Nowadays due to large demand for clean and defect-free steels, several techniques based on different characteristics of particles are applied to investigate the steel cleanness. Outokumpu Stainless AB in Avesta has performed extensive work in this field by applying several methods, which all of them have specific advantages and limitations. However, it is necessary to find an accurate technique to investigate real properties of inclusions in duplex stainless steels. For routine analytical methods, calibration and parameters adjustment can be followed by help of these investigation results. The aim of present work is to apply automated INCA-Feature method for controlling cleanness of LDX 6112 duplex stainless steels after electrolytic extractions (EE) as a reference method. Three methods of investigations, INCA-Feature on polished samples as two-dimensional and on film-filter as three-dimensional and EE as three-dimensional analyses, were compared. The results of comparison between running INCA-Feature on polished samples and film filters show an acceptable agreement which proves the possibility of performing EE on this steel grade and using INCA-Feature for investigating this as a fast method. These methods are compared statistically and quantitative results are reported in details.