Strain-induced martensitic transformation in fatigue crack tip zone for a high strength steel

The stability of retained austenite within the fatigue plastic zone of a high strength steel was studied through use of transmission electron microscopy with thin foil specimens containing fatigue cracks. The results show that retained austenite inside the plastic zone at the fatigue crack tip has been transformed into martensite due to plastic deformation. Because of the effect of the energy absorbed and crack closure in the process of strain-induced martensitic transformation, the propagation rate of fatigue crack can be reduced.