Abstract: Cold pressing welding has outstanding advantages in the connection of functional materials because it does not have melting zone and welding heat affected zone. In this investigation, the butt cold pressing welding for pure copper rod was tested with compression/diameter ratio of the rod as a single variable, and conditions for obtaining better strength of welded joint were discussed in combination with numerical calculations of rod strain and microstructure analysis of joint deformation process. The results show that with the increase of the compression/diameter ratio of the pure copper rod, the effective plastic strain of each region of the welded joint increases, and therefore the maximum effective plastic strain at the joint interface goes up from 2.6 to 2.9. With the increase of strain, the proportion of recrystallized grains increases, and the tensile strength of the joint exhibits a stepwise increasing.

Key words: pure copper, cold welding, mechanical property, microstructure evolution