Abstract
In this report, the tendency of blow hole formation was investigated for MIG welds of aluminum alloy A5083P-O, in case of which the surface treatments adopted for base metal were changed. The adopted treatments were three kinds, machining, wire brushing, and chemical treatment, and welds were produced in horizontal position, using mainly V-groove bead on plate test pieces.
Furthermore, the effect of intervals after treatment was also investigated.
The results obtained are summarized as following.
(1) Chemical treatment surface forms more blow holes than machining and wire brushing surface.
(2) Several days interval after chemical treatment increases the number of blow holes, but even about 30 days interval after machining does not affect.
(3) Butt welds form more and large blow holes than V-groove bead on plate in case of same surface treatment.
(4) At chemical treatment, temperature, concentration, dipping time of NaOH solution were changed, keeping HNO3 conditions constant. The heavier conditions (temp. was higher, conc. was stronger, time was longer), the more blow holes wer formed. Especially, in case of omission of dipping in HNO3 solution, blow holes increase markedly.
