Abstract
In this study, brazing AA6061 to Q235 steel using flame brazing was performed with 70.9 wt.% CsF-0.5 wt.% RbF-28.6 wt.% AlF3 fluxes doped with GaF3, ZnF2, Zn(BF4)2 and Ga2O3 nanoparticles, matched with a Zn-15Al filler metal, and the spreadability of the filler metal and the mechanical properties of brazed joints were investigated at the same time. The results showed suitable amounts of GaF3, ZnF2, Zn(BF4)2 and Ga2O3 doped into the base flux could strengthen the filler metal in wetting and spreading on the surface of aluminum alloy and steel to different degrees. The suitable ranges of GaF3, ZnF2, Zn(BF4)2 and Ga2O3, respectively, were 0.0075–0.01 wt.%, 0.0075–0.01 wt.%, 0.0075–0.01 wt.% and 0.009–0.01 wt.%, and the maximum spreading area was obtained via doping with GaF3. The shear strength of brazed joints reached the peak at 126 MPa when 0.075 wt.% GaF3 was added. Comparative tests proved that the activity of the CsF-RbF-AlF3 flux doped with GaF3 was the best. The reason was that the CsF-RbF-AlF3-GaF3 flux was competent in removing oxides of the base metal and decreasing the interfacial tension, in virtue of the activity of Ga3+ as well as F−.
Highlights
The increase in joining dissimilar metals has been prompted by the increasing demand for light weights and fuel efficiency in modern industries in recent years [1]
It was reported that the shear strength of brazed joints reached the peak at 131 MPa when the Zn–15Al filler metal was added in the joining of lap joints of 6061 aluminum alloy to the 304 stainless steel via a flame brazing process, with the Zn-xAl filler metals matching the CsF-0.5 wt.%
Zn-15Al filler metal was studied via spreading tests performed
Summary
The increase in joining dissimilar metals has been prompted by the increasing demand for light weights and fuel efficiency in modern industries in recent years [1]. It remains an unconquerable problem to get stable brazed joints between aluminum/metals dissimilar to steel because of the formation of brittle and hard intermetallic compounds, like Fex Aly [5]. EI-Sayed and Naka [7] found that the maximum bond shear strength of 127 MPa was obtained for an Al-steel joint brazed at 663 K with a 3 s ultrasound application time using a Zn-14Al alloy. It was reported that the shear strength of brazed joints reached the peak at 131 MPa when the Zn–15Al filler metal was added in the joining of lap joints of 6061 aluminum alloy to the 304 stainless steel via a flame brazing process, with the Zn-xAl filler metals matching the CsF-0.5 wt.%
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call