Influence of Si Addition on Microstructure, Mechanical Properties, and Corrosion Resistance of Al/Steel Brazing Joint Using Zn-15Al-XSi Filler Metals

The novel Zn-15Al-XSi filler metal was developed to join Al/stainless steel dissimilar metals via a high-frequency brazing method. The influence of Si addition on interface microstructures, joint shear strength, and corrosion resistance was investigated. The results show that with increasing Si content from 0 to 2%, the thickness of the interface reaction layer increased from 0.57 to 1.2 μ m. It was found that the Si element would be aggregated at the interface to form Fe 4 (Al, Si) 13 . The addition of the Si element reduced the shear strength of the joint but improved the corrosion resistance of the brazing joint. With the increase in Si content, the free corrosion potential of Zn-15Al-XSi filler metal increased gradually. The results of the neutral salt spray test showed that the addition of Si slowed down the corrosion rate of the joint. The residual strength of the joint indicated that the corrosion resistance was the best when 2% Si was added to the Zn-15Al filler metal.