Abstract:When the zirconium alloy plates with the same Fe content and different Cr content were used to make the butt joints with Zr-4 alloy plates, the hydrogen content in welding samples is obviously different after corrosion and is not in proportion to the thickness of oxide films. This shows that alloying element Cr has a significant effect on hydrogen uptake performance. The hydrogen content in welding samples, in which zirconium alloy plates being used to make the butt joints with Zr-4 plates dont contain Cr, decreases sharply after corrosion. The relationship between hydrogen content and the number and size of Zr(Fe,Cr)2 second phase particles in Zr-4 with different heat-treated states indicates that the formation of Zr(Fe,Cr)2 second phase particles is the main reason that the amount of hydrogen uptake increases. Adding Nb alloying element in zirconium alloys without Cr, not only improves the corrosion resistance, but also make hydrogen uptake not to increase. The zirconium hydrides induced by tensile stress are easy to precipitate in the front of faulty fusion, and they are also easy to precipitate along the interface between molten zones and matrix. These will influence the dispersity of mechanical properties.