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.

Double-electrode GMAW process and control : A novel welding process adds a GTAW torch to a conventional GMAW system to create a bypass arc for increasing melting current while controlling base current

Abstract: Double-electrode gas metal arc welding (DE-GMAW) is a novel process that decouples the melting current into base metal current and bypass current by adding a bypass torch to a conventional GMAW system to establish a bypass arc. This makes it possible to increase the melting current while the base metal current can be controlled at a desired level. Experiments have been done to find the conditions that can assure a stable bypass arc is established/maintained between the welding wire and the bypass torch. To control the base metal current at the desired level, a group of power resistors is added in the bypass loop. The resistance of the power resistor group is adjusted real-time by changing the combination of the resistors, and the change in the resistance results in a change in the bypass current and thus a change in the base metal current. A model has been developed to correlate the change of the resistance needed to achieve the desired base metal current to the deviation of the base metal current from its desired level. Experiments demonstrated that the developed control system can adjust the bypass current in a great range to maintain the base metal current at the desired levels.

Consumable Double-Electrode GMAW -Part 1: The Process Arc stability, bypass current, and metal transfer mode were studied to better understand the fundamental issues of the process

Abstract: Double-electrode gas metal arc welding (DE-GMAW) is a novel welding process recently developed to increase welding productivity while maintaining the base metal heat input at a desired low level. In this paper, the DE-GMAW process was improved by replacing its non-consumable tungsten electrode with a consumable welding wire electrode resulting in a new process called consumable DE-GMAW. To understand this new process and its prospects as an effective manufacturing process, the authors have studied fundamental issues and proposed solutions to resolve the problems encountered. These fundamental issues include the stability of the process, the adjustability of the bypass current, the effects of the bypass arc on the total current and the melting rate, and the mode of metal transfer of the bypass welding wire.

The influence of thermal properties and preheating on residual stresses in welding

Abstract: A 2D finite element model has been carried out to analyse temperature distribution in butt weld joints. Temperature fields have been investigated by varying both thermal properties and an initial preheating treatment. Successive thermo-mechanical analyses were performed to evaluate resulting residual stresses. Temperature distribution and residual stresses were determined in a single-pass butt joint welded by Gas Metal Arc Welding (GMAW) process. A finite element parametric model was carried out and the technique of 'element birth and death' was adopted to simulate the process of filler metal addition. By means of finite element analysis high stresses were evaluated, with particular regard to Fusion Zone (FZ) and Heat-Affected Zone (HAZ). The influence of thermal properties and preheating on residual stresses in welding was also investigated. In the last few years, various experimental destructive and non-destructive methods were developed to evaluate residual stresses. However it is impossible to obtain a full residual stress distribution in welded structures by means of experimental methods. This disadvantage can be solved by means of computational analysis, which allows to determine the whole stress and strain fields in complex structures. This paper demonstrates that the technique of 'element birth and death' is suitable to simulate welding processes. Moreover, the study of welded joints should take into consideration the effect of material thermal properties and preheating treatment. [Received 18 November 2005, Accepted 20 January 2007]

Numerical simulation of arc and droplet transfer in pulsed GMAW of mild steel in argon

Abstract: The process capability of gas metal arc welding (GMAW) processes is mainly determined by the arc properties and the material transfer. In recent years, numerical methods are being used increasingly in order to understand the complex interactions between the arc and material transfer in gas metal arc welding. In this paper, we summarize a procedure to describe the interaction between an arc and a melting and vaporizing electrode. Thereafter, the presented numerical model is used to investigate the arc properties and the metal transfer for a pulsed GMAW process of mild steel in argon. The results of the numerical simulation are compared with OES measurements as well as high-speed images at different times in the pulse cycle and show excellent agreement. The results illustrate the high influence of the changing vaporization rate on the arc attachment at the wire electrode in the high current phase. It could be shown that a substantial part of the current does not participate in the constriction of the wire electrode via the resulting lorentz force which explains the nearly spatter-free droplet detachment in pulsed GMAW processes of mild steel in argon shielding gas.