A high-voltage electrcn-beam welding machine with a maximum beam power of 1.5 kw (50 kV, 30 mA) has been operated in the Japan National Research Institute for Metals since July 1960. With this equipment, the characteristics of bead penetration and welded joints of Zirconium and Zircaloy-2, namely, microstructure, hardness, tensile and bending properties and corrosion resistance against high temperature, high pressure water studied as compared with the case of TIG welding, and the following conclusions were obtained :
(1) It is possible to make a butt-joint weld at a high welding speed such as 40 to 100cm/min up to about 2.0 mm thickness of sheet.
(2) Relationship between specific weld heat input and ratio of bead penetration-to-width is given by following equation. w/p X 100=76 log H-45
(3) About three times the specific weld heat input of electron beam welding is necessary for TIG welding to give the same bead penetration.
(4) To make a smooth and not-burn - through welding bead, it may be supposed that a low voltage type power source should be preferred type, especially, for a thin sheet.
(5) No evidence has been found to substantiate the occurrence of a change in oxygen and nitrogen composition due to this welding process.
(6) Metallography, hardness, mechanical-property evaluations and corrosion tests have revealed satisfactory properties in Zirconium and Zircaloy-2 wleded joints by this welding process.
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