In the first part of this paper, the fundamental characteristics of arc behavior and bead formation were made clear in non gas-shielded arc welding using flux cored wire.
Non gas-shielded arc welding is characterized by the following two properties in comparison with the other arc welding using solid wire.
(1) The digging action by arc force on molten pool is very weak.
(2) The arc is soft and formed in accordance with the surface shapes of mother plate or molten pool.
As a result of above mentioned property (1), the penetration in this method comes to be shallow one with wide bead-width, especially at low welding speed in which molten pool volume increases just under the arc.
The arc behavior such as property (2) is clearly observed at high speed V-groove welding where the arc is formed separately on the both faces of groove.
Such a separation of heat source strongly depends on arc voltage and groove angle and influences the bead formation and results in the lack of fusion at groove-bottom in the extreme case of high welding speed.
In the second, a study was made on the melting phenomena and bead formation in horizontal fillet welding on the basis of above mentioned characteristics.
The bead formation in high speed horizontal fillet welding is similar to that in downward V-groove welding, at low speed range, the effect of gravitational force on bead formation, however, appears remarkably as follows :
(1) The leg-length on vertical plate is considerably greater than that on horizontal plate, because the metal-flow in the direction of the vertical plate by plasma stream comes to be strong with hanging of molten pool and contributes to the melting process.
(2) Because of weak arc force in the present process, the bead surface shape is quantitatively close to the result of surface tensional analysis under gravity assuming two dimensional molten pool. Therefor, if the leg-lengths and the quantity of deposit metal are given, bead shape in horizontal fillet weld might be derived from the two dimensional analysis used in this study.
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