Effect of tool plunge depth on joint formation and mechanical performance of friction stir forming joints made between AA 5052-H32 and AA 6061-T6 sheet metals

The potential of friction stir forming for joining dissimilar grades of aluminum alloys namely,AA 5052-H32 and AA 6061-T6,was investigated.Study on the effect of tool plunge depth revealed that,lap shear load of 7.16 kN and cross-tensile load of 3.51 kN,recorded at medium tool plunge depth range from 0.5 to 0.7 mm,measured using a universal testing machine,were much larger than those of friction stir welded and friction stir spot welded joints fabricated on the same materials.Joint macrostructure observed with optical microscope revealed that joints were strengthened either by mechanical pin interlocking or by metallurgical bonding.The effect of tool plunge depth on the stir zone formation and the influence of frictional heat flux on the lower sheet were revealed through the microhardness measurement using Vickers hardness tester.Morphological studies revealed that tool plunge depth has a significant influence on the pin formation and the geometric features,generated in these joints.Occurrence of various failure modes such as pin pull-out,pin shear,partial bond delamination,and tear-off,were governed by the formation of critical weak zones at various tool plunge depths.

Effects of Processing Technologies on Mechanical Properties of SiC Particulate Reinforced Magnesium Matrix Composites

Mg matrix composites with SiC particles ranging from 5vol%-25vol% were prepared using stirring casting method. Die casting, squeezing casting, and extrusion were applied for inhibiting or eliminating the defects such as gas porosity and shrinkage void. Through die casting and squeezing casting, most of the defects in Mg matrix composites could be eliminated, but the mechanical properties were improved limitedly. On the other hand, after hot extrusion, not only most of the defects of as-cast composites ingots were eliminated, but also the mechanical properties were improved markedly. With the addition of SiC, the tensile strength, yield strength and elastic modulus of as extrusion SiCp/AZ61 composites increased remarkably, and the elongation decreased obviously.

Friction stir based welding and processing technologies-processes,parameters,microstructures and applications:A review

Friction stir welding [FSW） has achieved remarkable success in the joining and processing of aluminium alloys and other softer structural alloys. Conventional FSW, however, has not been entirely successful in the joining, processing and manufacturing of different desired materials essential to meet the sophis- ticated green globe requirements. Through the efforts of improving the process and transferring the existing friction stir knowledge base to other advanced applications, several friction stir based daughter technologies have emerged over the timeline, A few among these technologies are well developed while others are under the process of emergence. Beginning with a broad classification of the scattered fric- tions stir based technologies into two categories, welding and processing, it appears now time to know, compile and review these to enable their rapid access for reference and academia. In this review article, the friction stir based technologies classified under the categol^J of welding are those applied for join- ing of materials while the remnant are labeled as friction stir processing （FSP） technologies. This review article presents an overview of four general aspects of both the developed and the developing friction stir based technologies, their associated process parameters, metallurgical features of their products and their feasibility and application to various materials. The lesser known and emerging technologies have been emphasized.