Abstract
Fundamental researches and considerations for welding forces and bead formation in electronbeam welding were done to make use of the measured results of actual vertical force in welding.
The conclusions were as follows :
(1) Vertical force in electron-beam welding is generally increased with an increasing of welding current at constant anode voltage and welding speed.
The vertical force in carbon steel plate is about 2 to 3 times greater than that in aluminium at the same weld heat input.
(2) The vertical force is caused by the repulsion of metal vapour in evaporation because the repulsive force by calculation agrees with the measured force. However, forces of collision of electron-beam and repulsion by magnetic phenomenon are negligibly small compared with the repulsive force of evaporation
(3) It seems that maximum temperature in molten metal of carbon steel, aluminium, titanium or zirconium is about 200 to 400°C higher than the melting temperature of each metal.
(4) Forces which push up the molten metal backward in the back of electron-beam consist of the repulsive force of evaporation, capillary action in wedge-shape hole and surface tension in the solidus line of crater.
It seems that drilling action by electron-beam is stopped and held at the constant depth in molten metal when the push-up forces reach the counter-balance to the forces, such as weight of molten metal and repulsive force in crater, which pull down the molten metal to the bottom of the wedge-shape hole.
