A comparison study between combined severe plastic deformation methods in manufacturing magnesium microtubes for stent applications

Using biodegradable magnesium microtubes for fabricating vascular stent has got much attention during recent years. However, low deformability of Mg alloys presents a technological difficulty for the production of microtubes for a biodegradable stent application. Hence, in the last decade, a combination of different processes, including extrusion, rolling, severe plastic deformation (SPD) and drawing, are suggested to overcome these difficulties. Among all studies, a combination of equal angular channel pressing (ECAP) with hot extrusion and cyclic expansion extrusion (CEE) with hot extrusion reported the best mechanical properties for WE43 Mg microtubes. This paper compares the effect of ECAP and CEE in the final microtube properties in order to determine the best technique. The final grain size, mechanical properties and dimensions of microtubes were examined. The result shows, both methods provide desirable mechanical properties with a significant reduction in grain size. However, these combined methods are expensive, and because of the limitation in the length of final products, they are not yet suitable for mass production.

Keywords:

Microtubes , Severe plastic deformation , Mechanical properties