Arc characteristics and metal transfer behavior of CMT+P process for Q235 steel of titanium-steel composite plate

2019 ◽  
Vol 33 (01n03) ◽  
pp. 1940040
Author(s):  
Yang Wang ◽  
Zhongyin Zhu ◽  
Guoqing Gou ◽  
Lin Peng ◽  
Yali Liu ◽  
...  
Keyword(s):  
High Speed ◽  
Short Circuit ◽  
Welding Process ◽  
Metal Transfer ◽  
Pulse Period ◽  
Cold Metal Transfer ◽  
Q235 Steel ◽  
Spray Transfer ◽  
Transfer Mode ◽  
Transfer Behavior

The cold metal transfer (CMT) with addition of pulses (CMT[Formula: see text]P) process is a new CMT welding method. This paper uses a high-speed camera and electrical signal synchronization acquisition system to perform a CMT[Formula: see text]P welding test on a 10 mm thick Q235 steel plate, and performs arc characteristic and droplet transfer behavior in the welding process. It has been founded that under relatively small currents and voltages, the CMT[Formula: see text]P transfer mode is a combination of a projected transfer mode with one droplet in the pulse period and a short circuit transfer mode during the CMT period. The process is stable with little spatter; at relatively large currents and voltages, the transition mode is the combination of pulse transfer, spray transfer and short circuit transfer. It results in one or more droplets that enter the pool both in pulse transfer in the spray transfer mode during the pulse period and in the short circuit transfer mode during the CMT period in a weld cycle.

Effect of Helium Addition in Argon Shielding Gas on Metal Transfer Behavior in Gas Metal Arc Welding of Aluminum

2013 ◽  
Vol 545 ◽  
pp. 219-224 ◽  
Author(s):  
Pakpoom Jittavisuttiwong ◽  
Bovornchok Poopat
Keyword(s):  
Short Circuit ◽  
Welding Current ◽  
Metal Transfer ◽  
Gas Mixture ◽  
Spray Transfer ◽  
Arc Voltage ◽  
Pure Argon ◽  
Transfer Mode ◽  
Transfer Behavior ◽  
Current Region

Helium is widely used as mixing with argon for a shielding gas in GMAW process of Aluminum in order to improve weld quality and increase heat transfer to the weld pool. It has been known that helium could affect metal transfer behavior; however, its behavior has not been well understood. In this study, an analysis of the metal transfer behavior in the GMAW of aluminum was studied. The main objective is to study the effect of Helium on metal transfer in two main regions, short circuit (low welding current region) and spray transfer (high current region). The composition of 5 types of shielding gases were pure argon, 75%Ar + 25%He, 50%Ar + 50%He, 25%Ar + 75%He and pure helium. The welding parameters were fixed at 90A/17.0V, 100A/18.2V, 140A/24.6V and 180A/27.6V. Aluminum plates were welded bead-on-plate in a flat position. The metal transfer behavior was analyzed by using acoustic signals and arc voltage signals. For the result, at low welding current of 90A and 100A with pure argon, short-circuit transfer mode was observed. Adding helium in gas mixture gave no effect in metal transfer mode in low welding current regions but the metal transfer rate was slightly increased. At high welding currents of 140A and 180A with pure argon, spray transfer mode was observed and when increasing helium in gas mixture resulted in changing from spray transfer to combined mode of spray-globular. In these high welding currents, adding helium in gas mixture resulted in decreasing the metal transfer rate since helium gas tended to promote globular metal transfer. Acoustic signal and arc voltage signal can be used effectively in determining modes of metal transfer.

Dynamic Metal Transfer Behavior in Double-Wire DP-GMAW of Aluminum Alloy Under Different Pulse Phases

2020 ◽  
Vol 143 (4) ◽  
Author(s):  
Kaiyuan Wu ◽  
Jiatong Zhan ◽  
Xuanwei Cao ◽  
Xiaobin Hong ◽  
Peimin Xie
Keyword(s):  
High Speed ◽  
Droplet Diameter ◽  
Gas Metal Arc Welding ◽  
Metal Transfer ◽  
Double Pulse ◽  
Droplet Growth ◽  
Al Alloy ◽  
Spray Transfer ◽  
Pulse Phase ◽  
Transfer Behavior

Abstract The effects of pulse phase and pulse stage on the metal transfer characteristics in double-wire double pulse gas metal arc welding (DP-GMAW) of aluminum (Al) alloy were studied using high-speed camera images and current and voltage waveforms. In addition, the effects of various forces on dynamic metal transfer behavior were analyzed under different pulse phases and pulse stages. The results show that the spray transfer mode can be obtained in both the alternating pulse phase (APP) and synchronous pulse phase (SPP). The transfer pattern of the leading and trailing droplets is alternating in the APP, but changes to simultaneous metal transfer in the SPP, mainly owing to influence of the pulse phase on droplet growth. The transfer type is one drop double pulse (ODDP) during the strong pulse stage and one drop triple pulse (ODTP) during the weak pulse stage, regardless of the pulse phase. The pulse phase does, however, affect the Lorentz force between the leading and trailing droplets, causing droplet collision in the SPP, which results in a poorer weld bead appearance compared with in the APP. Finally, the droplet diameter was found to be similar during different pulse phases and pulse stages.

scholarly journals Complex Behavior of Droplet Transfer and Spreading in Cold Metal Transfer

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Shuai Yang ◽  
Yanfeng Xing ◽  
Fuyong Yang ◽  
Juyong Cao
Keyword(s):  
Control Method ◽  
Short Circuit ◽  
Continuous Process ◽  
Welding Process ◽  
Intelligent Manufacturing ◽  
Metal Transfer ◽  
Droplet Spreading ◽  
Cold Metal Transfer ◽  
Cmt Welding ◽  
Cold Metal

In intelligent manufacturing, an intelligent control method of welding process is an important process of intelligent welding manufacturing technology (IWMT). Metal transfer is a key factor to control the welding process. Metal transfer and droplet spreading are of vital importance for welding formation. A new theoretical model of cold metal transfer (CMT) in short-circuit transfer mode is proposed in this paper. In this model, the CMT welding process is regarded as a continuous process of arc heating, mass transfer, short-circuit, and spreading, and the relations between these processes are analyzed. The calculation equations used by the model can analyze the welding formation clearly and simplify the complex welding process into continuous physical behavior. The predicted welding width shows good agreement with the measurement results. The mechanism of increased welding width is also comprehensively analyzed. Results have a certain guiding effect on aluminum alloy welding process control.

scholarly journals Effects of active gases on droplet transfer and weld morphology in pulsed-current NG-GMAW of mild steel

2020 ◽  
Author(s):  
Guoqiang Liu ◽  
Xinhua Tang ◽  
Qi Xu ◽  
Fenggui Lu ◽  
Haichao Cui
Keyword(s):  
Mild Steel ◽  
High Speed ◽  
Gas Metal Arc Welding ◽  
Welding Process ◽  
Metal Transfer ◽  
Pulsed Current ◽  
Shielding Gas ◽  
Droplet Transfer ◽  
Spray Transfer ◽  
Pure Argon

Abstract Small amount of active gases CO 2 and O 2 were added into pure argon inert shielding gas to improve the weld formation of pulsed-current narrow-gap gas metal arc welding (NG-GMAW) of mild steel. Their effects on droplet transfer and arc behavior were investigated. A high-speed visual sensing system was utilized to observe the metal transfer process and arc morphology. When the proportion of CO 2 , being added into the pure argon shielding gas, changes from 5% to 5%, the metal transfer mode changes from pulsed spray streaming transfer to pulsed projected spray transfer, while it remains the pulsed spray streaming transfer when 2% to 10% O 2 is added. Both CO 2 and O 2 are favorable to stabilizing arc and welding process. O 2 is even more effective than CO 2 . However, O 2 is more likely to cause the inclusion defects in the weld, while CO 2 can improve the weld appearance in some sense. The weld surface concavity, which is sensitive to the formation of lack-of-fusion defect in NG-GMAW, is greatly influenced by the addition of active gas, but the weld width and weld penetration almost keep constant.

Characteristic of Hyperbaric GMAW Metal Transfer at 1-12 Bar Argon Environment

2014 ◽  
Vol 900 ◽  
pp. 565-569
Author(s):  
Kai Li ◽  
Hong Ming Gao ◽  
Hai Chao Li ◽  
Shan Gong
Keyword(s):  
High Speed ◽  
Ambient Pressure ◽  
Welding Process ◽  
Axial Direction ◽  
Metal Transfer ◽  
Large Droplet ◽  
Camera System ◽  
Transfer Mode ◽  
Feeding Speed ◽  
Different Characteristics

The metal transfer behavior in hyperbaric GMAW process was investigated by using a high speed camera system with infrared laser as backlight. The metal transfer mode at 1-12bar argon environment shows different characteristics. Three kinds were observed: large droplet repelled transfer, projected repelled transfer and hyperbaric streaming transfer. Large droplet repelled transfer occurs mostly in the welding process with low feeding speed and relatively low welding voltage. Projected repelled transfer appears at middle feeding speed and high ambient pressure. Transfer tracks of former two modes deviate from the axial direction of welding wire. The spatter is produced more frequently in the projected repelled transfer mode. Hyperbaric streaming transfer is found meanly at high feeding speed and relatively high voltage. Because of its stability reflected from metal transfer process, hyperbaric GMAW process with hyperbaric streaming transfer mode should be employed preferentially.

Effect of Laser Beam on Double Wire Pulsed MIG Welding Process

2011 ◽  
Vol 130-134 ◽  
pp. 4169-4173
Author(s):  
Li Yan Lou ◽  
Huan Li ◽  
Xu You Wang ◽  
Wei Wang ◽  
Ying Gao
Keyword(s):  
Laser Beam ◽  
High Speed ◽  
Welding Process ◽  
Welding Current ◽  
Metal Transfer ◽  
Wave Form ◽  
Hybrid Welding ◽  
Transfer Mode ◽  
Metal Transfer Mode ◽  
Set Up

Based on the coupling of laser beam and double arcs, a novel process was investigated. This research set up the laser-double wire pulsed MIG hybrid welding system. Meanwhile the current and voltage sensors were used to detect welding current and arc voltage wave-form and high-speed videography system was used to observe the metal transfer process and arc behavior. The three signals were acquired synchronously. The results showed that the synergic action of the three different heat sources leads to a change in metal transfer mode. It was revealed that the metal transfer mode was two droplets per pulse in laser-double wire hybrid welding process while one droplet per pulse in double wire welding process with the same certain experiment parameters. And we also discovered that the arcs were attracted strongly by the laser beam.

scholarly journals Influence of post weld heat treatment on tensile properties of cold metal transfer (CMT) arc welded AA6061-T6 aluminium alloy joints

2019 ◽  
Vol 28 (1) ◽  
pp. 135-145 ◽  
Author(s):  
Addanki Ramaswamy ◽  
Sudersanan Malarvizhi ◽  
Visvalingam Balasubramanian
Keyword(s):  
Heat Treatment ◽  
Tensile Properties ◽  
Gas Metal Arc Welding ◽  
Weight Ratio ◽  
Welding Process ◽  
Metal Transfer ◽  
Post Weld Heat Treatment ◽  
Cold Metal Transfer ◽  
Cold Metal ◽  
Weld Heat

AbstractAluminium alloys of 6xxx series are widely used in the fabrication of light weight structures especially, where high strength to weight ratio and excellent weld-ability characteristics are desirable. Gas metal arc welding (GMAW) is the most predominantly used welding process in many industries due to the ease of automation. In this investigation, an attempt has been made to identify the best variant of GMAW process to overcome the problems like alloy segregation, precipitate dissolution and heat affected zone (HAZ) softening. Thin sheets of AA6061-T6 alloy were welded by cold metal transfer (CMT) and Pulsed CMT (PCMT). Among the two joints, the joint made by PCMT technique exhibited superior tensile properties due to the mechanical stirring action in the weld pool caused by forward and rearward movement of the wire along with the controllable diffusion rate at the interface caused by shorter solidification time. However, softening still exists in the welded joints. Further to increase the joint efficiency and to minimize HAZ softening, the joints were subjected to post weld heat treatment (PWHT). Approximately 10% improvement in the tensile properties had been observed in the PWHT joints due to the nucleation of strengthening precipitates in the weld metal and HAZ.

Cold Metal Transfer Spot Joining of AA6061-T6 to Galvanized DP590 Under Different Modes

2015 ◽  
Vol 137 (5) ◽  
Author(s):  
HaiYang Lei ◽  
YongBing Li ◽  
Blair E. Carlson ◽  
ZhongQin Lin
Keyword(s):  
Heat Input ◽  
Mechanical Performance ◽  
Welding Process ◽  
High Strength ◽  
Metal Transfer ◽  
Cold Metal Transfer ◽  
Spot Joining ◽  
Predrilled Hole ◽  
Joint Quality ◽  
Cold Metal

In order to meet the upcoming regulations on greenhouse gas emissions, aluminum use in the automotive industry is increasing. However, this increase is now seen as part of a multimaterial strategy. Consequently, dissimilar material joints are a reality, which poses significant challenges to conventional fusion joining processes. To address this issue, cold metal transfer (CMT) spot welding process was developed in the current study to join aluminum alloy AA6061-T6 as the top sheet to hot dip galvanized (HDG) advanced high strength steel (AHSS) DP590 as the bottom sheet. Three different welding modes, i.e., direct welding (DW) mode, plug welding (PW) mode, and edge plug welding (EPW) mode were proposed and investigated. The DW mode, having no predrilled hole in the aluminum top sheet, required concentrated heat input to melt through the Al top sheet and resulted in a severe tearing fracture, shrinkage voids, and uneven intermetallic compounds (IMC) layer along the faying surface, leading to poor joint properties. Welding with the predrilled hole, PW mode, required significantly less heat input and led to greatly reduced, albeit uneven, IMC layer thickness. However, it was found that the EPW mode could homogenize the welding heat input into the hole and thus produce the most stable welding process and best joint quality. This led to joints having an excellent joint morphology characterized by the thinnest IMC layer and consequently, best mechanical performance among the three modes.

Effects of Wire Rotating Frequency on Metal Transfer Process in Rotating Arc Narrow Gap Horizontal GMAW

2011 ◽  
Vol 189-193 ◽  
pp. 3395-3399 ◽  
Author(s):  
Ning Guo ◽  
Yan Fei Han ◽  
Chuan Bao Jia ◽  
Yong Peng Du
Keyword(s):  
Transfer Process ◽  
High Speed ◽  
Stable Process ◽  
Welding Process ◽  
Metal Transfer ◽  
Welding Parameters ◽  
High Speed Photography ◽  
Narrow Gap ◽  
Weld Formation ◽  
Rotating Arc

The metal transfer process with different welding parameters in rotating arc narrow gap horizontal welding is successfully observed by the high-speed photography system. The effects of wire rotating frequency on metal transfer process in rotating arc narrow gap horizontal welding are novelly explored. The metal transfer with different wire rotating frequency presents different modes. The results indicate that the droplet transfer has stable process with the rotating frequency of 5-20 Hz. And the weld formation is quite shapely. But with the high rotating frequency of 50 Hz, the metal transfer process is not acceptable and the weld formation is very pool. Metal transfer process is one of the most important factors of effecting the weld formation in rotating arc horizontal welding process besides the molten pool behavior and welding thermal circles.

Influence of Metal Transfer Behavior Under Ar And CO2 Shielding Gases On Geometry And Surface Roughness of Single And Multilayer Structures In GMAW-Based Wire Arc Additive Manufacturing of Mild Steel

2021 ◽  
Author(s):  
Mitsugu Yamaguchi ◽  
Rikiya Komata ◽  
Tatsuaki Furumoto ◽  
Satoshi Abe ◽  
Akira Hosokawa
Keyword(s):  
Surface Roughness ◽  
Additive Manufacturing ◽  
Molten Pool ◽  
Multilayer Structure ◽  
Short Circuit ◽  
Metal Transfer ◽  
Geometric Accuracy ◽  
Transfer Behavior ◽  
Ar Gas ◽  
Wire Arc Additive Manufacturing

Abstract Wire arc additive manufacturing (WAAM) is advantageous for fabricating large-scale metallic components, however, a high geometric accuracy as that of other AM techniques cannot be achieved because of the deposition process with a large layer. This study focuses on the WAAM process based on gas metal arc welding (GMAW). To clarify the influence of shielding gas used to protect a molten metal during fabrication on the geometric accuracy of the built part obtained via the GMAW-based WAAM process, the influence of the metal transfer behavior on the geometry and surface roughness of the fabricated structures was investigated via visualization using a high-speed camera when single and multilayer depositions were performed under different heat inputs and gases. However, when using Ar gas, the heat flux from an arc to the workpiece is relatively low, limiting the depth of the molten pool during welding. The effect of its characteristics on the stair steps that are inevitably produced on the side face of the multilayer structure in the WAAM process was verified, and for a heat input of 1.17 kJ/cm under Ar gas, a higher geometric accuracy of the multilayer structure was obtained without interlayer cooling. The short circuit between the metal droplet and the fabricated surface, where the molten pool is insufficiently formed, resulted in a hump formation. Further, the metal transfer under Ar gas reduced the surface irregularities on the fabricated structure.

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