Influence of specimen geometry to the tensile property of 316L stainless steel: Study case on raw material of stents

Abstract

Considering the raw material of balloon-expandable stent that usually obtained from tube-type geometry, it is still unclear how the multilinear isotropic model obtained from flat-type specimen can be used to represent the actual behavior of stent expansion. In this experimental study, non-standard sheet-type and tube-type tensile test specimens are prepared, which are made from stainless steel 316L. To assure equality of both chemical composition, the testing is carried out using Optical Emission Spectrometer. For the tube-type (axial and tangential), three pieces of specimens are prepared for the tensile test. The forces and yielded elongations are recorded in order to generate stress-strain relationship. The study indicated that the correlation between the stresses and the strains was not similar among various geometry of specimens. Tangential tube-type specimen experienced increasing of total strain faster than other specimen type. It differed significantly compared to a sheet-type specimen. A moderate correlation between the stress and the strain is obtained by a axial tube-type specimen. This investigation suggested a new value of material properties obtained from tangential tube-type specimen to be used in the FE study of balloon-expandable stent.