Product Code: ICA11_603

Study on Laser Brazing Characteristics of Dissimilar Metals
Authors:
SookHwan Kim, Research Institute of Industrial Science of Technology; Pohang South Korea
Y. Norman Zhou, University of Waterloo; Waterloo Canada
Mok Young Lee, Research Institute of Industrial Science of Technology; Pohang South Korea
LiQun Li, Harbin Institute of Technology; Harbin Peoples Republic of China
Ali Nasiri, University of Waterloo; -
Presented at ICALEO 2011

Laser brazing between commercially Al coated steel and Mg alloy(AZ31) has been carried out in the Mg-based and Al-based insert metals.
The brazing bonds have been evaluated using light microscopy, micro hardness, electron probe microanalysis(EPMA), X-ray diffraction(XRD) technique and tensile shear testing. Light microscopy shows that different intermediate layers are formed in the reaction zone, and these layers changes with a kind of insert metals. EPMA revealed that, at any particular insert metal, MgAl-rich phases(intermetallic phases) formed in cell boundary of the Mg alloy side, but there is no MgAl-rich phases in steel side, whereas original coated layer still remained in the steel side.
This microanalysis also indicated different step formation in the concentration profile of Al, Mg, Zn and Si over different composition ranges in the fusion zone indicating formation of intermetallic phases that were detected by XRD. Brittle intermetallic phases lower the strength and ductility of the brazed couples significantly. Best tensile shear fracture load(RT), approx=520kg has been obtained at Mg-6.5Al-1Zn-0.3Mn due to minimal deleterious effects.