MAIN TOPICS，ABSTRACTS & KEY WORDS

Microstructureandmechanicalpropertiesoftitanium/steelcompositeplatefrictionstirweldedjoint

Cao Zhiming, Wu Xiaoyan, Jiang Haitao, Zhong Binbin

(University of Science and Technology Beijing, Beijing 100083, China).p1-8

AbstractThe TA2-Q235B titanium/steel composite plate with 2 mm thickness was welded by friction stir welding in butt joint. Optical microscope and scanning electron microscope were used to observe microstructure and fracture morphology of welded joints. Tensile testing machine and microhardness tester were adopted to test mechanical properties of welded joints and microhardness in different areas. The results showed that the welded joint of the titanium/steel composite plate was divided into three areas from top to bottom, namely the upper steel welding zone, the middle titanium/steel mixed zone and the lower titanium welded zone. The titanium/steel mixed zone had an alternately stacked microstructure. When the shaft shoulder rotation speed was 300 r/min and the welding speed was 40 mm/min, the tensile strength of the welded joint was 386 MPa, which was 80% of that of the base metal. The average hardness of the welded area was 243.5 HV. The fracture originated from the heat engine affected area on the forward side where the bond was weak.

Keywords:titanium/steelcompositeplate,frictionstirwelding,microstructure,mechanicalproperties

PredictionofcrosssectionmorphologyofNibasedcladdinglayerbylasercladding

Chen Shuxiang1, Li Hongyu2, Chen Hui2

(1.CRRC Qingdao Sifang Co., Ltd., Qingdao 266111, Shandong, China; 2. Southwest Jiaotong University, Chengdu 610031, China).p9-13

AbstractBP neural network was used to prediction model of key parameters(laser power, scanning speed, powder feeding voltage, powder carrier gas flow rate) of laser cladding and cross section morphology (melting width and reinforcement height) of cladding layer. Taking the laser cladding parameters as the input and the cross-section morphology of the cladding layer as the output, the network was trained by the process test data to realize the high mapping between input and output. The results showed that BP neural network could better predict morphology of cladding layer and the prediction error of double hidden layer BP neural network model fluctuates was less, which showed excellent stability. Compared with single hidden layer neural network, the maximum prediction error of BP neural network was greatly reduced.

Keywords:lasercladding,predictionofmorphology,neuralnetwork,doublehiddenlayer

Designoffiveaxisgroovecuttingrobot’scontrolsystembasedonmachinevision

Zhang Xuejian1,2, Mao Yebing1,2, Yang Fang3, Hu Xiaobing1,2

(1. Sichuan University, Chengdu 610065, China; 2. Industrial Technology Research Institute of Yibin Sichuan University, Yibin 644600, Sichuan, China; 3. Sinohydro Jiajiang Hydraulic Machinery Company Limited, Leshan 614100, Sichuan, China).p14-19,37

AbstractThe design of control system of the five axis groove cutting robot based on machine vision was mainly for the design of control scheme of the machine body of the five axis groove cutting robot. It was guaranteed that the robot could complete the whole process from the image acquisition of processing parts to the generation of machining path and to the completion of groove cutting in the working space. The upper computer of the whole control system was based on MFC module and OpenCV visual library, and the lower computer took PLC control unit as the core. The specific solutions were proposed from the aspects of image acquisition and processing, communication, trajectory calculation and motion control, design of PLC control unit and selection of circuit driving components. The feasibility of the experimental design was verified by building an experimental platform. The control system was strictly designed, which could realize the required five axis groove cutting operation

Keywords:controlsystem,uppercomputerdesign,lowercomputerdesign,imageprocessingmodule

Analysisofarctransitionofwave-shieldedplateweldedstructurebasedonnumericalsimulation

Fu Lei1, Lu Changyu1, Fang Hongyuan2

(1. Xuzhou XCMG Xuzhou Environmental Technology Co., Ltd., Xuzhou 221001, Jiangsu, China; 2. Harbin Institute of Technology, State Key Laboratory of Advanced Welding and Joining, Harbin 150001, China).p20-28

AbstractIn order to improve the reliability of the pavement cleaning machine’s water tank and reduce the fatigue crack failure of the welded structure of the wave plate in the water tank under the impact of water flow, a structural optimization program of circular arc transition was used to reduce the degree of stress concentration, thereby increasing the service life of the wave shield. The influence of the transition arc position and radius on stress distribution was analyzed by finite element simulation. The simulation results showed that the stress concentration of the welded structure weakened the fatigue life of the wave shield, while the arc transition structure had a significant mitigation effect on the stress concentration, and its degree of relief was significantly related to the arc position and radius. As the distance between the arc and the weld bead decreased, or the radius of the arc increased, the stress concentration of the wave shield decreased, and the transition was more obvious from low-cycle fatigue to high-cycle fatigue.

Keywords:waveshield,finiteelementsimulation,weldedstructure,stressconcentration

Numericalsimulationofdroplettransitioninultrasonic-MIGwelding

Huang Zepai, Li Huijun, Wang Ruichao, Wang Hao

(Wuyi University, Jiangmen 529020, Guangdong, China).p29-33

AbstractBased on theories of fluid mechanics and electromagnetics, the mathematical model of the transition behavior in ultrasonic assisted metal inert gas welding (ultrasonic-MIG) was established by adding ultrasonic vibration and radiation force conditions.FLUNET software was used to simulate the droplet growth, deformation and shedding under different welding currents and ultrasonic amplitudes. The simulation results showed that the droplet profile change and shedding time were in good agreement with the related test results. Compared with conventional MIG, the drop size of ultrasonic-MIG droplet was smaller and the transition frequency was faster under the condition of low current,while the drop time and size of ultrasonic-MIG droplet changed less obviously under the condition of high current.The dropping time of ultrasonic-MIG droplet was affected by ultrasonic amplitude, and the increase of ultrasonic amplitude could shorten the droplet transition period to some extent.

Keywords:ultrasonic-MIG,droplettransition,numericalsimulation,ultrasonicradiationforce

Analysisofon-orbitweldingoperationconditionandinterfacetechnologyforspacestation

Wang Min1,2

(1. Shenyang Institute of Automation, Chinese Academy of Sciences, State Key Laboratory of Robotics, Shenyang 110016, China; 2 Institutes for Robotics and Intelligent Manufacturing, Chinese Academy of Sciences, Shenyang 110016, China).p34-37

AbstractIn order to implement on-orbit welding technology in space station, the working conditions of on-orbit welding were analyzed from aspects of man, machine, material, method, ring and measurement. Furthermore, the interface and technical requirements for different on-orbit welding technologies were analyzed to ensure that on-orbit welding could match with the station's energy, load and extreme environment. This paper provides a reference for further research on on-orbit welding technology and equipment.

Keywords:on-orbitwelding,on-orbitmanufacturing,spacestation

Testingmethodsofferritecontentanditsuniversality

Liu Xiao1, Zhang Wei2, Wang Li1, Dang Ying1, Wei Guangqiang1, Wu Fangyun2

(1. Nuclear Power Institute of China, Science and Technology on Reactor Fuel and Materials Laboratory, Chengdu 610213, China; 2. CNNC Nuclear Power Operations Management Co., Ltd., Haiyan 314300, Zhejiang, China).p38-41

AbstractThe magnetic testing is the most effective and accurate method. However, due to the different manufacturing process and calibration principle, the magnetic testing instrument is not universal. In order to effectively evaluate the weld quality, the secondary standard samples were manufactured by multi-layer surfacing in this study. And the ferrite content of secondary standard samples were tested and analyzed by magnetic, diagram and metallographic testing methods respectively. The calibration curves of the secondary standard samples tested by domestic and imported magnetic testing instruments were obtained. The research result showed that results of magnetic method and the metallographic method were close, whereas the deviation of the diagram method was relatively large. In addition, the calibration curves of different instruments by using the secondary standard samples could achieve a unified evaluation of the testing results.

Keywords:ferritecontent,magnetictestingmethod,multi-layersurfacing,secondarystandardsamples

TIGweldingprocessof316Lstainlesssteelvalvecoreinsmallspace

Ma Jun1, Wang Xuepeng1, Qi Yanze2, Li Husheng1, Tang Hongfei2

(1. Wuzhong Instrument Co., Ltd., Wuzhong 751100, Ningxia Hui Autonomous Region, China; 2. Harbin Institute of Technology, State Key Laboratory of Advanced Welding and Joining, Harbin 150001, China).p42-45,51

AbstractTIG welding with filler wire was used in all position automatic welding of channel of stainless steel valve ball core in small space. An automatic welding platform was built by designing a TIG welding gun for small space operation and installing with wire feeder air protection cover red copper heat cooler and trolley walking device. Under the protection of multiple argon in small space of valve ball core, the weld of stainless steel valve ball core in V-shaped welding position was carried out. Cleaning up impurities and oil stains of the weld and its surrounding area before welding, using high purity argon for strict inert atmosphere protection during welding, it was to obtain weld with all performances that met technical requirements. After welding, microstructure and mechanical properties of the weld were tested and evaluated, the generation and cause of defects was analyzed, the process parameters were improved. Hardness of the weld, HAZ and the parent metal was tested and the corresponding process curve was drew to obtain the best combination of process parameters.

Keywords:TIGwelding,valveballcore, 316Lstainlesssteel,microstructure

Welddefectdetectionofaluminumalloybasedondigitalradiography

Hu Wengang, Lu Yunpeng, Guo Shixiong, Zeng Lixin, Bai Bing

(Capital Aerospace Machinery Corporation Limited, Beijing 100076, China).p46-51

AbstractDigital radiography method was used to detect welded joints of aluminum alloy with different thickness. The process parameters such as voltage, current, exposure time and magnification were optimized to make the detection sensitivity meet the standard requirements. On this basis, digital radiography and film radiography were respectively carried out on fusion weld and friction stir welded joint of aluminum alloy to obtain the typical defect images. The morphology distribution, size and properties of the defects were compared and analyzed. The defect detection ability of digital radiography was analyzed and the reliability of digital radiography detection results was verified. The result showed that the detection sensitivity of digital radiography was superior to the standard requirements. Meanwhile, the defect detection capability of digital radiography was basically the same as that of film radiography, and the dimension error was less than 5%.

Keywords:digitalradiography,filmradiography,testingsensitivity,defect,contrasttest

Effectofultrasonicimpactmethodonperformanceofmicro-arcsparkdepositedcoating

Gao Jiwen, Li Yongbin, Huang Xiaowang

(State-Owned Wuhu Machinery Factory, Wuhu 241007, Anhui, China).p52-56

AbstractMicro-arc spark deposited samples were prepared under the same conditions and mechanism. Before and after ultrasonic impact treatment, experimental methods such as tensile test, microhardness test, residual stress test, X-ray test, corrosion resistance test and microstructure observation test, were carried out on these samples to study the effect of ultrasonic impact treatment on the performance of micro-arc spark deposited coatings by comparative analysis. The result showed that by ultrasonic impacting on the micro-arc spark deposited coating, defects such as porosity, loose, and incomplete fusion could be reduced so as to densify the deposited coating and improve its tensile strength, which could effectively improve the stress distribution of the surface strengthened layer and make the surface appear in a state of compressive stress. Choosing deposition materials with stronger corrosion resistance to repair local damage and corrosion defects on the surface of aircraft parts and performing ultrasonic impact treatment would greatly improve corrosion resistance of aircraft parts.

Keywords:micro-arcsparkdeposition,ultrasonicimpacttreatment,performanceofcoating

Effectofplatethicknessonshearstrengthandfatiguestrengthoflaserlapweldedjointsforstainlesssteelcarbody

Luo Chao, Zhang Jinhua, Wang Yan, Liu Hailing, Li Xiyong

(CRRC Tangshan Co., Ltd., Tangshan 063035, Hebei, China).p57-61

AbstractIn order to investigate on effect of plate thickness on shear strength and fatigue strength of stainless steel laser lap welded joints, tensile tests and fatigue tests on stainless steel laser lap welded joints with two different plate thicknesses of 0.8 mm +2 mm and 2 mm +2 mm were conducted. The results showed that shear strength and fatigue strength of the 2 mm +2 mm joint were higher than those of 0.8 mm +2 mm. It was found by failure analysis that tensile fracture of the two joints was caused by shear fracture of weld, and fatigue cracks originated in heat-affected zone near the weld nugget on the inner surface of the incompletely welded plate. The crack propagated along the edge of the weld nugget to the outer surface of the incompletely welded plate until it penetrated the incompletely welded plate. It could be seen from the finite element force analysis of welded joints that the difference in the degree of stress concentration between the two joints was the main reason for the difference in their shear strength and fatigue strength.

Keywords:stainlesssteel,laserlapwelding,platethickness,shearstrength,fatiguestrength