1993 Volume 11 Issue 2 Pages 300-306
A Mild steel was welded in pressurized Ar-O2 gas mixture atmospheres up to 2.0 MPa, using a 1.6 mm diameter solid wire. The effects of ambient gas pressure and gas composition on the arc welding phenomena and mechanical properties of weld metal were studied. The main results are as follows :
The fluctuations of arc voltage and welding current are small and the arc stability is fairly good. The weld metals obtained in this experiments have no defects such as under-cutting, overlapping, blow holes. The Vickers hardness and tensile properties of weld metals were varied with the ambient gas composition, but did not depend on the ambient gas pressure. The Charpy V-notch toughness of weld metal was changed markedly with O2 partial pressure in atmosphere and showed a maximum at 0.02-0.05 MPa oxygen partial pressure which resulted in about 0.03 mass% oxygen content of weld metal having a fine ferrite structure. This suggests that toughness is strongly influenced by the oxygen content of weld metal.
