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The three-dimensional finite element method was used to analyse the effect of changing the buccal tube baseplate shape on the stress magnitude and distribution at the interface between the buccal t...

In order to study the effects of laser induced metal vapour on arc plasma during laser arc double sided welding (LADSW), emission spectroscopy techniques were utilised. The arc plasma in LADSW of 5A06 aluminium alloy was compared with conventional gas tungsten arc welding (GTAW) in this work. The electron temperature and density were estimated by the Saha–Boltzmann equation and the Stark broadening effect. The results indicated that the amount of metal vapour in the arc plasma during LADSW was larger than that of GTAW. Furthermore, the electron temperature of arc plasma in LADSW was lower than that in GTAW, and the electron density of arc plasma in LADSW was higher than that in GTAW near the arc anode. It was shown that the differences in arc properties between LADSW and the conventional GTAW processes were the result of laser induced metal vapour changing the composition of the arc plasma.

The experiments of CO2 laser TIG paraxial hybrid welding with 4 mm thick AISI 321 stainless steel sheet have been performed. The arc images and welding characteristics have been investigated with different energy ratios between laser and arc. The experimental results indicate that the hybrid welding is similar to laser welding and has also two welding mechanisms: deep penetration welding and heat conduction welding. Because of the effect of keyhole induced by laser, the arc root can be stabilised and compressed, and the current density and the penetration depth are all increased significantly, which show the characteristics of deep penetration welding. However, when the current is increased to a critical value, the laser induced keyhole disappears and the arc expands obviously, which decreases the penetration depth, so that the welding mechanism has been changed from deep penetration welding to heat conduction welding. Furthermore, the effects of distance between laser beam and electrode, pulsed l...