On the Porosity of Weld Steel With Low Hydrogen Type Electrode (Report 1)

Effects of Kind of Welding Current, Polarity and Contents of Deoxidizers of Electrode

Abstract

Though the low hydrogen type electrode can yield the superior mechanical properties of weld metal, its usability and arc stability is poorer than other kinds of electrodes. And more porosity of weld metal is observed in case of using this low hydrogen type electrode.
In this report, this porosity was examined with eighteen brands of the low hydrogen type electrodes in market and nine kinds of the similar type made for trial.
The results of experiments are as follows :
1. In case of adopting direct current reverse polarity, the porosity is less than that in adopting al-ternating current or direct current straight polarity, but it is not always possible to prevent the occurrence of pits or blowholes completely.
2. The porosity is the largest at the start of bead and comparatively large at the part of crater. At the middle part of bead, the porosity is smaller than other parts.
3. If the contents of deoxidizers, in electrode core wire or in coating of electrode, increase, the porosity shows a tendency to decrease.
4. The composition of coating of electrode has influence on this porosity and this is supposed to be based on the difference in their action to protect the molten metal in transfering and after deposition for the harmful atmosphere.