Researches on Hot-Start (Report 3)

Abstract

It has already been reported that in case of welding by low hydrogen electrodes, the Hot-Start method is quite effective to prevent porosity in starting point of beads, which method is now being adopted for practical use.
In order to find out the most effective condition in the current and the time of Hot-Start an experiment with short bead method has been carried out. As the result of X ray inspection for about 350 of the above short beads, time-porosity curves in each Hot-Start current drew our attention and interest. From these curves, we can find two important indices i.e. the severity of porosity elimininating time. By using these indices, we will be able to detect the best conditions of Hot-Start on each kind of the electrodes and furthermore, to make comparison of the prosity preventing caracteristics of two or more kinds of electrodes.