Abstract:

Biodegradable Zn alloys are a hot topic in the biodegradable vascular stent materials, the study on preparing Zn alloys microtubes for vascular stent is still insufficient and none of the tubes could well meet the mechanical requirement by present. In this study, we fabricate Zn-0.5Mn-0.05 Mg microtube with outer diameter of 3.5 mm and wall thickness of 0.2 mm by five passes three-roller rolling. The mechanical properties of the microtube are 277 ± 2.9 MPa, 330 ± 3.3 MPa and 39.8 ± 5.25% for the yield tensile strength (YTS), ultimate tensile strength (UTS) and break elongation, respectively, which well satisfies the requirements of the vascular stent. The leading factors to the variations of the mechanical property are texture evolution, grain size refinement and microstructure uniformity during the rolling process, and the main deformation mechanisms are twinning and dislocation movement. As a result of the dynamic recrystallization, the grain size decreases obviously and the microstructure gets more uniform as the rolling pass increases. The texture gradually changes from a basal texture < 01 $\bar{1 }$ 0 > ‖ED (extrusion direction) for the as-extruded tube blank to deformation texture < 0001 > ‖RD (rolling direction) and non-basal texture < 02 $\bar{2 }$ 1 > ‖RD for the 5-pass rolled microtube.

Key words: Zn alloys, Microtube, Microstructure, Mechanical property, Three-roller rolling