Avoiding accidents caused by equipment failure and ensuring structure quality are some of the challenges of the petroleum industry. Petroleum exploitation in salt-water has required the use of special materials, such as duplex stainless steels (DSS), that support highly aggressive corrosion conditions and, at the same time, are ductile facilitating equipment manufacture. But DSS can be embrittled when exposed to some heat treatments, such as welding (T > 800 deg). Deleterious phases might precipitated in this material, especially sigma phase (σ), which appears in higher volumetric fraction. This paper presents a proposal of a characterization procedure of deleterious phases in DSS using Eddy Current Technique (EC). A calculus model was elaborated using finite elements. The model was able to reproduce the behavior of this type of steel, and it will help to correctly recognize the signals generated by the material’s internal defects.