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Aluminum-based composite layers with different TiB2 contents were prepared by implanting TiB2 reinforcement powders with mass fractions of 1%, 3%, 5%, and 7% into 7075 aluminum alloy sheets using Friction Stir Processing (FSP) technique. The influence of TiB2 content on the friction and wear performance of the modified aluminum-based composite layers was investigated. The results showed that the incorporation of TiB2 reinforcement powders can reduce the friction coefficient and wear volume of the materials, thereby improving the friction and wear performance. Moreover, as the mass fraction of TiB2 reinforcement powder increases, the overall friction coefficient and wear volume of the composite materials exhibit a gradual decrease trend, with adhesive wear being the predominant wear mechanism. [ABSTRACT FROM AUTHOR]

The aluminum alloy performance gradient plate was prepared by friction stir joining. Analysis results of the macro morphology, microstructure, and hardness of the aluminum alloy performance gradient plate prepared under various parameters show that when the feed speed of the stirring tool is 250 mm/min, the downward pressure of the stirring tool is 6.6 mm, and the rotation speed of the stirring tool changes from 200 rpm to 800 rpm. The macroscopic morphology of the aluminum alloy gradient plates prepared by the method first changed from burr to smooth, and vice versa. There is a different cross-section morphology of the prepared aluminum alloy gradient plates, however, the aluminum alloy plates are stirred and involved with each other, and the grains of the prepared plates are refined. The hardness of the upper and lower surfaces of the aluminum alloy gradient sheet decreases, whereas that of the upper surface of the side increases, and that of the middle and bottom sides also decreases. However, the hardness of the middle side of the sheet prepared with the rotation speed of the stirring tool at 800 rpm increases, but that of the bottom side still decreases. Obtained through analysis that the performance of the aluminum alloy gradient sheet prepared at the stirring tool rotation speed of 500 rpm increases in equal proportion to achieve a good performance gradient change. [ABSTRACT FROM AUTHOR]

The 10 mm thick 7075-T6 aluminum alloy plate is welded by friction stir welding with the inclination of the main shaft of 0.5°. There is no obvious thinning on the weld surface, and the welded joint is well formed. The microstructure of the joint as a whole is "funnel" shaped, and there are multi gradient flat "onion rings". The grains in the weld nugget zone are equiaxed and the grains are significantly refined, and the grains in the heat-mechanical affected zone appear mixed crystal phenomenon and have obvious deformation. During the welding process, the hardness of the welded joint is reduced due to high temperature annealing. When the spindle speed is 500 rpm and the welding speed is 120 mm/min, the maximum surface hardness of the welded joint is 178.77HV. Compared with the base metal after annealing, the hardness of the weld nugget area is increased by about 25% due to the grain refinement strengthening and the precipitation of the reinforcing phase. The wear resistance of welded joints is inversely proportional to the hardness. When the spindle speed is 300 rpm and the feed speed is 120 mm/min, the wear resistance is the best. The friction type is mainly adhesive wear, supplemented by particle wear and fatigue wear. [ABSTRACT FROM AUTHOR]

The state of the simulation technology widely used in friction stir welding (FSW) studies requires greater and greater accuracy. An analysis is made of an FSW dynamic heat source model and related information. The model is combined with results from FSW experiments and the welding temperature field. A relationship is obtained for the friction coefficient between the tool and welding materials with temperature. By incorporating tool force measurements and analysis, a simulation model which is much more in line with actual FSW results is thus established. In the simulation process, the temperature of each part of the tool, the material model, fixture constraints, and the role of tool–material forces are analyzed and discussed in detail. In the new model, the different input heats on the advancing and retreating sides on the shoulder, the pin surround, and top of the pin are distinguished. The mechanical properties of the materials with change in temperature and the constitutive equations for the welding, before and after, are obtained. The contact relationship between the fixture and workpiece was built. In the welding process, the forces of the tool toward the welding material were applied. The 7022 aluminum alloy FSW process was simulated by the constructed simulation model. The temperature field, residual stress, and deformation in the simulations were in good agreement with the experiment results. [ABSTRACT FROM AUTHOR]

This study aimed to carry out the friction stir processing (FSP) modification of 7075 aluminum alloy mainly by slotting the base metal and adding the reinforcing phase, and to explore the electrochemical corrosion performance of the modified area. The results showed that the added phases with different mass fractions of TiB2, TiC, and Cf were beneficial to improve the electrochemical corrosion performance of the modified area. Among them, the TiB2 and TiC at different mass fractions had a relatively small improvement in the electrochemical corrosion performance of the FSP-modified area of the base metal, and both had a negative effect when the mass fraction was 5%. The Cf addition phase with a mass fraction of 2% had the most obvious improvement effect. Its corrosion potential E0 was −0.771 V, and the corrosion current density I0 was 4.80875E-6 A · cm2. The analysis showed that the electrochemical performance of Cf and the bonding performance with the base metal were better, and the corrosion process of the base metal could be suppressed during the corrosion process. [ABSTRACT FROM AUTHOR]

The hot rolled 7075 aluminum alloy was modified by friction stir processing (FSP) technology, and the effects of different processing parameters on impact toughness and microstructure of machining region were analyzed. The results showed that the impact toughness of machining region was 2.3 times that of the base metal when the rotation velocity was 1200 r/min and the feed rate was 60 mm/min, which much higher than base metal. The fracture morphology was observed by using scanning electron microscope and found that the morphology of fracture dimple was uniform and smooth. The grains in the weld nugget zone were obviously refined after friction stir processing, and the grain refinement effects were not the same in different processing parameters. [ABSTRACT FROM AUTHOR]