Effect of P element on microstructure and properties of Al-Si-Zn filler metal

The effect of P on the spreadability,microstructure of Al-Si-Zn filler metal and the mechanical properties of brazed joints were studied. Results show that the spreadability of the Al-Si-Zn filler metal was improved by the addition of P,and furthermore,both the plate shape primary silicon and needle shape eutectic silicon of the filler metal were refined effectively. Tensile tests indicate that the fracture position of lap joints locates at the base metal and butt joints locates at brazing seam respectively, and the tensile strength of the butt joint brazed with Al-Si-Zn filler metal increased firstly,and then decreased with the increasing of P addition. When the content of P was about 0.06%,the comprehensive properties of the Al-Si-Zn filler metal were the best.