High nitrogen nickel-free austenitic stainless steel: A promising coronary stent material

Currently commercialized coronary stents are mainly made of the medical 316L stainless steel and cobalt-based alloy (L605) due to their good combination of properties, especially excellent mechanical properties. However, the presence of high quantity of nickel and/or cobalt elements, the agents known to trigger the toxic and allergic responses, in these materials has caused many clinic concerns. The potential adverse effect of nickel ions release has prompted the development of high nitrogen nickelfree austenitic stainless steels for medical application. Nitrogen in steel is not only to replace the nickel but also improve the properties of steel. In this paper, the harmfulness and release of nickel from metallic stents, and the advantages in mechanical properties and hemocompatibility of high nitrogen nickel-free stainless steels for coronary stents are reviewed. Apart from the highlight of nickel-free, the superiority of high strength and better hemocompatibility of high nitrogen nickel-free stainless steels can guarantee to manufacture thinner strut coronary stents with remarkable anticoagulation ability. High nitrogen nickelfree stainless steels as a promising coronary stents material will attract more and more clinical doctors and stents makers to bring them into clinical application.