Experimental investigation on the weld pool formation process in plasma keyhole arc welding

Van, Anh Nguyen; Tashiro, Shinichi; Hanh, Bui Van; Tanaka, Manabu

doi:10.1088/1361-6463/aa9902

Cited by 34 publications

(24 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Besides, the keyhole in the LBW process is much unstable, causing the generation of keyhole induced porosity [7], spatter [8] and other welding defects [9]. In the KPAW process, the maximum temperature of the weld pool is very low, so the metal evaporation can be ignored [10]. Generally, the keyhole with large width is formed in several seconds, and the high arc pressure is proposed to be the dominant driven force for the keyhole formation [11].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

A novel electrode-arc-weld pool model for studying the keyhole formation in the keyhole plasma arc welding process

Tashiro

Hua

et al. 2019

J. Phys. D: Appl. Phys.

View full text Add to dashboard Cite

A novel electrode-arc-weld pool model considering the influence of the backside keyhole deviation on the heat source distribution, the influence of the keyhole constraint on the arc pressure and the keyhole geometry dependent plasma shear stress, is developed to study the keyhole formation in the KPAW process. The numerical and experimental results show that: the keyhole depth increases very quickly at first, then smoothly, and then quickly again. In the blind keyhole stage, the arc pressure deepens the keyhole. The plasma shear stress facilitates the fluid flow along the rear keyhole wall and decreases the curvature of the keyhole. The process between the weld pool penetration and the keyhole penetration is defined as the blasting penetration stage, in which the molten bridge under the arc is quickly broken. The pressure balance and mass conservation mechanisms are proposed to be responsible for the blasting penetration. The low melting temperature, low surface tension and bottom surface deformation promote the blasting penetration, while the high thermal conductivity suppresses the blasting penetration. In the penetrated keyhole stage, two contrary convective eddies are found inside the weld pool. At the top surface of the weld pool, the molten metal flows upward and backward near the keyhole, but obviously flows forward at the rear part of the weld pool. At the bottom surface of the weld pool, the molten metal flows downward and backward.

show abstract

Section: Introductionmentioning

confidence: 99%

“…Based on the comprehensive experimental observation of the fluid flow, the plasma shear stress was proposed to be the dominant driven force in the KPAW weld pool [10]. However, the plasma shear stress was ignored in previous weld pool simulations.…”

Section: Introductionmentioning

confidence: 99%

A novel electrode-arc-weld pool model for studying the keyhole formation in the keyhole plasma arc welding process

Tashiro

Hua

et al. 2019

J. Phys. D: Appl. Phys.

View full text Add to dashboard Cite

show abstract

“…As found out in recent papers [19,27], the driving forces in PAW process are shear force (plasma flow and arc pressure) and Marangoni force. Meanwhile, the buoyancy force and electromagnetic force are not large enough to control the material flow and convection patterns in the PAW process.…”

Section: Discussionmentioning

confidence: 90%

“…In order to overcome this difficulty, the zirconia tracers were fed to the motel pool surface by two ways: around the keyhole before welding through the holes on the workpiece surfaces (as indicated above) and at the middle part of the molten pool during welding by a supply device. Details for this supply technique can be seen in our recent paper [27]. In order to estimate the convection, tracer particles (zirconia) with a diameter of 0.03 mm were used.…”

Section: Wo Remmentioning

confidence: 99%

Relationship among Welding Defects with Convection and Material Flow Dynamic Considering Principal Forces in Plasma Arc Welding

Loc

Nguyen

Han

et al. 2021

Metals

Self Cite

View full text Add to dashboard Cite

The material flow dynamic and velocity distribution on the melted domain surface play a crucial role on the joint quality and formation of welding defects. In this study, authors investigated the effects of the low and high currents of plasma arc welding on the material flow and thermodynamics of molten pool and its relationship to the welding defects. The high-speed video camera (HSVC) was used to observe the convection of the melted domain and welded-joint appearance. Furthermore, to consider the Marangoni force activation, the temperature on the melted domain was measured by a thermal HSVC. The results revealed that the velocity distribution on the weld pool surface was higher than that inside the molten weld pool. Moreover, in the case of 80 A welding current, the convection speed of molten was faster than that in other cases (120 A and 160 A). The serious undercut and humping could be seen on the top surface (upper side) and unstable weld bead was visualized on the back side (bottom surface). In the case of 160 A welding current, the convection on the weld pool surface was much more complex in comparison with 80 A and 120 A cases. The excessive convex defect at the bottom side and the concave defect at the top surface were observed. In the case of 120 A welding current, two convection patterns with the main flow in the backward direction were seen. Almost no welding defect could be found. The interaction between the shear force and Marangoni force played a solid state on the convection and heat transportation processes in the plasma arc welding process.

show abstract

“…This reverse flow characteristic of plasma arc with the keyhole is the main reason causing irregular flow of liquid metal in the weld pool. [24] Current density/ASm Figure 6 shows the velocity of plasma arc on lines of r = 0 and r = 0.5. There are two peaks of velocity on each line.…”

Section: Resultsmentioning

confidence: 99%

Numerical analysis of plasma arc physical characteristics under additional constraint of keyhole

Xu¹,

Jiang²,

Chen³

et al. 2018

Chinese Phys. B

View full text Add to dashboard Cite

The physical characteristics of a plasma arc affect the stability of the keyhole and weld pool directly during keyhole plasma arc welding (KPAW). There will be significant change for these characteristics because of the interaction between the keyhole weld pool and plasma arc after penetration. Therefore, in order to obtain the temperature field, flow field, and arc pressure of a plasma arc under the reaction of the keyhole, the physical model of a plasma arc with a pre-set keyhole was established. In addition, the tungsten and base metal were established into the calculated domain, which can reflect the effect of plasma arc to weld pool further. Based on magneto hydrodynamics and Maxwell equations, a two-dimensional steady state mathematical model was established. Considering the heat production of anode and cathode, the distribution of temperature field, flow field, welding current density, and plasma arc pressure were solved out by the finite difference method. From the calculated results, it is found that the plasma arc was compressed a second time by the keyhole. This additional constraint results in an obvious rise of the plasma arc pressure and flow velocity at the minimum diameter place of the keyhole, while the temperature field is impacted slightly. Finally, the observational and metallographic experiments are conducted, and the shapes of plasma arc and fusion line agree with the simulated results generally.

show abstract

Experimental investigation on the weld pool formation process in plasma keyhole arc welding

Cited by 34 publications

References 23 publications

A novel electrode-arc-weld pool model for studying the keyhole formation in the keyhole plasma arc welding process

A novel electrode-arc-weld pool model for studying the keyhole formation in the keyhole plasma arc welding process

Relationship among Welding Defects with Convection and Material Flow Dynamic Considering Principal Forces in Plasma Arc Welding

Numerical analysis of plasma arc physical characteristics under additional constraint of keyhole

Contact Info

Product

Resources

About