Extrusion of Magnesium Tubes for Biodegradable Stent Precursors

Abstract

Production of stent precursors in the form of small-size tubes has been evaluated by hot compression tests and extrusion trials on the\ud 5 AZ31B and ZM21 magnesium alloys. The investigation here presented mainly reports on the effects of extrusion parameters on microstructure\ud and properties of the tubes. Processing at 410C and at slow strain rate (2.78 103 s1) by a laboratory hot-extrusion system allowed\ud producing small-size tubes featuring a homogeneous and refined equiaxed grain structure. Microstructural analyses showed that dynamic\ud recrystallization, often anticipated by deformation twinning, took place during hot forming. By a proper control of extrusion parameters,\ud tubes with wall thickness as low as 0.5mm could be successfully produced

Influence of ECAP process on mechanical and corrosion properties of pure Mg and ZK60 magnesium alloy for biodegradable stent applications

“…Extrusion of ECAP processed materials was performed by using a laboratory device already adopted for coarse grained alloys, described in details in a previous work 50 . Extruded minitubes were produced from the ECAP processed billets at temperatures of 150 °C and 230 °C for ZK60 alloy and pure Mg, respectively.…”

“…Extrusion of ECAP processed materials was performed by using a laboratory device already adopted for coarse grained alloys, described in details in a previous work. 50 Extruded minitubes were produced from the ECAP processed billets at temperatures of 150 °C and 230 °C for ZK60 alloy and pure Mg, respectively. The extruded tubes had an outer diameter of 4 mm and an inner diameter of 2.5 mm, corresponding to a reduction ratio of 9:1 performed at a ram speed of 5 mm/min and 2 mm/min for ZK60 and pure Mg, respectively.…”

Effect of 2θ-Punch Shape on Material Waste during ECAE through a 2θ-Die

“…1a and Fig. 2 11 algebraically satisfied inequalities α vol inclin punch < α vol rect punch and ∆α vol inclin punch < ∆α vol rect punch , which provide the experimental illustration of observable effects of macroscopic rotation decrease with the usage of inclined punches MNKL (Fig. 1a, Fig.…”

“…Q. Ge et al (2012) have investigated effects of extrusion parameters on workpiece grain structure refinement [11]. M. Sedighi tooling with 2θ=130°, where punch geometry has been replaced with a guide and feeding rolls [12].…”

Fibre Laser Cutting and Chemical Etching of AZ31 for Manufacturing Biodegradable Stents

“…Among a group of candidate magnesium alloys, AZ31 was found to be the most suitable, due to the higher availability of the alloying elements (i.e., the alloy does not include rare earth elements). Moreover, the formability of the alloy for extrusion of semi-finished hollow tubes was found to be better [32]. The AZ31 tubes used in stent fabrication were 2.5 mm in outer diameter and 0.2 mm in thickness.…”