MAIN TOPICS，ABSTRACTS & KEY WORDS

Effectofshieldinggasoncharacteristicsofarcbehaviorandheatoutput

Chen Shujun, Yan Zhaoyang, Jiang Fan, Zhang Hongwei

(College of Mechanical Engineering and Applied Electronics Technology，Beijing University of Technology，Beijing 100124，China).p1-5

To improve the arc pressure and energy density of tungsten insert gas (TIG) welding, a welding method of helium arc was proposed, in which helium was used as the shielding gas. The arc morphology was recorded by using a high speed camera, the arc pressure and current density were measured and calculated at the same time, and compared with that of the conventional TIG arc. The experimental results show that, the cross section diameter of helium arc is significantly less than that of he conventional TIG arc at the same current, the maximum of arc pressure in helium arc is significantly larger than that of TIG arc, and the current density of helium arc is more concentrated than that of conventional TIG arc. The arc was used to ablate a fixed spot on work-piece to clearly show the arc energy transformation of the helium arc and conventional TIG arc. The sizes of the surface of the molten pool and grain of welded joint were analyzed to study the heat transfer. The results show that the width and depth of welded joint by helium arc are larger than those by the traditional TIG arc.

heliumarc,arcmorphology,arcpressure,currentdensity

Laser-MIGarchybridweldingofaluminumalloy

Cheng Yongming1,Liang Xiaomei2, Zou Jipeng2,Huang Ruisheng2, Chang Jingshu2

(1.CSR Qingdao Sifang Locomotive & Rolling Stock Co., Ltd., Qingdao 266111, Shandong, China; 2. Harbin Welding Institute Limited Company, China Academy of Machinery Science and Technology, Harbin 150028, China).p6-9

The effects of laser-short-circuiting MIG arc hybrid welding, laser-CMT arc hybrid welding, laser-pulsed MIG arc hybrid welding process on weld appearance, the metal transfer stability of welding process, weld microstructure and joint performance were investigated. The results shown that the weld appearances obtained by laser-short-circuiting MIG arc hybrid welding are poor and do not meet the requirements. The laser-CMT arc hybrid welding and laser-pulsed MIG arc hybrid welding methods are easy to obtain continuous and stable weld appearances. The microstructures and tensile properties of welded joints of the middle of the weld, the fusion zone and heat affected zone are the same basically, the tensile strength and the elongation are not less than 90% and 50% above of that of the base metal, respectively.

aluminumalloy,laser-CMT,laser-pulsedMIG,metaltransfer

InfluencesofoxideparticlesandNiobiumonmicrostructureandimpacttoughnessofweldmetalwithlargeheatinput

Li li1, Luo qiang2, Tian hao1, Wang honghong2, Wu kaiming2

(1. Research Institute of Nanjing Iron and Steel Co., Ltd., Nanjing 210035, China; 2. Hubei Collaborative Innovation Center for Advanced steels, Wuhan University of Science and Technology, Wuhan 430081, China).p10-13

The microstructure and mechanical properties of weld metal were influenced by base metal when the interaction crystallization and the composition dilution occur. The influences of oxide particles and Niobium on the microstructure of weld metal with high heat input welding and its impact toughness were studied. The results showed that the oxide particles can be transited to the weld metal and promote the formation of acicular ferrite in weld metal. Niobium elements can refine the grains of fusion line and decrease the width of columnar crystal in the weld zone. Compared with the parent metal without oxide particles and Niobium, the parent metal with oxide particles and Niobium can form the weld metal with higher toughness. Therefore, the influence of the base metal must be considered in selecting welding material.

highheatinputwelding,weldmetal,niobiummicro-alloyed,microstructure,impacttoughness

Numericalsimulationinplatebuttmultipassweldingof7B05Al-alloy

Zheng Hong1，Wang Wenyan2

(1. Harbin Welding Institute Limited Company, China Academy of Machinery Science and Technology, Harbin 150028, China; 2. Department of Mathematics, College of Science, Northeast Forestry University, Harbin 150040, China).p14-17

A round-robin research on multipass butt welding of 7B05 Al-alloy plate was carried out to provide a reliable numerical simulation method for the complex welded structure. Welding heat source model and softening model were founded. The 3D thermal and mechanical analyses were carried out to simulate welding process. The simulated results were compared with the measured results to validate the reliability of welding numerical simulation method. The results show that the predicted temperature field, residual stresses and welding distortion have a good agreement with the measured results, which indicates the accuracy of the numerical simulation method.

aluminiumalloy,numericalsimulation,softeningmodel,heatsourcemodel

EffectofagingtemperatureonreliabilityofsolderedjointwithSn-0.7Cu-xFefillermetal

Song Bingbing1, Yang Li2, Zhou Shiyuan1, Wang Guoqiang1, Shi Xiaolong1

(1. School of Mechanical Engineering, Soochow University, Suzhou 215000, Jiangsu, China; 2. School of Automotive Engineering, Changshu Institute of Technology, Changshu 215500, Jiangsu, China).p17-20

The effects of aging temperature on the tensile strength, fracture morphology and microstructures of soldered joints with Sn-0.7Cu and Sn-0.7Cu-0.05Fe filler metals were investigated. The results show that the morphology of Cu6Sn5compound in the solder is changed from needle-shape to rod-shape with the increase of aging temperature. The addition of Fe particles can decrease the coarsening degree of Cu6Sn5in the microstructure of joint with Sn-0.7Cu-xFe solder during the aging process. The tensile strength of soldered joint with Sn-0.7Cu-0.05Fe solder is higher than that with Sn-0.7Cu solder at the same aging temperature. The fracture of joints with Sn-0.7Cu and Sn-0.7Cu-0.05Fe solders are mainly composed of dimple and river cleavage pattern. The fracture mechanism of the joint is changed from plastic fracture to brittle fracture during the range of the aging temperature.

solderedjoint,agingtemperature,microstructure,tensilestrength

Researchstatusanddevelopmentofweldingformagnesium/titaniumdissimilaralloys

Zhang Zequn1, Zhang Kaiping1, Tan Caiwang1,2, Zhou Li1,2, Zhou Zhenzhen3

(1.Shandong Provincial Key Laboratory of Special Welding Technology，Harbin Institute of Technology at Weihai, Weihai 264209, Shandong, China; 2. State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001, China;3.Harbin Welding Institute Limited Company, China Academy of Machinery Science and Technology, Harbin 150028, China).p21-27

The research status of joining magnesium alloy to titanium alloy in recent years were summarized. Aiming at the quite different melting points between magnesium and titanium with immiscible and nonreactive characteristics, some special welding technologies complemented with alloying elements added to improve interfacial state is the key to obtain the reliable welding joint. The control of metallurgical reaction on interface is considered to be the core. The latest developments of Mg/Ti dissimilar joint were introduced such as laser welding and transient liquid phase welding. The research tendency was indicated as well.

Mg/Tidissimilaralloys,weldingmethods,alloyingelements,interfacialreaction

FatiguepropertyofTjointofcarbonsteelwithlargetiltanglelaserweldingwithfillerwirefromdoublesides

Guo Lijuan1, Wang Xijun1, He Jia1， Li Xiaoyu2, Sun Qian2

(1.CRRC TANGSHAN Co.,Ltd., Tangshan 063035, Hebei, China;2.Harbin Welding Institute Limited Company, China Academy of Machinery Science and Technology, Harbin 150028, China).p28-30

According to T Joint of weathering steel plate with 2.5 mm and 3 mm in thickness, large tilt angle laser welding with filler wire of ER50-G was used. The fatigue properties of welded joint, at the optimized welding parameters were tested, and then the macro and micro characteristics of the fractures were analyzed. The results show that the fatigue strength of the welded joint is 222.5 MPa, the specimens fracture in the weld toe, where there is the higher stress concentration and which is the main reason of fracture. There is a typical fatigue characteristics in the initiation zone and propagation zone of the crack, the size of the propagation zone increases with fatigue cycles, and the micro characteristics of the final fracture zone are dimples. The results will support the application of the laser welding with the wire on the body structure of high speed train.

laserweldingwithfillerwire,Tjoint,largetiltangle,fatigue

Studyoncrackformationmechanismofremeltedplasmasprayedcoating

Liu Ming, Tian Yao, Dong Tianshun, Li Guolu

(School of Materials Science and Engineering，Hebei University of Technology，Tianjin 300130，China).p31-33,38

Ni based coating was prepared on 45# steel substrate by plasma spraying. After the remelting treatment of coating by TIG welding, the microstructure of the remelted coating was observed by scanning electron microscope (SEM), and the EDS spectrum of the crack was analyzed. The results show that the remelting current has an obvious influence on the crack tendency of the remelted layer. At the current of 50 A, the remelting layer is well formed and there is no crack. However, the current increases to 60 A and 90 A, the crack becomes more and more serious. In addition, the EDS spectrum shows that there are many B and Si elements in the crack. On this basis, the causes of cracks were analyzed and the solutions were proposed.

thermalspraying,coating,remelting,crack

Designofservopressurecontrolsystemforprecisionspotwelding

Huang Shaozhi1, Zhu Zhenbo1, Cao Biao1, Yang Kai2

(1. School of Mechanical & Automotive Engineering, South China University of Technology, Guangzhou 510640, China; 2. Guangzhou Jingyuan Electrical Equipment Co., Ltd., Guangzhou 510735, China).p34-38

A servo pressure control system for precision spot welding was designed to solve the high mechanical impact, high pressure fluctuation, non-control of pressure and electrode position during spot welding process with pneumatic welding gun. The system adopted the compression mode of servo pressure and spring follow-up, and used high-precision pressure sensor to check the electrode pressure. Based on the DSP controller, the precise control of welding pressure and electrode displacement was realized. With the method of staged control, the system realized the electrode rapidly pressing down and contacting with the workpiece in a soft way, and it was also beneficial to optimize welding pressure speed, which has wider process adaptability. The experimental results show that the system has high pressure speed, smooth transition of pressure curve, and obvious influence of welding starting pressure on welding quality.

precisespotwelding,servopressure,pressurecontrol,displacementcontrol

Qualitycontrolandblowholepreventioninweldingofsmalldiametertitaniumalloys(TA2)tube

Sun Liqun1, Wang Xungang1, Jiang Haihong2

(1.Shandong Shengyue Petrochemical Engineering Construction Co., Ltd., Zibo 255400, Shandong, China; 2. Institute of Advanced Welding Technology, Shandong University, Jinan 250061, China).p39-41

Titanium and its alloys have the characteristics of low density, high strength, good corrosion resistance, and widely applied in aviation, aerospace, chemical machinery industries and other industries. In the construction of the titanium alloys tube, if the tube diameter is small(φ20～100 mm), the difficulty of welding construction will increase. In order to improve the welding quality of small diameter titanium alloys tube and prevent the blowhole from welding, the preparation of welding environment, material and preventive measures during welding were introduced, and the methods of welding quality inspection were also expounded.

titaniumalloystube,welding,qualitycontrol

Effectofoverlapgaponmicrostructureandmechanicalpropertiesoflaserweldedjointofgalvanizedsteelplate

Liu Qingyong,Menggenbagen,Du Yanbing

(Tangshan Iron & Steel Group Technology Center, Tangshan 063016, Hebei, China).p42-46

High strength galvanized steel plates (HC450/780DPD+Z) are commonly used in automobile industry, the research about laser overlap welding is carried out by using fiber laser, the influence of overlap gap on the microstructure and mechanical properties of laser welded joint was analyzed, and then microstructure and microhardness of welded joint were obaserved and tested at a constant overlap gap. The results show that the shape of seam melting changes obviously with the increase of overlap gap, the shape changes gradually from “waist” to “barrel” type, and the phenomenon of tensile-shear stress increases first and then decreases.

dual-phasesteel,laseroverlapwelding,overlapgap,tensile-shear

Applicationofφ1.6mmweldingwiretorobotweldingofhydraulicsupport

Lan Zhiyu, Zhao Xu, Meng Hechao

(Zhengzhou Coal Mining Machinery Group Co., Ltd., Zhengzhou 450016，China).p47-50

The welding wire ofφ1.2 mm is usually used to welding hydraulic support structures. However, the low efficiency is hardly to meet the robot welding. The weld appearance, mechanical properties and welding efficiency of the robot welding with the welding wire ofφ1.6 mm were studied at the different welding parameter. The experimental results show that the welding seams have good appearance, less spatter, and the high mechanical properties at the welding current of 380-460 A. In addition, the weld seams by the current in 420-440 A have the best mechanical properties, and the welding efficiency is 48% higher than that with the welding wire ofφ1.2 mm at the welding current of 440 A.

weldingwire,mechanicalproperties,weldingefficiency

Effectsoflaplengthonelectricalandmechanicalpropertiesofresistancebrazedjointforgeneratorstator

Zhou Disheng, Che Sanhong, Wang Jie, Li Jinze

(Jiangsu CRCC Electric Co., Ltd., Yancheng 224100, Jiangsu, China).p51-54

The welding process of the end to end joint is very important in the production of large-scale directly-driven permanent-magnet wind generator stator. Its lap length is one of the most important resistance brazing parameters and directly affect the electrical and mechanical properties of the joint. Simulation samples with Different lap length of 10 mm, 15 mm, 20 mm and 25 mm were made. By testing the electrical and mechanical properties, the effects of lap length of resistance brazed joint were analyzed. The rationality of the existing lap length of 20 mm was evaluated. For the joint with 20 mm length lap, the conductivity is a little better than that of base metal, the temperature rise performance is better than that of the base metal and meets the tensile requirements, and the macro metallographic testing was qualified.

large-scaledirectly-drivenpermanent-magnetwindgenerator,endtoendjointwelding,resistancebrazing,laplength

MicrostructureandpropertiesofTIGweldingonTNW700titaniumalloysheets

Wang Chang1，Zhang Tao2,3,4，F(xiàn)u Mingjie2,3,4，Cai Hengxin1

(1. Shenyang AircraftIndustry Group Co., Ltd.，Shenyang 110034，China; 2. Beijing Aeronautical Manufacturing Technology Research Institute, Beijing 100024, China; 3. Aeronautical Key Laboratory for Plastic Forming Technologies，Beijing 100024, China; 4. Beijing Key Laboratory of Digital Plasticity Forming Technology and Equipment，Beijing 100024, China).p54-57

0.8 mm thick TNW700 titanium Alloy sheets were welded by the TIG welding. Microstructure, mechanical properties and hardness distribution were studied. The results show that the TIG welded joint of TNW700 sheets possesses excellent performance. The weld zone is mainly composed of acicular martensiteα′phases, HAZ is mainly composed ofαphases andβphases in small quantities and the microstructure in HAZ is asymmetrical. The strength of the welded joint is higher than that of the parent metal by about 15%, the elongation is about 54% of that of the parent metal. There was the highest microhardness in HAZ, and the microhardness of weld zone is higher than that of base material. There was obvious hardening tendency in HAZ.

TNW700,TIGwelding,microstructure,mechanicalproperties,hardnessdistribution

MicrostructureandmechanicalpropertiesofbuttjointsofthickQ345Bsteelplate

Zhang Jiwei1, Li Hongjia2, Feng Zhongzhi1, Fang Hongyuan2

(1. The 63926 Troop of Chinese People’s Liberation Army, China; 2. State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001, China).p58-61

In order to evaluate the mechanical properties of welded joint of thick Q345B steel plate, 67 mm thick plates was welded using MAG welding and submerged arc welding process, respectively, and the microstructure and mechanical properties of the welded joints were tested including tensile, bending, room temperature impact and low temperature impact test. The results show that the welded joint obtained in the welding process has good appearance and the defects are few, and the microstructure of SAW weld is coarse columnar grains of the first eutectoid ferrite and acicular ferrite. MAG weld is composed of first eutectoid ferrite and acicular pearlite, and microstructure of SAW weld interlayer is more uniform, consisting the lamellar pearlite and ferrite. The average yield strength and tensile strength of the welded joint are 349 MPa and 440 MPa, respectively, the average elongation is 29.3%. The bending specimens at different positions are not cracked at the bending angle of 90°. In addition to the samples containing pores, the impact absorption energy at room temperature is higher than 100 J, and it is higher than 65 J at low temperature. In general, the joints have good mechanical properties and meet the technical requirements.

Q345Bsteel,multi-layermulti-passwelding,microstructureanalysis,mechanicalproperties

Antigrindingtechnologyofnon-magneticdrillingtools

Xu Jianfei，Zhang Xiaoguang

(Yellow River Drilling Corporation Tubulars & Tools Company, Sinopec Shengli Petroleum Engineering Limited, Dongying 25700, Shandong, China).p61-64

Based on analyzing the characteristics, wearing mechanism, welding material of the non-magnetic drill, the plasma arc surfacing technique was used to anti grinding treatment on non-magnetic drill surface, and non-magnetic plasma surfacing technique, drilling technique and anti abrasion layer technique were introduced. By the inspection, the relative permeability of hardfacing layer is 1.008 2, and its hardness is from HRC50 to HRC55. And the surfacing layer has no intergranular corrosion. A non-magnetic drill collar withφ178 mm and a non-magnetic pressure drilling pipe withφ127 mm were treated by plasma surfacing, and used in three wells in Sulige oilfield drilling, completion of vertical section, oblique section and horizontal section construction, the total working time is 568 hours.

non-magneticdrilling,plasmaarcoverlaying,antiabrasion,drilling,oil

Designofautomaticfeedingframeworkforweldingofbatteryplate

Liu Junhua

(Changzhou College of Information Technology, Changzhou 213164, Jiangsu, China).p65-68

For the welding of battery plate and nickel strip, resistance welding was used to prefix the parts, and then ultrasonic welding was used to weld battery plate. In traditional production, the parts were fed manually, which hindered the increase of production efficiency. The automatic feeding framework was designed, which consisted of vibratory feeder mechanism, stop institutions, grab institutions, push institutions, turnover mechanism. After real production test, automatic feeding framework can run stable and continuously for 24 hour made, and save two labor cost.

batteryplate,welding,automaticfeedingframework