1965 Volume 34 Issue 2 Pages 137-145
The phenomena of horizontal fillet and vertical welding have been studied in the light of inte rfacial tension theory, and it was concluded as follows,
(1) The sectional curve of harizontal fillet weld is determined by both gravity and the interfacial tension γ of the molten metal drop, the mother drop, covered with molten slag, and there seems to be a limit value of leg length, for a system of metal and slag.
(2) The possibility of vertical welding depends upon that a mother drop can adhere on the vertical plate surface, and it can be realized by the most essential fact that the mother drop, confined within the concave penetration surface, behaves as if it were the more wettable liquid drop.
(3) The contact angle of mother drop determines the sectional shape of the weld bead. The great contact angle of the mother drop with high iron oxide type electrode yields the rather convex bead in flat welding, and bead of equal leg length in horizontal fillet welding, on the other hand, the small contact angle with ilumenite type electrode gives the flatter bead in flat welding and concave one in horizontal fillet welding. These facts has been proved by means of many measurement of solidification angle in the penetration surfaces.
(4) There are twe types of the state of the mother drop within the penetration surface. One of them is the advancing type and the other, receding one, each having the following characteristics.
advancing type receding type
blowing force of arc weak strong
contact angle small great
penetration shallow deep
bead appearance good undercut
bead surface smooth wavy
sectional shape of bead flat convexe