Abstract
The feasibility of gravity welding and welding phenomena under pressurized argon atmosphere (up to 5 MPa gauge) were investigated. The ilminite type, high titanium oxide type and low hydrogen type electrodes of 4 mm in diameter were used. As base metals, SM41A steel plates of 6 and 9 mm in thickness were used.
Main results obtained are summarized as follows:
1) Sound weld can be obtained under pressurized argon atmosphere up to 5 MPa by low hydrogen type electrode. Porosity and pits are not observed in the weld, but occurred by the other type in the pressure range of 0.1 to 0.7 MPa, which disappeared when pressure is over 1.0 MPa.
2) The suitable welding current to obtain sound welds increases with increasing ambient pressure.
3) Butt welded joints obtained by low hydrogen type electrodes under pressure up to 5 MPa have sufficient tensile strength and impact value. However, the tensile strength and the impact value decrease with increasing pressure.
4) The maximum voltage Vmax and the mean voltage Vmean increase with increasing pressure up to 2 MPa. However, they have a tendency to decrease over 2 MPa. The minimum voltage Vmin decreases with increasing ambient pressure.
5) The melting rate of electrode decreases with increasing pressure up to 0.5 MPa, while it increases over 0.5MPa.
6) The transfer period of droplet from electrode tip increases with increasing pressure up to 0.5 MPa, while it decreases over 0.5 MPa.
7) The diameter of droplet increases with increasing pressure up to 0.5 MPa, while it decreases over 0.5 MPa.
