Experimental and Numerical Analysis of Short Fatigue Cracks in Lean Duplex Stainless Steels

Transmission (TEM) and scanning electron microscopy (SEM) in combination with automated electron back-scattered diffraction (EBSD) techniques is used to study the surface damage as well as the initiation and propagation of short fatigue cracks in LDSS AL 2003 in two different thermal conditions. Whereas in the as received (AR) condition the initial deformation lines appear in the ferrite phase, in the heat treated (HT) condition the deformation lines appear in both phases at the same time. On the other hand, in both thermal conditions short cracks nucleate along intrusion/extrusions in the ferrite phase. Additionally, applying a numerical model it was found that the path of short cracks not only depends on the Schmid Factor but it is also conditioned by the angles of the crack-plane deflection at a grain boundary.