Studies on white rabbits also showed positive results with regard to biocompatibility, but the stents featured too low degradation rates in the in vivo experiments to be used as a biodegradable implant material 24. For instance, stents made of iron were tested on the coronary arteries of pigs 23. Iron as an implant material has already been successfully investigated in several animal studies 22. In addition to common biodegradable materials such as zinc or magnesium 19, 20, there is also a need for other types of materials with better mechanical properties, such as iron 21.
#Inklet 202 torrent crack#
If the microstructure is specifically designed to curtail crack nucleation or growth, the fatigue strength can even be increased compared to conventionally manufactured components, e.g., ref. In addition to the defects, the type and texture of the AM microstructure can significantly influence crack growth, and thus fatigue life 17. Such defects can occur as a result of AM processes, for example, in the form of lack of fusion (LOF) 16. Studies on defect tolerance with respect to fatigue behavior of martensitic steels have shown that small sharp defects can be regarded as equivalent to a crack 15 and thus significantly shorten the fatigue life. If defect formation can be avoided, the service life of AM manufactured components can be as long as those of conventionally manufactured components 14.
Defects caused by AM can significantly reduce the service life 11, 12, 13. Yet, studies on the corrosion behavior of 316L have already shown that pitting corrosion phenomena can be attributed to the surface porosity of the AM-manufactured structures 10.ĭepending on the location of an implant within the body, it might be subjected to pronounced cyclic loads during its lifetime. The number of studies addressing the corrosion behavior of additively manufactured structures is small. For example, the corrosion behavior can be adjusted by varying the microstructure of the material 6 or the surface morphology 7, 8, 9. In addition to the pure mechanical properties resulting from the different microstructures, the corrosion behavior also needs to be specifically adapted to match the demands set by use in biodegradable implants 5. Moreover, it is also possible to specifically adapt the microstructure by adjusting the cooling rates and thermal gradients within the manufacturing process, thus changing the microstructural and mechanical properties 2, 3, 4.
#Inklet 202 torrent series#
These different fatigue responses were observed under purely mechanical loading as well as with superimposed corrosion influence and are summarized in a model that describes the underlying failure mechanisms.Īdditive manufacturing (AM) is of increasing importance in biomedicine technology due to the high design freedom and low-cost production of small series 1. The EBM iron showed significantly lower fatigue strength compared to the HR iron. The investigated sample conditions showed significant differences in the microstructures that led to changes in corrosion and fatigue properties. The microstructure, the corrosion behavior and the fatigue properties were studied comprehensively. In the present study, conventional hot-rolled (HR) pure iron is compared to pure iron manufactured by electron beam melting (EBM). In combination with additive manufacturing, which facilitates great flexibility of the implant design, it is possible to selectively adjust the microstructure of the material in the process, thereby control the corrosion and fatigue behavior.
Pure iron is very attractive as a biodegradable implant material due to its high biocompatibility.
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