MAIN TOPICS，ABSTRACTS & KEY WORDS

Characteristicsandcausesofinertialfrictionweldingdefectsbetween2219aluminumalloyand1Cr18Ni9Tistainlesssteel

Liu Zhao1，3, Lan Ling2, Wang Ting3, Zhang Ke1, Jiang Siyuan3

(1.Shanghai Key Laboratory of Materials Laser Processing and Modification,Shanghai Jiao Tong University, Shanghai 200240, China; 2.Shanghai Shipbuilding Technology Research Institute, Shanghai 200032, China; 3.Shandong Provincial Key Laboratory of Special Welding Technology, Harbin Institute of Technology at Weihai, Weihai 264209, Shandong, China).p1-4

AbstractThe joint of 2219 aluminum alloy and 1Cr18Ni9Ti rotary body was connected by inertial friction welding technology.The microstructure and defects of the welded joint were analyzed by SEM and EDS.The results showed that the lamellar microstructure parallel to the weld interface formed on the side of the aluminum alloy, including equiaxed fine grain area formed by dynamic recrystallization and deformable grain area elongated along the direction of frictional shear.There were holes near the outer edge of the aluminum alloy side, Cu and O elements segregated around the holes.Brittle intermetallic compounds and oxides would cause stress concentration, hinder metal plastic flow and reduce joint performance.An intermetallic compound layer about 2 μm thick formed at the interface.

Keywords: 1Cr18Ni9Tistainlesssteel, 2219aluminumalloy,inertialfrictionwelding,holedefect,interfacialmicrostructure

Effectofassemblinggaponformationandmechanicalpropertiesofjointbybobbintoolfrictionstirwelding

Li Chong1, Li Shuohan1, Qi Zhenguo1, Meng Xiangchen2, Huang Yongxian2

(1.Hebei Jingche Rail Transit Vehicle Equipment Co., Ltd., Baoding 072150, Hebei, China; 2.State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001, China).p5-9,27

AbstractBobbin tool friction stir welding(BT-FSW)was successfully utilized in the welding of aluminum alloy with hollow or sealed structures, while formation and mechanical properties of the joint were decreased by the manufacturing accuracy or assembling gap of the work-pieces.Focusing on the problem, effect of the assembling gap(0～1.0 mm)on formation and mechanical properties of 4.0 mm thick AA6082-T6 BT-FSWed joint were investigated.The results indicated that with the increase of assembling gap, materials in the upper and bottom shoulders were not capable of filling the welds and voids defects were easy to occur in the bottom-shoulder affected zone under the effect of sucking-extruding, which decreased mechanical properties of joints.Formation and mechanical properties of the joint were superior under the assembling gap of 0～0.3 mm, tool rotational velocity of 700 r/min and welding speed of 300 mm/min.

Keywords:Tjoint,bobbintoolfrictionstirwelding,formationofjoint,mechanicalproperties,assemblinggap

NumericalsimulationandexperimentalverificationonformingmechanismofTi/Alexplosiveweldinginterface

Li Yan1,2, Li Yanbiao1, Liu Cuirong1, Ren Jinsuo2, Zhao Rui2

(1.Taiyuan University of Science and Technology, Taiyuan 030024, China; 2.Shanxi Yangmei Chemical Machinery(Group)Co., Ltd., Taiyuan 030032, China).p10-15

AbstractTaking Ti/Al composite plate prepared by explosive welding as an example, the transient forming process of explosive welding was reproduced by numerical simulation, and the interface characteristics of explosive welding were analyzed by experiments.The results showed that interface morphology of Ti/Al composite plate changed from flat bonding to wave bonding along the propagation direction of detonation wave due to the penetration of jet.The lower pressure at the initiation point led to the boundary effect of explosive welding.The high impact pressure in the impact zone of explosive welding was the cause of plastic deformation and grain refinement near the interface.The interface defects of explosive welding were increased by high velocity impact, which provided a channel for the diffusion of atoms and realized metallurgical bonding.The results of numerical simulation were consistent with the experimental results, which revealed the forming mechanism of Ti/Al explosive welding interface.

Keywords:Ti/Alcompositeplate,explosivewelding,interfaceformingmechanism,numericalsimulation

Laserultrasonicdetectionforsurfacedefectofstainlesssteeladditivemanufacturingparts

Fang Haiji1,2, Ye Guoliang2, Lü Bo1, Zhang Yanxi1, Gao Xiangdong1

(1.Guangdong Provincial Welding Engineering Technology Research Center, Guangdong University of Technology, Guangzhou 510006, China; 2.Dongguan University of Technology, Dongguan 523000, Guangdong, China).p16-21

AbstractLaser ultrasonic technology was used to detect surface defects of the additive manufactured parts, and the finite element method was used to simulate the propagation process of laser-excited ultrasonic waves under the thermoelastic mechanism.The surface wave reflection signals received from different detection positions were analyzed, and the influence of the depth and width of defects on the surface wave reflection signal was studied.Laser ultrasonic testing experiments on 316L stainless steel additive manufacturing parts verified the correctness of the model, and then the wavelet soft threshold denoising algorithm was used to process the collected laser ultrasound signal.The results showed that the numerical simulation was basically consistent with the experimental results.The arrival time difference of the RS wave and the RR wave generated by the surface wave and the defect could detect the depth of defects, and the width of defects had almost no effect on the detection result.

Keywords:laserultrasonicdetection,numericalsimulation,surfacedefects,additivemanufacturing

Interfacialmicrostructureandmechanicalpropertiesofcopper/stainlesssteelfabricatedbyexplosivewelding

Jiang Chao1, Long Weimin1,2, Feng Jian3, Zhang Lei1, Zhang Shuo2

(1.State Key Laboratory of Advanced Brazing Filler Metals and Technology, Zhengzhou Research Institute of Mechanical Engineering Co., Ltd., Zhengzhou 450001,Zhengjiang, China; 2.China Innovation Academy of Intelligent Equipment Co., Ltd., Ningbo 315700, Zhejiang,China; 3.Wugang Shenzhou Heavy Industry Clad Metal Materials Co., Ltd., Pingdingshan 462500, Henan, China).p22-27

AbstractT2 copper/06Cr19Ni10 stainless steel explosive welding clad plate was fabricated with welding parameters estimated by empirical formula.Interfacial microstructure and mechanical properties of copper/stainless steel clad plate were studied through optical microscope, scanning electron microscope, energy spectrum scanner, and mechanical test.It was founded that a regular wavy interface formed between copper and stainless steel after explosive welding.The interface was mainly solid-solid joining, and the discontinuous vortex-like cast microstructure was embedded in the wave peak and trough regions respectively.The microstructure was mainly composed of an ε-Cu matrix, γ-Fe precipitated phase, and stainless steel particles.Adiabatic shear band and austenite transformation were found in the microstructure of stainless steel after explosive welding.Annealing and recrystallization were observed in copper.Interfacial bonding strength was 280.3 MPa and microhardness of the microstructure near the interface was significantly improved.The maximum tensile strength of the clad plate was 561 MPa, mixed fracture characteristics were observed on the fracture of the bonding area, and the vortex microstructure defects had no obvious effect on the tensile fracture failure.

Keywords:explosivewelding,microstructure,mechanicalproperties,copper,stainlesssteel

EffectoflaserincidentangleonmicrostructureandmechanicalpropertiesofIr-RhalloyandNi-basedalloybylaserwelding

Yang Huimu1, Zhao Shifang2, Hu Guoyi1, Deng Jun1, Du Dekui1, Tao Wei1

(1.Weichai Torch Technology Co., Ltd., Zhuzhou 412001, Hunan, China; 2.Central South University, Changsha 410083, China).p28-33,38

AbstractEffect of laser incident angle on welding of Ir-Rh and Ni-based alloy was studied.Optical microscopy, scanning electron microscopy, and energy-dispersive spectroscopy were conducted to analyze microstructure, bonding mechanism of the weld as well as thermal fatigue.The weld mainly consisted of the Ir-Ni solid solution.Thermal fatigue experiment results indicated that the thermal fatigue resistance was affected by thermal stress and high-temperature oxidation.When the laser incidence angle was 10°, the break force of welded joint reached the maximum 163.3 N, and the best thermal fatigue resistance was obtained.However, the fracture position was less affected by the laser incident angle, and all fracture occurred on the interface between the Ir-Rh alloy and the weld, and the fracture form was mainly intergranular fracture.

Keywords:laserwelding,sparkplug,microstructureevolution,thermalfatigue,mechanicalproperties

MicrostructureandmechanicalpropertiesofGTAWjointof2205duplexstainlesssteelsmall-borethinwalltube

Shi Jinfeng, Lei Yucheng

(Jiangsu University, Zhenjiang 212013, Jiangsu, China).p34-38

Abstract2205 duplex stainless steel small-bore thin wall tube withφ18 mm×1.5 mm was welded by tungsten inert gas welding with ER2209 filler material and 98%Ar+2%N2shielding gas.Microstructure and mechanical properties of 2205 duplex stainless steel ultra-thin wall small diameter pipe welded joint were studied by means of nondestructive testing, mechanical properties test and metallographic observation.The results indicated that weld was well formed, and tensile strength of welded joint was 668 MPa, no less than that of the base metal.The fracture occurred in the heat-affected zone.The hardness of the base metal, heat affected zone and weld was 260～280 HV, which met ASTM A790 standard.The welded joint had good bending resistance.The phase boundary was smooth and there were no harmful intermetallic phases.According to ASTM E562 standard method, ferritic content in heat affected zone of welded joint was about 50%～70%, which was basically balanced with austenite.The pitting corrosion resistance of welded joint met the requirement of ASTM G48 standard, and the measured maximum corrosion rate was 5.1 mg/(dm·d).

Keywords: 2205duplexstainlesssteel,small-borethinwalltube,weldedjoint,mechanicalproperties,microstructure

Wearreliabilityofbrazeddiamondwheelbasedonstochasticprocess

Zheng Mingliang, Li Wenxia, Yang Deyun

(Taihu University of Wuxi, Wuxi 214064, Jiangsu, China).p39-43

AbstractIn order to achieve high efficiency grinding of high strength steel surface, the structure of a brazed diamond grinding disc was designed, and the wear reliability of abrasive tool under the interaction of friction and heat was predicted.Firstly, the material removal function model of brazed diamond grinding disc was established by grinding trajectory and contact zone characteristics.Then, white noise was introduced into the traditional wear analysis model to represent the dynamic and stochastic factors of grinding process.The wear dynamic reliability model of brazed diamond wheel was established by applying Wiener process theory and limit state equation.The estimation method of important statistical characteristic parameters in the model was given.Finally, the abrasive wear reliability and life characteristics of brazed diamond wheel grinding AH32 carbon rigid were calculated.The results showed that the average service life of the grinding disc under continuous grinding was more than 15 h, and the reliability curve first decreased slowly, then sharply, and then slowly with time.The process parameters such as rotational speed, feed speed, grinding depth and abrasive grain size had important effects on the life of abrasive tool.The reliability of brazed diamond grinding disc was directly proportional to the product of rotational speed, feed speed and grinding depth.This study could provide theoretical basis for quantitative life assessment and strength optimization design of advanced welding abrasive tools.

Keywords:brazeddiamondgrindingdisc,wienerprocess,parameterestimation,wearreliability

Ultrasonicphasedarraydetectionand3Dvisualizationofdeepdefectsinweldedstructuralpartsofbogies

Li Liangliang1, Zheng Shiwei1, Shan Qingqun1, Zuo Yuda2

(1.CRRC Qingdao Sifang Rolling Stock Co., Ltd., Qingdao 266111, Shandong, China; 2.Southwest Jiaotong University, Chengdu 614202, China).p44-50

AbstractIn view of the complex acoustic characteristics and defect display of deep defects in welded joints of key parts such as welded structural parts of rail train bogies, the phased array detection results of different shapes and sizes of defects were analyzed, and the influence of sound field mechanism of mild steel deep defects on phased array detection results were expounded in combination with sound field propagation simulation results.At the same time, the 3D visualization of different defects was realized based on OpenGL.The results showed that the strip defect had stronger reflection effect on the vertical direction of the phased array sound field, and the acoustic shadow area increased with the decrease of the defect width.Meanwhile, the phased array sound field with more concentrated reflection at the defect had higher detection sensitivity and resolution.The defect 3D display results based on 3D database could clearly and intuitively reflect the internal defects of components.This research had practical significance for ultrasonic phased array detection and three-dimensional visualization of defects in welded structural parts of high-speed train bogies.

Keywords:ultrasonicphasedarray,deepdefectsofweldedjoint,mildsteel,soundfieldsimulation, 3Dvisualization

Highreliabilityweldingtechnologyofcircumferentialweldsofmultilayerthin-wallbellows

Li Liang1, Wang Tao1, Yang Bingxu1, Wang Xu2

(1.Shenyang Aerosun-Futai Expansion Joint Co., Ltd., Shenyang 110141, China; 2.Liaoning Shihua University, Fushun 113001, Liaoning, China).p51-56

AbstractThe high reliability girth welding technology of 12 layers thin-wall bellows and nozzles applied in high flexible expansion joint under strong vibration, high temperature and high pressure was studied systematically.The influence of argon protection on the back, diameter of welding wire, position of reinforcing ring and clearance between bellows and nozzles on welding quality was mainly studied.The results showed that for argon arc welding process of bellows and nozzles, 1.6 mm wire diameter, 105 A welding current, strengthening thimble position and corrugated pipe straight segment end at the same height, 0.5 mm clearance between corrugated pipe and joint pipe were selected as the optimal welding parameters, the optimal welding quality was achieved with 3.1 mm maximum depth and best microstructure of fusion zone.

Keywords:bellows,multilayerthin-wall,circumferentialwelds,weldingtechnology,reliability

ApplicationofCPP900automaticweldingequipmentinweldingoflong-distancepipeline

Yuan Zehao, Li Guangchao, Xie Qingsheng

(Beijing Xingyou Engineering Project Management Co., Ltd., Beijing 100089, China).p57-60

AbstractCPP900-IW48 and CPP900-W2N automatic welding equipment developed by China Petroleum Pipeline Research Institute was briefly introduced.Welding parameters in a long-distance pipeline project were briefly described.According to the requirements of national standards and project design documents, the mechanical properties of circumferential welds welded by CPP900 automatic welding system were analyzed by using Charpy impact test, tensile test, bending test and drop weight tear test.The experimental results showed that the circumferential weld with good mechanical properties could be obtained by adopting reasonable welding process in CPP900 automatic welding system.Result of engineering practice showed that CPP900 automatic welding system had a good performance in the welding construction of large diameter, large thickness and high steel grade long distance pipeline in China.

Keywords:long-distancenaturalgaspipeline,weldingparameters,CPP900automaticweldingequipment,mechanicalproperties