2004, Vol.25 , N o .4 T RAN SACT IO NS OF T HE W EL DING IN ST IT UT IO N Ⅲ

MAIN TOPICS , ABSTRACTS &KEY WORDS

Coaxial monitoring and penetration control in CO2 laser welding(Ⅰ)——— developed by us is discussed .The swing welding experiment for V-type w eld- Penetration status characteristics and coaxial monitoring ZHAGN Xu- ing groove is done and the results show that the system has high resolution of Dong , CHEN Wu-zhu, LIU Chun , GUO Jing(Department of Mechanical tracing w eld in real time, works stably and efficiently .The shape of weld Engineering , Tsinghua University, 100084 , China).p1 -4 mark is good . Abstract:The various penetration status in deep penetration laser weld- Key words:real-time control;structure-light vision ;visual measure- ing is classified .The w elding condition and the weld bead formation of “w eld ment;visual control;arc welding robot pool penetration” and “ moderate full penetration (keyhole penetration)” are described .A system for coaxial monitoring the penetration status in CO2 laser Analysis of interfacial structure of Ti/ Cu/ Ti diffusion brazing heated with w elding is established.The influence of welding process variables and penetra- oxy-acetylene flame Yuan Qing-long , Su Yon-gan, Tang Bin , Xu Zhong tion status on the coaxial optical signal is studied in laser w elding of planar (Institute of Surface Engineering, Taiyuan University of Technology , plate.The experimental results show that as the heat input increases, the Taiyuan 030024 , China).p15 -18 variation slope of the signal intensity is maximal w hen the penetration status Abstract:Ti/ Cu/ Ti diffusion brazing, w hich is heated w ith oxygen- changes from “w eld pool penetration” to “moderate full penetration” . acetylene flame and pressed simultaneously , is realized under protection of the Key words:laser welding;coaxial monitoring ;penetration coating.The measurement results of interfacial microstructure, composition and cohesion strength of joint by backscattered electron , energy dispersive Pulsed MIG welding process of high strength A-l Cu alloy GUO Xu- spectroscopy and tensile test indicate that full diffusion occurs betw een Cu and ming, YANG Cheng-gang, QIAN Bai-nian , ZHANG Hong-yan(Institute of Ti in the joint w ithin the test temperature range .In the temperature range

Metal Research , The Chinese Academy of Sciences, S henyang 110015 , Chi- from 840 ℃ to 870 ℃, the microstructure consists of Cu4Ti and Cu(Ti) na).p5 -9 (solid solution)in the middle part of the joint and the cohesion strength is rel- Abstract:The effects of single-wire unitary pulsed metal inert-gas ative high .In the temperature range from 870 ℃ to 900 ℃, the microstruc-

(MIG), synergic pulsed MIG and double-w ires tandem MIG w elding pro- ture is composed of CuTi and Cu4Ti+Cu(Ti)(solid solution)in the middle cesses on the microstructures and properties of high strength Al-Cu alloy part of the joint and the cohesion strength is relative low .The cohesion w elds were investigated .The results showed that the enhanced stirring action strength has something to do w ith heating temperature. of the liquid metals in weld pool due to peak-current fluctuating periodically Key words:titanium ;copper foil;diffusion brazing ;oxygen-acetylene under single-wire synergic pulsed MIG w elding decreased temperature gradi- flame;interface ents and increased heterogeneous nuclei within the region of constitutional su- percooling just ahead of the solid-liquid interface.As a result, the microstruc- Dynamic focal spot and extremum effect of deep penetration of electron ture of the weld w as refined.The strength and ductility of the weld in- beam ZHOU Qi1, 3 , LIU Fang-jun2 , GUAN Qiao2(1.Ningbo Sub-a- creased.The high heat inputs and rapid w elding speed of double-wires MIG cademy of the National Weapons Science Research Academy , Ningbo w elding enhanced the formation of coarse equiaxed dendrites in the weld and 315103 , Zhejiang , China;2 .Beijing Aeronautical Manufacturing Technology increased the eutectic constituents at grain or dendrite boundaries.The Research Institute, Beijing 100024 , China;3 .Beijing University of Aeronau- strength , hardness and ductility of the w eld decreased. tics & Astronautics, Beijing 100083 , China).p19-22 Key words:high strength Al-Cu alloy ;synergic pulse;tandem metal Abstract :The measurement methods of focal spot with welding charac- inert-gas w elding;weld microstructure teristic are analyzed .Using the simple model of molten pool, the inherence relation of the different measurement methods with the w elding property is il- Study on arc welding robot visual control XU De, TU Zhi-guo , ZHAO luminated.The conception of dynamic focal spot is set up , and the factors Xiao-guang, TAN Min(The Key Laboratory of Complex System and Intelli- which influence the dynamic focal spot are discussed .Furthermore, the char- gence Science, Institute of Automation , Chinese Academy of Sciences, Bei- acters of dynamic focal spot are analyzed, and the most important character is jing 100080 , China).p10 -14 the extremum effect of deep penetration of electron beam. Abstract:A real-time arc w elding robot visual control system based on Key words:electron beam welding;dynamic focal spot ;extremum ef- local network with multi-level hierarchy is presented , w hich consists of intel- fect of deep penetration ;space-charge effect;self-focusing effect ligence and human-machine interface (HMI)level, motion planning level, motion control level and servo control level.The last three levels form local Control optimization for pulsed MIG weding machine LI He-qi, LI real-time open robot controller (LRTORC).The master computer as the Chun-xu, LI Fang , LU Guang, (Education Ministry Key Lab of Advanced first level is for visual measurement, movement command generator, w elding Processing Technology for Non-ferrous Materials, Lanzhou University of torch controller and HMI .LRTORC realizes motion planning and motion Technology , Lanzhou 730050, China).p23 -26 control of the robot.The system has the function of automated recognition Abstract :A self-designed microcomputer control system for pulsed met- and tracking weld .The principle of the visual control system and LRTORC al inert-gas(MIG)w elding power source, the selection of proportional-inte- Ⅳ M A IN T OPICS , ABST RA CTS & K EY WO RDS 2004, Vol .25 , N o .4 gral-differential(PID)algorithms, and the optimization stratege of system ement software conntrol software w ere introduod.To solve the conflict betw een proportional- integral(PI) control and real time display of w elding parameters in MIG Study on valid exponent and welded restrict of explosive welding XIE w elding, the w orking Timing Diagram of serial display component MAX Fei-hong1 ,GUAN Hui-ping1 , WANG Jun2 ,3 , LUO Guan-w ei4(1 .College of 7219 was analyzed, and the data and command transfer w ays of it and the Civil Engineering , Lanzhou Jiaotong University , Lanzhou 730070, China;2 . w ay to optimize PID control algorithms on the premise of avoiding system Yaojie Coal and Electricity Group, Lanzhou 730084 , China;3 .Xi' an Jiao- damping were improved .PI control time is only 80 μs and one bit digital dis- tong University , Xi' an 710049, China;4 .College of Mechanical-Electronics play w as refreshed every 200 times(about 16ms).The display flash problem Engineering , Lanzhou Jiaotong University , Lanzhou 730070 ,China).p35 - w as solved .The result show ed that the optimized program run very fast, re- 38 sponded very quick , and w as very accurate, and the w elding proass was very Abstract :In view of the hypothesis of upset plate move bearing and gas stable. dynamic equation in explode, blast w ave equation is made up, and explosive Key words:inverter welding power source;proportional-integral-differ- gasaction is thought vertical reflection on fixed w all.So confine of valid expo- ential controller ;serial component ;pulsed metal inert-gas w elding nent is yet deduced .It is reliable supply for practical engineering .2 # rock nitramon and petnaerythritoltetranitrate or trinitrotoluene explosive is used to Vision detecting of weld pool image for depositing copper with automatic weld aluminum upset plate and mild steel base plate, the equation upset plate TIG welding WANG Ke-hong , XIONG Liang-tong , XU Yue-lan, YU and explosive thickness can be deduced from Richter equation .It is effectual Jin(Department of Materials Science & Engineering , Nanjing University of for being used in practice by example of analysis. Science & Technology , Nanjing 210094 , China).p27 -30 Key words:explosive welding parameter;effective exponent;motive Abstract:An idea of imaging in near-infrared spectrum is proposed , and shock w ave reflected on fixed wall;gas dynamic equation two kinds of composite narrowband filter system with different imaging mechanism are designed.Images of copper w eld pool in tungsten inert-gas Safety assessment of duplex stainless steel pipe mismatch welded joints with (TIG)and pulsed TIG(PTIG)welding are obtained from the front side of surface flaw JIN Xiao-jun1, HUO Li-xing1 , ZHANG Yu-feng1 , BAI w ork pieces using normal charge coupled device sensor , and results of imaging Bing-ren2 , LI Xiao-w ei2, CAO Jun2(1.School of Material Science and Tech- w ith different observing window are discussed .Then , comparatively better nology , University, Tianjin 300072 , China;2 .China Offshore Oil imaging windows are found , and comparatively clear images of copper w eld Engineering Ltd., Tianjin 300452 , China).p39 -42 pool are obtained .From the experiment , it can be found that it iseasy to ob- Abstract :Structure Integrity Assessment Procedure(SINTAP)-Fail- tain clear image in near-infrared spectrum in TIG welding and images obtained ure Assessment Diagram (FAD)method w as applied to the SAF2205 pipe in the base of PTIG welding are clearer than that of TIG welding .Finally, mismatch welded joints with surface flaw (The height and length are 1.1 mm the features of copper weld pool and control of depth are analyzed and re- and 2 .5 mm respectively)at the weld toe.The failure lines of analysis level 1 searched . and 2 of weld metal were derived from the tensile test results including the Key Words:tungsten inert-gas w elding;copper w eld pool;vision de- yield and tensile strength and full engineering stress-stain curve.The crack tecting ;w ithout penetration;control tip opening displacement values were obtained through fracture mechanics tests at -18 ℃.Assessment results show ed that all assessment points w ere Calculated GMAW temperature field based on ANSYS LEI YU-cheng1 , located within the failure lines of analysis level 1 and 2 .So the pipeline struc- ZHANG Cheng1 , CHENG Xiao-nong1 , HU Xiao-jun2 , FENG Ya-ming1(1 . ture with surface flaw at the weld toe was safe.Critical flaw size was calcu- School of Materials Science and Engineering , Jiangsu University , Zhenjiang lated and fatigue life w as estimated according to the above assessment results. 212013 , Jiangsu, China;2 .Zhenjiang Baohua Special Vehicle Co LTD, Key words:structure integrity assessment procedure;duplex stainless Zhenjiang 212013 , Jiangsu , China).p31 -34 steel;mismatch;safety assessment;welded joint Abstract:Based on principle of heat transfer, fluid dynamics and physi- cal metallurgy, three-dimensional dynamic w eld pool mathematical model of Mel-t brazing chromium-copper to double-phase stainless steel by electron gas metal arc w elding(GMAW)with locomotory arc w as built.A finite ele- beam ZHANG Bing-gang1 , FENG Ji-cai1, WU Li1 , HE Jing-shan1 , ment model w as setup based on the mathematical model, and the w eld pool YANG Wei-peng2 , ZHU Chun-ling2(1 .National Key Laboratory of Ad- temperature w as calculated using universal finite element method soft AN- vanced Welding Production Technology , Harbin Institute of Technology , SYS .Unsymmetrical mesh was used in the calculation , and influnce of melt- Harbin 150001 ,China;2.Xi' an Spaceflight Engine Factory , Xi' an 710061 , ing drop on the weld pool energy and exterior distortion w as considered .Dou- China).p43 -45 ble-apex model of double gauss heat source w as adopted and the dead-birth Abstract:The microstructure and tensile strength of the joints of method was used.The error w as controlled within 8 %.The calculated value QCr0 .8 / 1Cr21Ni5Ti welded by electron beam located on copper side were and experimental value of weld w idth and w eld depth w ith different technical investigated.The results show ed that w ith the increment of the offset of elec- parameter w ere compared .The result indicates that it is credible and feasible tron beam located on copper side from central line of butt joint the distribution using ANSYS to calculate GMAW temperature field and introducing double- of the microstucture and compositon of w eld become gradually uniform, so apex heat flux . the joining state was improved ;as the offset on copper side equals 0 .8～ 1 .0 Key words:gas metal arc welding ;temperature field ;ANSYS finite el- mm, the melt-brazing joint with uniformity of the microstructure and compo- 2004, Vol.25 , N o .4 T RAN SACT IO NS OF T HE CHINA W EL DING IN ST IT UT IO N Ⅴ nents w as formed , and the maximum tensile strength was about 330 MPa. Fracture behavior and mechanism of T-i 6A-l 4V electron beam welded joint key words:dissimilar materials;electron beam;melt-brazing ;chromi- WU Hui-qiang , FENG Ji-cai, HE Jing-shan , ZHANG Bing-gang(Na- um-copper and stainless steel tional Key Laboratory of Advanced Welding Production Technology , Harbin Institute of Technology , Harbin 150001 ,China).p59 -62 Abstract :The effect of microstructure on fracture behavior and mecha- 3 dimensional flow modeling of friction stir welding WANG Da-yong, nism of Ti-6Al-4V electron beam welded joint w as investigated by means of FENG Ji-cai(National Key Lab of Advanced Welding Production Technolo- scanning electron microscopy , transmission electron microscopy, and micro- gy , Harbin Institute of Technology , Harbin 150001 , China).p46 -50 hardness.The results indicated that the weld microstructure were composed Abstract:This paper established a model about the flow process of soft- of coarse needleα+β phases and martensite of multi-direcitonal short needle ened material around rotational tool during friction stir w elding .According to morphology.The w eld coarse grain w ith size of 200 -350 μm , and the mi- the flow pattern of different parts of softened material, the flow process was crohardness was 536 HV.High brittleness of the microtructure makes it easy divided into three parts:flow process near the shoulder , near the pin top and to fracture in the region.The uneven distribution of the partial micropores lo- near the pin end .The softened material near the shoulder firstly flew into the cated at the interior of the specimen acting as crack initiation sites lead to non- cavum behind the pin , and the residual material rotated around the shoulder linear branch propagating path.The α+β interlaced structure results in frac- side slowly, forming the arc crest of arc corrugation on friction-stir w eld. ture near α/β interface because of the different thermal expansion coefficient . The softened material near the pin top flew to retreating side from advancing The existence of stacking fault structure caused pile-up of dislocation to pro- side in a shear way .The softened material near the pin end flew to the re- duce micropores as new fracture initiation sites. treating side from the advancing side in an extrusion w ay. Key words:electron beam w elding ;titanium alloy ;microstructure; Key words:friction stir welding;flow model;three dimension fracture behavior

Control strategy of waveform with median phase in droplet transfer for Microstructure and mechanical properties in simulated HAZ of 1 1 pulsed MIG welding W U Kai-yuan , HUANG Shi-sheng , MENG 0Cr13Ni5Mo martensitic stainless steel ZHOU Shi-feng1, WANG Yu- 2 1 Yong-min , LI Yang (1 .South China University of Technology , cheng1 , LI Xiang-yang1 , ZHOU Bao-jin1 , LI Xiao-yu1 , LI Bin2 , LI Wei- 510640 , China;2 .GP Electronics () Ltd., Sheuzhen 518008 , dong2(1.Harbin Welding Institute, Harbin 150080 , China;2 .Harbin Elec- , China).p51 -54 , 58 tric Machinery Ltd .Co, Harbin 150040 , China).p63 -66 Abstract:For the droplet transfer for pulsed metal inert-gas(MIG) Abstract :By simulating the welding thermal cycle, the continuous cool- w elding, a new w aveform control method of w aveform with median phase ing transformation diagram of heat-affected zone (HAZ)of ZG0Cr13Ni5Mo w as presented .The effect of median current and median time on the droplet martensitic stainless steel was established .The diagram indicates that there transfer was studied .The optimum median current and median time were are no other transformation but austenite※martensite in HAZ, and the cool- found by experiment when w elding steel using w aveform with middle median ing rate has no obvious effect on the temperature Ms of martensite initial phase .The experiment result show s that instantaneous short circuit occurs transformation .The hardness of simulated HAZ decreases slightly as the cool- w hen the median current is small and the median phase has not effect on the ing rate decreases.By using Gleeble thermal simulation technique the mi- droplet transfer when the median current is large, and w hen the median cur- crostructures of HAZ at various welding thermal cycles were simulated, and rent is an optimum value, the w elding effect is satisfactory .On the basis of the hardness, impact toughness and microstructures were investigated .The defining the median current as an optimum value, the w elding effect is satis- results show that the hardness of simulated HAZ is much higher than base factory when the median time is an optimum value.There is not droplet metal' s hardness, and the impact toughness of simulated HAZ is much low er transfer w hen the median time is small and there is multitude droplets transfer than the base metal' s.In the single thermal cycle simulating the root pass w hen the median time is large. welding , the cooling rate has no effect on hardness and impact toughness of Key words:pulsed metal inert-gas welding ;droplet trarsfer ;median simulated HAZ .In multi-thermal cycles simulating the multi-pass welding , w aveform;waveform control Microstructure feature analysis of activating the heat treatment between passesand layers is not significant.Postw eld heat TIG welded joint ZHANG Zhao-dong, LIU Li-ming , WANG lai (De- treatment at 590 ℃ is an essential way to improve the impact toughness of partment of Material Engineering , Dalian University of Technology , Dalian HAZ greatly. 116023 , China).p55 -58 Key words:simulated heat-affected zone;martensitic stainless steel;

Abstract:The effect of activating fluxes with single component TiO 2 on postweld heat treatment w eld form in tungsten inert-gas(TIG)welding of magnesium alloy is studied. The experimental results show that the penetration is more than 2 times com- Material flow pattern in friction stir welding of AZ31 magnesium alloy pared to the conventional TIG w elding .Compared w ith weld made w ithout ZHANG Hua, LIN San-bao , W U Lin, FENG Ji-cai(National Key Lab of flux the penetration increases, and the width decreases.The flux developed Advanced Welding Production Technology , Harbin Institute of Technology , has no effect on the microstructure. Harbin 150001 , China).p67 -69 Key words:magnesium alloys;activating tungsten inert-gas w elding; Abstract :A thin Cu coating was deposited on both sides of AZ31 mag- flux ;w eld penetration nesium alloy to be joined to study the material flow in friction stir welding . The results show that the probe wipes the material from the advancing side Ⅵ M A IN T OPICS , ABST RA CTS & K EY WO RDS 2004, Vol .25 , N o .4 into a rotating and moving zone , and material rotates, advances, and descends hydrogen is cut dow n , as a result , the proportion of IG decrease , w heras helically in the stir zone and rises in the outer part of the rotating zone. those of QCHE and sub-crack increase signifcantly , and more plastic de-

Key words:friction stir welding;material flow ;advancing side;re- formation appears clue in QCHE .The reason for high resistance to CR of treating side;AZ31 magnesium alloy SA106C cast steel is mainly due to the low er content of hydrogen of CO 2 arc welding process, and also related to the microstructures and as-

Application of image processing automatic tracking of CO2 arc welding quenched hadness of over heated zone near the w eld interface, w hich is GU Chun-yan1, ZHANG Li-bin2 , HU Bao-jian1 , LIU Chao-ying1 , largely bainite with hardness of 321HV ,less than critical hardness of 350 HUANG Wei1(1.Department of Electronic Engineering ,Zhaoqing Universi- HV . ty , Zhaoqing 526061 , Guangdong , China 2.Maoming College, Maoming Key words:SA106C cast steel;im plant tests;CO 2 gas shielded arc 525000 , Guangdong , China).p70-72 w elding ;cold cracking Abstract:Based on plane array charge coupled device(CCD)computer image processing, an averaging filtering increment processing w as designed Influence of ambient humidity on weld delayed crack of Cu-age-harden- w ith CCD imaging and computer w elding pool direct visual sensing method. ing steel ZHANG Xiao-mu , PENG Yun , XIAO Hong-jun , YANG And the edge of welding pool w as draw n with morphological method.In this Bai(Central Iron & Steel Research Institute, Beijing 100081 , China). w ay, the center of the w elding poolw as determined.And that w as the center p81 -84 of the torch .So the offset of the torch to the seam was determined .The Abstract:To test the w eld cold crack sensitivity of Cu-age-harden- w hole time of image processing w as 25 ms. ing steel in humid ambience, tw o kinds of specimens with oblique Y- Key words:vision-sensing method ;image processing ;weld-tracking groove and straight Y-groove, respectively , w ere w elded using gas metal arc welding.Weld delayed crack experiment of Cu-age-hardening steel w as conducted in artificial environment .The results indicate that weld- Finite element analysis of circular welds in LF6 aluminum annular plate ing at high temperature and in high humidity ambience results in higher FANG Hong-yuan, WANG Xiao-teng , FAN Cheng-lei, YANG Jian-guo. delayed cracking tendency than welding at 0 ℃.In the highest humidity (National Key Laboratory of Advanced Welding Production Technology , ambience the delayed crack of Cu-age-hardening steel could be prevented Harbin Institute of Technology , Harbin 150001 , China).p73 -76 by preheating or keeping the inter-pass temperature higher than 45 ℃ Abstract:The residual stresses and distortion produced by a circular for gas metal arc w elding . w eld in LF6 aluminum thin plate w ere analyzed from the viewpoint of me- Key words:Cu-age-hardening steel;ambient humidity ;cracking chanics.In order to simulate the residual stresses and distortion produced by a resistance test;w eld delayed crack circular w eld in LF6 aluminum thin plate, a finite element model w as built and a coupled thermal-mechanical analysis was employed.The result shows Inverter CO2 arc welding power source with DSP-based waveform con- that the temperature field and the distribution of stress in circular w eld are trol S UN Guang1 , HE Jian-ping1 , BAI Ri-hui1 , W U Yi-xiong1 , 2 greatly different from the ordinary butt weld .At the start point of the w eld, (1 .Welding Institute, S hanghai Jiaotong University , 200030 , the maximum radial stress can be as high as the material' s yield strength .A China;2 .State Key Laboratory of Metal Matrix Com posite , Shanghai deduction based on the elastic theory shows that the buckled plate produced 2 200030 , China).p85 -88 circumferential waves.The numerical analysis of buckling shows the same Abstract :A CO 2 inverter w elding system w ith w aveform control is tendency. established , in w hich the T MS 320C240 digital signal processing (DSP) Key words:welding residual stress;buckling ;finite element method is adopted as the central con troller .The structure of the system is intro-

Study of cold cracking susceptibility of CO2 gas shielded arc welded duced , and the working p rinciple of the subsystems are given in detail, SA106C cast steel using implant tests WANG Xue, SH I Yu-xiang , such as the main circuit, m ulti-system of DS P, setting system of the REN Yao-yao, LAI Jing-ping(Wuhan University , W uhan 430072 , Chi- w elding parameters, and the wire feeding system and the w elding se- na).p77 -80 quence control circuit.The output characteristic is controlled using a col- Abstact :Implant tests w ere performed on the S A106C cast steel lateral double close-loop method , w hich is fulfilled by software.The w elded using CO 2 gas shielded arc w elding , w hich intended to investi- principle of this control method and the output w aveform are given .The gate the susceptibility of cold cracking(C R)and the fracture morpholo- results show that besides its simple structure and easy operation , the gy .The results show that in the case of heat input being 16kJ/ cm and no system has good controlling performance . p reheating , the critical fracture stress of implant is 560 MPa , near to Key words:digital signal processing ;w aveform control;collateral the value of tensile strength , consequently , its resistance to CR is so double close-loop ;CO 2 arc welding pow er source high that it can be welded w ithout preheating .If the restraint stress is higer than tensile strength , the fracture w ill occur .T he features of the Characteristic of solute-diffusion bonding between stainless steel and fracture is typical hydrogen-induced crack (HIC).The rupture mode of N-ibased micro-crystal powder XU Jin-feng1 , ZHAI Qiu-ya1 , the fracture is found to consist of sugar like intergrannular(IG)and quasi WANG Yu-feng2 , CHEN Li-min1(1 .S chool of Materials Science and

-cleavage(QCHE), some sharp , perfectly straight , short sub-crack can Engineering , Xi' an University of Technology , Xi' an 710048 , China ; be also observed additionally .With the crack propagating , the content of 2 .Qing' an Group Corperation , Xi' an 710077 , China).p89 -92 2004, Vol.25 , N o .4 T RAN SACT IO NS OF T HE CHINA W EL DING IN ST IT UT IO N Ⅶ

Abstract:Microstructures and properties of liquid film solute-diffu- Mechanism of Ni/ NiCr joint formation by parallel micro gap welding sion bonding interface of 0C r18Ni9Nb stainless steel(S S)w as studied . WANG Chen-xi, WANG Chun-qing , KONG Ling-chao(National It show s that Ni-based alloy pow ders with metastable structure can real- Key Laboratory of Advanced W elding Production Technology , Harbin ize the solute-diffusion bonding of 0Cr18Ni9Nb stainless steels.The Institute of Technology , Harbin 150001 , China).p99 -102 w eld has good connection w ith base materials and the joint is composed Abstract:Ni leads (diameter of 0 .15 mm)were w elded to NiCr of w eld , bonding interface , and near interface base metal zone, of alloy thin film (5 μm thick )with strong current and short duration by w hich , bonding interface zone is constructed by tw o parts:a single method of parallel micro gap w elding .A two -dimensional thermal con- phase γ(Ni)layer of 185 μm thick and a poly-phase layer with γphase duction model of w elding w as developed .It w as calculated that the posi- and metallic compounds.The w eld zone is com posed of homogenous and tion of top temperature w as related to electrode gap .W hen the gap of fine equioxed γ(Ni)grains w hose mean size is about 50 μm and inter- two electrodesis greater than a critical gap , the top temperature position granular (γ(Ni)+Fe4 .5Ni8 .5B6)eutectic .While the microstructure is in the middle of the two electrodes.Results show that the temperatu re of γ-matrix in SS near interface show s no remarkable phase transforma- in the middle of electrodes reaches the melting point of Ni or NiC r alloy tion .The joint has a tensile strengths up to 280 MPa and a reasonable firstly , how ever there are no nuggets in this position during the w elding distribu tion of hardness, therefore, good matching hasbeen obtained be- process.With electrode force, the formation of joint depends on diffu- tw een the w eld and the stainless steel. sion below the tw o electrodes. Key words:stainless steel;liquid film ;in terface structure;diffu- Key words:parallel micro gap welding ;Ni/ NiCr joint;mechanism sion behavior ;solute-diffusion bonding of joint formation

Calculating and measuring of heating power of friction stir welding Dada acquisition and weld defects analysis in resistance spot welding WANG Xi-jing , GUO Rui-jie, CHEN S hu-jin , A Rong(Education process XUE Hai-tao1 , 2, SONG Yong-lun3 , LI Huan2 , NI U Yong2 , Ministry Key Lab of Advanced Processing Technology for Non-ferrous LI Juan-juan2(1 . Politechnic University , Tianjing 300130 , China ; Materials, Lanzhou University of Technology , Lanzhou 730050 , China 2 .Tianjing University , Tianjing 300072 ,C hina ;3 .Beijing University of ).p93 -95 Technology , Beijing 100085 , China).p103 -106 Abstract:This paper w as objected to the calculating and measu ring Abstract:Using the Graphics Language —based virtual instruments of the heating pow er during friction stir w elding .Through certain sim- developing tool LabVIEW , this paper develops a virtual instrument — plification , using the methods of experiment and curve-fitting , the rela- dada acquisition and w eld defects analysis in resistance spot w elding sys- tion of light-load to rotation speed w as obtained and the relation w as pu t tem w hich has friendly interface and is easy to operate.T he system real- in the Monitor and Control Generated System .According to the rela- izes real time data acquisition in the aluminum resistance spot w elding tionship of the energy transfer during friction stir welding , introducing process, data transfer and storage , waveform display and data process- measured light and heavy load pow er to calculation , the direct relation ing .Furthermore , it ex tracts characteristic information of evaluating betw een input power and output torque of main motor was ob tainted . w eld defects of aluminum resistance spot w elding .Based on the suffi- Meanw hile, the softw are adopted in this study , MCGS , has multi-func- ciently study of the acquired data, this paper builds an algorithm of judg- tion not only in measuring and calculating the parameters namely pow er , ing splash according to the slope coefficient of the voltage waveform and torque and rotation speed , but also in real-time controlling w elding pro- an algorithm of judging loose weld according to the energy .The algo- cess. rithms built in this paper have been p roved accurate. Key words:friction stir w elding ;heating pow er ;load ;aluminium Key words:virtual instrument ;data acquisition ;data processing ; alloy ;curve-fitting resistance spot welding ;weld defect Simulation on welding stress field of Francis turbine runner simplified Control system design in equipment of flash butt welding based on CAN model JI S hu-de, FANG Hong-yuan , LI U Xue-song, MENG bus ZHANG Qi-dong , YE Hao-feng , XU Bu-gong(The Lab of Re- Qing-guo(National Key Laboratory of Advanced Welding Production al-Time Control Through Internet and Fieldbuses, Automation Science Technology , Harbin Institute of Technology , Harbin 150001 , China). and Engineering Institution , South C hina University of Technology , p107 -110 Guangzhou 510640 , C hina).p96 -98 Abstract:A runner stress field du ring w elding is simulated on the Abstract:The hardw are and softw are design in equipment of flash basis of attaining simplified model of Francis turbine runner , realizing butt w elding based on controller area netw ork(CAN) bus w as intro- the thermal source loading of m ulti-pass w elding and solving the prob- duced.In the software design , the application layer protocol of CAN bus lem of conduction between independent entities.Evolvement of longitu- w as defined .Use of the predominance of CAN bus to control the nodes dinal stress and residual stress field after w elding are obtained .The sim- to w ork w as discussed, and that made the equipment of flash butt w eld- ulation result show s that maximal w elding stress appears along the adja- ing to be a real distributed con trol system . cent area between blades and bands or blades and crow n .The result can Key words:distributed control system ;controller area network explain w hy fatigue crack on the turbine runner blade appears and ex- bus;equipment of flash butt welding tends. Key words:runner ;blade;simulation ;stress field ;w elding Ⅷ M A IN T OPICS , ABST RA CTS & K EY WO RDS 2004, Vol .25 , N o .4

Analysis of temperature field in TC4 titanium alloy inertia friction fect of the major laser welding parameters on weld shaping w as investi- 1 ,2 1 welded joint MENG Wei-ru , NI U Rui-feng , WANG Shi- gated , and the differences between CO 2 laser and YAG laser fully pene- yuan2 , LIU Xiao-fang3 , SONG Xi-ping2(1 .Departmen t of Material S ci- trated w eld shaping w ere compared .It show ed that the cross section of ence and Engineering , Xi' an University of Technology , Xi' an 710048 , both CO 2 laser and YAG laser fully penetrated w eld of titanium alloy China ;2 .Department of Material Science and Engineering , Xi' an Jiao- w ere typically of nail shape or near X shape, w hich w as related to heat tong University , Xi' an 710049 , China;3 .Beijing Institute of Aeronau- input and laser pow er density in w elding .W ith increase of heat input tical Materials, Beijing 100095 , China).p111 -114 and laser pow er density , the cross section of the weld transformed from Abstract:The effects of w elding parameters on the interface fric- nail shape to near X shape.And YAG laser weld of near X shape was tion process w as investigated by analyzing friction principle during the more symmetrical than CO 2 laser w eld w ith the same laser welding pa- TC4 titanium alloys inertia friction w elding .The temperature distribu- rameters.By adjusting the laser w elding parameters, such as laser pow- tion in the joint is measured using thermocouple.The results show that er , w elding speed and focus position , the w eld shaping could be con- the w elding p rocesses could be finished in less than 1 .6 second and there trolled effectively and the welding quality could be im proved . is great temperature grads along the radius from the center(near 800 ℃) Key words:laser fully penetration w elding ;titanium alloy ;w eld to the edge(1 360 ℃), w hich is validated by microstructure in the w eld . The center of the joint is characterized by fine equiaxial grains and the edge is by lamellar structu re . Study on inverter arc welding power supply of ZVZCS three level con- Key words:TC4 titanium alloy ;inertia friction w elding ;tem pera- verter BAI Zhi-fan , BAI Jian-guo , ZHENG Qing-jie, KONG Xi- ture field ang-tian(Jilin University , Changchun 130025 , China ).p123 -125 Abstract: A novel zero-voltage and zero-current sw itching (ZVZCS)three-level converter , and the drive circuit of the transistor CO laser-weldability of galvanized steel sheets CUI Huai-yang1 ,2 , 2 w ere analyzed.The feasibility in application of w elding power supply CHEN Kai2 ,ZUO Tie-chuan2(1 .Department of Applied Physics, Beijin w as investigated .And the circuit w as simulated using softw are PSPIC E University of Aeronautics and Astronautics, Beijing 100083 ;2 .National 9 .2 .The results show that ZVZCS three level converter has not only Center of Laser Technology , Beijing University of Technology , Beijing the merit of convertional soft-sw itching pulse w idth modulation convert- 100022 , China).p115 -118 er , but also other merit .Therefore , it fits for occasion of active power Abstract:The CO laser butt w elding of galvanized steel sheets cu t 2 factor correction or high input voltage. by the CO laser was investigated for automotive manufactu ring applica- 2 Key words:zero-voltage and zero-current ;three-level converter ; tion .4 kW was used to w eld the galvanized steel sheets of differen t arc w elding power supply thickness, and the maximum speed reaches 0 .1 m/ s.The laser w elded seams w hose butt sides were cut by laser or mill was compared , and the hardness distribu tion was measu red.The width of the laser w elded seam Effect of elastoplastic deformation on stainless steel welding compo- w as in the range of 0 .5 ～ 1 .0 mm , and the maximum hardnes of the nents in low-temperature aging XU Yang , XIA Cheng-yu , TIAN w elded seam overpass the matrix hardness 1 ～ 1 .5 times.The laser Wei , ZHANG Bing-yi (Xi' an University of Technology , Xi' an w elding produced similar qualities for the steel sheets cut by laser or 710048 , China).p126 -128 mill. Abstract:The simulated test for corrosion leakage w hich often oc- Key words:tailored w elded blank ;laser w elding ;galvanized steel curs in the internal w all of single crystal g rowing furnace lid was carried sheet out.Specimens undergone plastic deformation w ere aged at different low-temperature.Then the specimens undergone elastic deformation Research on weld shaping for laser fully penetration welding titanium w ere conducted corrosion test .The results show that corrosion crack in- alloy (Ⅰ) YAO W ei1 , GONG S hui-li1 , CHEN Li2(1 .National crease w ith temperature increasing .Therefore , austenitic stainless steel, Key Laboratory For High Energy Density Beam Processing Technology , undergone large elastic and plastic deformation after rolling or pressing , Beijing Aeronautical Manufacturing Technology Reasearch Institute, is inadvisable to perform low-tem peratu re aging . Beijing 100024 , China ;2 .Huazhong University of Science and Technol- Key words:elastoplastic deformation ;stainless steel;w elding ogy , Wuhan 430074 , China).p119 -122 stress;low-temperature aging Abstract:According to the characteristics of weld shaping , the ef-