2004 Volume 22 Issue 2 Pages 315-322
Dissimilar diode-laser brazing of A5052/IF steel and A5052/SUS304 has been conducted using BA4047 filler metal with Nocolock flux (KAlF4+K3AlF6). The processing parameters such as laser power, wire feeding speed and travel speed were varied while defocusing distance and shielding gas (Ar) flow rate were constant. Strength of lap joints of A5052 on steels was evaluated by tensile shear test. Fracture strength of A5052/steels joints was increased with increasing laser power and reached the maximum strength more than about 80% of the A5052 base metal strength at laser power of 1300 W. Fracture position shifted from at the A5052/braze layer interface to at the steels/braze layer interface with increasing laser power. The voids and incomplete penetration of filler metal were observed at the A5052/braze layer interface when the laser power was below 1100 W. The Fe-Al intermetallic compounds were formed at the steels/braze layer interface and grew drastically when the laser power exceeded 1300 W. The superior brazability of A5052/steels was indicated at the brazing conditions corresponded to the temperature of melted droplet of BA4047 filler metal being 1050-1250 K during laser brazing process.