Research On The Welding Of SiCp/2024Al Aluminum Metal Matrix Composite

Discontinuously reinforced aluminum-matrix composites are now widely used because of its high specific stiffness and strength, high temperature resistance and wearing resistance. The trustiness joining of the aluminum matrix composite is the serious problem rejecting its use. Because the complex macro and micro structure of the aluminum matrix composite, joining of aluminum matrix composite is more difficult than the homogeneous material. So the welding of SiC particle reinforced aluminum metal matrix composite has important theory significance and application value.According to the special characteristics of SiCp/2024Al aluminum metal matrix composite, two difference welding methods was used.In the SiCp/2024Al aluminum matrix composite vacuum brazing process, surface particle exposing technology and SiC surface metallization method were used. The shearing strength of the brazing joint was 202MPa. (NaOH+HNO3) technology can partly expose the SiC reinforcement on the surface. The exposing SiC particle became part of the brazing joint, and the brazing joint became the metal matrix composite plateform.Using M6 filler metal and depositing Cu on the surface of the parent composite can get better brazing joint. There is no Al4C3 formed in the joint. The fracture analysis indicated the main reason for the lost of the joint strength is the un-wetting of the filler metal. The porosity causing by high brazing temperature and the aggregation reinforcement on the parent composite two other important reasons for the brazing joint strength lost.GT35 steel-bonded carbide ingots were used to fabricate the friction stir welding tool. The bolt bonding particle friction stir welding tools were designed, which could ensure the friction stir welding process. There was typical"onion circle"structure in the friction stir welding joint. The interface of the SiC/Al was distinct and no brittle phase was formed. The friction stir welding joint strength analysis indicated that the tensile strength of the friction stir welding joint could reach 80% of the base MMC. Changing the friction stir welding parameters, the equal strength joint could be reached. The fracture analysis indicated there were concentric cleavage fractures on the surface.Hydrodynamic theory and viscosity equation were used to characterize the physical model of the friction stir welding process. The Al MMC was the high-viscosity, non-Newtonian and incompressible liquid, and a nonlinear coupling numerical analysis model was constructed. The models contained having or no pitch angle friction stir welding tool. The simulation results of having pitch angle were anastomotic with the base metal flowing condition in the"emergent stop"experiment results. There was circling flowing condition in the thread groove, which was the main reason forming the"onion circle"structure in the friction stir welding joint. The strenuous flowing band following the friction stir welding tool was the position of formatting tunnel hole in the welding joint.