enzinger, Weld. World, 53 (1-2) (2009) R13-R23.
[22]	K. Chen, X. Liu, J. Ni, J. Mater. Process. Technol. 249 (2017) 452-462.
[23]	K. Ohishi, M. Sakamura, K. Ota, H. Fujii, Weld. Int. 30 (2) (2016) 91-97.
[24]	V.-X. Tran, J. Pan, Int. J. Fatigue, 32 (7) (2010) 1167-1179.
[25]	I. Ibrahim, Y. Uematsu, T. Kakiuchi, Y. Tozaki, Y. Mizutani, Sci. Technol. Weld. Join. 20 (8) (2015) 670-678.
[26]	K. Feng, M. Watanabe, S. Kumai, Mater. Trans. 52 (7) (2011) 1418-1425.
[27]	T. Gendo, K. Nishiguchi, M. Asakawa, S. Tanioka, Spot friction welding of aluminum to steel, SAE Technical Paper (2007).
[28]	K. Miyagawa, M. Tsubaki, T. Yasui, M. Fukumoto, Weld. Int. 23 (9) (2009) 648-653.
[29]	G. Padhy, C. Wu, S. Gao, J. Mater. Sci. Technol. 34 (2017) 1-38.
[30]	C. Schilling, Google Patents 2004.
[31]	Z. Shen, X. Yang, Z. Zhang, L. Cui, Y. Yin, Mater. Des. 49 (2013) 181-191.
[32]	Z. Shen, X. Yang, S. Yang, Z. Zhang, Y. Yin, Mater. Des. 54 (2014) pp. 766-778, 1980-2015.
[33]	Y. Zhao, C. Wang, J. Li, J. Tan, C. Dong, J. Mater. Sci. Technol. 34 (2017) 185-191.
[34]	Z. Shen, Y. Ding, O. Gopkalo, B. Diak, A.P. Gerlich, J. Mater. Process. Technol. 252C (2018) 751-759.
[35]	Z. Shen, X. Yang, Z. Zhang, L. Cui, T. Li, Mater. Des. 44 (2013) 476-486.
[36]	Z. Shen, Y. Chen, J. Hou, X. Yang, A. Gerlich, Sci. Technol. Weld. Join. 20 (1) (2015) 48-57.
[37]	A.M. Nasiri, Z. Shen, J.S.C. Hou, A.P. Gerlich, Eng. Failure Anal. 84 (2018) 25-33.
[38]	Y. Chen, J. Chen, B. Shalchi Amirkhiz, M. Worswick, A. Gerlich, Sci. Technol. Weld. Join. 20 (6) (2015) 494-501.
[39]	Z. Shen, J. Chen, Y. Ding, J. Hou, B.S. Amirkhiz, K. Chan, A. Gerlich, Sci. Technol. Weld. Join. 23 (2018) 462-477.
[40]	Y. Ding, Z. Shen, A. Gerlich, J. Manuf. Process. 30 (2017) 353-360.
[41]	Z. Shen, J. Hou, K. Chan, N. Scotchmer, N. Zhou, A. Gerlich, Spot welding aluminum 6022-T4 to galvanized DP600 sheet by refill friction stir spot welding, SWMC XVII Conference (2016).
[42]	H. Dong, S. Chen, Y. Song, X. Guo, X. Zhang, Z. Sun, Mater. Des. 94 (2016) 457-466.
[43]	S. Fukada, R. Ohashi, M. Fujimoto, H. Okada, Refill friction stir spot welding of dissimilar materials consisting of A6061 and hot dip zinc-coated steel sheets, Proceedings of the 1st International Joint Symposium on Joining and Welding: Osaka Japan(2014) p. 183.
[44]	U. Suhuddin, V. Fischer, A. Kostka, J. dos Santos, Sci.Technol. Weld. Join. 22 (2018) 658-665.
[45]	Y. Wang, B. Al-Zubaidy, P.B. Prangnell, Metall. Mater. Trans. A, 49 (1) (2018) 162-176.
[46]	Z. Shen, Y. Ding, J. Chen, A. Gerlich, Int. J. Fatigue 92 (2016) 78-86.
[47]	T.B. Massalski, H. Okamoto, P. Subramanian, L. Kacprzak, W.W. Scott, Binary Alloy Phase Diagrams, American Society for Metals, Metals Park, OH (1986).
[48]	Y. Chen, T. Komazaki, T. Tsumura, K. Nakata, Mater. Sci. Technol. 24 (1) (2008) 33-39.
[49]	A. Marder, Prog. Mater. Sci. 45 (3) (2000) 191-271.
[50]	R. Richards, R. Jones, P. Clements, H. Clarke, Int. Mater. Rev. 39 (5) (1994) 191-212.
[51]	J. Mackowiak, N. Short, Int. Metals Rev. 24 (1) (1979) 1-19.
[52]	W.J. Cheng, C.J. Wang, Intermetallics, 19 (10) (2011) 1455-1460.
[53]	A. Bahadur, Mater. Trans. JIM, 32 (11) (1991) 1053-1061.
[54]	X. Liu, B. Diak, TEM Precipitate Identification in Artificial Aged 6022-T4 Alloy and 7075 Artificial Ageing at near Welding Temperature, Report to Ford (2016).
[55]	AWS D 17.2, Specification for Resistance Welding for Aerospace Applications, American Welding Society (2007).
[56]	H. Springer, A. Kostka, E. Payton, D. Raabe, A. Kaysser-Pyzalla, G. Eggeler, Acta Mater. 59 (4) (2011) 1586-1600.
[57]	H. Springer, A. Szczepaniak, D. Raabe, Acta Mater. 96 (2015) 203-211.
[58]	P. Su, A. Gerlich, T. North, G. Bendzsak, Sci. Technol. Weld. Join. 11 (2) (2006) 163-169.
[59]	M. Reimann, J. Goebel, T.M. Gartner, J.F. dos Santos, J.Mater. Process. Technol. 245 (2017) 157-166.
[60]	A. Gerlich, P. Su, M. Yamamoto, T.H. North, J. Mater. Sci. 42 (14) (2007) 5589-5601.
[61]	A. Gerlich, M. Yamamoto, T.H. North, J. Mater. Sci. 43 (1) (2008) 2-11.
[62]	A. Oosterkamp, L.D. Oosterkamp, A. Nordeide, Weld. J. N.Y. 83 (8) (2004) 225-S.
[63]	T. Maitra, S. Gupta, Mater. Charact. 49 (4) (2002) 293-311.
[64]	G. Gautam, G. Petzow, G. Effenberg (Eds.), Aluminium- Iron- Silicon(2005) pp. 394-438.
[65]	Specification for Automotive Weld Quality— Resistance Spot Welding of Steel, An American National Standard, (2007).