High power beam welding has a power density of 105 W/cm2 or more. The beam consists of a single electron, photon, electron, and ion or a combination of two or more particles. Heat sources belonging to high power density include: plasma arc, electron beam, laser beam, and composite heat source laser beam + Arc (TIG, MIG, Plasma). Currently, the main areas of concern for high-energy beam welding are: 1 Large-scale high-energy beam equipment - Larger power and large-sized parts (and even parts integration). 2 The development of new types of equipment such as pulsed mode of operation and short wavelength lasers. 3 intelligent equipment and processing flexibility. 4 Beam quality improvement and diagnosis. 5 beam, workpiece, process media interaction mechanism research. 6 beam composite. 7 New material welding. 8 Application area expansion. 1. New Progress in Laser Welding 1.1 New Laser (1) DC Slab CO2 Laser, (2) Diode-pumped YAG Laser, (3) CO Laser, (4) Semiconductor Laser, (5) Molecular lasers. 1.2 Larger Laser Power, Pulsed Mode, and High-Quality Beam Modes Take the example of PRC Inc. in the United States. A few years ago, CO2 lasers used for cutting were powered by 1500~2000W, and the recent leading products were 4000~6000W, 6000W can be cut. The stainless steel thickness and carbon steel thickness are 35mm and 40mm, respectively. 1.3 The intelligentization of equipment and the flexibility of processing, especially for YAG lasers, have brought great convenience to processing due to the available optical fiber transmission. Its main features are: 1 more use of a machine. 2 Use a laser machine for multi-station (up to 6) machining. 3 The length of the optical fiber can be as long as 60m. 4 open control interface. 5 has long-distance diagnosis function. The composite of the 1.4 beam is mainly laser-arc composite. In deep penetration welding, a plasma is generated above the molten pool. During the composite processing, the plasma generated by the laser is conducive to the stability of the arc; the composite processing can improve the processing efficiency; the welding of poor weldability materials such as aluminum alloy and dual phase steel can be improved. Sex; can increase the stability and reliability of welding; usually, laser wire welding is very sensitive, through the complex with the arc, it becomes easier and more reliable. Laser-arc recombination is mainly laser and TIG, Plasma and GMA. Through the interaction between the laser and the arc, each method's own deficiencies can be overcome and a good composite effect can be produced. GMA's low cost, use of filler wire, strong applicability, the disadvantage is shallow penetration, low welding speed, the workpiece to withstand the heat load. Laser welding can form deep and narrow welds, high welding speed, low heat input, but high investment, high requirements for workpiece preparation accuracy, poor adaptability to aluminum and other materials. The composite effect of Laser-GMA is manifested in the following: The arc increases the bridging of gaps. There are two reasons for this: one is to fill the welding wire; the other is that the arc heating range is wider; the arc power determines the width of the weld top; the plasma generated by the laser is reduced. Small arcs ignite and maintain the resistance, making the arc more stable; laser power determines the depth of the weld; further, the composite leads to increased efficiency and enhanced weldability. From the energy point of view, laser arc welding has a significant increase in welding efficiency. This is mainly based on two effects, one is that higher energy density leads to higher welding speed; the other is the additive effect of interaction of two heat sources. Comparison of Line Energy, Weld Section, and Energy Utilization Efficiency in Three Different Methods of Welding: GMA, Laser Wire, and Laser Arc. Laser-TIGHybrid can significantly increase the welding speed, which is about 2 times that of TIG welding. Tungsten pole burn-out is also greatly reduced and the service life is increased. The angle of the bevel also reduces the weld area similar to that of laser welding. A double-arc laser hybrid welding was developed at the Francois Laser Technology Institute of Ahang University. Compared with laser single-arc hybrid welding, the welding speed can be increased by about 1/3, and the line energy can be reduced by 25%. Laser-plasma hybrid welding was also reported at the Modern Connection Center at the University of British Columbia. Its advantages are: to increase the welding speed and penetration depth; due to the arc heating, the temperature of the metal increases, reducing the reflectivity of the metal to the laser and increasing the absorption of light energy. On the basis of the low-power CO2 laser test, it was also performed on a 12,000 WCO2 laser and a 2 kW YAG laser with optical fiber transmission, and a PALW foundation was established for the robot. 1.5 Interaction of laser, workpiece and shielding gas 1.6 Laser-welded aluminum alloys are widely used due to their high specific strength and good corrosion resistance. The difficulty of CO2 laser welding of aluminum alloys is mainly due to the high reflectivity and thermal conductivity, difficulty in reaching evaporation temperatures, difficulty in inducing the formation of pinholes (especially when the Mg content is relatively small), and the proneness of pinholes. In addition to the surface chemical modification (such as anodization), surface coating, surface coating, etc., the measures to increase the absorption rate are also reported by laser-TIG and laser-MIG, in which the MIG-DC electrodeposition method is strong due to the cleaning effect of the surface and addition. The alloying effect of the wire is good. More recently, LCretteur in Belgium and SMarya in France conducted CO2 laser welding on 6061 aluminum alloys with mixed gas and flux. Under the given experimental conditions, it shows that 70% He+30% Ar, the gas flow direction is opposite to the welding direction, the effect is good; for the penetration welding, the back surface of the weld is prone to sagging, using 75% LiF + 25% LiCl The flux, which removes oxidation and improves the bonding between the molten metal and the backside base metal, gives the backside weld a “warp up†effect, forming a regular weld bead over a wide range of parameters. Welding of 6061 aluminum alloy shows that the weld strength can reach 90% of the base metal. 1.7 Laser Cladding Laser Cladding Compared with other surface modification methods, the heating speed is quick, the heat input is small, the deformation is minimal; the bonding strength is high; the dilution rate is low; the thickness of the modified layer can be accurately controlled, and the localization is good. Good performance and high production efficiency. In addition to laser cladding used in civilian products, the United Kingdom, the United States and other countries have also been used for aircraft engine Ni-based turbine blade heat and wear layer cladding and repair. 2. Recent developments in electron beam welding and plasma arc welding The development of foreign electron beam welding can be attributed to the development of ultra-high energy density devices, intelligent and flexible equipment, diagnosis of electron beam currents, research on the mechanism of beam and material interaction, and non-vacuum Electron beam welding equipment and process research. In Japan, an ultra-high voltage electron beam welding machine with an accelerating voltage of 600 kV and a power of 300 kW has been introduced. It can weld 200 mm stainless steel at a time, and its aspect ratio is 70:1. Japan, Russia and Germany have carried out research on double-gun and wire-filled electron beam welding technologies. On the basis of the previous welding of large thickness plates, the second filling was used to make up for the top concave or undercut defects; Japan used double looting to achieve ultra-high speed welding of thin plates with no spatter on the reverse side and good formation. The successful development of double- and three-metal thin-strip electron beam welding machines in France is also of interest. With regard to non-vacuum electron beam welding, Germany has achieved the filler wire welding of the rotating part with the base material of AlMg0.4Si1.2. The wire-added material is AlMg4.5Mn, the wire feed speed is 35m/min, and the welding speed is as high as 60m/min. The study was completed on a 25kW electron beam welder at the University of Stuttgart. Non-vacuum electron beam welding has been highly valued in the automotive manufacturing field. For example, the non-vacuum electron beam welding of the synchronizer ring and gear in the manual transmission has exceeded 500 pieces per hour. More recently, German and Polish scholars have jointly developed a non-contact temperature measuring device installed in a vacuum chamber during vacuum electron beam welding. The measuring point has a relatively small diameter of 1.8 mm and is mainly used for brazing ceramics and hard alloys. The interference of random heat flow can be eliminated and the measurement accuracy is high. In plasma arc welding, variable polarity plasma arc welding and aluminum alloy perforated plasma vertical welding are among the concerns. 3. Current Status of Domestic High-energy Beam Welding In China, high-energy beam welding has attracted more and more attention from related parties such as welding, physics, lasers, materials, machine tools, and computers. Domestically, there is a certain gap with foreign countries on the level of equipment, but in terms of process research, the level is relatively close, and even in some aspects has its own characteristics. 3.1 Laser Welding In the production and research of equipment, it mainly produces CO2 laser equipment of kilowatts and solid YAG laser equipment of less than 1 kilowatt. Domestic laser welding research mainly focuses on laser welding plasma formation mechanism, characteristics analysis, detection, control, deep-melt laser welding simulation, laser-arc composite heat source application, laser surfacing and so on. Tsinghua University analyzed the acoustic signals in the penetration state from the perspective of acoustic and electrical power, and proposed the equivalent circuit and mathematical model of the electrical characteristics of the laser welding plasma; in suppressing the negative effects of plasma, Tsinghua University, Zhang Xudong, Chen Wuzhu and others proposed Side suction method; National Academy of Industry and Laser Technology Center Xiaorong poetry, Zuo Tiexi proposed a double layer inside and outside the tube blowing heterogeneous gas method; Northwestern Polytechnical University, Liu Jin He proposed an external magnetic field method. 3.2 Electron Beam Welding China's self-developed electron beam welding machine began in the 1960s and has so far produced and produced hundreds of electron beam welding machines of various types and functions, and has formed a research and production technical team that can provide the domestic market with Low power electron beam welder. In recent years, the introduction of key components (electron guns, high-voltage power supplies, etc.) and the introduction of other components domestically have emerged. The advantages of this method are that the equipment not only maintains a high level of technology, but also can significantly reduce costs. Provide users with better after-sales service. At present, the electron beam welding machines for automotive gear represented by the EBW series of the Institute of Electrical Engineering occupies the major market share of domestic automotive gear electron beam welding; China's medium and small power electron beam welding machines have approached or caught up with advanced foreign similar products. Level, and the price is only about 1/4 of similar foreign products, there is a clear advantage of the price-performance ratio. In the mechanism and process research, Beijing Aviation Technology Research Institute, Beijing University of Aeronautics and Astronautics, Tianjin University, Shanghai Jiaotong University, Northwestern Polytechnical University, China Institute of Science and Technology, Guilin Institute of Electrical Science, Xi'an Aero Engine Company, aerospace materials and technology research The work carried out involved the hole hole dynamics, electron beam brazing, joint fatigue crack propagation behavior, joint residual stress, filler wire welding, weld trajectory teaching during partial vacuum welding, and so on. 3.3 Plasma Arc Welding In the field of plasma arc welding equipment, Northwestern Polytechnical University conducted a study of pulsating plasma spray welding technology, and achieved successful transfer of arcs by inserting a high-frequency IGBT contactless switch between the workpiece and the nozzle anode (nozzle). Non-transferring arcs work alternately at high frequencies to achieve plasma spray under a single power supply. Xi'an Jiaotong University has carried out research on variable polarity plasma arc welding equipment suitable for Al, Mg and its alloys. The positive and negative half-waves of the main arc are respectively supplied by two DC power supplies, and the workpiece (aluminum) has been changed polarity Welding, it not only stabilizes the arc, but also has a reliable cathode cleaning effect. Beijing Institute of Aeronautics and Astronautics carried out the "one pulse and one hole" technology research of pulsed plasma arc welding; in the feature and behavior detection of perforated plasma arc welding holes, Harbin Institute of Technology, Beijing Institute of Aeronautical Technology and Tsinghua University passed the spectrum respectively. Spectral analysis of information, arc voltage and current, detection of pinhole establishment, closure, and pinhole size; Wang Xibao, Zhang Wenxuan of Tianjin University analyzed the transport and operation of powder during transfer arc in plasma arc powder overlay and its main influencing factors. The distributions of iron-based alloy powders and boron carbide powders in the arc column with different parameters and the powder flux distribution along the cross-section of the arc column were calculated. In important applications, Xi'an Aero Engine Co., Ltd. uses its own power supply equipment and imported plasma torches to achieve an aeroengine process improvement.