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Controlling of weld hot cracks of aluminum alloy sheets by transverse pre-stressing

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Rare Metals 2007年第S1期26卷 157-161页

作者： liu xuesong,zhou guangtao,wang ping,and fang hongyuan state key laboratory of advanced welding technology production,harbin institute of technology,harbin 150001,china harbin Inst Technol State Key Lab Adv Welding Technol Prod Harbin 150001 Peoples R China

A new ideological and theoretical model—a technology to control weld hot cracks by transverse compressive pre-stress in the welding of aluminum alloy was put forward,which was further proved by the subsequent self-designed test *** are conducted on the fishbone shaped specimen under conventional welding and welding with various pre-stress *** experimental results turn out that,the initiation rate of the weld hot cracks decreases with increasing values of the compressive *** the pre-stress reaches 0.3-0.4 of the yield stress,the cracks even *** mechanical viewpoint,the researches here develop a new way to control weld cracks.

关键词： welding with transverse pre-stress weld hot cracks crack initiation rate

Al2_3/Al2O3 Joint Brazed with Al2O3-particulate-contained Composite Ag-Cu-Ti Filler Material

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Journal of Materials Science & technology 2005年第5期21卷 782-784页

作者： Jianguo YANG hongyuan fang and Xin WANstate key laboratory of advanced welding production technology, harbin institute of technology, harbin 150001, china state key laboratory of advanced welding production technology Harbin Institute of Technology Harbin 150001 China

Microstructure and interracial reactions of Al2O3 joints brazed with Al2O3-particulate-contained composite Ag-Cu-Ti filler material were researched by scanning electron microscopy （SEM）, electron probe microscopy analysis （EPMA）, energy dispersive spectroscopy （EDS） and X-ray diffraction （XRD）. The interracial reaction layer thickness of joints brazed with conventional active filler metal and active composite filler materials with different volume fraction of Al2O3 particulate was also studied. The experimental results indicated although there were Al2O3 particulates added into active filler metals, the time dependence of interracial layer growth of joints brazed with active composite filler material is t^1/2 as described by Fickian law as the joints brazed with conventional active filler metal.

关键词： Composite filler materials Braze Interface Al2O3

Molecular Simulations in Tin Droplet Spreading on Different Surface of Copper Plate

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Journal of Wuhan University of technology(Materials Science) 2009年第S1期24卷 87-89页

作者：程宏涛杨建国 state key laboratory of advanced welding production technology Harbin Institute of Technology

Molecular simulations using MEAM(Modified Embedded Atom Method) potentials have been applied to research the interfacial properties of the different(hkl) Cu substrate in the *** the simulation,the surface energies and the process of Sn spreading on the different(hkl) copper plate surface were simulated,and the results show that the different(hkl) plane substrates have few effects to the soldering spreading process,the solid-liquid interfacial energy is still the dominant ingredient practically in the wetting process.

关键词： wetting surface energy molecular simulations miller surface

Control of Titanium Alloy Thin Plate’s welding Distortion by Trailing Peening

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Control of Titanium Alloy Thin Plate’s Welding Distortion b...

Fatigue crack initiation for Al-Zn-Mg alloy welded joint

The Fourth International Conference on Physical and Numerical Simulation of Materials (ICPNS’2004)

作者： xuesong liu hongyuan fang Shude JI and Zhibo DONGstate key laboratory of advanced welding production technology harbin institute oftechnology

＜正＞The technology of trailing peening is a kind of promisingly bran-new technology which can be used to control welding stress and distortion of Titanium alloy thin plate. Control of TC4 Titanium alloy thin plate’s welding stress and distortion under the condition of conventional welding and trailing peening is performed respectively. The results show that the technology of trailing peening effectively reduces deflection and transverse shrinkage of thin plate weldment. The maximum deflection is decreased from 15mm under the condition of conventional welding to 5mm, while the weld transverse shrinkage is decreased from 0.5mm to about 0.1mm.

关键词： Control of residual stress and distortion Trailing peening TC4 Titanium alloy

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Acta Metallurgica Sinica(English Letters) 2012年第3期25卷 235-240页

作者： Liang ZHANG xuesong liu Linsen wang ping wang hongyuan fang state key laboratory of advanced welding and Joining Harbin Institute of Technology Harbin 150001China welding Process Section Dongfang Boiler Group Co. Ltd. Zigong 643001 China

To investigate fatigue crack initiation characteristics of A1-Zn-Mg alloy welded joint, notched specimens were used in fatigue test for the base metal, welding bead and heat affected zone （HAZ）. The fatigue fracture surface near the fatigue crack initiation site was observed by scanning electron microscope （SEM）. The results show that the differences of fatigue crack initiation life among base metal, welding bead and HAZ are not obvious. Inhomogeneity in microstructure and mechanical performance of HAZ influences the fatigue crack initiation life. The ratio of fatigue crack initiation life （Ni） to fatigue failure life （Nf） for the base metal, welding bead and HAZ of A7N01 aluminium alloy welded joint are 26.32%, 40.21% and 60.67%, respectively. Fatigue crack initiation life can be predicted using a uniform model. Observation of fatigue fracture surfaces shows that for the welding bead a fatigue crack initiates from the smooth surface due to the welding process, the blowhole in HAZ causes fatigue crack and the crushed second phase particles play an important role in fatigue crack initiation for the base metal.

关键词： A1-Zn-Mg alloy Welded joint Fatigue crack initiation Life pre- diction

Effect of Sheet Configuration on Microstructure and Mechanical Behaviors of Dissimilar Al–Mg–Si/Al–Zn–Mg Aluminum Alloys Friction Stir welding Joints

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Journal of Materials Science & technology 2016年第12期32卷 1378-1385页

作者： Zhongjie Yan xuesong liu hongyuan fang state key laboratory of advanced welding and Joining Harbin Institute of Technology

Friction stir welding（FSW） was used to weld dissimilar Al-Mg-Si/Al-Zn-Mg aluminum alloys in this *** of sheet configuration on microstructure and mechanical properties of the joints were mainly *** showed that rather different joint cross sections were obtained when using different sheet *** β＇ phases can be observed at the heat affected zone（HAZ） of the Al-Mg-Si alloy side,which was the main factor affecting the tensile properties and the fatigue *** strengths of the dissimilar Al-Mg-Si/Al-Zn-Mg joints using both configurations were higher than that of the Al-Mg-Si FSW *** the Al-Zn-Mg alloy was located at the advancing side（AS）,the joints owned better fatigue properties due to the bridging effect of the big secondary phase particles.

关键词： Friction stir welding Dissimilar aluminum alloys Microstructure Tensile properties Fatigue life

Control of Titanium Alloy Thin Plate welding Distortion by Trailing Peening

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Journal of Materials Science & technology 2003年第z1期19卷 184-186页

作者： xuesong liu hongyuan fang Shude JI Zhibo DONG state key laboratory of advanced welding production technology Harbin Institute of TechnologyHarbin 150001 China State Key Laboratory of Advanced Welding Production Technology Harbin Institute of TechnologyHarbin 150001 China State Key Laboratory of Advanced Welding Production Technology Harbin Institute of TechnologyHarbin 150001 China State Key Laboratory of Advanced Welding Production Technology Harbin Institute of TechnologyHarbin 150001 China

The technology of trailing peening is a kind of promisingly bran-new technology which can be used to control weldingstress and distortion of Ti alloy thin plate. Control of TC4 Ti alloy thn plate welding stress and distortion underthe condition of conventional welding and trailing peening is performed, respectively. The results show that thetechnology of trailing peening effectively reduces deflection and transverse shrinkage of thin plate weldment. Themaximum deflection is decreased from 15 mm under the conditior of conventional welding to 5 mm, while the weldtransverse shrinkage is decreased from 0.5 mm to about 0.1 mm.

关键词： Control of residual stress and distortion, Trailing peening, TC4 Ti alloy

RAPID AND NONDESTRUCTIVE MEASUREMENT SYSTEM FOR welding RESDlUAL STRESS BY ULTRASONIC METHOD

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Chinese Journal of Mechanical Engineering 2008年第6期21卷 91-93页

作者： LU Hao liu xuesong ZHU Zheng ZHANG Shiping fang hongyuan state key laboratory of advanced welding production technology Harbin Institute of Technology Harbin 150001 China School of Electrical Engineering and Automation Harbin Institute of Technology Harbin 150001 China

Traditional methods of residual stress measurement are generally destructive or semi-destructive, as well as expensive, time-consuming and complex to implement. With the new development of welded structure, traditional methods can not satisfy the need of full life task management. So the acoustical theory is introduced, since the ultrasonic technique provides a useful nondestructive tool in the evaluation of stresses. In this study an ultrasonic stress measurement experimental installation is established, which consists of a special transducer, a signal emission unit and a signal recipient processing unit. Longitudinal critically refracted wave is selected as the measurement wave mode. The supporting software is programmed by Labview software. The longitudinal residual stress and transverse residual stress of twin wire welded plate are measured by this installment, in which the measuring process is real-time, quick and nondestructive. The experiment results indicate that the system can satisfy the need of life evaluation for welded structure. The system is light and portable.

关键词： Ultrasonic Longitudinal critically refracted wave Residual stress

INFLUENCE OF BLADES' STRESS state ON FRANCIS TURBINE RUNNER'S INVALIDATION

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Chinese Journal of Mechanical Engineering 2006年第1期19卷 113-115页

作者： JI Shude fang hongyuan YANG Jianguo Astronautical Science and technology Academy Shenyang Institute ofAeronautical EngineeringShenyang 110034 China state key laboratory of advanced welding production technology Harbin Institute of Technology Harbin 150001. China

Numerical simulation on Francis turbine runner＇s welding temperature field and welding stress field is carded out on the base of solving the problem of welding heat source＇s movement along any spatial routes and the problem of heat elimination between the complicated blade and air. The evolvement law of welding stress and the distribution of the stress field after welding are obtained. The results indicate that the peak value of the welding residual stress appears on the outlet edge of blade near the contact area between blade and band or blade and crown. Associated with the distribution of the runner＇s working stress, the invalidation reason of the Francis turbine runner is explained.

关键词： Runner Blade Stress field Invalidation