Abstract
It is essential for the estimation of energy given to electrode of arc to know how much heat energy is included in the melted globule, which seems not to have ever been measured directly.
The calorimetric method is used for the measurement of heat involved in the globule from the melted electrode of arc. The heat quantity per unit weight of melted metal depends upon the apparent current density of electrode, having much more than the value corresponding to its melting point. With MIG welding method, the melted globule has the heat quantity 550 cal/g which is approximately equal to that at its boiling point.
The results are as follows ;
1) With hand welding method, the heat quantity in melted metal depends upon the apparent current density of electrode.
2) The heat quantities of melted iron and aluminium electrodes increase with apparent current density between 600 and 2000 A/cm2 but saturate over that, while in copper it is almost constant under 5000 A/cm2.
3) The heat quantity of iron anode metal depends upon the surface conditions, while that of cathode is almost independent of them.
4) The heat quantity of melted anode metal is generally higher than that of melted cathode metal, and their difference is 30-50 cal/g with MIG welding method.
5) With MIG welding method, the shorter the electrode extension, the higher the heat quantity is, and it approaches the value corresponding to its boiling point.
