Dominant Heat Transfer Mechanisms in the GTAW Plasma Arc Column

Multiphysics modelling of Gas Tungsten Arc Welding on ultra-thin-walled titanium tubing

“…This difference manifests as a different focus of the work. For instance, work by Velázquez-Sánchez et al [5] presents a highly detailed representation of the GTAW process through simulating much of the physics involved with of goal of identifying the dominant heat transfer mechanisms in GTAW. Thus by definition it does not seek to provide a practitioner with a WPS for a particular welding job.…”

“…Photograph of a selection of welds with 'low limit' inner diameter pressurization (1,2), correct inner diameter pressurization (3,4) and 'high limit' inner diameter pressurization (5,6). .…”

“…A common intuition when considering the physics of welding is how the temperature of the GTAW arc affects the weld pool. However, given the main heat transfer mechanism in GTAW is joule heating [5], the maximum temperature of a GTAW arc (>20 000 K) is not particularly relevant. Despite this, the temperature gradient from the peak at the centre of the arc to the edge is important.…”

“…Modelling the GTAW arc accurately requires a detailed representation of the cathode (the electrode in DCEN), the plasma column (the highly visible portion of the electric arc) and the cathode layer (the sources of the various electron emissions) [28]. Whilst some issues still remain [29,30], in recent years there have been multiple sophisticated models of the GTAW arc that elucidate the plasma physics involved [31][32][33]. These accurate GTAW arc models enable a understanding of the heat input into the work piece.…”

“…Therefore, purely from an experimental perspective, successfully welding the ATLAS ITk cooling system tubes would demonstrate a novel advance. The requirements for this advance against previous research is compared in Table 2 [31] presents a richly detailed and sophisticated understanding of the temperature profile of a welding arc. But, this is for a stationary arc in a steady state simulated in two dimensions.…”