Stable keyhole welding process with K-TIG

Liu, Zuming; Fang, YueXiao; Cui, ShuangLin; Luo, Zhen; Liu, Weidong; Liu, Zhiyi; Jiang, Qu; Song, Yu

doi:10.1016/j.jmatprotec.2016.07.005

Cited by 61 publications

(16 citation statements)

References 11 publications

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“…4(g,h). The results suggest that for K-TIG welding of 9mm armour grade Q&T steel, stable keyhole process can be achieved with current range of 545-565A at travel speed of 28cm/min -1 , which is narrower compared with stainless steel as reported in [30]. The cross-sectional macrographs of the four joints are shown in Fig.…”

Section: The Effect Of Varying Heat Input On Surface Morphologymentioning

confidence: 59%

Investigation into the viability of K-TIG for joining armour grade quenched and tempered steel

Fei

Pan

Cuiuri

et al. 2018

Journal of Manufacturing Processes

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Motivated by significant loss of mechanical properties during conventional fusion arc welding processes owing to under matching filler materials used and low efficiency associated with multipass welding, the viability of keyhole tungsten inert gas (K-TIG) welding for joining armour grade quenched and tempered (Q & T) steel was presented. Single pass full penetration was achieved on 9 mm thick plates at a speed of 28 cm/min −1 without using any filler materials and edge preparation. In-depth investigation into the weld was conducted by optical microscope, scanning electron microscope, electron back-scattered diffraction, microhardness and tensile test. The results show that the weld metal consists of dendritic structure and predominantly bainitic microstructure and is dominated by low angle grain boundaries. Hardness distribution across the weld is higher than current practice, which would lead to improved ballistic performance. Although the joint efficiency of the weld is 65% due to reduction in weld metal hardness, it is still much higher than that produced via conventional fusion welding, which is not surpassing 50%. It has been demonstrated that the K-TIG welding process offers a new way to weld medium thick armour grade Q & T steel with high efficiency and low cost, while maintaining the mechanical properties at a high level. . (2018). Investigation into the viability of K-TIG for joining armour grade quenched and tempered steel. Journal of Manufacturing Processes, 32 482-493. Hightlights• The feasibility of K-TIG for joining medium thick (6-13mm) materials with relatively high thermal conductivity was first investigated.• Single pass full penetration was achieved on 9mm thick armour grade quenched and tempered steel at a speed of up to 28cm/min -1 without using filler materials and edge preparation.• Tensile properties and hardness distribution of weld were higher than current practice, which would lead to improved ballistic performance. Graphical abstract2 ABSTRACT Motivated by significant loss of mechanical properties during conventional fusion arc welding processes owing to under matching filler materials used and low efficiency associated with multipass welding, the viability of keyhole tungsten inert gas (K-TIG) welding for joining armour grade quenched and tempered (Q&T) steel was presented.Single pass full penetration was achieved on 9mm thick plates at a speed of 28cm/min -1 without using any filler materials and edge preparation. In-depth investigation into the weld was conducted by optical microscope, scanning electron microscope, electron backscattered diffraction, microhardness and tensile test. The results show that the weld metal consists of dendritic structure and predominantly bainitic microstructure and is dominated by low angle grain boundaries. Hardness distribution across the weld is higher than current practice, which would lead to improved ballistic performance. Although the joint efficiency of the weld is 65% due to reduction in weld metal hardness, it is still much higher than that pr...

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Section: The Effect Of Varying Heat Input On Surface Morphologymentioning

confidence: 59%

Investigation into the viability of K-TIG for joining armour grade quenched and tempered steel

Fei

Pan

Cuiuri

et al. 2018

Journal of Manufacturing Processes

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“…K-TIG mitigates the traditionally insufficient energy densities of TIG based techniques by surrounding the tungsten electrode with a cooling shoulder which passes water around it to restrict the high temperature area of the electrode to the tungsten tip. Combined with the magnetic 'pinching' effect in plasmas -a process whereby the flow of charged particles induce a magnetic field around themselves which in turn constricts the flow of the charged particlesthe arc jet diameter is restricted and thus the energy density of the arc in increased [18]. When the Arc Pressure reaches a sufficient level, the surface tension of the weld pool can be overcome, and a keyhole is formed [19].…”

Section: Deep Penetration Weldingmentioning

confidence: 99%

A Feasibility Study Comparing Two Commercial TIG Welding Machines for Deep Penetration

2019

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Developing a deep penetration TIG welding technique to produce welds of equal quality to the industrial standard practise of laser-based welding techniques has the potential to lower production complexity and cost. Higher currents levels are required to increase penetration depth in conventional TIG welding but this results in excessive weld bead width amongst other detrimental effects. However, through K-TIG and A-TIG techniques these detrimental effects can be circumnavigated. Prior experimental work on weld pool dynamics in conventional TIG welding in higher current regions has been sparse as TIG welding enhanced through novel techniques provides the best quality welds. This paper is an early feasibility study for novel deep penetration welding techniques motivated by observations made during research done at The University of Sheffield where unexpected activity in the weld pool was identified during TIG welding with a VBC IE500DHC between 300A – 1000A. This current range is labelled the ‘Red Region’. Understanding the fluid dynamics of the molten metal in the weld pool at the ‘ Red Region' current level will help in the creation of novel techniques for deep penetration TIG welding. Addressing this, this paper compares the quality of welds produced between 100A and 200A on 316 Stainless Steel by two industrially leading welding machines; the Miller Dynasty 350 and the VBCie 500DHC.

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“…Although heat density of K-TIG is far lower compared to high power density welding, it is easier to operate and more cost-effective, as stated by Liu et al [3]. In addition, Liu et al [4] reported that K-TIG was able to achieve continuous open keyhole and was more stable than PAW. It was also demonstrated by Liu et al [5] that K-TIG had much wider operating window compared with PAW owing to the fact that it has much smaller arc pressure/arc current ratio.…”

Section: Introductionmentioning

confidence: 99%

Effect of Heat Input on Weld Formation and Tensile Properties in Keyhole Mode TIG Welding Process

Fei

Pan

Cuiuri

et al. 2019

Metals

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Keyhole mode Tungsten Inert Gas (K-TIG) welding is a novel advanced deep penetration welding technology which provides an alternative to high power density welding in terms of achieving keyhole mode welding. In order to facilitate welding procedure optimisation in this newly developed welding technology, the relationship among welding parameters, weld formation and tensile properties during the K-TIG welding was investigated in detail. Results show that except for travel speed, the heat input level also plays an important role in forming undercut defect by changing the plasma jet trajectory inside keyhole channel, leading to the formation of hump in the weld centre and exacerbation of undercut formation. Both undercut defect and root side fusion boundary can act as a stress concentration point, which affects the fracture mode and tensile properties considerably. The research results provide a practical guidance of process parameter optimisation and quality assurance for the K-TIG welding process.

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Stable keyhole welding process with K-TIG

Cited by 61 publications

References 11 publications

Investigation into the viability of K-TIG for joining armour grade quenched and tempered steel

Investigation into the viability of K-TIG for joining armour grade quenched and tempered steel

A Feasibility Study Comparing Two Commercial TIG Welding Machines for Deep Penetration

Effect of Heat Input on Weld Formation and Tensile Properties in Keyhole Mode TIG Welding Process

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