最新刊期
期 6 ， 2022
钛合金焊接
龙伟民
- 摘要：In view of the current application status of titanium alloy plate-fin heat exchanger has become the core component of high-end equipment power and environmental control system, this paper is based on the brazing method of titanium alloy plate-fin heat exchanger manufacturing method, from the aspects of brazing methods and equipment, brazing process technology, titanium alloy brazing materials, etc., a comprehensive analysis and review of the related theoretical knowledge and technology research at home and abroad is made. And pointed out the existing problems and difficulties of titanium alloy plate-fin heat exchanger brazing. The future development of titanium alloy plate-fin heat exchanger brazing manufacturing is put forward in terms of developing new equipment, developing new brazing materials, and developing new processes.关键词：titanium alloy;plate-fin heat exchanger;brazing;brazing material
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发布时间：2022-06-30 - 摘要：Titanium alloy is widely used in aerospace, marine equipment and other fields because of its high specific strength, good corrosion resistance and high temperature performance. In recent years, with the increasing demand for thick-walled titanium alloy in aerospace, marine equipment and other fields, the welding technology of thick-walled titanium alloy shows great research value. Therefore, this paper reviewed the research progress of welding technology of thick-walled titanium alloy, mainly involving argon arc welding, electron beam welding and laser welding, and prospected the welding research of thick-walled titanium alloy.关键词：thick plate;titanium alloy;fusion welding;electron beam welding;laser welding
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发布时间：2022-06-30 - 摘要：TC4 titanium alloy plate with a thickness of 96 mm was joined through ultra-narrow gap laser welding using filler wire. Microstructures as well as properties of the joint were investigated. It was found that the appearance of the weld was like a nail, and welding defects including porosity, crack and incomplete fusion were not observed; weld zones in the upper, center and lower parts of the welded joint mainly consisted of a great deal of elongated acicular and interlaced α' phases; width of heat affected zones in the three parts of welded joint, width of α' martensite laths, and dislocation density of weld zones were decreased; α' phase grain boundary misorientation was less in high-angle grain boundaries of 55°~65°in lower the part of the welded joint than that in the center and upper parts. The microhardness of the upper, middle and lower parts of the welded joint is obviously higher than that of the heat affected zone and the base metal, and the tensile strength of the welded joint is similar to that of the base metal, the fracture of the welded joint occurred at the weld with higher hardness value, and the maximum local strain appeared in the lower part of the welded joint near the base metal, the local strain reached 26.3%, while the minimum local strain appears in the upper part of the welded joint near the base metal, and The local strain is about 14.5%.关键词：large thickness;titanium alloy;laser welding using filler wire;ultra-narrow gap welding;properties and microstructures
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发布时间：2022-06-30 - 摘要：With excellent comprehensive properties, titanium alloys are widely used in aerospace, marine and other fields. Brazing technology is the key connection method of titanium alloy components, but there are many problems. It is of great scientific and engineering significance to solve the high reliable brazing connection of titanium alloy. Starting from the physical and chemical properties of titanium, the brazing characteristics is analyzed, the common brazing methods of titanium alloys is introduced, the research progress of brazing filler metals for titanium alloys at home and abroad is expound, the microstructure and mechanical properties of several typical titanium-dissimilar metal brazed joints are described, and the action mechanism of process parameters on the toughening of joints are discussed. For the difficulties in titanium and titanium alloy brazing, such as the absence of low corrosion and high strength and toughness brazing filler metals, the limited production efficiency of brazing equipment, the contradiction between full diffusion corrosion and toughening, and the difficulty in simulating joint residual stress, etc., the basic ideas of systematically studying the relationship between filler metal elements and forming ability, developing vacuum brazing equipment with multi-heat source coupling, exploring formation mechanism and control measures of brittle compounds, and predicting the joint performance by computational materials science and CAE simulation are put forward.关键词：titanium alloy;brazing;Ti-based filler metals;process parameters
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发布时间：2022-06-30 - 摘要：The application range of titanium alloys has been expanding, and higher requirements have been put forward for their properties. Therefore, the surface modification of titanium alloys has become a research hotspot. This paper reviews the application of laser cladding, micro-arc oxidation and spraying technology in the surface modification of titanium alloys, analyzes the research progress of various methods, factors affecting the quality and performance of coatings, and their existing problems and development trends are summed up. The application of laser cladding technology in titanium alloy coating mainly adopts autogenous preparation of ceramic coating. This method has a clean bonding interface between the reinforced phase and the substrate, and the bonding force is large, and it is not easy to fall off; the most popular micro-arc oxidation of titanium alloy is laser composite Micro-arc oxidation technology, but the application of micro-arc oxidation technology on the surface of titanium alloys also has problems of film-base bonding and film porosity of the oxide film, which affect the corrosion resistance of the substrate; cold spraying technology has the characteristics of low preparation temperature, high coating deposition rate and low porosity. The control means of cold spraying titanium alloy coating are mainly in the aspects of spraying parameters, powder state, matrix state and nozzle. The future research trend is the integration of cold spraying technology and other technologies such as laser cladding and friction stir welding.关键词：titanium alloy;laser cladding;micro-arc oxidation;spray
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发布时间：2022-06-30 - 摘要：In order to understand and master the development status and research trend of titanium alloy welding technology in China, the keywords "titanium alloy welding" are searched in the patent retrieval and analysis system and online academic platform, a statistical analysis is made about the annual application quantity, field evolution trend, applicants and regions of the titanium alloy welding technology patents, and the key patents for titanium alloy welding protection device and the welding of titanium alloy and dissimilar materials such as stainless steel, copper and copper alloy are expound. The statistics show that the annual patent application quantity of titanium alloy welding technology increases obviously, and the technical fields involved increase from part B to parts A, B, C, E, F, G, H and so on. The welding technology of titanium alloy and dissimilar materials has become a research hotspot. There are many patents for welding of titanium alloy and stainless steel, copper and copper alloy, and the technology is relatively mature, but there is few patent applications for welding of titanium alloy and other materials, especially non-metallic materials.关键词：titanium alloy welding;patent;application quantity;dissimilar material welding
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发布时间：2022-06-30 - 摘要：With the wide application of titanium and titanium alloy, the welding technology titanium and titanium alloy is paying more and more attention, and the formulation and application of the corresponding welding standards has been the attention of various industries. At present, China's existing standards cover three aspects: welding materials (welding wires), welding process and nondestructive testing of welding defects. Seven national standards have been issued, three of which are independently formulated, and the other four are the standards coming from ISO transformation. The standards of welding materials for titanium and titanium alloys are summarized, and the national standards for welding process and non-destructive testing of weld defects for titanium and titanium alloys are comprehensively reviewed. On the whole, the number of existing standards is still insufficient, such as the electron beam welding process standard for the thick plate or ultra-thick plate, the fluorescent testing method of surface welding defects of thin sheet components, all of them are lack of corresponding standards. It is suggested to be supplemented and improved as soon as possible.关键词：titanium and titanium alloy;welding wire;welding process;non-destructive testing;national standard
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发布时间：2022-06-30 - 摘要：The inertia friction welding technology to connect Ti52/304 stainless steel/titanium alloy, explore under two kinds of welding process parameters, by means of optical microscope, scanning electron microscopy (sem) and energy spectrum analyzer after butt welding joint organization and interface intermetallic compound were characterized and analyzed by means of microhardness meter and electronic tensile testing machine for mechanical properties test and verify. The results show that dynamic recrystallization occurs on both sides of the weld near the interface, resulting in a high microhardness value near the weld zone, and the microhardness value decreases continuously as the distance from the weld site is increased. The peak microhardness value of Ti52 alloy far from the weld site is at 450 HV0.5, which is due to the microstructure fragmentation and refinement under the action of thermodynamic coupling. At high heat input and low welding pressure, the brittle phase Ti/FeTi with thickness of 5 μm and inhomogeneity is formed at the welding interface, which is not good for the bonding of titanium steel and reduces the joint properties, the tensile strength is 159 MPa. Under low heat input and high welding pressure, the cr-rich intermetallic compound Ti5Fe17Cr5 with uniform thickness of 2 μm is formed at the center of the welding interface, which is beneficial to the joint interface bonding and improves the joint properties, the tensile strength is 350 MPa.关键词：titanium/steel material connection;inertia friction welding;interface organization;intermetallic compound
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发布时间：2022-06-30 - 摘要：In order to solve the problem that the brittle compound layer at the interface of the Al/Ti joint leads to the deterioration of joint performance, a nanosecond laser was used to treat the titanium alloy surface with laser surface texturing to change the surface microstructure. Then, laser brazing of 6061 aluminum alloy and TC4 titanium alloy was carried out. The study showed that the laser surface texturing effectively improved the weld surface formation, with a significant increase in brazing spreading ability as the dot density increased, linear processing was weaker than dot matrix processing. The laser texturing had little effect on the types of interfacial compounds, which were brittle Ti Al compounds, and more importantly, it changed the direction of growth and morphology of the compound in the pits. The properties of Al / Ti laser welded joints were improved by 5%~21% after dot matrix processing. The pits of texturing treatment hindered the crack propagation, while the linear processing had little effect on the properties of Al / Ti joints. It is pointed out that the next work focus is how to improve the wetting effect of molten solder on the premise of roughening treatment, so as to improve the mechanical properties of joints and ensure the wetting of dissimilar metals at the same time.关键词：laser surface texturing;laser welding-brazing;dissimilar metals;wetting;interface
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发布时间：2022-06-30 - 摘要：In this paper, the microstructure evolution and mechanical properties of electron beam welded joints of 30 mm thick TC4 titanium alloy were systematically studied. The results show that the central part of the fusion zone is composed of coarse primary β columnar crystals, the interior is a mixed structure composed of grain boundary α phase, massive α cluster and part of the basket structure, and the fusion zone near the heat-affected zone is composed of equiaxed primary β grains. There is significant microstructure inhomogeneity in the heat-affected zone. As the distance from the fusion zone increases, the content of β-transition microstructure (secondary α-sheet + residual β-phase) gradually decreases, while the content of primary α-phase gradually increases. The average microhardness of the fusion zone is ~50 HV higher than that of the base metal, the tensile strength of the joint reaches 906 MPa, and the joint strength coefficient reaches 96%. The tensile fracture position is located in the fusion zone.关键词：TC4 titanium alloy;thick plate electron beam welding;microstructure;mechanical properties
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发布时间：2022-06-30 - 摘要：High temperature titanium alloy Ti150 was developed for the aero-engines with high thrust-weight ratio and with long-term service temperature of 600 ℃. TC19 is a two-phase (α+β) titanium alloy with high strength and toughness. The vacuum brazing process of the two titanium alloys was conducted using Ti-21Cu-13Zr-9Ni（wt.%）as filler metal. The joint microstructure and element distribution of joint were analyzed by means of SEM and EDS, meanwhile the tensile strength of the joint was measured at the room temperature and high temperatures by universal testing machine. The results showed that under the brazing condition of 930 ℃/35 min, the joint tensile strength at room temperature reached up to 955.3 MPa, and the strength of 540.0 MPa and 505.6 was maintained at 500 ℃ and 550 ℃, respectively. The tensile specimens at room temperature fractured within the brazed seam and the fractured surface exhibited brittle characteristics. The tensile specimens fractured within the Ti150 metal substrate when tested at 500 ℃ and 550 ℃, and plastic deformation was observed at the fractured surface.关键词：Ti150 high temperature titanium alloy;TC19;dissimilar material connection;brazing;mechanical properties
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发布时间：2022-06-30 - 摘要：Titanium/aluminum dissimilar metals welding structures with respective advantage of the two materials has broad application prospects in aerospace, automobile manufacturing and other fields. However, these dissimilar metals are prone to hydrogen diffusion caused by galvanic corrosion in wet environments such as sea, resulting in hydrogen embrittlement of titanium alloys. A reconstruction method of welded joints of dissimilar metals based on the concept of wire beam electrode is electrode, which can realize the coupling test between various sub-regions of dissimilar metal welded joints. Subsequently, a hydrogen diffusion behavior monitoring device is designed. Through experimental verification, the parameters such as hydrogen diffusion coefficient and adsorbed hydrogen concentration of hydrogen in metals are obtained, which lays a foundation for revealing the environmental hydrogen embrittlement of dissimilar metals welded structures. The hydrogen permeation test method for dissimilar metal welded joints proposed in this paper can be extended to detect the hydrogen diffusion behavior of dissimilar metal welded joints such as aluminum / steel and magnesium / steel, which provides a theoretical guidance for evaluating the effect of hydrogen embrittlement in galvanic corrosion, and makes up for the deficiency that the existing methods can only study the anodic dissolution behavior.关键词：electrochemical test;galvanic corrosion;hydrogen diffusion;Ti/Al dissimilar material connection;friction stir welding
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发布时间：2022-06-30 - 摘要：With excellent shape memory effect (SME) and super-elasticity (SE), biological compatibility, damping resistance, corrosion resistance and comprehensive mechanical properties, NiTi shape memory alloys (SMA) was widely used in the fields of aerospace, artificial intelligence and biomedicine, etc. In order to expand its application in intelligent development, dissimilar welding of NiTi alloy and other structural materials (such as Al6061 aluminum alloy, steel, Ti6Al4V alloy) has attracted much attention. In this study, NiTi/6061 aluminum alloy was welded by magnetic pulse welding (MPW). The microstructural features of base metal and welded joint at different heat treatment states (T6 state and fully annealed state) and discharge energy were investigated by optical microscope (OM) and scanning electron microscope (SEM). Martensitic transformation properties of NiTi before and after welding under different discharge energy was analyzed by DSC. The fully annealing treatment was beneficial to the joining between 6061 aluminum alloy and NiTi, and the thickness of the interface zone is less than 5 μm. The MPW has little effect on the shape memory effect of NiTi alloy.关键词：magnetic pulse welding;NiTi shape memory alloys;6061 aluminum alloy;martensitic transformation;heat treatment
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发布时间：2022-06-30 - 摘要：Vacuum brazing of commercial pure Titanium TA2 was realized by using Ti37.5Zr37.5Cu15Ni10 powder BFM at 940 ℃×20 min. The microstructure and mechanical properties of the brazing joint were studied by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), universal testing machine and microhardness tester. The results show that the typical interfacial structure of brazing joints is TA2/ acicular α-Ti+eutectoid structure (α-Ti+(Ti,Zr)2(Cu,Ni))+ residual filler metal /TA2.Cu and Ni elements mainly exist in eutectoid structure and residual filler metal, while Zr distributes in eutectoid structure, residual filler metal and acicular α-Ti. The room temperature shear strength of the brazing joint is 322 MPa. The Vickers hardness increases gradually from the base metal to the center of the brazing seam, and the eutectoid hardness of the center of brazing seam is about 307 HV10, which is more than twice that of the base metal. The fracture analysis results show that the crack propagates along the brazing seam, and the fracture morphology has the characteristics of intergranular dimple, elongated dimple and cleavage fracture. The fracture is ductile and brittle composite fracture mode.关键词：CP titanium TA2;brazing;TiZrCuNi BFM;interfacial microstructure;mechanical properties
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发布时间：2022-06-30 - 摘要：Ti/Al dissimilar metals joint has the advantages of high specific strength and good corrosion resistance, and has broad application prospects in the fields of aerospace and rail transportation. However, there is huge difference of physical, chemical and metallurgical properties between the two metals. It is easy to produce cracks, pores and a large number of brittle intermetallic compounds in the welded joints when using traditional fusion welding technology, which seriously deteriorates the mechanical properties of the dissimilar joints and limits the wide application of the Ti/Al joints. Magnetic pulse welding technology is a solid-phase welding technology. During the welding process, the material to be welded does not melt, which can effectively avoid various metallurgical defects caused by melting. In this paper, Ti6Al4V/ pure Al dissimilar metals were joined by magnetic pulse welding. The effects of discharge energy and stand-off distance on the microstructure and mechanical properties of the joint were systematically studied. The results show that the discharge energy is the main reason for the formation of interfacial wave, and the stand-off distance affects the interface waveform under the same energy. The maximum shear load is 4 820 N at the stand-off distance of 1.5 mm and the discharge energy of 24 kJ. The high-speed collision in the MPW process leads to obvious grain refinement of the interface compared with the base metal.关键词：magnetic pulse welding;microstructure;mechanical properties;grain refinement;interface
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发布时间：2022-06-30 - 摘要：TC4 titanium alloy has attracted extensive attention in various fields because of its excellent weldability. The butt welding of 0.2 mm TC4 titanium alloy sheet was carried out by pulse laser welding. The effects of pulse width on weld formation, microstructure and joint strength were studied. The results show that the microstructure of the weld is composed of needle martensite α' phase with random orientation due to the high cooling rate. With the increase of pulse width, the joint morphology changes from semicircle to X shape. When the pulse width is between 2.7 ms and 4.9 ms, the tensile strength of the sample increases gradually, and reaches the maximum value (898.58 MPa) when the pulse width is 4.9 ms. The hardness test results show that the increase of pulse width leads to the increase of welding line energy. When the pulse width is 4.5 ms, the microhardness of weld zone reaches the maximum value (379 HV).关键词：ultra-thin titanium alloy;pulse laser welding;microstructure;mechanical properties
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发布时间：2022-06-30
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