1949 Volume 18 Issue 9-10 Pages 143-151
The author studied the weldability of an electrode core, with the intention of determining whether the quality of an electrode could be determined by summing up the weldability of its core and flux. The most important factors of the core weldability seems to be the size of molten-metal drops, stillness of molten-metal pool and melting speed of the core at the welding operation.
The author found that there was another important factor apart from the ones already discussed generally, namely chemical constituents such as C, Si, Mn, etc, and the non-metallic inclusions, which seriously affect the core weldabilitY, as a result of investigations of the manufacturing process and trial-making of various cores. It is desirable that the inclusions should be less than 0.01% (analysed by the acid dissolving method) for pure iron and standard mild steel core. Many difficulties are expected in the steel making process, especially under such bad conditions as in our country, but efforts should be made to decrease the inclusions as much as possible even under these conditions for obtaining a core of good quality.
Next, the author made some studies on a core containing more Si than the above-mentioned two types, and found the core could not show so good a weldability as the two types.
The immediate cause of the bad weldability seems to be existence of CO gas produced when the inclusions are reduced by C included in the core and parent metals at a very high temperature of the welding arc.