Weld pool oscillation during pulsed GTA welding

Book · Tue Dec 31 04:00:00 EST 1996

OSTI ID:443008

Aendenroomer, A J.R.; Ouden, G den ^[1]

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1. Delft Univ. of Technology (Netherlands)

This paper deals with weld pool oscillation during pulsed GTA welding and with the possibility to use this oscillation for in-process control of weld penetration. Welding experiments were carried out under different welding conditions. During welding the weld pool was triggered into oscillation by the normal welding pulses or by extra current pulses. The oscillation frequency was measured both during the pulse time and during the base time by analyzing the arc voltage variation using a Fast Fourier Transformation program. Optimal results are obtained when full penetration occurs during the pulse time and partial penetration during the base time. Under these conditions elliptical overlapping spot welds are formed. In the case of full penetration the weld pool oscillates in a low frequency mode (membrane oscillation), whereas in the case of partial penetration the weld pool oscillates in a high frequency mode (surface oscillation). Deviation from the optimal welding conditions occurs when high frequency oscillation is observed during both pulse time and base time (underpenetration) or when low frequency oscillation is observed during both pulse time and base time (overpenetration). In line with these results a penetration sensing system with feedback control was designed, based on the criterion that optimal weld penetration is achieved when two peaks are observed in the frequency distribution. The feasibility of this sensing system for orbital tube welding was confirmed by the results of experiments carried out under various welding conditions.

• OSTI ID: 443008
• Report Number(s): CONF-950682--; ISBN 0-87170-567-2
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ELECTRIC CURRENTS
ELECTRIC POTENTIAL
EXPERIMENTAL DATA
FREQUENCY DEPENDENCE
GAS TUNGSTEN-ARC WELDING
LIQUID METALS
ON-LINE CONTROL SYSTEMS
OSCILLATIONS
PULSES
STEELS