The Paton Welding Journal, 2025, №11

2025 №11 (06)

DOI of Article 10.37434/tpwj2025.11.01

2025 №11 (02)

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The Paton Welding Journal, 2025, #11, 3-9 pages

Optimization of the pulsed current waveform and parameters in HFPC TIG welding

I. Krivtsun¹, V. Demchenko¹, D. Nomirovskii², D. Kovalenko¹, U. Reisgen³, O. Mokrov³, R. Sharma³

¹E.O. Paton Electric Welding Institute of the NASU. 11 Kazymyr Malevych Str., 03150, Kyiv, Ukraine. E-mail: d_v_kovalenko@ukr.net
²Taras Shevchenko National University of Kyiv 60Volodymyrska Str., 01033 Kyiv, Ukraine
³RWTH Aachen University, ISF – Welding and Joining Institute Pontstr. 49, 52062 Aachen, Germany

Abstract
Experimental studies have shown that high-frequency pulsed modulation of welding current allows for an increase in penetration capacity of the welding process with tungsten electrode. This effect is attributed to intensified convective flows in the weld pool, excited by a high-frequency electromagnetic field. The article examines the problem of determining the shape and parameters of welding current pulses that maximizes the force exerted by the modulated current on the weld pool metal. The square of the effective value of the welding current is taken as an integral measure of the force action of the electromagnetic field on the molten metal of the weld pool. The difference between the squares of the effective and average values of the modulated current, which characterizes the excess of the force action of the arc with pulsed current modulation over the force action of the direct current arc, is taken as a criterion for optimizing the shape of the current pulse. The problem of variational calculus on finding such a current pulse shape, at which the maximum of the specified difference is achieved, is solved. Two optimization methods are considered: at a given modulation amplitude and at a given average value of the modulated current. It is rigorously shown mathematically that in the first case the optimal pulse shape is a square wave, in the second case — a rectangular current pulse, the duty cycle and amplitude of which are determined by the value of the maximum current of the welding generator. The optimization of parameters of current pulses of trapezoidal and triangular shapes generated by existing welding current generators has been carried out. The proposed theory can serve as a guideline in the development of effective pulse current generators, as well as in the design the modes of the tungsten inert gas welding process with high-frequency pulsed modulation of welding current in order to increase the penetration depth and improve welding productivity.
Keywords: TIG welding, arc plasma, weld pool, electromagnetic force, direct current, pulsed current, mean and RMS values, wave form, duty cycle, amplitude, frequency

Received: 12.05.2025
Received in revised form: 24.07.2025
Accepted: 11.11.2025

References

1. Lucas, W. (1992) Shielding gases for arc welding — part I. Welding and Metal Fabrication, 6, 218??225.
2. Lu, S., Fujii, H., Nogi, K. (2004) Marangoni convection and weld shape variations in Ar–O2 and Ar–CO2 shielded GTA welding. Materials Sci. and Eng. A, 380(1–2), 290–297.
3. Lucas, W. (2000) Activating flux — improving the performance of the TIG process. Welding and Metal Fabrication, 2, 7–10.
4. Yushchenko, K.A., Kovalenko, D.V., Kovalenko, I.V. (2001) Application of activators for TIG welding of steels and alloys. The Paton Welding J., 7, 37–43.
5. Jarvis, B., Ahmed, N. (2000) Development of keyhole mode gas tungsten arc welding process. Sci. and Techn. of Welding and Joining, 5(1), 1–7.
6. Omar, A.A., Lundin, C.D. (1979) Pulsed plasma — pulsed GTA arcs: A study of the process variables. Welding J., Res. Suppl., 4, 97s–105s.
7. Saedi, H.R., Unkel, W. (1988) Arc and weld pool behavior for pulsed current GTAW . Welding J., Res. Suppl., 11, 247s–255s. 8. Onuki, J., Anazawa, Y., Nihei, M. et al. (2002) Development of a new high-frequency, high-peak current power source for high constricted arc formation. Jpn. J. Appl. Phys., 41, 5821–5826.
9. Qi, B.J., Yang, M.X., Cong, B.Q. et al. (2013) The effect of arc behavior on weld geometry by high-frequency pulse GTAW process with 0Cr18Ni9Ti stainless steel. Int. J. Adv. Manuf. Technol., 66, 1545–1553.
10. Yang, M., Yang, Z., Cong, B. et al. (2014) A study on the surface depression of the molten pool with pulsed welding. Welding J., Res. Suppl., 93(8), 312s–319s.
11. Krivtsun, I., Demchenko, V., Krikent, I. et al (2024) Comparative numerical analysis of electromagnetic forces in DC and HFPC TIG welding. Applied Mathematical Modelling, 127, 366–378.
12. Yang, M., Yang, Z., Qi, B. (2015) The effect of pulsed frequency on the plasma jet force with ultra high frequency pulsed arc welding. Welding in the World, 8, 875–882.

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Suggested Citation

I. Krivtsun, V. Demchenko, D. Nomirovskii, D. Kovalenko, U. Reisgen, O. Mokrov, R. Sharma (2025) Optimization of the pulsed current waveform and parameters in HFPC TIG welding. The Paton Welding J., 11, 3-9.

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