The Experimental Research Of Contact Reactive Brazing On Wrought Magnesium Alloys

The characteristics and industrial applications of magnesium alloys were summerized in this paper, and the main problems in magnesium alloy welding were analyzed, some welding methods that may be used on magnesium alloys, its procedure factors as well as its updated research results were reviewed. Forwarding problems to be researched were pointed out.In this paper,The research on magnesium alloy (ME20M and AZ31B) by contact reactive brazing(CRB) in furnance,Copper foil and BAl88SiMg were selected as intermediate layer.Microstructure,Element Behavior and Mechanical properties with different technology parameters were analyzed by means of optical microscope,scanning electron microscopy(SEM) accompanied by EDS and strength analyzer. The good brazing joint status was obtained by the optimization of the technological parameter.Distribution of microhardness was unanimous as a whole.The results show that: Good surface welding joint can be got under proper brazing parameter. CRB with copper foil and BAl88SiMg intermediate layer both have dissolution tendency to two parent metals.Main factor of dissolution were brazing temperature,holding time and thickness of intermediate layer. Copper foil as intermediate layer,Interface zone of ME20M showed up that the granular compound internect lamellar and then incrassated,Interfacial zone showed distinct feature of diffusion reaction with AZ31B. While BAl88SiMg as intermediate layer,Interface of brazing seam manifested typical interaction crystal structure,the liquid phase extended forward with form of eutectic reaction.The extension behaved more obvious as brazing temperature rosing.Distribution of microhardness are unanimous as a whole,Indicating that parent metal realized good metallurgical combination with intermediate layer. As brazing temperature went up,Shear strength of the joint was first increased and then decreased with copper foil.Within a certain range , Shear strength of the joint was increased with BAl88SiMg.Higher shear strength of the joint be got with intermediate layer of BAl88SiMg for AZ31B,Achieving practical extent. Dispersion and distribution of alloyelement were concerned with brazing temperature and holding times. Dispersion and distribution of interface element more distinct and shear strength of the joint more high in a certain area.While brazing temperature and holding time in excess would result in decline of joint shear strength.