Aiming at the problems of poor structural stability and low service life caused by the traditional forming method of round tube wrapped with iron wire and fixed by spot welding at both ends, this paper proposes to use multi-pass cold drawing and intermediate annealing process to realize the integral forming and precision forming of ribbed tube for nuclear fuel cladding, and microstructure evolution of the ribbed tube during the process is investigated. The stress and strain distribution during cold drawing showed that there were severe stress concentrations at the junction of the rib and tube on the outer surface, which restricted the radial and circumferential metal flow and thus inhibited rib filling. The excessive radial and circumferential metal flow on the inner surface leads to serious rib groove defects, which are more likely to appear during cold drawing compared to rib filling. The effects and mechanisms of process parameters and geometric parameters on the cold drawing forming accuracy of ribbed tube were investigated and applied to multi-pass cold drawing to obtain defect-free ribbed tube. In the multi-pass cold drawing and intermediate annealing process, stainless steel tube produces grain refinement, which is due to the martensite produced in the cold drawing process reverses to austenite in the annealing process resulting in grain split, and the multi-pass cold drawing increase the degree of grain refinement.

针对圆管缠绕铁丝、两端点焊固定的传统成型方法造成的结构稳定性差、使用寿命低的问题，提出采用多道次冷拔和中间退火工艺来实现研究了核燃料包壳用带肋管的整体成形和精密成形，以及过程中带肋管的微观组织演变。冷拔过程中的应力应变分布表明，外表面筋与管的连接处存在严重的应力集中，限制了径向和周向的金属流动，从而抑制了筋的填充。内表面过度的径向和周向金属流动导致严重的肋槽缺陷，与肋填充相比，这种缺陷在冷拔过程中更容易出现。研究了工艺参数和几何参数对带肋管冷拔成形精度的影响及机理，并将其应用于多道次冷拔以获得无缺陷带肋管。在多道次冷拔和中间退火过程中，不锈钢管会产生晶粒细化，这是由于冷拔过程中产生的马氏体在退火过程中反转为奥氏体导致晶粒分裂，多道次冷拔提高晶粒细化程度。