英文標題，摘要及關鍵詞

Numericalanalysisofweldedimpeller’soutletflowpassagedeformationinlargecentrifugalcompressor

Han Long, Xu Zhenzhen, Niu Jing, Zhang Jianxun

(Xi’an Jiaotong University, State Key Laboratory for Mechanical Behavior of Materials, Xi’an 710049, China).p1-7

AbstractIn this paper, the finite element method was used to analyze the deformation law and influence factors of the outlet flow channel caused by welding the impeller of a large centrifugal compressor. The research results showed that the deformation of the outlet runner after welding and heat treatment of impeller was mainly caused by the deformation of the cover disc, and the final deformation of the outlet height of the runner was about 2.3 mm. After welding, the outlet height of the runner was deformed too much, so a limit block was designed to optimize the outlet runner deformation. Through the numerical simulation analysis of different positions of the limit block, the results showed that the welding deformation of the outlet runner height was reduced to about 50% after the limit block was added on the obtuse angle side of the blade, and the overall deformation amplitude of the impeller decreased.

Keywords:impeller,weldingdeformation,finiteelementmethod,centrifugalcompressor,limitblock

Modelinganddetectinganalysisformicrogapweldmagnetical-opticalimagebasedonmagneticchargetheory

Zhen Renhe1,2, Xiong Jianbin1, Zhou Wei1

(1. Guangdong Polytechnic Normal University, Guangzhou 510635, China; 2. Guangdong University of Technology, Guangzhou 510006, China).p8-11

AbstractMagnetical-optical (MO) sensor could be used to detect and track microgap weld (≤0.1 mm) for laser welding. In the case of using a DC magnetic field to magnetize the weld of the weldment, the magnetic charge theory was used to set up leakage magnetic field distribution model for nearby microgap weld surface. And then, this magnetic field distribution feature was converted to microgap weld MO image by MO sensor. Through the comparative analysis and study of the magnetic field distribution characteristics near the surface of the weld and the corresponding characteristics of the transitional zone in the MO image of the weld, the transitional zone center of the weld in the MO image of the microgap weld was determined to correspond to the actual weld center. The research result showed that the model could effectively explain MO weld information, which provided a reasonable theoretical basis for weld tracking and identification by MO image of the weld.

Keywords:magneticcharge,laserwelding,microgap,leakagemagneticfield,magneto-opticalimage

Numericalsimulationofresidualstressinmulti-layerandmulti-passhomogenousrepairweldingofP91steel

Guo Qinghu1,2,3, Xu Guoxiang2, Chen Donggao1, Ma Liangchao1, Wang Dafeng1, Tang Jiayun1

(1. Ningbo Branch of China Academy of Ordnance Science, Ningbo 315000, Zhejiang, China; 2. Jiangsu University of Science and Technology, Zhenjiang 212000, Jiangsu, China; 3. Ningbo Surface Engineering Research Institute Co., Ltd., Ningbo 315000, Zhejiang, China).p12-18

AbstractBased on thermal-elastic-plastic theory, a three-dimensional numerical analysis model for multi-layer and multi-pass homogenous repair welding residual stress of P91 steel was established by considering solid phase transformation. The heat input of shielded metal arc welding was described by a double ellipsoid heat source model. Based on the established model, SYSWELD finite element analysis software was used to simulate and calculate the temperature field, microstructure distribution and post-welding residual stress in multilayer and multipass repair welding of P91 steel, and to study its distribution characteristics. The results showed that the solid-state phase transformation could make the transverse stress show more obvious compressive stress at the last weld, and the compressive stress value was -93 MPa. The longitudinal stress was characterized by the staggered distribution of tensile stress and compressive stress on the near surface. The longitudinal compressive stress of the last weld was larger and the stress value was -155 MPa.

Keywords:solid-statephasetransformation,residualstress,P91steel,multi-layerandmulti-passrepairwelding,numericalsimulation

LowtemperatureimpacttoughnessintheCGHAZofhighNbfire-resistantsteel

Chen Linheng1, Liu Pan2, Cui Qiang1, Fan Yi1, Meng Lingming1, Wang Honghong2

(1. Nanjing Iron and Steel Group Co., Ltd., Nanjing 210035, China; 2. Wuhan University of Science and Technology,Collaborative Innovation Center for Advanced Steels, Wuhan 430081, China).p19-23,26

AbstractThe reversed austenite growth mechanism and low temperature impact toughness of coarsen-grain heat-affected zone (CGHAZ) were studied through methods of welding thermal simulation and high-temperature laser scanning con-focal microscopy (LSCM) for high-Nb fire-resistant steel. The chemical composition system that was designed with low-Mn, high-Nb and super low-C increased the reverse austenite transformation temperature and shortened the austenite growth time on heating of welding thermal cycle. LSCM showed that the reversed austenite grew in the mode of grain boundary migration with the low growth rate at the first growth stage on heating of welding thermal cycle. Then it grew in the mode of grain merging without growth mode of swallowing up, and the austenite grains did not grow up on cooling of welding thermal cycle. Thus, austenite grains were not coarsened largely in the investigated steel. The grain size was around 24～41 μm in submerged arc welding CGHAZ under heat input of 15 kJ/cm, 50 kJ/cm, 75 kJ/cm. The fine grains increased the impact toughness at -40 ℃ and the impact absorption energy was greater than 240 J.

Keywords:compositefire-resistantsteel,reversedaustenite,CGHAZ,graingrowth,impacttoughness

Effectofsinglefluorideonlaserweldingoftitaniumalloy

Xu Aiping, Dong Junhui, Zhen Zhenyang, Zhang Yicheng

(Inner Mongolia University of Technology, Hohhot 010051, China).p24-26

AbstractSingle fluoride NaF, Na2SiF6and YbF3were selected as active fluxes for welding experiment of TC4 titanium alloy, and their weld penetration, weld width and plasma morphology were analyzed by 5 mm single laser welding test. The results showed that the active fluxes selected in the single laser welding test had different effects on weld width and weld penetration, but all of them could reduce weld width and increase weld penetration, among which YbF3had the best effect. The electron density of the welding plasma was effectively reduced after active fluxes were applied.

Keywords:TC4titaniumalloy,laserwelding,activatingflux,plasmamorphology

Developmentandapplicationofconvenienttemperaturemeasuringdeviceforelbowautomaticbrazingfurnaceofairconditioningheatexchanger

Yang Yukai1, Zhang Pengpeng2, Zhao Yue1, Wu Guangzong2

(1.Ocean University of China, Qingdao 266100, Shandong, China; Qingdao Haier (Jiaozhou) Air Conditioner Co., Ltd., Qingdao 266100, Shandong, China).p27-30

AbstractIn order to solve the problem of temperature measurement method of flame temperature field and the lack of temperature measurement device in the tunnel type brazing furnace of air conditioning heat exchanger, a temperature measurement device based on thermocouple was designed and developed with the heat exchanger welding line of an air conditioning manufacturing enterprise as the application object. The specific form of flame temperature field in the tunnel brazing furnace was explored, which was used to measure the flame temperature field during the production of the production line. A mathematical model of the temperature field was constructed which fully showed the temperature field at the melting time of the welding ring on the workpiece. According to the temperature field model, the control mechanism of the technological parameters of the tunnel type brazing furnace was established to judge the distribution of the temperature field during the processing of the workpiece, which provided a scientific basis for the adjustment direction of technological parameters. The development of the temperature measurement device filled the vacancy of the automatic flame brazing temperature measurement mode of the air conditioning heat exchanger. The temperature field mathematical model established on this basis was more in line with the actual situation. At the same time, the mathematical model had a certain guiding role in the regulation of process parameters, which was conducive to process standardization and replication promotion.

Keywords:manufactureofairconditioningheatexchanger,tunnelflamebrazingfurnace,thermocoupletemperaturemeasurementdevice,mathematicalmodel

Areviewofwirearcadditivemanufacturingfromaspectsofphysicalprocess,researchstatus,applicationsituationanddevelopmenttrend

Li Yan1,2, Su Chen1, Zhang Jixiang1,2

(1. China University of Petroleum, Beijing 102249, China; 2. Beijing Key Laboratory of Process Fluid Filtration and Separation, Beijing 102249, China).p31-37

AbstractProcess characteristics, system composition of the wire arc additive manufacturing (WAAM), as well as physical processes that occurred in WAAM were introduced. The research status of WAAM was mainly discussed from four aspects, the development of additive equipment system, process inspection and control, microstructure performance and defects and forming process factors. Current research hotspot was to investigate on the microstructure and mechanical properties of the formed parts, and analyze defects such as residual stress, deformation, porosity, cracking and delamination. Another research hotspot was to investigate on key factors affecting the precision and surface morphology for different material systems and different welding process. The application of WAAM at home and abroad was also briefly introduced in the paper. It was founded in the review that the basic research of WAAM was relatively weak, especially that the heat and mass transfer mechanism was very lacking. It was urgent to promote the development of this technology by accurate and systematic theoretical and simulation research, which might provide refined guidance for WAAM.

Keywords:additivemanufacturing,arc,review,basicresearch

Researchprogressofweldingtechnologiesfor2195Al-Lialloy

Yuan Linlin1,2, Wang Wei1, Chen Xiaoyu1

(1. Beijing Non-ferrous Metals and Rare Earth Research Institute, Beijing 100012, China; 2. Beijing Engineering Research Center of New Brazing Materials for Electronic Information, Beijing 100012, China).p38-42,46

AbstractIn this paper, three problems of joint softening, porosity and crack in 2195 Al-Li alloy during welding were discussed. The research status of 2195 Al-Li alloys in TIG welding, MIG welding, friction stir welding, laser welding and electron beam welding were reviewed. In particular, the influence of welding technology on microstructure and mechanical properties of welded joints was introduced. Furthermore, the development trend of 2195 Al-Li alloy welding technology was prospected.

Keywords:Al-Lialloy,weldingtechnology,researchprogress

ProcesscontrolofnickelplatebuttplasmaarcweldingbasedonPLC

Shen Liang1, Zhao Qian2, Wu Qiangqiang1, Wu Lan1, Xu Yongsheng1

(1. Northwest Minzu University, Lanzhou 730030, China; 2. Lanzhou Overseas Chinese Experimental School, Lanzhou 730030, China).p43-46

AbstractIn order to realize automatic control of plasma arc welding process, the control system using the OMRON CP1H PLC as the core combined with touch screen was designed in accordance with the plasma arc welding requirements in the paper. Characteristics of plasma arc welding process, together with the control object and control sequence of the core PLC in the welding process were analyzed. Two independent welding power sources were selected as pilot arc and main arc power sources to enhance the stability and anti-interference ability of the system. RS-485 was used for data transmission between PLC and touch screen, and centralized control and adjustment of corresponding welding parameters was carried out. The human-machine interface of touch screen was constructed with Easy Builder 8000 design software and the composition and relationship of the whole system was systematically introduced. Finally, two welding processes, plasma welding without filler wire and with ERNi-1 welding wire were used as the filler material to butt weld N6 nickel plate with 6 mm thickness. The weld formed well. The system ran safely and reliably and had high maintainability. It realized automatic control of plasma arc welding process.

Keywords:PLC,touchscreen,buttweldingofnickelplate,plasmaarcwelding

Preparationoftitaniumalloypipefittingsbycontinuousdrivenfrictionwelding

Xi Jinhui, Ge Peng, Hou Peng

(Western Metal Materials Co., Ltd., Xi’an 710201, China).p47-51

AbstractTi6246 titanium alloy, TA2 pure titanium pipe and TC4 titanium alloy blind-hole pipe were prepared by continuous driven friction welding. The influence of welding parameters on the macro-appearance of welded joints, especially on the microstructure and mechanical properties of welded joints under the condition of heat treatment, was analyzed. The results showed that welding parameters had little influence on performance of welded joints within the range of welding parameters in the study. Welding coefficients of Ti6246 and TA2 pipes could reach 0.99. Friction welding could break microstructure of weld zone, which made microstructure of weld zone obviously fine than that of the base material. After friction welding, microstructure of weld zone in TC4 blind-hole pipe changed from widmanstatten to basket microstructure. The tensile strength was reduced by about 60 MPa, but the welding coefficient was still 0.94, and the plasticity and toughness were better than that of the base metal.

Keywords:continuousdrivefrictionwelding,titaniumalloy,pipefittings,microstructure,mechanicalproperties

Developmentofgas-shieldedflux-coredwireforhardfacingofcoldworking-roll

Xu Libao1,2, Zhang Jian1,2, Li Shichen1, Huang Rui1, Jiang Xue1

(1. Tianjin Golden Bridge Welding Materials Group Co., Ltd., Tianjin 300300, China; 2. Tianjin Key Laboratory of Enterprise of Upmarket Equipment Manufacturing and Welding Material and Technology,Tianjin 300300, China).p52-56,60

AbstractThe gas-shielded flux-cored wire for hardfacing of cold working-roll was studied. The experimental results showed that the hardness of the hardfacing layer was the highest when the C content of the deposited metal was 0.69%. The total amount of Cr, Mo, W and V in the deposited metal was 6%～10% and (Cr+V)/(Mo+W)=1～1.4, friction and wear-resistance of the hardfacing layer was better. When the addition of (RE + Ti) was 2%, metallurgical metamorphism was the best, the grain size was greatly reduced, and toughness was better. The developed wire had excellent welding technology. After 580 ℃ heat treatment, it were balanced between precipitation strengthening and matrix softening, and the hardness of the hardfacing metal reached the maximum, which satisfied the site repairing and operation requirement of cold-roll.

Keywords:coldworking-roll,hardfacingflux-coredwire,hardnessandtoughness,grainrefinement,temper

ElementaryanalysisofFCAWapplicationinboilermanufacturing

Xu Xiangjiu1, 2

(1. State Key Laboratory of Efficient & Clean Coal-Fired Utility Boilers, Harbin 150046, China; 2. Harbin Boiler Company limited, Harbin 150046, China).p57-60

AbstractAccording to characteristics of gas shielded flux-cored arc welding, combined with the relevant standards of China and the development status of boiler manufacturing industry, the feasibility of adopting gas shielded flux-cored arc welding were analyzed and discussed for various common structures of boiler, such as large pipe joint, ear plate and container’s small pipe joint, through the welding test of simulated parts. The results showed that welding quality and performance could be guaranteed by gas shielded flux-cored arc welding for large pipe joint and ear plate structure. However, the defects such as slag inclusion, incomplete fusion and incomplete penetration were easy to produce by manual operation of gas shielded flux-cored arc welding for small pipe joint structure. When gas shielded flux-cored arc welding was adopted for important parts in boiler manufacturing, the volume type nondestructive testing should be carried out for the welded joints to ensure that there were no defects in welded joints of products.

Keywords:boiler,flux-coredwire,welding