Abstract: Welded joints of pure nickel sheets were cold rolled and annealed between 800-1100 ℃. The effects of cold rolling and annealing processes on microstructure and mechanical properties of pure nickel sheets were studied. The results show that after cold rolling with 75% deformation, the grains of the welded joints are broken, and the microstructure is linear and fibrous along the rolling direction, the tensile strength is about 611 MPa and the elongation is about 5.6%. When annealed at 800 ℃, the microstructure is partially recrystallized, but there are still a large number of elongated linear fibers, the tensile strength is 387.9 MPa and the elongation is 20.4%. When annealed at 900 ℃ most of the linear fibers recrystallized, the tensile strength is 363.5 MPa and the elongation is 23.7%. When annealed at 1000 ℃, all the linear fibers disappeared, and the microstructure is completely recrystallized,the tensile strength is 357.5 MPa and the elongation is 32.3%. When annealed at 1100 ℃, the change of microstructure and mechanical properties are not obvious compared with annealed at 1000 ℃, the tensile strength is 355.3 MPa and the elongation is 30.9%. Compared with the mechanical properties and microstructure, 1000 ℃ is the best intermediate annealing temperature.

Key words: pure nickel welded joints, cold rolling, annealing, mechanical properties, microstructure