Friction Stir Welding--Efficient Connection Technology of Cast Aluminum
The Chinese friction stir welding center is widely used for ZL114A alloy. The friction stir welding process adaptability of the material is developed in China Friction Stir Welding Center. The test data shows that the material has good adaptability to the friction stir welding process and the joint tensile strength reaches 91% of the base metal, joint mechanics comprehensive performance is better than electron beam and other welding methods. ZL114A alloy (formerly known as ZAlSi7Mg1A) is an Al-Si-Mg high-strength cast aluminum alloy developed by increasing the content of Mg element on the basis of ZL101A alloy. It has excellent casting process performance and higher mechanical properties than ZL101A alloy. Due to its superior characteristics, it is widely used in the aerospace manufacturing industry to manufacture large thin-walled structural parts of important parts. ZL114A alloy has broad application prospects and has created an urgent need for efficient material joining technology. Due to the welding method, the heat input amount is large, the welding deformation is large, and it is difficult to meet the precision requirements of the thin-walled parts; and the weld seam is prone to defects such as pores, slag inclusions, incomplete penetration, burn-through, cracks, etc., and the defect rate is high; The post-weld post-weld treatment process is cumbersome. Friction stir welding is an emerging metal solid phase joining technology. The metal does not melt during the welding process, and the heat input is small. The joint of the weld is completed under the condition that the metal is extruded, and the welded joint does not produce fusion welding. Weld joints have such defects as pores and cracks, and there are few weld defects; friction stir welding is similar to mechanical processing, easy to achieve automatic control, and there is no voltage, current, strong light, metal dust, etc. in the fusion welding, working environment Environmentally friendly and clean. Most importantly, the mechanical properties of the friction stir welded joint are superior to those of the welded joint. The test data shows that the tensile strength of the welded joint reaches 91% of the base metal, the elongation of the sample reaches 2.5%, and the grain of the joint structure is refined, uniform and dense, eliminating the casting defects of the base metal. The figure below shows the microstructure of the ZL114A base metal and the welded joint. From the figure, it can be observed that the microstructure of the weld nugget is non-directional, fine equiaxed grains, and the base material area is a coarse dendritic cast structure. Friction stir welding is a new welding technology that is different from fusion welding and mechanical connection. Based on its technical advantages, it has great potential in the aviation manufacturing industry, providing solutions for efficient connection of various lightweight alloys. method.
The cover glass is covered on the material on the glass slide, which can avoid the contact between the liquid and the objective lens, so as not to contaminate the lens, and can make the top of the observed cells in the same plane, that is, the distance from the objective lens is the same, so that the observed Images are clearer.Why do you need a coverslip when using a microscope
The purpose of staining the specimen with iodine solution is to make the cells more obvious under the microscope, and it can also kill the cells and prevent the cells from migrating.
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(a) Base metal microstructure 
(b) weld nugget microstructure
2. Make the specimen relatively fixed;
3. It is convenient to use the capillary phenomenon to form a gradient when adding various reagents (staining agent, acid, salt solution);
4. Avoid contamination of the specimen.
