Microstructural Evaluation of Similar and Dissimilar Welding of Aluminum Metal Matrix Hybrid Composite by Friction Stir Welding

摘要

To address the challenges of reducing the CO_2 emission in automotives, Aluminum metal matrix hybrid composites have been extensively used in automotive and aerospace industries for the fabrication of light weight structure. Huge demand in joining dissimilar metals increased day by day, because it reduces the weight and cost of components by utilizing hybrid structures. The friction stir welding is adopted for dissimilar AA5754 rheo-squeeze cast (RSC) with AA7075 stir casted hybrid composite. Micro sized B4C and nano sized Al_2O_3 are reinforced into this material. Friction stir welding of these alloys by varying the tool material, pin and shoulder profiles, rotational speed, tool traverse speed and tilt angle. Microstructure of the joint are studied and inferences drawn are presented. The better welding was obtained with triangular and square pin profile when compared to cylindrical pin whereas triangular pin profile was more better than square pin. Tapered shoulder possessed greater strength, which resulted in a good weld in contrast to flat shoulder. The high carbon high chromium steel (HCHCr) tool exhibited a higher tool wear rate than stainless steel (SS) tool and found to be an appropriate one to weld aluminum hybrid composite.