Gas metal arc welding

About: Gas metal arc welding is a research topic. Over the lifetime, 11706 publications have been published within this topic receiving 109555 citations. The topic is also known as: metal active gas welding & GMAW.

The effects of welding parameters on ultra-violet light emissions, ozone and CrVI formation in MIG welding

Abstract: This paper describes the relationships between ultra-violet emission, ozone generation and CrVI production in MIG welding which were measured as a function of shield gas flow rate, welding voltage, electrode stick-out and shield gas composition using an automatic welding rig that permitted MIG welding under reproducible conditions. The experimental results are interpreted in terms of the physico-chemical processes occurring in the micro- and macro-environments of the arc as part of research into process modification to reduce occupational exposure to ozone and CrVI production rates in MIG welding. We believe the techniques described here, and in particular the use of what we have termed u.v.-ozone measurements, will prove useful in further study of ozone generation and CrVI formation and may be applied in the investigation of engineering control of occupational exposure in MIG and other welding process such as Manual Metal Arc (MMA) and Tungsten Inert Gas (TIG).

Full penetration laser beam welding of thick duplex steel plates with electromagnetic weld pool support

Abstract: Full penetration high power bead-on-plate laser beam welding tests of up to 20 mm thick 2205 duplex steel plates were performed in PA position. A contactless inductive electromagnetic (EM) weld pool support system was used to prevent gravity drop-out of the melt. Welding experiments with 15 mm thick plates were carried out using IPG fiber laser YLR 20000 and Yb:YAG thin disk laser TruDisk 16002. The laser power needed to achieve a full penetration was found to be 10.9 and 8.56 kW for welding velocity of 1.0 and 0.5 m min−1, respectively. Reference welds without weld pool support demonstrate excessive root sag. The optimal value of the alternating current(AC) power needed to completely compensate the sagging on the root side was found to be ≈1.6 kW for both values of the welding velocity. The same EM weld pool support system was used in welding tests with 20 mm thick plates. The laser beam power (TRUMPF Yb:YAG thin disk laser TruDisk 16002) needed to reach a full penetration for 0.5 m min−1 was found to be 13.9 kW. Full penetration welding without EM weld pool support is not possible—the surface tension cannot stop the gravity drop-out of the melt. The AC power needed to completely compensate the gravity was found to be 2 kW.

Monopulse investigation of drop detachment in pulsed gas metal arc welding

Abstract: The drop detachment process in pulsed welding was investigated by a novel, non-continuous method. A pendent drop was formed on a fixed electrode by a low-current arc. The drop was then detached by a single high-current pulse. The detachment process was studied by high-speed filming and by current and voltage measurements. The shielding gas was Ar with various amounts of CO2, O2, H2 and He. Comparative experiments with ordinary pulsed welding were also done. The authors found ample evidence for an upward force on the pendent drop, most likely caused by the recoil force of evaporating metal. The force increases with CO2 concentration, base current and base current duration. The recoil force gives rise to a critical concentration of the molecular additive, above which it is impossible to detach the drop almost regardless of pulse width. This critical concentration decreases with increasing base current and base current duration. It also seems to decrease with increasing dissociation energy of the molecular additive. The drop velocity decreases with increasing CO2 concentration. For 95Ar5CO2 they also present results on the effect of drop mass and pulse current on drop velocity, minimum pulse width for detachment, and shortest detachment time (tdmin). They find evidence for a minimum detachable drop mass being smallest for large pulse currents. In the pulse current range 210-350 A they observe Ip1.7 tdmin=43, and in the range 350-600 A, Ip1.2 tdmin=2.4 (basic SI-units).

A fuzzy logic system for process monitoring and quality evaluation in GMAW: Monitoring weld quality in real time is proposed using voltage and current for raw data to develop graphic histograms

Abstract: This paper introduces a fuzzy logic system that is able to recognize common disturbances during automatic gas metal arc welding (GMAW) using measured welding voltage and current signals. A statistical method was employed to process the captured transient raw data, and the probability density distributions (PDDs) and the class frequency distributions (CFDs) were obtained. Based on the processed data (PDD values of welding voltage and current and CFD values of the short-circuiting timel, the system automatically generates fuzzy rules and membership functions of linguistic variables, conducts inference and defuzzification, and completes the evaluation process without further expert knowledge.