Microstructural changes in a Duplex stainless steel during low cycle fatigue.

HEREÑÚ, S.; ALVAREZ-ARMAS, I.; ARMAS, A.; DEGALLAIX, S.; CONDÓ, A.; LOVEY, F.

MP Materials Testing

Carl Hanser Verlag

Lugar: München; Año: 2009 vol. 51 p. 359 - 364

0025-5300

Low cycle fatigue of SAF 2507 duplex stainless steel has been studiedat different temperatures in two thermal conditions: unaged(as-received) and aged (100 hours at 475°C).The corresponding cyclicflow stress components, the friction, sF, and the back stresses,sB, have been analyzed in relation to the observed microstructure.sF attains higher values at room temperature than in the intermediaterange of temperatures in both thermal conditions due tothe influence of the lattice friction stress on screw dislocations inthe ferrite phase.The cyclic softening observed at all temperaturesin aged samples is caused by the decrease of the back stress sB.The increase of sB in unaged samples at 300 °C is consistent withthe high dislocation density observed in the ferrite phase ascribedas a typical manifestation of dynamic strain aging.