Microstructure associated with crack initiation during low-cycle fatigue in a low nitrogen duplex satinless steel

I. ALVAREZ, M. C. MARINELLI, J MALARRÍA, S. DEGALLAIX, A. AR

INTERNATIONAL JOURNAL OF FATIGUE

Elsevier

Lugar: Amsterdam; Año: 2007 vol. 29 p. 758 - 764

0142-1123

In the framework of an extensive investigation regarding crack initiation and propagation during low-cycle fatigue in Duplex Staniless Steel (DSS). the present study was focused on the fatigue surface damage in a low nitrogen DSS. The Coffin-Manson curve is presented for DIN W Nr.1.4460 DSS and compared with that of a high nitrogen steel. The surface damage has been observed by optical and electronic microscopy and analysed in relation with the underlying dislocation structure by transmission electron microscopy. The results for the present low nirogen steel DIN W Nr. 1.4460 show that, at Det = 0.8 x10-2, the preferred sit for short crack initiation seems to be the intense slip marks formed mostly in the ferrite and less frequently in the phase boundary. On the contrary, at  Det = 1.2 x 10-2, short cracks form mostly in phase boundary