Dissimilar metals TIG welding-brazing of aluminum alloy to galvanized steel

Abstract

Dissimilar metals TIG welding-brazing of aluminum alloy to galvanized steel was investigated, and the wettability and spreadability of aluminum filler metal on the steel surface were analyzed. The resultant joint was characterized in order to determine the brittle intermetallic compound (IMC) in the interfacial layer, and the mechanical property of the joint was tested. The results show that the zinc coated layer can improve the wettability and spreadability of liquid aluminum filler metal on the surface of the steel, and the wetting angle can reach less than 20°. The lap joint has a dual characteristic and can be divided into a welding part on the aluminum side and a brazing part on the steel side. The interfacial IMC layer in the steel side is about 9.0 μm in thickness, which transfers from (α-Al+FeAl₃) in the welded seam side to (Fe₂Al₅+FeAl₂) and (FeAl₂+FeAl) in the steel side. The crystal grain of the welded seam is obviously larger in size in the aluminum side. The local incomplete brazing is found at the root of the lap joint, which weakens the property of the joint. The fracture of the joint occurs at the root and the average tensile strength reaches 90 MPa.

Keywords

aluminum alloy/galvanized steel / TIG welding-brazing / intermetallic compound / microstructure / mechanical property

References

[1] Rathod M J, Kutsuna M. Joining of aluminum alloy 5052 and low-carbon steel by laser roll welding. Welding Journal, 2004, 83(1): 16-26

[2] Zhang H P, Huang P F, Yin S Y, . Study status of the new arc joining of steel and aluminum. Welding & Joining, 2005, 12: 9-13 (in Chinese)

[3] Рябов В Р. Welding and Joining of Aluminum and Its Alloy to Other Metals. Beijing: Astronavigation Press, 1990

[4] Lin S Y, Lei Z. One kind of flux using for dissimilar metals joining by Nd: YAG laser pulsed MIG hybrid welding. Chinese Patent, <patent>CN200710143866.8</patent>, 2007

[5] Fukumoto S, Tsubakino H, Okita K, . Amorphization by friction welding between 5052 aluminum alloy and 304 stainless steel. Scripta Materialia, 2000, 42(8): 807-812

[6] Chen Y C, Komazaki T, Kim Y G, . Interface microstructure study of friction stir lap joint of AC4C cast aluminum alloy and zinc-coated steel. Materials Chemistry and Physics, 2008, 111(2-3): 375-380

[7] VranakovaR, Fussel U, Zschetzsche J,et al. Arc welding of joints between zinc-coated steel and aluminum. Welding in the World, 200549(9), : 105-109

[8] Roulin M, Luster J W, Karadenz G, . Strength and structure of furnace-brazed joints between aluminum and stainless steel. Welding Journal, 1999, 78(5): 151-155

[9] Lei Z, Qin G L, Wang X Y, . Analysis for local incomplete brazing in fusion2brazed joints between aluminum and zinc coated steel by hybrid welding. Transactions of the China Welding Institution, 2007, 28(10): 37-40 (in Chinese)

[10] Zhang H T, Feng J C, He P, . Interfacial microstructure and mechanical properties of aluminum-zinc-coated steel joints made by a modified metal inert gas welding-brazing process. Materials Characterization, 2007, 58(7): 588-592

[11] Bahadur A, Mohanty O N. Structural studies of hot dip aluminized coatings on mild steel. Materials Transactions JIM, 1991, 32(11): 1053-1061

[12] Zhang W. Study on microstructures of hot dip aluminized coatings and effects of La. Dissertation for the Doctoral Degree in Engineering. Xi’an: Xi’an University of Technology, 2006, 4-8 (in Chinese)

Acknowledgements

This research was supported by the National Natural Science Foundation of China (Grant No.50874033).

RIGHTS & PERMISSIONS

2014 Higher Education Press and Springer-Verlag Berlin Heidelberg