Duplex Steels: Structure, Experiments, Macrophenomenological Constitutive Models (Review)

Duplex stainless steels are widely used in many branches of modern industry due to the combination of unique mechanical properties and corrosion resistance, but the complex phase composition and microstructure evolving under external thermomechanical effects (including during operation) can lead to significant changes in the properties of steel. A brief overview of studies for duplex steels mechanical behavior under various loading conditions (cyclic loading, fatigue testing, corrosion resistance analysis, hot and cold forming processes) is given. The methods and results of experimental studies, as well as macrophenomenological constitutive relations (constitutive models) proposed in the literature based on these studies, allowing one to describe the behavior of the considered class of materials under thermomechanical effects, are considered. Based on the data presented in the review, one can conclude that the behavior of the materials under consideration is very complex, and there is a variety of physical mechanisms implementing and accompanying deformation processes under various temperature and rate loading conditions. It is also necessary to note the significant influence on the response of the material of the complex phase and component composition, characteristic of the class of steels under consideration. The above circumstances probably determine the absence of universal physical equations, a significant number of various phenomenological constitutive relations and their modifications, oriented on the description of the specific grades of steels behavior. In this regard, the most promising for description the behavior of duplex steels seems to be using the physically oriented multilevel constitutive models. The data presented in this review can be used to determine the most important physical mechanisms of deformation, as well as identifying and verifying the parameters of this class of models.