Using 55 kinds of electrodes of mild steels of home and foreign make, the single V butt joints of mild steel plates were made by an alternating current welding machine, and the effects of quantity, thickness and ignition loss of the e'ectrode-coating on the mechanical properties of the deposited metals were investigated.
The welding properties of the electrodes were at first observed and terminal voltages of the machine and melting times of the electrodes of constant length were also measured. After a radiographic examination of the welded part was made, apparent specific gravity, nitrogen content and mechanical properties of the deposited metal were measured. Microscopic examination was also made. From these experiments the following conclusions were drawn statistically.
(1) As the quantity or thickness of coating increases, (a) terminal voltage of the machine and electric energy to melt a constant length of electrode increase, and (b) tensile strength and yielding point of the deposited metal are nearly constant, while its elongation and shock value increase.
(2) If the quantity of coating is constant, the elongation and shock value of the deposited metal increase as the ignition loss increases.
The conclusions of (1, b) and (2) are mainly attributed to the amount of nitrogen and blow holes in the deposited maial, which depend upon the quantity or thickness of electrode-coating.
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