Bending fatigue behavior of metastable and stable austenitic stainless
steels with different surface morphologies
Abstract
The surface morphology has a significant influence on the fatigue
behavior of components. For austenitic stainless steels (ASSs), this
issue is even more pronounced due to their metastability. Based on the
complex deformation mechanisms of metastable ASSs, which include
dislocation slip, deformation twinning, and deformation-induced
martensitic phase transformation, the metastable stainless steel AISI
347 was investigated in this study together with the stable AISI 904L as
a reference material. 4-point bending fatigue tests with load ratio R =
0.1 and testing frequency f = 10 Hz at ambient temperature were carried
out on specimens with 5 technically relevant surfaces morphologies:
mechanical polished, milled, micro-shot peened, laser shock-peened, and
ultrasonic modified. Systematic material characterizations were carried
out to clarify the key influences of these morphologies on the fatigue
behavior. Deformation-induced martensite layers were proven to improve
the fatigue life in metastable austenitic steels, which open
perspectives to extend the lifetime of components.