In-situ tensile tests on notched AISI 316L and L605 wires

Anushia Kaneswaran, Uni Duisburg-Essen, Duisburg, Germany
Bojan Mitesvki, Uni Duisburg-Essen, Duisburg, NRW
Alfons Prof. Dr.-Ing. habil. Fischer, Uni Duisburg-Essen, Duisburg, NRW
Sabine Prof. Dr.-Ing. habil. Weiß, Brandenburgische Technische Universität (BTU) Cottbus - Senftenberg, Cottbus, Brandenburg

The field of medical technology often requires components with very small dimensions. Moreover, the requirements for materials in this field of application are extremely high. One example is a coronary artery stent consisting of a small tube made of wire mesh, which is often implanted in diseased arteries to stabilize them permanently. Due to the small size of the structural elements, there is no conventional testing procedure to analyse their material and mechanical characteristics. In-situ tensile tests inside scanning electron microscopes for components of comparable dimensions are particularly suitable for this task.

Non-notched and notched wires consisting of stainless steel 316L (1.4441) as well as cobalt chromium alloy L605 used in medical technology undergo a series of tensile tests. The influence of different states of stresses and notches on the mechanical properties of oligo-crystalline grade materials was analysed. Furthermore, wires in non-notched condition were compared with notched ones. The microstructure was investigated by electron backscattered diffraction (EBSD) in combination with conventional scanning electron microscopy (SEM).

The dependence of the mechanical properties on the microstructure and the notch development was proven in this study. In addition, the visible outer crack initiation for different notch geometries was detected. The tensile tests show a correlation between tensile strength and fracture extension on the one hand and notch geometry as well as number of grains in diameter on the other hand.

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