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Metastable austenitic stainless steels can undergo a diffusionless phase
transformation from austenite to martensite by deep cooling or plastic
deformation under monotonic and cyclic loading. The fcc austenite transforms to
the bcc α’-martensite or to the hcp ε-martensite phase [1]. It is well known that
the α’-martensite can be used to modify the monotonic strength properties and
that this transformation can also be beneficial for the LCF properties [2].
Investigations about the influence of martensite formation on short crack initiation
and growth are very rare. Only in publications by Stolarz [3] information
regarding the interaction between microstructure, plastic deformation induced
martensite and short crack propagation can be found. However the design and
production of cyclically loaded parts made of metastable stainless steel demands a
substantial understanding of the correlation between fatigue life, martensitic
transformation and damage mechanisms. This study focuses on these aspects and
presents recent results with regard to in-situ-fatigue testing and fatigue strength
derived from load increase-tests.