Quantification of Damage Progression in a Thermally Aged Duplex Stainless Steel

Ferrite of austeno-ferritic stainless steels maintained for a long time at temperatures in the range of 270 °C to 400 °C is embrittled like the known 475 °C embrittlement of ferritic stainless steels. Deformation and damage micromechanisms of a material must be known in order to apply the “local approach to fracture” (LAF) methodology. In this work we test a previous model of damage nucleation and evolution, extending its validity to low temperature long term aging. We have determined cracking damage evolution by taking replicas of planar tensile specimens during uniaxial traction tests. Voronoï (Dirichlet) tessellation quantitative metallography was applied to characterize and quantify non-uniform damaging. Clustering criteria allowed the determination of the size, density and internal damaging rate of damage clusters.