P. Poncin, B. Gruez, P. Comte-Gaz, Minitubes, Grenoble Cedex 2, France; J. L. Proft, Metallurgical Solutions, Redwood City, CA
The control of the mechanical properties and transformation temperatures are important requirements for Superelastic Nitinol tubing used in stent application. These properties can be influenced by the choice of the melt, the material history, the cold work and the last heat treatment which is generally associated with the straightening process. The first aim of this work is to study the influence of the industrial process parameters of the continuous straightening anneal on Nitinol tubing properties. The focus will be on short heat treatment times and on the influence of stress. A full characterization of the mechanical properties and of the transformation temperatures will be performed. An interpretation of the results based on the current knowledge will be discussed. This analysis is designed to achieve a better control of the tubing process, taking also into account the effect on dimensions and straightness control.
Summary: The control of the mechanical properties and transformation temperatures are important requirements for Superelastic Nitinol tubing used in stent application. These properties can be influenced by the choice of the melt, the material history, the cold work and the last heat treatment which is generally associated with the straightening process. The first aim of this work is to study the influence of the industrial process parameters of the continuous straightening anneal on Nitinol tubing properties. The focus will be on short heat treatment times and on the influence of stress. A full characterization of the mechanical properties and of the transformation temperatures will be performed. An interpretation of the results based on the current knowledge will be discussed. This analysis is designed to achieve a better control of the tubing process, taking also into account the effect on dimensions and straightness control.
