最新刊期
期 7 ， 2020
- 摘要：The change rule of powder properties of SS316L stainless steel powder after recycling is studied,and the evolution mechanism of powder morphology and particle size distribution is clarified. The results show that as the number of powder cycles increases,the particle size distribution of the powder becomes narrow and coarser,the apparent density and tap density of the recycled powder are improved to a certain extent,and the flowability of the powder is also improved comparing with the original powder,but the change trend of Hausner’s ratio is opposite to that of Hall’s flow rate. The surface chemical components of recycled powder particles are oxidized severely,and the ellipsoidal oxidation spots and metal vapor condensate are found on the surface of powder particles. In this study,the irregular particles in the recycled powder are divided into two categories: the first is laser-induced molten pool spatter particles,the second is gas entrainment induced particles,and the formation mechanism of the two kinds of irregular particles is described respectively. The results of this study emphasize that in the recycling process of raw materials,the oxidation of powder and the generations of irregular particles are unavoidable.In the future,more consideration should be given to the effects of irregular particles,vapor condensates and oxide particles on the quality of the processed parts.关键词：selective laser melting;recycling;oxidation;powderproperties;evolutionmechanism
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发布时间：2022-03-15 - 摘要：High service performance equipment with lager wall thickness,multi structure and high service environment is widely applied in the field of marine equipment and national defense.Arc welding is a common welding method for these structures, while the characteristics of slow welding efficiency, large heat input and deformation limit its development prospect. At present,high energy beam laser is widely used in welding of thick wall components. The performance feature and development status of high-power laser device were introduced. The current laser welding technologies of high-power laser autogenously welding,laserMIG hybrid welding and narrow gap laser wire feeding welding and their application conditions were analyzed.Among them,narrow gap laser wire feeding welding has the advantages of large weldability thickness,strong adaptability and small deformation,which is considered as one of the suitable welding methods for thick wall components. The key techniques of all-position narrow gap laser wire feeding welding were emphatically introduced. Finally,the develop-ment potential of laser welding on the manufacturing field of lager thick-wall component was summarized and expected.关键词：large component;laser welding;all position;narrow gap welding
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发布时间：2022-03-15 - 摘要：The low-power laser-TIG hybrid welding technology was used to test the based welding of the 15 mm and6 mm TC4 titanium alloy fillet structures. Analyze the difference in weld formation of fillet joint structures of unequal thickness plates with different welding parameters,typical microstructure characteristics and microhardness distribution of welded joints.The results show that the best welding joint is obtained when the laser power is 485 W,the TIG arc current is 240 A,and the reserved gap is 0.3 mm;the matching use of the laser and arc allows a wider range of welding parameter choices,which enhances welding adaptability to special structures. The joints of unequal-thickness plate of titanium alloy have asymmetric joints after welding. The microstructures on the two sides are different and the grains on the thin plate side grow significantly and columnar grains appear. The basketweave structure in the TC4 α-β titanium alloy after welding can improve the strength of the weld.关键词：unequal thickness;fillet structure;welding adaptability;TC4 α-β titanium alloy;basketweave structure
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发布时间：2022-03-15 - 摘要：Aiming at high-speed arc-assisted laser welding of 0.5 mm pure titanium TA2 thin plate,the influence of heat source distance and relative position of laser source on laser-arc coupling and molten pool shape was studied. The high-speed photography was used to analyze the arc shape and molten pool shape and explore the effects of different heat source distances and relative positions of heat sources on the stability of high-speed welding of thin plates were investigated. The results show that the TIG arc area will increase with the decrease of the heat source distance in the two modes of laser source relative position（Laser Leading,LL and Arc leading,AL）;in the AL state,the arc plays a role of preheating,in the LL state,when the heat source distance is reduced to 6 mm,the laser and TIG arc work together to form the eutectic pool phenomenon;the standard deviation of the TIG arc area in the LL state is smaller,and the welding process stability in the LL state is better than the AL state.关键词：arc-assisted laser welding;different heat source distances;relative positions of heat sources;arc morphology;molten pool morphology
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发布时间：2022-03-15 - 摘要：Based on the effects of different technological parameters of laser wire filler cladding on the forming of Q235 steel cladding layer,the melting processes of filler wire under different parameters are recorded by high speed photography system,the morphology and cross section of the cladding layer are analyzed,and the effects of the relative position of the filler wire and laser spot,laser power,cladding rate and wire feed rate on the forming of cladding layer are obtained. The result shows that:（1） the relative position of the filler wire and laser spot is the key factor affecting the melting behavior of filler wire and the forming quality of the cladding layer. When using the pre-wire feed,the laser beam overlaps partially with the filler wire,and the wire feed angle is between 40° and 70°,the cladding process is stable and the forming is the best.（2） When the laser power increases,the size of the molten pool and the width of the cladding layer increase,the reinforcement reduces. When the cladding rate increases,the solidification rate of the molten pool increases,which narrows the bridge,and the width and penetration of cladding layer reduce,the reinforcement increases. When the wire feed rate increases,the penetration of cladding layer reduces and the reinforcement increases.关键词：laser wire filler cladding;forming of cladding layer;melting process;cross sectional characteristics
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发布时间：2022-03-15 - 摘要：In this study,taking advantages of free design,high geometric flexibility and forming complex structure combining of the 3D printing technology,combining with the traditional manufacturing process features of low cost and high efficiency,and using 304L austenitic stainless steel for nuclear as the object of study,an additive and reductive hybrid manufacturing procedure combining with traditional rolling and selective laser melting（SLM） is used for 3D printing forming of 304 L stainless steel parts based on direct laser deposition（DLD） technology. The DLD technological parameters of 304 L stainless steel for unclear are verified,including microstructure,mechanical properties and inter-granular corrosion resistance tests. The result shows that 304 L stainless steel processed by DLD technology has high performance stability,small dispersion between parallel samples,and good tensile strength,high impact property and excellent corrosion intergranular corrosion resistance property, which all meet the acceptance requirements. The verified DLD proce-dure is used to join the SLM material and the traditional rolling plate,the joint part is well fused with no micro-cracks and precipitation affecting the joint performance and the nondestructive testing on the sample surface also meets the acceptance requirements. Based on DLD technology,the additive and reductive hybrid manufacturing procedure combining with traditional manufacturing and SLM process has the technical advantages of traditional procedure and 3D printing,and the material performance meets the acceptance requirements.关键词：selective laser melting;direct laser deposition;hybrid manufacturing;nuclearstainlesssteel;mechanicalproperties
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发布时间：2022-03-15 - 摘要：In order to solve the problem that the wear of H13 die steel affecting the die service life,the process of laser cladding Ni-based coating on H13 die steel was simulated and analyzed using finite element analysis software.In the laser cladding process,two heat conduction processes,rapid heating and rapid cooling were experienced,and its cladding temperature can reach up to 1551 ℃. At the same time,the influence of different coating thickness on the temperature field was investigated,and the thicker the coating,the lower the temperature. In the laser cladding process,the welding residual stress on the coating surface is mainly tensile stress,and the compressive stress is mainly on the substrate surface. The effect of different coating thickness on the stress field was also studied,and the thicker the coating,the greater the resid ual stress. It is verified by experiments tha t the temperature field of laser repair of die wear calculated by numerical simulation is close to the experimental value,and the cross-sectional view of the welding melting zone obtained by the laser cladding test is basically consistent with the simulation result. The actual melting zone width is 1.19 mm and the depth is 0.20 mm;the simulated melting zone width is 1.21 mm and the depth is0.21 mm. The simulation results of the laser cladding repair layer on the wear surface of the die are proved to be correct and the method is effective.关键词：laser cladding;finite element simulation;temperature field;stress field
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发布时间：2022-03-15 - 摘要：For welding control rod guide tube 304 stainless steel for nuclear power,the " ○ "-shaped laser scanning welding,the " | "-shaped laser scanning welding and the "8"-shaped laser scanning welding methods were used to compare with the conventional laser welding. The influence of the main welding parameters such as scanning amplitude and scanning frequency on the appearance of weld and the welding pores were analyzed,in addition,a comprehensive quality evaluation was performed on the butt joints of the 7 mm thick guide cylinder simulation. The results show that the three laser scanning welding methods are superior to the conventional laser welding in the aspects of the appearance of weld and the welding pore,and there are differences in the inhibition degree of welding pores by different spot scanning paths,in general,the "○"-shaped laser scanning welding is the best. If want the laser scanning welding takes effect to inhibit the welding pores,the scanning amplitude and scanning frequency need to reach the threshold,and when exceeding the threshold,increasing the scanning amplitude or frequency properly can enhance the effect of inhibiting pores. When the scanning amplitude is 2 mm and the scanning frequency is 50 Hz,there is no welding pore in weld. The welded joint has a good corrosion resistance,and the deformation can be controlled within 0.3 mm.关键词：guide tube;stainless steel;laser scanning welding;spot scanning path;welding pores
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发布时间：2022-03-15 - 摘要：Using Laser-MIG hybrid welding,the effect of welding current of 180 A and 220 A on the microstructure and properties of 6 mm SUS304 stainless steel was compared. EBSD analysis showed that the preferred orientation of the weld was <001 > direction,and the texture orientation intensity of the joint with welding current of 220 A was greater than that of the welding current of 180 A. The test of mechanical properties shows that the hardness of the joint varies from 170 HV to 195 HV. The strength and plasticity of the joint with welding current of 180 A are higher than that of the joint with welding current of220 A and lower than that of the base metal.关键词：SUS304 stainless steel;Laser-MIG composite welding;metallographic structure;mechanical properties
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发布时间：2022-03-15 - 摘要：The application and development trend of laser welding technologies for car body-in-white is analyzed in details,and the optical characteristics of laser welding light source and the absorption characteristics of different materials are studied. Combining with car body product characteristics and the application of new materials such as high-strength aluminum alloy,the relative principles,technical characteristics and application of laser welding technologies are introduced and compared,including laser fusion welding technology,laser fusion wire filler welding technology,laser brazing technology and laser +MIG hybrid welding technology. Based on the different product structures and material characteristics,the reasonable solutions of laser welding technology are provided from above mentioned laser welding methods. Considering the development of car body-in-white in the future and the requirements of higher quality welding body,the laser welding technology with three spots and the laser spot welding technology are proposed,and their welding principles,technical characteristics and technological characteristics are also analyzed and introduced. This has certain application value and guiding significance for future automobile body welding solutions.
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发布时间：2022-03-15 - 摘要：As a safe,clean and efficient energy source,the development of nuclear power will be the main trend of power development in the future. Key components and reactor internals of nuclear power plants need to be repaired and decommissioned after long-term operation in a high-radiation and high-temperature environment. To reduce the hazards of nuclear radiation on the operator,repair work needs to be carried out underwater. Underwater laser processing technology has broad application prospects in the field of nuclear power due to the characteristics of low heat input,precise acting position,and long-distance transmission. In this article,it summarized the principle and research status of underwater laser processing technology,such as underwater laser welding,peening,cutting,mainly introduced the application of underwater laser processing technology in nuclear power plant maintenance,it also pointed out the future development trend and key research directions of underwater laser processing technology.关键词：underwater laser welding;underwater laser peening;underwater laser cutting;nuclear power plant maintenance
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发布时间：2022-03-15 - 摘要：Large-area laser cladding is formed by multiple overlaps. At present,laser cladding is widely used in industrial production applications,and the laser cladding processing scale of hydraulic support columns for mining is the largest. However,pores,trachoma and cracking have become prominent common problems in the laser cladding industry. In order to control the cladding per formance of stainless steel columns and reduce defects,27SiMn hydraulic support column is used as the base to carry out multi-lapping laser cladding procedure experiment. The lap zone of multi-lapping cladding and its influence on corrosion resistance are discussed. The multi-lapping cladding procedure test is performed by adjusting the cladding steps,and the influence of cladding flatness and dilution rate on the finished column products is analyzed,and the metallographic microstructure of the cladding layer is also analyzed. The results show that there are differences in the microstructure of the lap zone,and it is easy to have defects such as pores and sand holes. Weak corrosion resistant area is around the exposed lap wire on the column surface after machining,so the standardized procedure should be strictly implemented to ensure the performance of this area;the cladding flatness needs to be controlled within 0.03 mm;the cladding layer whose dilution rate is controlled within 10% has flat surface and uniform microstructure,and is metallurgically bonded to the substrate.关键词：hydraulic support column;laser cladding;multi-lapping cladding;cladding step
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发布时间：2022-03-15 - 摘要：The fiber laser welding is used to weld the T6 state Mg-10 Gd-3 Y-0.5 Zr plate for creating welding procedure window. The welding parameters are optimized by orthogonal experimental design method with the high temperature tensile strength of welded joints as the evaluation index. The optimal welding parameters are achieved by range analysis and variance analysis,and the degree of influence of each welding parameter and optimum welding procedure are determined. The effect of laser power on the high temperature mechanical properties of the welded joint is studied. The high temperature mechanical properties and high temperature tensile fracture morphology of welded joints under the optimal welding parameters are analyzed.The result shows that the laser power has the most significant influence on the high temperature mechanical properties of the welded joint. Under the optimal welding parameters,the average tensile strength of the welded joint at 200 ℃ is 281.1 MPa,which is 86.3% of the base metal,and the elongation is 7.4%,which is 65.4% of the base metal. And the joint is well formed,the grain size in the weld metal zone is small,and the fracture mode of the base metal and the joint both are ductile fracture.关键词：laser welding;rare earth magnesium alloy;orthogonalexperiment;high-temperaturetensileproperties
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发布时间：2022-03-15 - 摘要：Combine the structural characteristics of laser overlay welding of stainless steel body,the automatic on-line EMAT technology for laser overlay welding are developed,adopts EMAT automatic detection technology on-line inspect the quality of laser overlay welding of stainless steel car body. The research shows that the reflection wave height has a good correspondence with the laser overlay welding depth of stainless steel,and the penetration can be detected according to the echo ability of the weld. In the application research,the relationship between penetration and weld width is compared,and the robot is used for automatic detection to judge the weld quality of laser overlay welding. The robot has fast scanning speed and improves the detection efficiency. It has obvious advantages in the quality inspection of stainless steel laser overlay welding.关键词：stainless steel car body;laser overlay welding;EMAT;robot
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发布时间：2022-03-15 - 摘要：The anti debris plate of fuel assembly for the PWR is a precision machined part,which requires high dimensional accuracy and mechanical properties. At present,the anti debris plate adopts the EDM technology,which needs to process thousands of special-shaped square holes on the 210 mm square thin plate. The machining cycle of a single part is long and the efficiency is low. In order to meet the demand of mass production of new nuclear fuel,it is necessary to study the advanced laser manufacturing technology in the world and find a new processing method that takes both quality and efficiency into account. From the perspectives of raw material preparation,manufacturing process and post-processing methods,the project studies the application of advanced laser SLM manufacturing technology in the processing of the anti debris plate of fuel assembly. The research results are of great significance to solve the technical problems of autonomous nuclear fuel assembly manufacturing and improve the technological level of fuel assembly manufacturing technology.关键词：fuel assembly;the anti debris plate;nuclear austenite stainless steel;laser 3D prin-ting;SLM
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发布时间：2022-03-15 - 摘要：The Ar+CO2 gas shielded welding method was used in the condition of non-preheating,and the low-alloy basic slag flux-cored wire was selected to weld Q620 steel under three heat inputs. The weldability and engineering usability of high strength and low alloy Q620 steel were studied by welding joint quality analysis,weld metal chemical composition analysis,microstructure observation and mechanical property test. The results show that Q620 steel has good weldability at room temperature,and the alloying elements in the weld zone are evenly distributed. When the welding heat input changes from low to high,the microstructure of the weld zone changes from ferrite +pearlite to bainite +martensite,and the strength and hardness of the weld zone decrease. With the increase of heat input,the impact fracture morphology of weld zone changes from ductile fracture to hybrid fracture mode of dimple and quasi-cleavage.关键词：laser weld joint;resistance spot welding;stainless steel railway vehicle;side wall composition;finite element numerical simulation
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发布时间：2022-03-15 - 摘要：From the perspective of the combination of macroscopic numerical simulation and microscopic EBSD experiment,the weld grain growth and its effect on the mechanical properties of the laser welding joint for 1060 aluminum alloy are studied. The results show that the grain size reduces as the heat input decreases,and dense equiaxed crystals gradually generates in the center of the weld,which will enhance grain boundary strengthening effect and the plasticity of the weld metal zone;in the process of heat input reduction,the shape of the molten pool transitions from elliptical shape to teardrop shape. The growth shape of the columnar crystal changes from bending to vertical under the influence of the columnar crystal. The growth direction of columnar crystals is consistent with the heat flow distribution and perpendicular to the end of fusion boundary,and the angle between the growth direction of columnar crystals and the weld center line increases as the heat input decreases. The characteristic of columnar crystal anisotropy makes its tensile strength higher when it is close to the tensile force;with small heat input,the weld grain will produce a obvious cubic texture,which helps to improve the plasticity of the weld metal zone;the tensile strength of the joint gradually increases when the heat input reduces from 120 J/mm to 75 J/mm,and when the heat input reduces to 58 J/mm,the welding speed is too fast,which will produce obvious pore defects,and the tensile strength of joint declines comparing with that when heat input is 75 J/mm.关键词：1060 aluminum alloy;welding heat input;grain growth;mechanical properties;numerical simulation
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发布时间：2022-03-15 - 摘要：At present,domestic laser welding equipment generally uses embedded board-based control methods,which have the disadvantages of low stability and poor multi-axis linkage effects. This paper designs a standard laser welding equipment control system based on Siemens PLC with high stability and high accuracy. It breaks through key technologies such as the compilation and import of arbitrary plane interpolation curves,realizes linear and circular interpolation motion control between any two axes,and has the functions of importing and analyzing arbitrary curve files and G code online compilation to meet the equipment processing requirements.关键词：laser welding;PLC;interpolation curve;online compilation
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发布时间：2022-03-15 - 摘要：Cladding a thin and uniform layer of Inconel625 nickel-based alloy onto the heat-exchanger panels for high-temperature corrosion resistance purpose could effectively extend the service life of a refuse incinerator,and is proved to be a feasible and reliable solution with the best cost perfor-mance ratio. Conventional arc cladding technology could do this surface modification job but it has some disadvantages such as high substrate dilution,low deposition efficiency and the workpieces should be welded vertically. In this paper,a hot-wire laser cladding system is described,witch adopts a high power diode laser generator with a specific wavelength and homogeneous energy density and a 35 kHz ultrahigh frequency pulsed low voltage hot-wire laser power supply,and successfully clads the Inconel 625 onto a wall surface placed horizontally by gantry type welding tractor. The experiment shows that the dilution rate of the cladding layer is less than5%,while the efficiency of cladding is about 8.8 kg/h. This innovative system can significantly improve the quality of the cladding layer and the productivity,simplify workpiece installation procedures,reduce labor costs and avoid potential safety hazards.关键词：laser hardfacing;water-cooled film wall;dilution rate;INCONEL 625;hot-wire
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发布时间：2022-03-15 - 摘要：In the fields of aviation, aerospace,shipbuilding,etc.,there are a large number of welding manufacturing requirements for small amount,flexible components that lack computer geometric models,for which model-based offline automatic programming systems are unsuitable. In response to this situation,a model-free robot automatic programming system for large complex components is designed.Through rapid 3D reconstruction of the processed components and analysis based on the 3D reconstruction results,the machining plan is pre-planned and the robot program is automatically generated. The deviation between the geometric model and the actual component is measured by the sensor,and the robot program is corrected online. The experiment results show that the system can analyze the large complex components lacking models online,and complete the corres-ponding welding tasks without the aid of work fixtures,providing a technical basis for the further automation of the robot processing.关键词：model-free components;3D reconstruction;automatic programming;online correction
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发布时间：2022-03-15 - 摘要：In the multi-layer and multi-pass welding of Inconel 690/321 stainless steel dissimilar metals,cracks,incomplete penetration,incomplete fusion and other defects may occur,accompanied by deterioration structure,resulting in the degradation of joint performance. In view of the above problems,the microstructure and properties of dissimilar metal welded joints are studied by means of metallographic structure analysis,chemical composition analysis and microhardness test.The results show that there is normal welding microstructure in each region and no obvious welding defects;there is TiC in degradation zone,the hardness of welded joint is generally low,but has good plasticity;in the multi-layer and multi-pass welding process,the tempering effect of the latter layer on the weld metal zone of the former layer improves the microstructure and the performance is not significantly affected.关键词：Inconel 690;321 stainless steel;dissimilar metal welding;microstructure;properties
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发布时间：2022-03-15 - 摘要：<正>最近发现网络上有大量假冒的《电焊机》杂志的官方网站,并以编辑部名义进行征稿及收取征稿、审稿费用。《电焊机》杂志在此声明:一、《电焊机》杂志投稿途径如下:投稿官方网站:《电焊机》杂志官网www.71dhj.com（在线投稿）
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发布时间：2022-03-15
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