scholarly journals Effect of Filling Rate on Underwater Wet Welding Process and Weld Appearance

Materials ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1061 ◽  
Author(s):  
Xin Zhang ◽  
Ning Guo ◽  
Changsheng Xu ◽  
Haoran Kan ◽  
Yanbo Tan ◽  
...  
Keyword(s):  
Surface Tension ◽  
Molten Pool ◽  
Welding Process ◽  
Electric Signal ◽  
Radius Of Curvature ◽  
Filling Rate ◽  
Welding Pool ◽  
Transfer Mode ◽  
Arc Stability ◽  
Flux Cored Arc Welding

Real-time electric signal, matter transfer mode and welding pool behavior were obtained to investigate the effect of wires’ filling rate on arc stability and joints’ appearance during underwater wet flux-cored arc welding (FCAW). The electric signal results showed that arc stability first decreased and then increased rapidly because the raise of filling rate affected the number of charged particles and the electrical conductivity of welding arc atmosphere. Two typical transfer modes, globular repelled transfer mode and surface tension transfer mode, were observed in this study. The ratio of surface tension transition could be increased by adding wires’ filling rate. Meanwhile, the geometry of molten pool was changed and the distance between droplets to welding pool reduced as the filling rate increased. The fusion line became more regular and the radius of curvature increased under the effect of bubbles in the molten pool. As the filling rate improving, more slags on the welds surface were acquired and the welds were much flatter and smoother.

Investigation of Arc Bubble Affecting the Arc Stability and Improvement of Weld Appearances Using Bubble Constraint Device in Underwater Wet Welding

2019 ◽  
Vol 972 ◽  
pp. 215-221
Author(s):  
Hao Chen ◽  
Ning Guo ◽  
Ji Cai Feng ◽  
Guo Dong Wang
Keyword(s):  
Real Time ◽  
Transfer Process ◽  
Welding Process ◽  
Electric Signal ◽  
Process Stability ◽  
Droplet Transfer ◽  
Transfer Mode ◽  
Arc Stability ◽  
Weld Appearance ◽  
The Impact

The generating, floating and collapsing of arc bubble is a special phenomenon in underwater flux-cored wet welding. The configuration changing process of bubble will change the stress on droplet and influence the droplet transfer process. In this study, the shape changing of bubble is captured in graphic and the real-time electric signal data is obtained. The impact of bubble floating and collapsing results in the globular repelled transfer mode, which also reduces the arc stability. A self-designed gas-shield cover is used as a bubble constraint device to improve the welding process stability and weld appearances by limiting the free floating and expansion of arc bubble. The relationships between the cover diameter and the characteristics of weld appearance are studied.

Numerical Prediction of the Shape of the Molten Pool in a Stationary TIG Welding Process

2007 ◽  
Vol 344 ◽  
pp. 699-706 ◽  
Author(s):  
Riccardo Bini ◽  
Michele Monno
Keyword(s):  
Surface Tension ◽  
Molten Pool ◽  
Welding Process ◽  
Jet Impingement ◽  
Electric Arc ◽  
Tig Welding ◽  
Sulphur Content ◽  
Welding Parameters ◽  
Stainless Steel Sheet ◽  
Temperature Distributions

A numerical model of the electric arc is coupled to a model for the convective flow in the molten pool of a stainless steel sheet during a stationary TIG welding process. This approach allows us to predict the shape of the bead, which is determined by the balance between the Marangoni forces on the free surface and the radial drag from the arc jet impingement. The surface tension of the molten steel is greatly influenced by its temperature and sulphur content, as experiments showed very different bead shapes associated to the same welding parameters. We simulate three sulphur contents, namely 10 ppm, 40 ppm and 100 ppm, showing their effects on the velocity and temperature distributions in the molten pool. A transition between drag-dominated and surface tension-dominated pools is found at a sulphur content of few dozens, in agreement with previous experimental observations.

Segmentation of Molten Pool Infrared Images Using Morphology during High Power Disk Laser Welding

2012 ◽  
Vol 201-202 ◽  
pp. 91-94
Author(s):  
Yan Xi Zhang ◽  
Xiang Dong Gao
Keyword(s):  
Laser Welding ◽  
High Power ◽  
Molten Pool ◽  
Welding Process ◽  
Histogram Equalization ◽  
Welding Quality ◽  
Infrared Images ◽  
Traditional Methods ◽  
Disk Laser ◽  
Laser Welding Process

Configuration of a molten pool is related to the laser welding quality. Analyzing the configuration of a molten pool is important to monitor the laser welding process. This paper proposes a method of segmentation of a molten pool and its shadow during high power disk laser welding, consequently provides the groundwork for reconstruction of the molten pool and analysis of welding quality. Subsection linear stretching histogram equalization was applied to enhance the contrast of the original images firstly, and then edge detection was used to highlight the edges. After that we used the morphology filtering method to produce the segmentation mask, and then combined the mask with the original images to get the final segmentation results. Also, the proposed method was compared with other traditional methods. The experimental results showed that our method not only could give better segmentation results and process large quantities images automatically, but also overcame the less-segmentation problems of traditional methods.

Correlation between wire feed speed and external mechanical constraint for enhanced process stability in underwater wet flux-cored arc welding

2018 ◽  
Vol 233 (10) ◽  
pp. 2061-2073 ◽  
Author(s):  
Jianfeng Wang ◽  
Qingjie Sun ◽  
Jiangkun Ma ◽  
Peng Jin ◽  
Tianzhu Sun ◽  
...  
Keyword(s):  
Welding Process ◽  
Electrical Signal ◽  
Feed Speed ◽  
Process Stability ◽  
Underwater Wet Welding ◽  
Extinction Process ◽  
Flux Cored Arc Welding ◽  
Wire Feed Speed ◽  
Wire Feed ◽  
Mechanical Constraint

It is a great challenge to improve the process stability in conventional underwater wet welding due to the formation of unstable bubble. In this study, mechanical constraint method was employed to interfere the bubble generated by underwater wet welding, and the new method was named as mechanical constraint assisted underwater wet welding. The aim of the study was to quantify the combined effect of wire feed speed and condition of mechanical constraint on the process stability in mechanical constraint assisted underwater wet welding. Experimental results demonstrated that the introduction of mechanical constraint not only suppressed the bubble without floating but also stabilized the arc burning process. The degree of influence of mechanical constraint, which changed with wire feed speed, played an important role during the mechanical constraint assisted underwater wet welding process. For all wire feed speeds, the fluctuations of welding electrical signal were decreased through introduction of mechanical constraint. The difference in the proportion of arc extinction process between underwater wet welding and mechanical constraint assisted underwater wet welding became less with increasing wire feed speed. At wire feed speed lower than 7.5 m/min, the improvement of process stability was very significant by mechanical constraint. However, the further improvement produced limited effect when the wire feed speed was greater than 7.5 m/min. The observation results showed that a better weld appearance was afforded at a large wire feed speed, corresponding to a lower variation coefficient.

Effects of heat input on arc stability and weld quality in underwater wet flux-cored arc welding of E40 steel

2018 ◽  
Vol 31 ◽  
pp. 833-843 ◽  
Author(s):  
HongLiang Li ◽  
Duo Liu ◽  
YaoTian Yan ◽  
Ning Guo ◽  
YiBo Liu ◽  
...  
Keyword(s):  
Heat Input ◽  
Arc Welding ◽  
Weld Quality ◽  
Arc Stability ◽  
Flux Cored Arc Welding

scholarly journals Multivariate Stochastic Optimization Approach Applied in a Flux-Cored Arc Welding Process

IEEE Access ◽  
2020 ◽  
Vol 8 ◽  
pp. 61267-61276 ◽  
Author(s):  
Alexandre F. Torres ◽  
Franco B. Rocha ◽  
Fabricio A. Almeida ◽  
Jose H. F. Gomes ◽  
Anderson P. Paiva ◽  
...  
Keyword(s):  
Stochastic Optimization ◽  
Arc Welding ◽  
Welding Process ◽  
Optimization Approach ◽  
Flux Cored Arc Welding ◽  
Arc Welding Process
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