On The Carbon Dioxide-Sekiguchi's Filler Wire-Arc Welding Process (Report 7)

From the results of the determinations of hydrogen, nitrogen and oxygen contents of the weld metals obtained by the various welding processes, the authors recognized the following facts:1. In comparison with the argon-metal-arc, the submerged arc and the manual arc welding with two types of coated electrodes, the C. S. arc welding gives a weld with the smallest content of hydrogen.2. It is deduced that the shielding effect of thesupplied gas in case of the C. S. are welding process is the same degree as well as the argon-metal-arc and the submerged arc welding processes, because the nitrogen content of the weld metal by the former process is the same degree as the latter.3. A manual arc welding with a low hydrogen type electrode has the poorest shielding effect, because it gives a weld with the largest nitrogen content in comparison with the other welding processes.4. The total oxygen content of weld increases with welding process in order as follows ; the argon-metal-arc, the C. S. arc, the manual arc with a low hydrogen type electrode, the one with a ilmenite type electrode and the submerged arc welding.Then the authors clarified experimentally the relation between the dew point of supplied gas and the hydrogen content of weld by the C. S. arc welding, and the fact that the hydrogen content increases steeply with the increment of the dew point of the supplied gas over-10°C. And the ductility of the weld metal, obtained by the shielding with the gas having such a high dew point, is lower than the one with the gas having a lower dew point.Moreover, the authors showed that the moisture in a conduit and the rust on an electrode increases the hydrogen content of the weld by the C. S. arc welding process. If the sufficient attention is paied on such points, i.e., if the dried gas and conduit and a rustless electrode are used, the C. S. arc welding gives a weld having the lowest hydrogen content in comparison with all other arc welding processes.Accordingly, the C. S. arc welding showed also a very low frequency of fisheye occurrence, which is due to hydrogen in weld metal, on the fracture of tension test specimen. This was ascertained experimentally by many tension tests in comparison with the manual arc welding using a low hydrogen or an ilmenite type electrode.