Application of pulse distribution analysis with optical emission spectroscopy (PDA/OES) method during production of duplex stainless steel

Abstract

Liquid steel samples were taken during ladle treatment and continuous casting of 37 heats of two duplex stainless steel grades. These samples were used to study inclusion characteristics and potential process control using the pulse distribution analysis with optical emission spectroscopy method (PDA/OES). In addition, a few samples were chosen for a scanning electron microscope examination. A simplified approach of presenting the inclusion composition in ternary diagrams using the PDA/OES method is discussed. More specifically, by defining an operating window, potential deviations can be identified early in the steelmaking process. The variation of the B factor for Al (B _Al) with process time was presented showing similar tendencies for several heats. For that reason, the B factor is considered to be a reliable parameter to study any process changes with respect to inclusion characteristics. Parameters such as B _Al and the number of inclusions per unit volume larger than 4 μm obtained using the PDA/OES method showed a moderate correlation with a slivers index. Statistically, more data have to be collected for further studies. Nevertheless, the PDA/OES method is judged to be a promising tool to determine a slivers risk factor at an early stage of the process.