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.

Numerical simulation of metal transfer in argon gas-shielded GMAW

Abstract: The gas metal arc welding (GMAW) process combines aspects of arc plasma, droplet transfer, and weld pool phenomena. In the GMAW process, an electrode wire is melted by heat from an arc plasma, and molten metal at the wire tip is deformed by various driving forces such as electromagnetic force, surface tension, and arc pressure. Subsequently, the molten droplet detaches from the tip of the wire and is transferred to the base metal. The arc plasma shape changes together with the metal transfer behavior, so the interaction between the arc plasma and the metal droplet changes from moment to moment. In this paper, we describe a unified arc model for GMAW, including metal transfer. In the model, we do not account for heat transfer in the metal, but the wire melting rate is determined by the arc current. The developed model can show transition from globular transfer at low currents to spray transfer at higher currents. It was found that electromagnetic force is the most important factor at high currents, but surface tension is more important than electromagnetic force at low currents in determining the transfer mode.

Effective heat input in pulsed current gas metal arc welding with solid wire electrodes

Abstract: In this work, the heat input of the welding arc, calculated from the measured values for voltage and current, is compared to the heat gained by the weldment for pulsed and nonpulsed current welding. The effects of shielding gas composition, arc length, weld geometry and weld position on heat transfer are examined. Methods for calculating the heat received by the weld during pulsed current welding are discussed

Friction stir welding of 2219 aluminum: Behavior of θ (Al2Cu) particles

Abstract: An experimental study was conducted to determine if the maximum temperature in the workpiece can reach the lower bound of the melting temperature range and trigger liquation during friction stir welding (FSW) of aluminum alloys as some computer simulation has suggested. Alloy 2219, which is essentially a binary Al-Cu alloy, was selected as the material for study because of its clear lower bound of the melting temperature range, that is, the eutectic temperature 548°C. In addition to FSW, gas metal arc welding (GMAW) of Alloy 2219 was also conducted to provide a benchmark for checking liquation in FSW of Alloy 2219. The microstructure of the resultant welds was examined by both optical and scanning electron microscopy. It was found that in GMAW of Alloy 2219, θ (Al 2 Cu) particles acted as in-situ microsensors, clearly indicating the onset of liquation by reacting with the surrounding aluminum matrix and forming distinct composite-like eutectic particles upon reaching the eutectic temperature. In FSW, on the other hand, no evidence of θ-induced liquation was found as the welds contained θ particles alone and no eutectic particles, suggesting that the eutectic temperature was not reached during FSW. However, in most friction stir welds large θ particles were observed, some exceeding 100 μm and even 1 mm in length as compared to the normal θ particles of only about 10-15 μm in length in both the base metal and the weld, that is, the stir zone or nugget. The large θ particles appeared to have formed during FSW from agglomeration of fractured θ particles and the smaller ones of the θ particles in the workpiece. No apparent correlation between the extent of agglomeration and the welding condition was found.

Process for laser-arc hybrid welding aluminized metal workpieces

Abstract: Process for laser welding at least one metal workpiece ( 1 ) by a laser beam ( 3 ), the workpiece having a surface coating ( 2 ) containing aluminum, characterized in that the laser beam ( 3 ) is combined with at least one electric arc ( 4 ) so as to melt the metal and actually weld the workpiece(s).

Effects of shielding gas compositions on arc plasma and metal transfer in gas metal arc welding

Abstract: This article presents the effects of shielding gas compositions on the transient transport phenomena, including the distributions of temperature, flow velocity, current density, and electromagnetic force in the arc and the metal, and arc pressure in gas metal arc welding of mild steel at a constant current input. The shielding gas considered includes pure argon, 75% Ar, 50% Ar, and 25% Ar with the balance of helium. It is found that the shielding gas composition has significant influences on the arc characteristics; droplet formation, detachment, transfer, and impingement onto the workpiece; and weld pool dynamics and weld bead profile. As helium increases in the shielding gas, the droplet size increases but the droplet detachment frequency decreases. For helium-rich gases, the current converges at the workpiece with a “ring” shape which produces non-Gaussian-like distributions of arc pressure and temperature along the workpiece surface. Detailed explanations to the physics of the very complex but interesting transport phenomena are given.