The effect of nitriding 316L stainless steel on the kinetics of reaction layers formation in molten 55% Al-Zn alloy

L. PAOLINELLI; A. CABO; D. MIGLIORINO; S. N. SIMISON

Genova

Conferencia; International Conference on Zinc and Zinc Alloy Coated Steel Sheet “Galvatech 2011; 2011

Continuous Galvanizing Lines that manufacture 55%Al-Zn products require frequent down time for maintenance due to corrosion, wear, and buildup of dross on submerged hardware. Several research projects have been devoted in recent years to the improvement of materials in contact with molten Al-Zn alloys to extend the performance life of the metallic hardware and consequently to decrease energy and productivity losses . In the present work the effect of nitriding 316L stainless steel on the kinetics of reaction layers formation and dross buildup is analyzed. Nitriding treatment was done at two different temperatures in order to vary the nitrogen content and depth of the nitrided layer. In –Plant Corrosion Tests were performed on 316L with and without surface modification. The samples were immersed in a 55% Al-Zn alloy bath for various periods of time. In order to separate the effect of temperature, nitrided samples were also exposed at 600 oC in a furnace during the same periods of time. The morphology and thickness changes of the reaction layers were analyzed by optical and electronic microscopy. EDS measurements were carried out to evaluate the chemical composition profile. Normal and glazing incidence X-ray diffraction were used to identify intermetallic compounds. Microhardness profiles were also assessed for all the tested conditions and correlated with chemical composition profiles. The results show that nitrogen modifies the thickness and mechanical properties of reaction layers.