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Thermal shape memory alloys show extraordinary material properties and can be used as actuators, dampers and sensors. Since their discovery in the middle of the last century they have been investigated and further developed. The majority of the industrial applications with the highest material sales can still be found in the medical industry, where they are used due to their superelastic and thermal shape memory effect, e.g. as stents or as guidewires and tools in the minimal invasive surgery. Particularly in recent years, more and more applications have been developed for other industrial fields, e.g. for the household goods, civil engineering and automotive sector. In this context it is worth mentioning that for the latter sector, million seller series applications have found their way into some European automobile manufacturers. The German VDI guideline for shape memory alloys introduced in 2017 will give the material a further boost in application. Last but not least the new production technologies of additive manufacturing with metal laser sintering plants open up additional applications for these multifunctional materials. This paper gives an overview of the extraordinary material properties of shape memory components, shows examples of different applications and discusses European trends against the background of the most recent standard and new production technologies.
Dass sich Stoffe bei Temperaturänderungen zusammenziehen beziehungsweise ausdehnen, ist eine uralte Erkenntnis. Diesbezüglich stechen Formgedächtnislegierungen heraus, da diese die verblüffende Eigenschaft besitzen, sich bei Temperaturänderung ungewöhnlich rasch zusamenzuziehen beziehungsweise auszudehnen. Eine physikalische Besonderheit, die sich auf vielfältige Weise nutzen lässt.
Mechanical properties after stretching testings were calcu-lated and experimentally determined via Tempcore method for bar core, bar surface and whole bar cross section. It was displayed on the base of experiments and imitating simulation that deformation in core and surface areas of a bar are equal and therefore influence of structural parameters in the core area is principally decisive for initiating of neck forming in the surface area. The results showed that resistance to destruction of martensite surface layer has rather less effect on bar properties in general in comparison with previous investigations. It is concluded that improvement of core structure quality can help to lower brittleness of the whole bar. It was also proved that used techniques provide good concordance between the obtained results and experimental data. Therefore, the additivity rule for structural components can be used successfully for determination of whole bar parameters, taking into account thickness of surface layer that can be measured easily using hardness sensor. It will simplify practically quality control of products.