摘要:Based on the problem that the weld of high-speed MAG welding is poorly formed and easy to produce hump bead,the effects of four kinds of one component active agent,Fe2O3,Cr2O3,K2O and CaF2,on the arc stability,metal transfer and appearance of weld of high-speed MAG welding are studied. The results show that four kinds of active agents can increase the arc stability and metal transfer frequency of high-speed MAG welding,among which Cr2O3 corresponds to the most stable arc with reigning arc voltage drops to about 25 V,the K2O corresponds to the highest metal transfer frequency,reaching 110 droplets per second. The Fe2O3,Cr2O3 and K2O all significantly increase the penetration of high-speed MAG welding weld,optimize the surface appearance of weld,and eliminate hump bead under 1 000 mm/min high speed MAG welding condition.
关键词:high speed welding;active agent;hump bead;metal transfer
摘要:The investigation status of Sn-Ag lead-free solders Is reviewed comprehensively. The effects of Bi,In,Zn,Al,Cu,Ni,Sb et al rare earths and nanoparticles on the wetting properties,melting temperature,mechanical properties,microstructure and interfacial reactions are discussed. In addition,the problems in the study of Sn-Ag solders are discussed and solutions are proposed. It provides a reference for the research of Sn-Ag lead-free solder.
AN Xiaodong,WANG Xin,SUN Yongtao,GU Xiaoman,LIU Jie
Vol. 49, Issue 9, Pages: 19-23(2019)
摘要:In this paper,the effect of the cooling time t12/8 on microstructural transformation of the SAF2507 heat affected zone(HAZ),which was simulated by GLEEBLE3800 thermal simulation machine was studied. The results indicated that secondary austenite and Widmanstatten austenite made the precipitation increased in the ferrite grain and grain boundary with the increase of cooling time t12/8,Meanwhile,the banded austenite gradually grew up and transformed into dendritic or plume,eventually form a net structure with the increase of cooling time of t12/8. When the cooling time of t12/8 added to 69 seconds,the intermetallic phase which was χ phase precipitated at the boundary between α/γ and α/α.
摘要:The welding technology of ultra-narrow gap wire filler welding could improve the general properties of welded joints when the filler metals could change the microstructure and chemical elements. This paper focused on the 20 steel-Q345C pipe welded joints properties which welded with the ultra-narrow gap wire filler welding and the tensile strength,bending properties,impact properties and microstructure were studied. The results showed that the tensile strength,bending properties and impact toughness were all in accordance with the standard. Because the higher heat input and faster cooling speed with quench trend then the weld showed the highest microhardness. The microstructure of HAZ was composed of Widmanstatten structure,while the main components of the weld center were proeutectoid ferrite precipitated along grain boundary and acicular ferrite and pearlite in grain boundary. The microstructure of the base metal was lamellar pearlite and ferrite. So the ultra-narrow gap laser wire-filling welding technology for 20 steel-Q345C pipe has good engineering application value.
WANG Zhiguo,DOU Chao,YIN Yuhuan,XU Kui,MA Qianlong
Vol. 49, Issue 9, Pages: 29-33(2019)
摘要:Crescent-shaped inclusion was found in the friction stir weld of 2219 aluminum alloy,X-ray detection,optical microscopy and energy spectrum analysis were used to study the distribution characteristics,microstructure and chemical composition of inclusions. The cause of inclusion formation was determined by experimental verification. At last,the influence of inclusion formation mechanism and tensile properties on joints was analyzed. The results show that the inclusions were composed of many abnormally grown Al2Cu particles. The abnormal growth of Al2Cu was due to metal material attached at the thread and the groove of friction stir weld tool during the welding process. Al2Cu particles coarsened under high temperature,Al particles were segregated and peeled off into the weld during welding randomly,the separated Al2Cu formed crescent-shaped inclusion under the action of friction stir weld tool. Crescent-shaped inclusions could be avoided by improving friction stir weld tool structure. It was found by tensile test that the inclusion had no effect on the tensile properties of the joint.
摘要:It is a key problem in ship construction to improve and guarantee the welding quality of crane base system. In this paper,the welding performance of DH36 thick plate is studied experimentally. The new technology of ceramic backing is adopted to avoid the adverse effects caused by root cleaning. The problem of incompletely welding defects and controlling assembly clearance has been solved about high strength thick plates for ships. The results such as stretch,bend,impact and hardness tests for welded joints can meet the requirement. It has a good reference for welding high-strengthen steel for marine thick plate.
摘要:The INCONEL 625 alloy surfacing layers are obtained by four different welding methods:CO2 gas shielded flux cored wire arc surfacing,electrode arc surfacing, double-layer submerged arc surfacing with band-electrode and double-layer electroslag surfacing with band-electrode. A series of physical and chemical properties of this alloy surfacing layer are analyzed and compared.The rationality of each welding method is verified by comparison. Combining with the results of physical and chemical properties,the surfacing of the inner wall of PTA crystallizer is performed. And the productive task is completed on time and guarantees both quality and quantity.
摘要:The nickel-base alloy cladding and low alloy steel base material of tube-sheet were melted down owing to the abnormal heat input during seal welding between the heat transfer tube and the tube-sheet on a fabricating Steam Generator of a Nuclear Power Plant. Three potential repair schemes were proposed,and which were contrastively analyzed and evaluated from the aspects of operability,technical difficulty,leakage risk and in-service maintenance,etc. As a result,the temper bead welding scheme was determined and performed. Furthermore,the implementation schedule,procedure tests and results of the temper bead welding are introduced. The method of temper bead welding has been applied in engineering and can be used for the reference in dealing with similar cases in nuclear power engineering.
FU Qiang,LUO Ying,LIU Zhaodong,MIN Yuansheng,GAO Yingxian,ZHEN Hao,WANG Xuxin
Vol. 49, Issue 9, Pages: 49-54(2019)
摘要:Welding residual stress is the inherent product of welding process and it has great effect on the welding quality and the service performance of welded structures. In this paper,the welding residual stress induced by arc welding in nuclear power structures is mainly concered,the detrimental effect and influencing factors of welding residual stress are introduced,and the internal stress distribution in the butt-welded specimens and the girth weld specimens are also illustrated;the methods to mitigate the welding residual stress and their merits and demerits are simply demonstrated. The paper can provide references for structure design and stress mitigation of nuclear power welded structures.
关键词:nuclear power equipment;welded structure;residual stress;stress mitigation
YANG Yatao,XUE Song,GUO Baochao,QI Danhong,MI Dawei
Vol. 49, Issue 9, Pages: 55-59(2019)
摘要:The hardfacing procedure of the latch with cobalt-base alloys about the third-generation nuclear power control rod drive mechanism is mainly studied from the aspects of the material weldability,oxyacetylene welding method,welding flame type,welding nozzle size and preheat. And the chemical composition,metallographic microstructure and surface hardness of the hardfacing layer are analyzed. The results show that the oxyacetylene surfacing are adopted as the welding method of hardfacing with cobalt-base alloys.The different nozzle diameters and preheating temperatures have an effect on the chemical composition,hardness and microstructure of the hardfacing layer. The main microstructure of the hardfacing layer is dendritic crystal. The larger nozzle diameters,the more dendritic crystal,the greater probability of secondary dendritic crystal formation. The grain size of hardfacing layer grows up and intragranular precipitation phase increases when the preheating temperature increases.
摘要:TThe existing problems of spare parts management and their improvements in domestic nuclear power station at present and the additive manufacturing features are briefly expounded. The coherence points of additive manufacturing and spare parts management are put forward. Based on the model of spare parts united storage,the model of supplier virtual united storage is put forward,the advantage of this model which can reduce the spare parts management cost and promote management quality is introduced. The generalized and applied routes of additive manufacturing in spare parts field is pointed out.
摘要:The welding for main pressure-retaining welds is a key procedure in the manufacturing of nuclear island steam generator.The welding experiments of SAW and SMAW for 18MND5 and SA508Gr3Cl2 are respectively performed. The chemical composition and mechanical properties of these two materials under different welding procedures are compared and analyzed. The results show that the test pieces of 18MND5 and SA508Gr3Cl2 with SAW and SMAW have good tensile property and stable test performance, and both can meet the related standard design requirements.
摘要:The grade evaluation of the welding filler material(hereinafter referred to as: welding material evaluation) is the grade-selecting process for the batches of welding materials used for civil nuclear power installation; it provides the basis for the utilization of the specific grade of welding material on construction site. The practice of evaluating the welding material grade used for M310 PWR nuclear power installation engineering is analyzed and the issues that are prone to emerge during the process is discussed, which provides referable information for the grade evaluation of the welding materials used for M310 PWR nuclear power installation engineering.
关键词:M310 PWR nuclear power installation engineering;welding material evaluation;effective rang
摘要:The linkage model of the arc weld is established,and the relative displacement relationship between the arc weld and the robot arm space is derived. Based on the linkage model,the relationship between wire deposition speed and torch movement speed and equipment limit speed is studied through dynamic simulation experiments. On this basis,the influence law of welding robot wire feeding speed on welding gun moving speed and arc radius is further studied,and the small-scale arc linkage model of steering frame is established. Based on the linkage model of arc welding seam, the method of "year-on-year reduction" is established,which can effectively ensure the consistency of welding wire deposition speed and filling quantity of weld seam after the change of welding speed. The maximum reduction ratio of welding speed of bottom layer of weld seam is 11%. The radius of weld seam is increased after the merging of adjacent arcs. The contour blurring method can reduce the moving speed of the external axle by 10%. The method of taking the center arm of the large external axle supporting the robot axle to the middle position of the straight-fingered arc line is established to optimize the data in the model of arc seam linkage welding,and reduce the nine-axis linkage welding to seven-axis linkage welding,so that the axes of the welding robot can be connected. The stability of dynamic welding is the best.
摘要:Atmosphere protection system is a vital functional unit of selective laser melting(SLM)devices,which ensures the low oxygen environment necessary for SLM processing and affects the performance of SLM formed parts directly. The four options with different number and position of the inlets are simulated by FLUENT. The flow field state of the inert gas in the chamber and its influence on the SLM forming process are simulated,and the optimal option is determined. The results show that the shortest inflating time and the best dust removal effect will be obtained when adopting five inlets: one on the right rear side and four on the top of the chamber,and the intake air volume accounts for 1/4,3/4 of the total,respectively.
MENG Xianwei,XIAO Yulong,TANG Yutong,LIU Shiduo,WANG Yan
Vol. 49, Issue 9, Pages: 84-87(2019)
摘要:Welding robot is the main research hotspot of intelligent welding. With the rapid development of industry,the requirements for the performance of welding robots are constantly improving. The development status of welding robot intelligentialize is expound from five aspects: weld tracking system,off-line programming and path planning technology,remote welding technology,virtual simulation and human-computer interaction technology and transformation research technology based on PC. And the application of welding intelligentialize in welding robots,teaching,intelligent welding station systems and et al is summarized in China.
关键词:welding intelligentialize;welding robot;application direction
CHEN Yuhua,XU Mingfang,XIE Jilin,XU Zhangliang,CHEN Yi
Vol. 49, Issue 9, Pages: 88-90(2019)
摘要:Based on the problem of the connection between platinum resistance leads and multi-strand wires with dissimilar metal in aerial sensing components,the device and method for precision resistance brazing of fine wires and multi-strand wires with dissimilar metal are developed. The device has simple structure,convenient operation and reliable jigs,and realizes a good connection between platinum resistance leads and multi-strand wires with dissimilar metal. And the obtained joints are fully filled with good performances and appearances,the properties of the joints are better than these of conventional resistance brazing joints,which improves the joint quality and welding efficiency are d and meets the needs of open experimental teaching.
摘要:An automatic girth welding machine,which based on passive vision technology,was designed to solve the problems of low welding efficiency and poor welding quality of spherical tank girth welding. The walking tracks are attracted on the surface of the spherical tank through the switch magnetic seat,and the welding tractor walks along the tracks to complete the welding of the circular seam. The welding tracking system uses welding images,which collected by the passive vision sensor,to extract the deviation between the weld seam and the weld pool. Furthermore, the extracted deviation is used by the control system to control the rectifying mechanism and realize the welding seam tracking. The result shows that the tracking system corrects the welding deviation,which caused by the installation of walking track and greatly improves the precision of girth seam welding.
摘要:Double-sided FSW technology with dynamic support was applied in the large diameter spiral tube of aluminum alloy for the first time in this paper,the spiral tube with diameter of 900 mm and length of 20 m was successfully produced in one time,and the welding process was stable and reliable. Dye penetration inspection,ultrasonic inspection and X-ray inspection were carried out on the whole weld of spiral tube,and X-ray inspection were carried out on the partial weld of spiral tube,and the weld thinning and tube roundness were measured. The results showed that no defects were found in the three kinds of inspection,and the weld thinning was strictly controlled in the range of 0.3 ~0.5 mm and the tube roundness was 0.15 ~2 mm. The successful application of double-sided FSW technology with dynamic support in the production of large diameter aluminum alloy spiral tube will effectively avoid low efficiency,metallurgical defects,large deformation,environmental pollution of traditional welding technology. This project will truly realize the welding production of large diameter aluminum alloy spiral tube with high efficiency,high yield,high quality,and green environmental protection.
摘要:Closed-loop control of friction stir welding process is helpful to realize welding automation in order to improve the stability and reliability of welding quality. Based on the friction stir welding pressure control system,this paper studies the variation of servo drive parameters in the welding process,in order to find out the optimal closed-loop control method. The results show that the spindle torque and Z-axis torque fluctuate greatly in the stable welding stage,and it is difficult to achieve closed-loop control as feedback signal. The closed-loop control of spindle power in welding process can be well carried out under different process parameters,and can be used as an index to measure the heat input of the weld. A closed-loop control method for welding process based on spindle power feedback is proposed,which provides a new idea for welding process control.
摘要:According to the fatigue crack propagation behavior of complex shape welds in actual engineering application and based on the Paris rate propagation model,the M-integral independent of the integral path is used to calculate the stress intensity factor of the crack front. And the stress intensity factor at the intermediate point of the crack front is used as the control parameter of crack propagation. Adopt different crack propagation direction criterion,and the initial surface crack of the weld toe is described by a semicircle. Simulate the dynamic evolution process of the entire crack front at different propagation stages. The fatigue crack growth is divided into three stages. The distribution and variation of stress intensity factors KⅠ,KⅡ and KⅢ of crack front in different propagation stages are calculated and compared. The influence of crack load type on fatigue crack growth is revealed,and the proportion of fatigue life in different expansion stages is calculated.
关键词:complex shape welds;fatigue crack;evolution;M-integral;crack front
摘要:Friction Stir Welding(FSW) of 2024 aluminum alloy is carried out by selecting the optimized welding parameters. According to the microstructures and morphologies of the joints,the welded joints are divided into different regions,and the residual stresses in different parts of the joints are measured by the small hole method. MT type crack growth test specimens are selected to conduct crack growth tests at different parts of friction stir welded joints. The effects of residual stress on crack growth are studied by comparing crack growth rate between different regions and between welding state and rolling state. The experimental results show that the residual stress of friction stir welding is tensile stress,which promotes crack opening and propagation. In the crack growth test,the residual stress gradually releases with the crack growth,and the crack growth rate in the welded state is close to that in the rolling state. Rolling can eliminate the residual stress and make the residual stress in each area of welded joint tend to be the same,and the crack growth rate also tend to be the same.
摘要:Nickel base alloy has good high temperature resistance and corrosion resistance, adopting 625 nickel-based alloy for the overlaying on the surface of carbon steel or alloy steel can guarantees the strength of the base material,ensures the corrosion resistance of material,and saves the material procurement cost. The dilution rate affects the microstructure and mechanical properties of nickel base alloy,also affects the corrosion resistance of the overlaying layer. The effect of postweld heat treatment on the dilution rate of Fe content in overlaying layer is investigated,which supply feasibility solution for production. The Inconel 625 is used for overlaying of different base materials respectively, the thickness of overlaying layer is not less than 3 mm,and it should be at least two layers. And then the postweld heat treatment with or without contrast test is carried out. By comparing and analyzing the Fe element contents in different areas,the results show that postweld heat treatment has no significant effect on the dilution rate of Fe content in overlaying layer. The closer the distance from weld fusion line,the higher the dilution rate of Fe content.
LI Zhigang,HUANG Wei,LI Yang,XU Xiang,YE Jianxiong
Vol. 49, Issue 9, Pages: 119-123(2019)
摘要:Underwater wet welding arc is an arc produced in liquid dielectric and is very different from that in terrestrial gas environment arc. In this paper,an underwater wet welding arc model are created from the angles of electrostatics and particle physics,and it divides the underwater medium into ionized bubbles,transition layer,and liquid layer. Considering the heat emission at the saturation current density described by Sommerfeld’s formula, the underwater DC arc discharge is simulated. The analysis results show the shape of the arc formed by the electron beam and its arc velocity map,and the influence of the arc’s own magnetic field on the electron beam trajectory under the effect of high energy and high current density accompanying the underwater wet welding process.The shape of the arc track is shrunk to a "bell shape".
关键词:underwater welding;DC arc discharge;particle physics;electromagnetic finite element analysis
摘要:The four types of welded joint of 304 stainless steel sheet were obtained by TIG welding. They are full penetration butt joint, tee joint,one-side fillet joint and the lap joint. Their mechanical properties,microstructure,residual stress distribution,chloride ion sensitivity are tested and analysized. The results show that among the four types of welded joints,the full penetration butt joint is the best in terms of mechanical properties,residual stress distribution and corrosion resistance,while the one-side fillet joint is the worst in terms of mechanical properties,residual stress distribution and corrosion resistance.
关键词:materials processing engineering;water box in the passenger train;304 stainless steel sheet;sheet welding;residual stress analysis;corrosion resistance