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Effect of Surface Treatment and Cutting Orientation to the Changes in Stents Surface Roughness

During the implantation process, an expandable balloon stent undergoes a change in mesh shape with a high strain rate. Permanent mesh shape changes to the stents indicate plastic deformation has occurred. On a micro-scale, plastic deformation has significant influence when interacting with the soft tissue of human blood vessels. This experimental study aims to investigate the effect of surface treatment and cutting orientation on the changes in surface roughness that definitely occurs when a stent deployed. To study the effect of surface treatment, two types of surface treatment were applied after surface polishing, i.e. etching and electropolishing. Surface polishing is carried out to enable microscopic observation. As for examining the effect of cutting orientation, the plate is cut in lateral and longitudinal orientation against the predicted-rolling direction of 316L sheet-type of stainless steel. An intermittent tensile test is conducted to obtain information about the changes in surface roughness. The surface observation is carried out three times on a similar surface of testpiece after reaching plastic deformation. The experimental study shows that the orientation of raw material has an insignificant effect on the changes in stent surface roughness. As for the surface treatments, electropolishing tended to decrease the tensile property of material.