title: The influence of passivation and electropolishing on the performance of medical grade stainless steels in static and fatigue loading.
abstract: The effects of surface passivation and electropolishing on the mechanical performance of a group of biomedical grade stainless steels have been investigated. Surface roughness measurements showed that the treatments had a significant effect on the final surface finish. However, static mechanical testing demonstrated no difference in static mechanical properties, regardless of surface treatment. High cycle fatigue testing was carried out at a frequency of 120 Hz with a load ratio of R=0.1, in both air and a simulated in vivo wet corrosive environment. 316LVM (cold worked) proved superior to 316L (annealed) in fatigue performance, in both dry and wet environments. The fatigue performance of both materials did depend on the surface treatment, with electropolishing resulting in better performance than passivation. The fatigue performance of both materials was significantly better in the dry environment in comparison to the wet environment. The dry-to-wet deterioration in fatigue performance was somewhat dependent on the surface treatment for the 316L material but almost independent of surface treatment for the 316LVM material. Significant surface pitting and damage was evident for 316L during fatigue in the wet environment, whereas almost no pitting and damage was observed for 316LVM.
authors.affiliation: Department of Mechanical and Biomedical Engineering, National University of Ireland, Galway, Ireland.
authors.forename: L M
authors.initials: LM
authors.lastname: Weldon
authors.forename: P E
authors.initials: PE
authors.lastname: McHugh
authors.forename: W
authors.initials: W
authors.lastname: Carroll
authors.forename: E
authors.initials: E
authors.lastname: Costello
authors.forename: C
authors.initials: C
authors.lastname: O'Bradaigh
mesh_terms: D001672:Biocompatible Materials / Q000032:analysis / Q000737:chemistry*; D019245:Compressive Strength; D004572:Electrolysis; D008422:Materials Testing; D017942:Nitric Acid / Q000737:chemistry; D013193:Stainless Steel / Q000032:analysis / Q000737:chemistry* / Q000145:classification*; D013499:Surface Properties; D013718:Tensile Strength
chemical_list: D001672:Biocompatible Materials; D013193:Stainless Steel; D017942:Nitric Acid
references.citation: Tex Heart Inst J. 1997;24(3):156-9
references.pmid: 9339501
references.citation: J Am Coll Cardiol. 1998 Sep;32(3):562-71
references.pmid: 9741494
references.citation: J Biomed Mater Res. 2000 Nov;52(2):323-32
references.pmid: 10951371
references.citation: J Biomed Mater Res. 1988 Jun;22(6):529-40
references.pmid: 3410871
references.citation: J Biomed Mater Res. 1992 Sep;26(9):1131-9
references.pmid: 1429762
references.citation: Ann Biomed Eng. 1992;20(5):505-16
references.pmid: 1416288
references.citation: Ann Biomed Eng. 2003 Jun;31(6):686-91
references.pmid: 12797618