The butt joints of Zircaloy-4 plates are made by electron beam welding. The
corrosion resistance of welding seams is poor
to form white oxide films on the surface of molten zone after autoclave tests at 400oC 10.3MPa superheated steam for 3 to 14 days. The relationship between the variation of the contents of alloying elements in molten zone,which were analyzed by means of electron microprobe,and the
corrosion resistance have been investigated. It is proved that the degradation of corrosion resistance of welding seams is mainly due to the loss of the alloying elements of Sn,Fe and Cr by the vaporization in molten zone. When the
zirconium alloy plates,in which the alloying element contents are higher than that of Zircaloy-4, are employed for making butt joints with Zircaloy-4 plates, the loss of alloying elements in molten zone can be compensated,so that the degradation of corrosion resistance can also be remedied. Adding 0.4-0.5%Nb alloying element in zirconium alloy is advantage for further improvement of the corrosion resistance of welding seams,but annealing should be carried out at 500~600oC after welded in order to get the decomposition of βZr into αZr+βNb.