3. Characteristics of friction stir
The proposal of friction stir welding is closely related to the welding of A1 alloy. A1 alloy is widely used in the manufacture of aircraft, spacecraft, ships, high-speed trains, etc. In particular, high-strength A1 alloys, when using conventional fusion welding methods, are prone to weld defects such as weld cracks even with very good variable polarity welding equipment. Friction stir welding is solid phase welding. Taking the 6016-T6 high-strength A1 alloy as a convenience, the melting temperature of the alloy is about 582 ° C, and the maximum temperature of the center of the weld is only about 450 ° C, so there is no welding defect related to metal melting during friction stir welding.
Moreover, other welding consumable materials, such as welding rods, welding wire, flux and shielding gas, are not required during the welding process. The only thing that is consumed is the welding stirrer. Usually, when the A1 alloy is welded, a tool steel mixing head can be welded to a weld of 800 m length.
At the same time, the residual stress or deformation of the structure after welding is much smaller than that of the fusion welding because the temperature during the friction stir welding is relatively low. Especially when the A1 alloy sheet is melted and welded, the out-of-plane deformation of the structure is very obvious. Whether it is the non-deformation welding technique or the post-weld cold and hot calibration technology, it is very troublesome and increases the manufacturing cost of the structure.
At present, friction stir welding is mainly used for non-ferrous metals with lower melting temperatures, such as alloys such as A1 and Cu. This is related to the material selection of the mixing head and the working life of the mixing head. Of course, this is also related to the relative difficulty of fusion welding of non-ferrous metals, forcing people to look for non-melting welding methods when welding non-ferrous metals. For black materials with good ductility and plastic deformation, it is also possible to achieve friction stir welding by auxiliary heating or by using superplasticity, but it depends on which technical and economic indicators of fusion welding and friction stir welding are more reasonable.
Friction stir welding has been successfully applied in the connection of non-ferrous metals, but due to the limitations of the welding method, it is currently limited to simple structural components, such as flat or cylindrical structures, and the workpiece during the welding process. Have good support or padding. In principle, friction stir welding can be used for a variety of position welding, such as flat welding, vertical welding, overhead welding and down welding; various types of welded joints can be completed, such as butt joints, gussets and lap joints, and even thickness variations. The connection to multi-layer materials can also be used to weld dissimilar metal materials.
In addition, friction stir welding is a solid phase welding method, and the environmental pollution is small before welding and during welding. Pre-weld workpieces do not require strict surface cleaning preparation requirements. Friction and agitation during welding can remove oxide film on the surface of the weldment, and smokeless and splashing during welding, while low noise.
Since the friction stir welding only rotates and moves by the welding head to gradually realize the welding of the entire weld, it is more energy-saving than the fusion welding or even the conventional friction welding.
4. Friction stir welding process
At present, friction stir welding has been the most studied in the connection of aluminum alloys. The aluminum alloys that have been successfully friction stir welded include 2000 series (Al-Cu), 5000 series (Al-Mg), 6000 series (Al-Mg- Si), 7000 series (Al-Zn-Mg), 8000 series (Al-Li), and the like.
The friction stir welding process parameters are very simple. The most important parameters are: the size of the mixing head, the peripheral speed of the mixing head and the relative movement speed of the mixing head and the workpiece. Table 1 shows the welding speeds commonly used for several non-ferrous metals. In general, for the welding of aluminum alloys, the rotational speed of the welding head can range from a few hundred r/min to thousands of r/min. The welding speed is generally between 1 mm/s and 15 mm/s. Therefore, friction stir welding can be easily realized automatically. In addition, the welding head is pressed against the workpiece during the welding process.
| material | Plate thickness (mm) | Welding speed (mm/s) | Number of weld beads |
| A16082-T6 | 5 | 12.5 | 1 |
| A16082-T6 | 6 | 12.5 | 1 |
| A16082-T6 | 10 | 6.2 | 1 |
| A14212-T6 | 25 | 2.2 | 1 |
| A16082-T6 | 30 | 3.0 | 2 |
| Cu 5010 | 0.7 | 8.8 | 1 |
| Cu 5010 | 7.4 | 6.3 | 1 |
| A14212+Cu5010 | 1+0.7 | 8.8 | 1 |
Table 1 Common welding speed of non-ferrous metals
For example, 1100 and 6061 cold-rolled sheets were subjected to friction stir welding with a sheet thickness of 6.3 mm. The mixing head has a diameter of 6.3 mm and a length of 5.8 mm. When the welding speed is 1 to 4 mm/s and the rotation speed of the stirring head is changed in the range of 200 to 2000 r/min, the optimum rotation speed for forming a high quality weld is 400 r/min. When the rotational speed is too high, for example, more than 10000 r/min, the strain rate of the introduced material increases, which may affect the recrystallization process of the weld.
Previous Next
LED Solar Sensor Lights are a popular choice for outdoor lighting for homeowners and businesses alike. These lights are a great addition to any outdoor space as they are a cost-effective, environmentally-friendly, and energy-efficient lighting solution. Solar Sensor Outdoor Lights are equipped with sensors that detect changes in the surrounding environment, particularly motion. These lights, also known as solar motion lights or solar powered motion lights, are a perfect Illumination solution for your outdoor security needs. With solar power, you can relish the convenience of always-on outdoor lighting, without the hassle or expense of traditional wiring. This introductory article highlights why LED Solar Sensor Lights are an excellent choice for anyone looking to add outdoor lighting to their space.
solar sensor light,Solar Sensor Outdoor Lights,solar motion lights,solar powered motion lights
Ningbo Le Monde Import & Export Co., Ltd. , https://www.zjlemonde-lighting.com