Achieving a strong polypropylene/aluminum alloy friction spot joint via a surface laser processing pretreatment

doi:10.1016/j.jmst.2020.02.035

Abstract

Abstract:

Strong metal/non-polar plastic dissimilar joints are highly demanded for the lightweight design in many fields, which, however, are rather challenging to achieve directly via welding. In this study, we designed a laser processing pretreatment on the Al alloy to create a deep porous Al surface structure, which was successfully joined to the polypropylene (PP) via friction spot welding. A maximum joint strength of 29 MPa was achieved, the same as that of the base PP (i.e. the joint efficiency reached 100%), much larger than ever reported. The joining mechanism of the Al alloy and the PP was mainly attributed to the large mechanical interlocking effect between the laser processed Al porous structure and the re-solidified PP and the formation of chemical bond at the interface. The deep porous Al surface structure modified by laser processing largely changed the Al-PP reaction feature. The evidence of the C—O—Al chemical bond was first time found at the non-polar plastic/Al joint interface, which was the reaction result between the oxide on the Al alloy surface and thermal oxidization products of the PP during welding. This study provides a new way for enhancing metal-plastic joints via surface laser treatment techniques.

Key words: Friction stir welding, Hybrid joint, Metal, Polymer, Surface treatment, Interface

S.C. Han, L.H. Wu, C.Y. Jiang, N. Li, C.L. Jia, P. Xue, H. Zhang, H.B. Zhao, D.R. Ni, B.L. Xiao, Z.Y. Ma. Achieving a strong polypropylene/aluminum alloy friction spot joint via a surface laser processing pretreatment[J]. J. Mater. Sci. Technol., 2020, 50: 103-114.

Figures/Tables 14

Fig. 1. Typical surface morphologies with separation directly after friction stir spot welding of 5182 Al alloy and PP using a tool without a pin.

Fig. 2. (a) Schematic of laser processing pretreatment on Al alloy surface, and metallographic photos of Al alloy surface, (b) before pretreatment, (c) after laser processing pretreatment, (d) cross section after pretreatment, (e) topographical view of Al alloy surface measured by surface profilometer.

Fig. 3. Groove depth and roughness of Al alloy surface after laser processing for different scanning number.

Fig. 4. (a) Typical macro surface image of friction spot joint of PP to Al alloy after laser processing pretreatment, (b) variation of tensile shear force and strength of joints with laser scanning number.

Fig. 5. Maximum normal tensile shear strength and force of non-polar plastic-metal hybrid joints from different researches. FLW and FSLW represent friction (stir) lap welding and friction (stir) spot lap welding, respectively. The red and black columns represent normal tensile shear strength and force, respectively in this figure.

Fig. 6. (a) Temperature measurement position, (b) temperature measurement results, (c-f) cross sections of Al?PP joints with laser scanning number of 5, 10, 20 and 40, (g) typical microstructure of Al?PP joint for laser scanning 10 times.

Fig. 7. SEM images of Al?PP joint for laser scanning 5 times: (a, b) interface at joint center ("position 1" in Fig. 6(a)), (c, d) high magnification of red frame in (b), (e, f) high magnified images of groove bottom at joint position of 3.75 mm away from joint center ("position 2" in Fig. 6(a)) and at joint position of 7.5 mm away from joint center ("position 3" in Fig. 6(a)).

Fig. 8. SEM images of Al?PP interface of joints: (a) laser processing for 10 times, (b) laser processing for 40 times, (c, d) high magnification of Al?PP interface for 40 times.

Fig. 9. (a) Joint surface morphology after stretching at laser scanning 5 times, (b) PP remained on metal side, (c, d) residual PP on metal side by SEM-EDS analysis.

Fig. 10. (a) Typical fractured surface morphology of Al?PP joint for laser scanning 40 times after fracturing, (b) cross section of Al?PP joint for 10 times after fracturing, (c) high magnified SEM image of joint interface between Al alloy and PP for 10 times after fracturing, (d) most joint interface between Al alloy and PP for 40 times after fracturing, (e) Al anchors was pulled to fracture in some position of Al?PP joint for 40 times, (f) tight bonding at joint interface between Al alloy and PP for 40 times after fracturing.

Fig. 11. FT-IR analysis of (a) as-received PP, (b) residue on metal side after joint fracture for laser scanning 5 times.

Fig. 12. XPS analysis of (a) as-received PP, (b) residue on metal side after joint fracture for laser scanning 5 times.

Fig. 13. XPS analysis of residue on Al alloy fracture surface of Al/glass fiber reinforced PP joint.

Table A1 Maximum normal TSS and TSF of non-polar polymer-metal hybrid lap joints.

Method (materials)	Max TSF (kN)	Max normal TSS (% of plastic BM)	Normal joining area (mm²)	Remark	Ref.
FLW (Al alloy-PP)	～0.37	～0.71* (2.8%)	20 × 25.8	Tool Φ20 mm; Interface fracture	[28]
FLW (Al alloy-PP)	～0.37	～0.71* (2.8%)	20 × 25.8	Reported max TSS: ～5.1MPa	[28]
FSLW (Al alloy-PP based composite)	0.35	～1.1*	π × 10²	5052 Al alloy: Pre-threaded hole Φ4 mm;	[27]
		(～3.2%)		Tool Φ20 mm without pin; Interface fracture
		(～3.2%)		Reported max TSS: ～28 MPa
FSLW (Al alloy-PP)	0.54	～3.5* (～10%)	π × 7²	2219Al alloy: Pre-threaded hole Φ4 mm;	[30]
FSLW (Al alloy-PP)	0.54	～3.5* (～10%)	π × 7²	Tool Φ14 mm without pin; Interface fracture	[30]
FLW(SPCC alloy-PE)	0.95	～4.2 (--)	15 × 15	PE: Corona-discharge;	[29]
FLW(SPCC alloy-PE)	0.95	～4.2 (--)	15 × 15	Tool Φ15 mm without pin; Interface fracture	[29]
FSLW (Al alloy-PP)	1.23	～3.9* (--)	π × 10²	5052 Al alloy: plasma electrolytic oxidation; Pre-drilled hole Φ5 mm;	[31]
FSLW (Al alloy-PP)	1.23	～3.9* (--)	π × 10²	Tool Φ20 mm; Interface fracture	[31]
FLW (Mg alloy-PE)	～1.4	4.67 (--)	15 × 20	Low density PE: Corona-discharge;	[19]
				Mg alloy: plasma electrolytic oxidation;
				Tool Φ15 mm without pin; Interface fracture
FSLW (Ti alloy-PE)	～1.35	～22.5 (～64%)	π × 5²	Ti-6Al-4 V alloy: 3D printed, porous;	[32]
FSLW (Ti alloy-PE)	～1.35	～22.5 (～64%)	π × 5²	Tool Φ10 mm without pin; PE fracture	[32]
FSLW (Al alloy-PP)	2.4	29 (100%)	π × 7.5²	5052 Al alloy: laser processing, porous;	This study
FSLW (Al alloy-PP)	2.4	29 (100%)	π × 7.5²	Tool Φ15 mm without pin; PP BM fracture	This study

References 34

[1]	B. Wielage, D. Richter, H. Mucha, T. Lampke, J. Mater. Sci. Technol. 24 2008 953-959.
[2]	A. Pramanik, A.K. Basak, Y. Dong, P.K. Sarker, M.S. Uddin, G. Littlefair, A.R. Dixit, S. Chattopadhyaya, Compos. Part A 101 (2017) 1-29.
[3]	J.M. Arenas, C. Alía, J.J. Narbón, R. Oca˜na, C. González, Compos. Part B 44 (2017) 417-423.
[4]	J.P. Kabche, V. Caccese, K.A. Berube, R. Bragg, Compos. Part B 38 (2007) 66-78.
[5]	F. Balle, G. Wagner, D. Eifler, Adv. Eng. Mater. 11 2009 35-39.
[6]	F. Balle, G. Wagner, D. Eifler, Materialwiss. Werkstofftech. 38 2007 934-938.
[7]	X.H. Tan, J. Zhang, J.G. Shan, S.L. Yang, J.L. Ren, Compos. Part B 70 (2015) 35-43.
[8]	S. Katayama, Y. Kawahito, Scr. Mater. 59 2008 1247-1250.
[9]	K. Nagatsuka, S. Yoshida, A. Tsuchiya, K. Nakata, Compos. Part B 73 (2015) 82-88.
[10]	L.H. Wu, K. Nagatsuka, K. Nakata, J. Mater, Sci. Technol. 34 2018 192-197.
[11]	F. Balle, D. Eifler, Materialwiss. Werkstofftech. 43 2012 286-292.
[12]	K.W. Jung, Y. Kawahito, M. Takahashi, S. Katayama, J. Laser Appl. 25 2013 032003.
[13]	L.H. Wu, X.B. Hu, X.X. Zhang, Y.Z. Li, Z.Y. Ma, X.L. Ma, B.L. Xiao, Acta Mater. 166 2019 371-385.
[14]	R. Nandan, T. DebRoy, H.K.D.H. Bhadeshia, Prog. Mater. Sci. 53 2008 980-1023.
[15]	L.H. Wu, D. Wang, B.L. Xiao, Z.Y. Ma, Scr. Mater. 78-79 2014 17-20.
[16]	L.H. Wu, H. Zhang, X.H. Zeng, P. Xue, B.L. Xiao, Z.Y. Ma, Sci. China Mater. 61 2018 417-423.
[17]	F.C. Liu, Y. Hovanski, M.P. Miles, C.D. Sorensen, T.W. Nelson, J. Mater. Sci. Technol. 34 2018 39-57.
[18]	Y.X. Huang, X.C. Meng, Y.M. Xie, J.C. Li, L. Wan, Compos. Part A 112 (2018) 328-336.
[19]	F.C. Liu, J. Liao, Y. Gao, K. Nakata, Sci. Technol. Weld. Joining 20 (2015) 291-296.
[20]	F.C. Liu, J. Liao, K. Nakata, Mater. Des. 54 2014 236-244.
[21]	S. Eslami, P.J. Tavares, P.M.G.P. Moreira, Int. J. Adv. Manufact. Technol. 89 2016 1677-1690.
[22]	Y. Huang, X. Meng, Y. Wang, Y. Xie, L. Zhou, J. Mater. Proc. Technol. 257 2018 148-154.
[23]	S.M. Goushegir, J.F. dos Santos, S.T. Amancio-Filho, Mater. Des. 54 2014 196-206.
[24]	L.H. Wu, K. Nagatsuka, K. Nakata, J. Mater. Sci. Technol. 34 (9) (2018) 1628-1637.
[25]	F.C. Liu, P. Dong, W. Lu, K. Sun, Appl. Surf. Sci. 466 2019 202-209.
[26]	Z. Zhang, J.-G. Shan, X.-H. Tan, J. Zhang, Int. J. Adhes. Adhes. 70 2016 142-151.
[27]	H. Karami Pabandi, M. Movahedi, A.H. Kokabi, Compos. Struct. 174 2017 59-69.
[28]	H. Shahmiri, M. Movahedi, A.H. Kokabi, Sci. Technol. Weld. Joining 22 (2) (2016) 120-126. DOI URL
[29]	K. Nagatsuka, D. Kitagawa, H. Yamaoka, K. Nakata, ISIJ Int. 56 2016 1226-1231. DOI URL
[30]	M. Paidara, O.O. Ojob, A. Moghanianc, H.K. Pabandid, M. Elsae, J. Mater. Process. Technol. 273 2019 116272. DOI URL
[31]	S. Aliasghari, M. Ghorbani, P. Skeldon, H. Karami, M. Movahedi, Surf. Coat. Technol. 313 2017 274-281. DOI URL
[32]	K. Chen, B. Chen, S. Zhang, M. Wang, L. Zhang, A. Shan, Mater. Des. 132 2017 178-187. DOI URL
[33]	S. Qian, T. Igarashi, K. Nitta, Polym. Bull. 67 2011 1661-1670. DOI URL
[34]	Y. Feng, L. Zhou, N. Dong, X. Hong, China Plast. 17 2003 87-90 (In Chinese).