The evolution mechanism of interface coordination and mechanical properties of hot spinning Mg/Al bimetal composite tube under different rotate speeds

In this study, Mg/Al bimetallic composite tubes (BCTs) with varying diffusion band lengths were successfully fabricated using the hot spinning process at different spindle speeds. The deformation behavior of Mg/Al BCTs was analyzed in-depth using the finite element simulation platform. The results revealed that lower rotational speeds facilitated the formation of metallurgical bonding at the interface, resulting in a diffusion zone width of 6 μm and a shear strength of 14.2 MPa. However, excessive external loads at lower speeds led to wall cracking, while alternating loads at higher speeds caused the bonded interface to re-separate. BCTs fabricated at optimal rotational speeds (300 r/min) demonstrated enhanced base tube strength due to interfacial strengthening, with a tensile strength of 385.1 MPa, which is 30.5 % higher than that of the base tube. The appearance of gradient and bimodal crystal structures caused the tensile strength on the Mg side to increase as spindle speed rose. The interface bonding and re-separation mechanism of Mg/Al BCTs at different rotational speeds were elucidated using SEM, EDS, and other characterization techniques. The BCTs exhibited good interface bonding and high bonding strength at a spindle speed of 300 r/min. The discontinuous dynamic recrystallization on the Mg side dominated the grain refinement process, while continuous dynamic recrystallization on the Al side was responsible for the grain refinement. This study provides a practical selection range for optimal parameters in the preparation of high-performance Al/Mg BCTs. The interfacial bonding and re-separation mechanisms, as well as the recrystallization processes, offer valuable theoretical insights and practical guidance for the preparation of Al/Mg BCTs.