Effect of cold process drawing parameters on the formability and microstructure of ribbed cladding tubes

To address the issue of wire detachment from the external surface of cladding tubes during operation, an integrated structure known as the ribbed cladding tube (RCT) has been introduced. Nonetheless, this novel form of cladding tube encounters challenges in fully filling the rib heights and is susceptible to inner wall depressions (IWDs) during the cold drawing process. In order to tackle these problems, a multiscale constitutive model incorporating multiple deformation mechanisms was developed and employed to establish a finite element model (FEM) for cold drawing of RCT. The credibility of the established FEM was verified by comparing the experimental and simulation results. Additionally, the influence of drawing process parameters on formability and microstructural evolution was investigated. The results indicate that under the conditions of a die semi-die angle of 6 degrees, a rib-groove angle of 10 degrees, a drawing speed of 5 mm/s, and a friction coefficient of 0.05, optimal filling effects for ribs can be realized. The resulting RCTs exhibit high contents of martensite and twins along with fine grain size on both inner and outer walls. Finally, by utilizing these optimized process parameters, RCTs that meet the dimensional specifications and exhibit reasonable microstructure distribution were successfully fabricated through multi-pass drawing. This research augments the forming theory associated with thin-walled shaped tube and provides theoretical guidance for the development and application of novel cladding tubes.