C.S. Wu

C.S. Wu
Shandong University | SDU · School of Material Science and Engineering

PhD

About

429
Publications
76,913
Reads
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7,575
Citations
Introduction
C.S. Wu (ChuanSong Wu) currently works at the School of Material Science and Engineering, Shandong University. Prof. Wu does research in Materials Welding and Joining. He is the Fellow of American Welding Society, and Humboldtian Scholar in Germany. His research interests include the physics of welding, numerical simulation and experimental sensing & control of various welding processes. He is the member of Editorial Board of Science and Technology of Welding and Joining (Taylor & Francis), and the Vice Chair of the Editiorial Board of Chinese Journal of Mechanical Engineering (Springer).
Additional affiliations
April 1996 - present
Shandong University
Position
  • Professor (Full)
December 1991 - March 1996
Harbin Institute of Technology
Position
  • Professor (Full)
December 1989 - November 1991
Harbin Institute of Technology
Position
  • Professor (Associate)
Education
April 1985 - March 1988
Harbin Institute of Technology
Field of study
  • Welding Science and Engineering
February 1982 - November 1984
Harbin Institute of Technology
Field of study
  • Welding Science and Engineering
March 1978 - January 1982
Harbin Institute of Technology
Field of study
  • Welding Science and Engineering

Publications

Publications (429)
Article
K-PAW (Keyhole Plasma Arc Welding) has a wide range of applications in welding medium-thick metal workpieces. However, the welding processes are vulnerable due to the fragile force balance on the liquid metal around the keyhole, and burn-through or lack of fusion might be caused. In order to optimize the welding quality, considerable work has been...
Article
Friction stir welding (FSW) has been applied to many fields including aerospace manufacturing and the railway industry. However, the interfacial friction behavior remains unclear due to the lack of reliable thermo-mechanical-flow-coupled analysis. In this study, the frictional behaviors, including the interfacial temperature, friction-induced heat...
Article
TIG-MIG hybrid welding produces better weld formation than traditional MIG welding at higher welding speeds. The adaptive heat source and arc pressure models of inclined TIG-MIG arcs on curved surface were improved based on their distribution on flat surface. A 3D transient model of heat and mass transfer in a weld pool was established to analyze t...
Article
Full-text available
It is difficult to achieve Al/Cu dissimilar welds with good mechanical properties for medium-thick plates due to the inherent high heat generation rate at the shoulder-workpiece contact interface in conventional friction stir welding. Thus, double-side friction stir welding is innovatively applied to join 12-mm medium-thick 6061-T6 aluminum alloy a...
Article
The anisotropy of mechanical properties was introduced into the computational fluid dynamics (CFD) model of the AA6061 friction stir welding (FSW) process. According to the calculated results, the distribution of anisotropy and the distribution of the flow stress/yield strength drop degree due to the mechanical anisotropy are analyzed. Considering...
Article
Plasma arc welding (PAW) can produce deep-penetration weld when a keyhole mode appears with high welding currents. The process involves complex thermal-hydrodynamical effect and electromagnetic effect, which requires fundamental research in multi-disciplinary fields to give full understanding. Therefore, an easy-to-use model, which includes an arc...
Article
Full-text available
A model including the acoustic plasticity and ultrasonic induced friction reduction (UiFR) effect was developed and experimentally validated for ultrasonic vibration enhanced friction stir welding (UVeFSW) of dissimilar Al/Mg alloys. It was found that the ultrasonic sound pressure and energy are stronger at the aluminum alloy side, and the distribu...
Article
Full-text available
To get deep insight into the interaction mechanism of ultrasound with the plastically deformed metal in the ultrasonic-assisted friction stir welding (UaFSW) process, the ultrasonic effect on the heat generation and material flow is quantitatively analyzed. The Coulomb friction model is modified via considering both the vibration direction and inte...
Article
In this work, plates of dissimilar Al/Cu alloys were butt jointed by friction stir welding (FSW) with and without ultrasonic vibration. It was found that the assistance of ultrasonic vibration produced slight variations of both mechanical interlocking and material intermixing of dissimilar material, as well as fracture location during tensile tests...
Article
Comparative experiments of friction stir welding (FSW) of Al/Mg alloys were conducted with and without ultrasonic assistance. The copper powders were preset inside the workpieces as the marker material, and computer tomography technique was employed to obtain the three-dimensional information of material flow around the tool. The top view of copper...
Article
Full-text available
The controlled pulse welding current combined with ultrasonic vibration was used to increase the keyholing/penetrating capability of plasma arc, and a mathematical model was developed to elucidate the underlying mechanism of periodic interaction between the ultrasound field and the plasma arc. The exerted ultrasonic vibration on the tungsten electr...
Article
Friction stir welding (FSW) and ultrasonic vibration enhanced FSW (UVeFSW) of dissimilar Al/Mg alloys were conducted to elucidate the effect of ultrasonic vibration on the main process variables like material flow velocity, strain and strain rate. 1060 aluminum foils as the marker material were embedded respectively in the Mg on the advancing side...
Article
The periodic material flow behavior has been widely considered as one of the most crucial characteristics during friction stir welding (FSW) process, but its formation and evolution mechanisms are still not fully understood. Recently, increasing evidences indicate that the original cause of the periodic feature is supposed to be tool eccentricity,...
Article
An ultrasonic frequency pulse high-current (UFPHC) was utilized to improve the stability of underwater wet flux-cored arc welding on Q235 steel. Based on the studies of the bubble evolution, arc behavior, droplet geometry, weld formation, and mechanical properties of the joint, the arc extinguishing phenomenon was suppressed effectively by the addi...
Article
Comparative experiments are performed in friction stir welding (FSW) of dissimilar Al/Mg alloys with and without assistance of ultrasonic vibration. Metallographic characterization of the welds at transverse cross sections reveals that ultrasonic vibration induces differences in plastic material flow in two conditions. In FSW, the plastic material...
Article
Process stability and weld formation for cold metal transfer gas metal arc welding (hereafter referred to as C-GMAW) of 6061 aluminum alloy with ER4043 filler wire were investigated under different welding current waveforms via collecting the metal transfer images and current waveforms simultaneously. Low boost current (80 A) causes the occurrence...
Article
Underwater wet welding plays an important role in marine engineering. The negative influences from the surrounding water inevitably causes unstable processes and weld defects. Underwater submerged arc welding with mixed epoxy resin and flux was proposed to isolate the water and the welding area, and it showed many advantages with highly improved we...
Article
The effects of tool pin thread on the interfacial heat generation, temperature field, material flow and mixing in friction stir welding of Al/Mg alloys was considered to develop a dissimilar FSW model. The physical parameters of materials in the mixing zone were obtained by weighted summation, and the volume fractions of two phases in each control...
Article
Enhancing the keyholing capability of the plasma arc is of great significance for the welding of medium-thick plate structures. A novel new process of pulsed power ultrasonic vibration assisted plasma arc welding was proposed to realize the effective use of ultrasonic energy and the effective improvement of the plasma arc keyholing ability. Three k...
Article
Full-text available
Understanding of the microstructure evolution and the influence of ultrasonic vibration on friction stir welding (FSW) of dissimilar Al/Mg alloys is of great significance in optimizing the process parameters and improving the joint quality. In this study, the microstructure evolutions in the weld nugget zone (WNZ) of dissimilar Al/Mg joints during...
Article
Full-text available
Friction Stir Welding (FSW) is the most promising solid-state metals joining method introduced in this era. Compared to the conventional fusion welding methods, this FSW can produce joints with higher mechanical and metallurgical properties. Formerly, FSW was adopted for low melting metals like aluminum alloys. In recent years it has made significa...
Article
The effect of tool tilt angle has not been appropriately considered in modelling friction stir welding process. In this study, the expressions to determine incomplete contact region caused by tool tilt were derived and experimentally verified. Correspondingly, the axial stress, slip rate, friction coefficient were modified separately in complete an...
Article
Full-text available
Accurate keyhole status prediction is critical for realizing the closed-loop control of the keyhole plasma arc welding (K-PAW) processes for acquiring full-penetration weld joints with high efficiency. Visually captured weld pool images from topside provide sufficient information of the liquid metal as well as keyhole behaviors. Weld pool, plasma a...
Article
There is a substantial demand in transportation industries to join dissimilar Al and Mg alloy to reduce the structural weight further. However, it is challenging to produce high-strength joints of Al/Mg even with friction stir welding due to the formation of intermetallic compounds (IMCs). In a quest to suppress/eliminate the IMCs, we propose to ad...
Article
Full-text available
Friction stir welding (FSW) tool pin, as a critical component of FSW tool, plays an important role in determining the final joint properties by affecting the heat generation, plastic material flow, welding loads, and so on. However, the effects of tool pin on heat and mass transfer in FSW are not elucidated and quantitative studied. In the present...
Article
Full-text available
In underwater wet welding, the unstable welding process caused by the generation and rupture of bubbles and the chilling effect of water on the welding area result in low quality of welded joints, which makes it difficult to meet the practical application of marine engineering. To improve the process stability and joining quality, a mixture of weld...
Article
Full-text available
The assistance of ultrasonic vibration during the friction stir welding (FSW) process has been verified as an effective approach for the improvement of joint strength. In the present study, experimentation on Al/Mg dissimilar alloys in butt joint configuration is implemented by employing FSW with and without the assistance of ultrasonic vibration....
Article
Ultrasonic vibration (UV)-enhanced friction stir welding (UVeFSW) is used for welding of 2195 Al–Li alloy plates. A model is developed to study the heat and mass transfer in UVeFSW of 2195 Al–Li alloy. It reveals that additional UV in FSW could reduce the heat flux and temperature at the contact interfaces when compared to those in conventional FSW...
Article
Dissimilar joints made of aluminium alloy (Al) and copper (Cu) have great prospective applications in the electrical and electronic industries. Still, it is a challenging task to join them and obtain good performance. In this study, dissimilar AA6061-T6 and C10100 joints were produced by friction stir welding (FSW), and ultrasonic vibration-assiste...
Article
Full-text available
A compound external magnetic field (EMF) can be used to prevent weld bead defects by controlling the metal transfer and arc behaviors during high-speed gas metal arc welding. A unified model containing the filler metal, arc, weld pool, and compound EMF was established to study the effect of the compound EMF on the welding process. The heat and mass...
Article
A computational fluid dynamics model was established to investigate the undercut formation in high speed gas metal arc welding (GMAW). A double-ellipse integrated "arc current density-arc pressure-electromagnetic force-arc heat" distribution model, which could be self-adaptive to weld pool surface evolution, was developed. The multi-coupling transp...
Article
Full-text available
Current research of binocular vision systems mainly need to resolve the camera’s intrinsic parameters before the reconstruction of three-dimensional (3D) objects. The classical Zhang’ calibration is hardly to calculate all errors caused by perspective distortion and lens distortion. Also, the image-matching algorithm of the binocular vision system...
Article
Arc welding processes are still widely used in manufacturing industry. To further improve the arc welding efficiency and the joint quality, secondary energy field/source is usually applied to assist the conventional arc welding process. Modelling, sensing and control of such arc welding processes are efficient and powerful ways for process modifica...
Article
Ultrasonic assistance in friction stir welding of dissimilar metals has proven efficacious in suppressing intermetallics and enhancing joint quality. In a quest to multiply the ultrasonic effects, a tool-mounted ultrasonic vibration system is used to characterize the welds. The ultrasonic vibrations are enforced in the stirred zone (SZ) along the w...
Article
The joint strength of friction stir welded Al/Mg alloys is a critical factor for the wide applications of dissimilar joints. In this study, dissimilar Al/Mg alloys joints were made by friction stir welding (FSW) and its variant, ultrasonic vibration enhanced FSW (UVeFSW), respectively. The tensile strength, fracture toughness and fracture location...
Article
Ultrasonic vibration-assisted plasma arc welding with controlled pulse current waveform was developed to weld the 8 mm thick stainless steel plates. Both bead-on-plate and butt welding experiments were carried out with open-loop and closed-loop control strategies under different welding conditions. The signals of welding current and efflux plasma v...
Article
The dynamic recrystallization (DRX) process and grain structure evolution during friction stir welding determine the final microstructure and performance of weld joints. In this study, Monte Carlo method is applied to develop a model for numerical simulation of dynamic recrystallization in friction stir welding of aluminum plates. An appropriate DR...
Article
Comparative experiments were performed to investigate how the ultrasonic vibration exerted on the tungsten electrode affect the molten metal flow on weld pool surface and the sizes of weld pool and keyhole in plasma arc welding (PAW). The fluid flow velocity on the molten pool surface was measured by tracer particle approach. The images of front mo...
Article
An atomic diffusion model is developed to predict the thickness of intermetallic compounds (IMCs) at the interface of aluminum/magnesium alloys in dissimilar friction stir welding. Both the temperature and the strain rate associated with dislocation density at the checking point are used to determine the diffusion coefficients. The variations of th...
Article
A two-dimensional computational fluid dynamics model is established to verify the correlation between periodic material flow and tool eccentricity during friction stir welding (FSW) process. In the model, the marker material is tracked by employing the Volume of Fluid technique. Besides, a novel boundary condition is proposed, which is not only non...
Preprint
Full-text available
Friction stir welding (FSW) tool pin, as a critical component of FSW tool, plays an important role in determining the final joint properties by affecting the heat generation, plastic material flow, welding loads and so on. However, the influence of tool pin on heat and mass transfer in FSW are not elucidated. In the present study, a validated model...
Article
Full-text available
The application of appropriate constitutive equation describing the relationship between the flow stress, temperature and strain rate is essential to get deep insight into the process mechanism of friction stir welding (FSW). The phase-field simulation of dynamic recrystallization (DRX) suitable for FSW process is specifically integrated into the m...
Article
The tool with polygonal pin profile has been widely employed in friction stir welding (FSW) of aluminum, but there is hardly an effective optimization methodology existed as the thermomechanical characteristics affected by pins with various flats number have not been understood comprehensively. Therefore, the present work employs a 3-dimensional co...
Article
Full-text available
The acoustic radiation force driving the plasma jet and the ultrasound reflection at the plasma arc-weld pool interface are considered to modify the formulas of gas shear stress and plasma arc pressure on the anode surface in ultrasonic-assisted plasma arc welding (U-PAW). A transient model taking into account the dynamic changes of heat flux, gas...
Article
The formation of intermetallic compounds (IMCs) in friction stir welding of Al and Mg alloys worsens the strength and toughness of dissimilar joints. Understanding of the morphology and thickness variation of IMCs at different locations inside the weld will lay solid foundation for mitigating the unfavorable effects of IMCs. In this study, friction...
Article
This study shows the influence of ultrasonic vibrations on the nature and thickness of intermetallic compounds (IMCs) and the correlation with the weld shear load. An ultrasonic vibration assembly comprised of novel horn attachments and a special welding tool has been developed to impart a thermomechanical-acoustic effect on the stirred zone (SZ)....
Article
Full-text available
Abstract This article reviews the status of thermomechanical analysis of the friction stir welding (FSW) process for establishing guidelines for further investigation, filling the available research gaps, and expanding FSW applications. Firstly, the advantages and applications of FSW process are introduced, and the significance and key issues for t...
Article
Underwater pulse-current wet welding was proposed in part 1 of this two-part report. The novel technology obtained improved metal transfer and welding process stability. The main reason for droplet oversizing and long transfer cycles was found to be the deviated large droplet stage. In this part, the waveform optimization for both bubble behaviors...
Article
Full-text available
Keyhole-mode plasma arc welding (PAW) has a good prospect in the manufacturing industry. Unified models of plasma arc and workpiece help to reveal the physical mechanism in PAW for a better application. Previous unified models either deal with a constant keyhole situation or take too much computational time to display the dynamic keyhole process wi...
Article
The dynamic behaviors of underwater bubbles and arcs are critical to welding processes and weld quality in underwater wet flux-cored arc welding. In this study, bubble evolution promoted by an arc plasma and flux decomposition was simulated using hydrodynamic equations. The influence of water on bubble and arc behavior was considered with regard to...
Article
Full-text available
Complete understanding of ultrasonic interaction with aluminum alloys is essential to promote application of ultrasonic-assisted friction stir welding process in manufacturing industry. In this study, the ultrasonic-assisted compression tests were performed to investigate the effect of ultrasonic vibration on the stress-strain characteristics of AA...
Article
Plasma technology involves complex and coupled electric, magnetic, thermal and hydrodynamical interaction. It’s important to understand all the multiphysics mechanism for a wider industrial application. A 3D unified model was established, which includes a combination of hydrodynamical equations, heat transfer equation and electromagnetic equations,...
Article
The tool tilt angle is an important factor determining the microstructure and properties of friction stir weld joints. In this study, both experiments and numerical simulations are made to investigate the influence of tool tilt angle on heat generation, temperature field and material flow behavior in friction stir welding (FSW). The tool tilt angle...
Article
Full-text available
Tungsten inert gas-metal inert gas hybrid welding (TIG-MIG) combines the advantages of tungsten and metal inert gas welding. It can e�ciently produce high-quality weld joints that meet modern manufacturing quality and e�ciency requirements. Based on heat transfer, fluid dynamics, and electromagnetic theory, a three-dimensional coupled transient mod...
Article
The wire and arc additive manufacturing (WAAM) method based on an indirect arc between two non-consumable tungsten electrodes in confined space has been proposed and preliminarily investigated, which is applicable in vacuum or sub-atmosphere ambient conditions. Visual inspection results showed that the stable burning arc kept continuously melting t...
Article
The ultrasonic vibration assisted plasma arc welding process was developed to enhance the welding efficiency while the underlying mechanism of ultrasonic interaction with plasma arc is not yet elucidated. In this study, a numerical model of ultrasonic vibration assisted plasma arc is proposed, which takes into account the influence of plasma flow v...
Article
Full-text available
Gas tungsten arc welding with an external magnetic field is proven to suppress weld defects while improving welding speed. A three-dimensional numerical model that considers interactions among the arc plasma, weld pool, metal vapor, and external magnetic field is developed. The influences of the external magnetic field and metal vapor on arc and we...
Article
Understanding of the ultrasonic effects on the dynamic recrystallization in ultrasonic vibration enhanced friction stir welding is critical to the improvement of microstructure and mechanical properties of welds. Through considering preheating, softening as well as residual hardening effects of ultrasound, the multi-phase field model is developed t...
Article
Butt joint welding of 6 mm thickness of 6061 aluminum alloy was used to characterize the high frequency (HF) pulse modulated square wave AC TIG (HFPM AC TIG) welding with filler wire addition. The heat input required for achieving fully penetrated weld is remarkably reduced by the modulation HF pulse. The weld penetration is increased and weld widt...
Article
In ultrasonic assisted friction stir welding (UaFSW) system, the ultrasonic vibration is exerted onto the tool radially, and can achieve synchronously thermo-mechanical action with the tool. A mathematical model is established to investigate the coupled “acoustic action-heat generation-plastic deformation” behaviors in UaFSW. The ultrasonic stress...
Article
The developed ultrasonic assisted friction stir welding (UaFSW) process can reduce the welding load and improve the joint quality, but the interaction mechanism between the exerted ultrasonic vibration and the thermo-mechanical behavior induced by friction stir welding is not yet elucidated. In this study, the classical Norton friction model is mod...
Article
An elementary analysis is proposed to quantify the effects of ultrasonic vibrations during friction stir welding (FSW) of AA6061-T6 to AZ31B Mg alloy. In the present context, the ultrasonic vibrations are applied in the stirred zone (SZ) via a specially designed welding tool. The influence of ultrasonic vibration has been analyzed for a wide range...
Article
Bead-on-plate welding of 6-mm thick AA6061-T6 aluminum alloy is used to characterize the high-frequency (HF) pulse-modulated square wave AC TIG (HFPM AC TIG) welding. The modulation HF pulse reduces the reignition voltage of negative half-wave arc. However, its effectiveness on increasing weld penetration is not evident until the penetration rate (...
Article
The visual measurement system was established to investigate the fluid flow during high-speed gas metal arc welding. The two-dimensional fluid flow velocity on weld pool surface was measured using the tracer particles. The characteristic parameters of the backward liquid metal flow were extracted, then the speed of the liquid metal flow was compare...
Article
The compound magnetic-field generator was designed to simultaneously generate transverse magnetic-field and alternating parallel magnetic-field during pulsed gas metal arc welding at high welding speed. The influence of compound magnetic field on the temperature distribution was studied based on infrared camera, and droplet and arc behaviour was st...
Article
This article aims to discover the effects of ultrasonic vibration during friction stir butt welding of AA6061-T6 and AZ31B Mg alloys. In the present attempt, the ultrasonic vibrations are enforced along the welding direction via novel horn attachments and welding tool. The experimental outcomes result in a significant improvement in weldment mechan...
Article
Based on the VOF method, a three-dimensional numerical analysis model coupling both droplets and arc behaviors is developed to simulate the metal transfer and arc plasma flow processes in underwater wet flux-cored arc welding. The relationships between several physical quantities such as droplet shape and temperature, electromagnetic force and curr...
Article
To study the dissimilar materials mixing and understand the underlying mechanism, a model for friction stir welding of aluminum to magnesium alloys is developed. The mixing dissimilar materials in the stirred zone are treated by a method similar to the functionally graded material, the physical parameters are exponentially related to the real volum...
Article
Full-text available
The arc plasma behavior for gas metal arc welding (GMAW) with an external compound magnetic field was numerically investigated. A three-dimensional finite element model for the external magnetic field (EMF) and a three-dimensional finite volume model for the arc plasma were established. The effects of the EMF on the redistribution of the temperatur...
Article
The typical metal transfer mode in conventional underwater wet flux cored arc welding (FCAW) delivers large droplet repulsive transfer with low frequency. The process stability and the weld quality are seriously deteriorated with significant spatter and frequent arc extinctions. It is thought the repulsive forces applied on droplets can be reduced...