Abstract
This paper reports the effects of mixing ratios among argon, helium, and nitrogen on welding usability, grain size of beads, and cracks.
The following results were obtained.
(1) When the mixing ratios of gases in MIG welding were proper, welding usability was as good as that in He-N2 gas.
(2) Generally, mixed gas of helium (30-60%) nitrogen (about 14%), and argon (the balance) was effective for the welding of Al-Zn-Mg alloys and Al-Mg alloys.
(3) The grains in bead of welded specimens containing titanium and zirconium were refined by the addition of nitrogen to the shield gas, the same as the results in the previous report.
(4) Welding cracks were decreased in the specimens, of which the grains in bead had been refined by the addition of nitrogen.
