Fractal Characterization of the Fractured Surface of a Duplex Stainless Steel and Their Relation with the Strength and Ductility

Abstract Due to the very good combination of the most outstanding properties of ferrite and austenite, the microstructure of duplex stainless steels allows them to obtain high strength and toughness levels even at low temperatures. As a result of these combined effects, duplex stainless steels have become very popular for many applications. In practice, the prolonged use of these materials at temperatures below approximately 500°C may cause an embrittlement of the ferrite phase, which has been called 475°C embrittlement. Thus, the isothermal aging at 475°C can be exploited to produce a variety of strength values associated with the corresponding decreases in ductility and variations of the fractal dimension of the fracture surfaces. No experimental measurements of the fractal dimension - tensile properties relationships are available for many commercial metallic alloys, then, the present experiments on a duplex stainless steel were conducted to show that the fractal dimension, D, many be used as a characterization parameter in fracture morphology - mechanical properties studies.