Abstract: The inner AA5052 extruded tubes of steel/aluminum clad tubes were difficult to coordinate with the outer tube deformations to the target tube shape requirements for its poor forming performance at room temperature. Based on this point, a new project of aluminum alloy tube annealing treatment, assembly and granule medium bulging processes was proposed on clad tubes. Ω shape clad tubes satisfied with industrial requirements were prepared successfully by the processes. The bulging ratio reached 1.40, diameter-thickness ratio was as 3/102 and the maximum thinning rate was less than 20%. The experimental researches show that the plastic deformation capacity of AA5052 extruded tube nearly reaches the maximum value and the elongation rate increases by more than 3 times when the annealing treatment is at 440 ℃ for 60 min. The distributions of wall-thickness are related to the friction coefficients between tube layers during the bulging processes. Reducing the friction at Q235/AA5052 interfaces is beneficial for preventing  decrease of wall-thicknesses and improving bulging limit of clad tubes. The expansion processes of granule medium have low requirements for the dimensional accuracy of tube blanks. And this processes may be realized by universal equipment and simple dies.

Key words: clad tube, aluminum alloy tube, forming limit, granule medium bulging, annealing treatment

摘要： 钢/铝复合管内衬的AA5052挤压铝管成形性能极差，室温下难以与外覆钢管协调变形至目标管件的形状要求。基于此，提出了挤压铝管退火处理、复合装配、颗粒介质胀形的工艺流程，使复合管胀形比达到1.40，成功制备了厚径比为3/102的复合凸环管件，最大减薄率不超过20%，满足产品技术要求。试验研究表明，AA5052挤压管材采取加热440℃保温60min的退火处理后成形性能最优，延伸率提高了3倍以上；复合管胀形过程中的壁厚分布规律与管层间摩擦因数相关，降低管层间摩擦作用能够抑制内衬铝管减薄，有利于复合管胀形极限的提高。颗粒介质胀形工艺对胀形管坯的尺寸精度要求较低，可采用通用设备和简便的模具装置实现成形工艺。

关键词: 复合管, 铝合金管, 成形极限, 颗粒介质胀形, 退火处理