title: The cold-rolling behaviour of AZ31 tubes for fabrication of biodegradable stents.
abstract: Mg alloys are receiving considerable attention for biomedical stents due to their combination of good mechanical properties and high biodegradability. Cold rolling is necessary to process Mg alloy tubes before final drawing and fabrication of the magnesium stents. In this paper, cold-rolled tubes were subjected to a cross-sectional reduction rate (ε) of up to 19.7%, and were further processed at various ratios of wall-thickness to diameter reduction (Q) from 0 to 2.24 with a constant ε of 19.7%. The results show that the cold-rolled tubes exhibited a rise in ultimate tensile strength (UTS), yield strength (YS), and a reduction in elongation as ε increased from 5.5% to 19.7%. UTS, YS and elongation decreased when Q was increased from 0 to 2.24. Mechanical twinning was observed and analysed. Extension twins increased with increasing ε and were almost saturated at a ε of 16.5%. Extension twins play an important role in determining the evolution of mechanical behaviour in the case of increasing ε, whilst contraction/double twins and secondary extension twins have a large effect on mechanical behaviour in the case of varying Q. The results indicate that the proportions and types of twins play a major role in determining the mechanical behaviour of the AZ31 tubes.
authors.affiliation: Queensland Centre for Advanced Materials Processing and Manufacturing (AMPAM), School of Mechanical and Mining Engineering, The University of Queensland, Brisbane, QLD 4072, Australia. Electronic address: y.zhang20@uq.edu.au.
authors.forename: Yaowu
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Queensland Centre for Advanced Materials Processing and Manufacturing (AMPAM), School of Mechanical and Mining Engineering, The University of Queensland, Brisbane, QLD 4072, Australia.
authors.forename: Damon
authors.initials: D
authors.lastname: Kent
authors.affiliation: Queensland Centre for Advanced Materials Processing and Manufacturing (AMPAM), School of Mechanical and Mining Engineering, The University of Queensland, Brisbane, QLD 4072, Australia.
authors.forename: Gui
authors.initials: G
authors.lastname: Wang
authors.affiliation: Queensland Centre for Advanced Materials Processing and Manufacturing (AMPAM), School of Mechanical and Mining Engineering, The University of Queensland, Brisbane, QLD 4072, Australia.
authors.forename: David
authors.initials: D
authors.lastname: StJohn
authors.affiliation: Queensland Centre for Advanced Materials Processing and Manufacturing (AMPAM), School of Mechanical and Mining Engineering, The University of Queensland, Brisbane, QLD 4072, Australia.
authors.forename: Matthew S
authors.initials: MS
authors.lastname: Dargusch
mesh_terms: D020341:Absorbable Implants; D000497:Alloys; D001672:Biocompatible Materials; D003080:Cold Temperature; D003343:Corrosion; D008274:Magnesium / Q000737:chemistry; D008422:Materials Testing; D015607:Stents; D013314:Stress, Mechanical; D013499:Surface Properties; D013718:Tensile Strength
chemical_list: D000497:Alloys; D001672:Biocompatible Materials; D008274:Magnesium
keywords: AZ31 tubes; Cold rolling; Mechanical behaviour; Processing; Twinning