Manufacturers need to lower the cost of their products, under stringent requirements for higher performance, lower material cost, compliancy with emerging norms, higher product liability and shorter time to market.

Therefore the product materials need to be tested on fatigue in an early stage of design & prototyping under realistic load & cycling conditions close to real usage.

While the standard static tensile tests are still done as before for the basic material differentiation, today leading manufacturers of products and their material suppliers rely on thorough fatigue testing, providing data on the material behaviour under the failure modes that are relevant for the application.

Materials degrade very differently under high cyclic dynamic load than in the case of a single ultime break load, because of long-lasting initiation of the occuring failure by material inclusions, surface defects, aging, corrosion, composite delamination, wear & fretting.

Looking to the typical Woehler load-cycles curves of the test method, one should also stay at the "right side of the crossing region" of the curves of the different qualities & grades, to choose for the material that is really needed.

The qualities are improving fast with time, thanks to smaller inclusions, lower surface defects, increased purity & higher grade materials.

To be able to further differentiate between the better qualities, one has therefore to define fatigue tests conditions for higher cycle counts than originally used. The trend in the industries is thereby to move from LCF (low cycle fatigue) to MCF (medium cycle fatigue) , even up to HCF (high cycle fatigue) when the requirements are very high on the survival requirement like in medical or aerospace applications.