Studies on the Friction Stir Welding Characteristics of Pure Copper Plate with 15 mm Thickness

In this study, a welding tool made of high-speed steel is used to weld pure copper plates with a thickness of 15 mm under the speed of 1000 rpm and feed speeds of 45, 60, 86 mm/min to study the mechanical properties and microstructure of the weld. Results show that with the increase of feed speed, the maximum average temperature in the feed process is decreased from 875°C to 800°C and the maximum downward force is increased from 15 kN to 19.5 kN. With the increase of feed speed, the ultimate tensile strength decreases slightly, but it can still achieve more than 90% of that of the base metal, and the elongation is reduced significantly, but it still achieve more than 75% of that of the base metal. For the stir zone (SZ), the grain size is increased significantly at lower feed speed of 45 mm/min, but the grain structure is more refined at a higher feed speed of 86 mm/min. The grains are elongated at the thermo-mechanically affected zone (TMAZ) under different feed speeds. Using the X-ray radiography to detect the internal defects of the weld, it was found that no defects were found in the weld except at the bottom of the starting and ending points of the weld. © 2017, Chinese Mechanical Engineering Society. All right reserved.