Abstract:With the development of miniaturization of heat pipes for heat dissipation of electronic products, there is a growing demand for the shell to exhibit excellent processing performance without significant wrinkles, which requires better control of the microstructure of oxygen-free copper tubes as the shell material. Therefore, in this paper, the optimal processing technology for oxygen-free copper tubes in heat pipes was obtained by characterizing the microstructural features of oxygen-free copper tubes and corresponding heat pipes produced by different annealing processes, comparing the proportion and distribution of various textures and twinning, and analyzing the changes in mechanical properties of heat pipes. The results showed that the online annealing process improved the tensile strength of oxygen-free copper tubes and heat pipes. However, it promoted the generation of twinning and suppressed the growth of Goss texture, reducing the uniformity of the microstructure, which made it easy for local stress concentration and large wrinkles to occur during bending processing. In addition, the reduction in recrystallized grains of oxygen-free copper tubes was beneficial for improving the formation of Goss texture with good longitudinal deformation ability in the final heat pipe microstructure. The heat pipe annealed at 420 ℃ for 30 min showed the highest proportion of Goss texture, the best microstructure uniformity, suitable tensile strength, and highest qualification rate of heat pipes of 97.30%. This indicated that the above process conditions were the optimal production process for oxygen-free copper tubes for heat pipes.