Friction Stir Brazing: a Novel Process for Fabricating Al/Steel Layered Composite and for Dissimilar Joining of Al to Steel

• Published in: Metallurgical and materials transactions. A, Physical metallurgy and materials science Vol. 42; no. 9; pp. 2850 - 2861
• Main Authors: Zhang, Guifeng, Su, Wei, Zhang, Jianxun, Wei, Zhongxin
• Format: Journal Article
• Language: English
• Published: Boston Springer US 01.09.2011; Springer; Springer Nature B.V
• Subjects: Aluminum; Applied sciences; Brazing. Soldering; Characterization and Evaluation of Materials; Chemistry and Materials Science; Composite materials; Exact sciences and technology; Friction stir processing; Friction stir welding; Iron and steel industry; Joining, thermal cutting: metallurgical aspects; Materials Science; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metallic Materials; Metals. Metallurgy; Nanotechnology; Sheet metal; Steel alloys; Steel making; Structural Materials; Structural steels; Surfaces and Interfaces; Thin Films; Zinc; Traverse Speed; Filler Metal; Peel Strength; Peel Test; Steel Side; Mechanical properties; Joining; Brazing; Friction brazing; Friction; Composite material
• ISSN: 1073-5623; 1543-1940
• DOI: 10.1007/s11661-011-0677-0

A novel process of friction stir brazing (FSB) for fabricating Al/steel layered composite (by multipass) and for joining Al to steel (by single pass) was proposed to avoid the wear of pin by steel, in which a tool without pin was used. FSB of 1.8-mm-thick Al sheet to steel sheet was conducted using a cylindrical tool with 20-mm diameter but without pin and using 0.1-mm-thick zinc foil as filler metal. For the rotational speed of 1500 rpm, sound joints were reliably obtained at the medium range of traverse speed of 75 to 235 mm/min, which fractured within Al parent sheet during tensile shear test. Furthermore, for peel test on the sound joints, Al and steel parent sheets tended to crack and deform, respectively. Metallographic examination showed that most Zn was extruded and the resultant interfacial structure consisted of several Al-Fe intermetallic compounds (IMCs) with a little Zn, less than 3 at. pct. The thickness of IMCs can be controlled to be less than 10  μ m by properly increasing traverse speed ( e.g. , 150 mm/min). The metallurgical process of FSB was investigated by observing the microstructure of the longitudinal section of a friction stir brazed joint obtained by the suddenly stopping technique.