Ferrite Quantification Methodologies for Duplex Stainless Steel

• Main Authors: Arnaldo Forgas Júnior, Jorge Otubo, Rodrigo Magnabosco
• Format: Article
• Language: English
• Published: Departamento de Ciência e Tecnologia Aeroespacial 2016-07-01
• Series: Journal of Aerospace Technology and Management
• Subjects: Duplex stainless steels; Ferrite quantification; Ferritoscope; Quantitative metallography; X-ray diffraction; ThermoCalc®
• Online Access: http://www.jatm.com.br/ojs/index.php/jatm/article/view/653/536
• ISSN: 1984-9648; 2175-9146

In order to quantify ferrite content, three techniques, XRD, ferritoscope and optical metallography, were applied to a duplex stainless steel UNS S31803 solution-treated for 30 min at 1,000, 1,100 and 1,200 °C, and then compared to equilibrium of phases predicted by ThermoCalc® simulation. As expected, the microstructure is composed only by austenite and ferrite phases, and ferrite content increases as the solution treatment temperature increases. The microstructure presents preferred grains orientation along the rolling directions even for a sample solution treated for 30 min at 1,200 °C. For all solution treatment temperatures, the ferrite volume fractions obtained by XRD measurements were higher than those achieved by the other two techniques and ThermoCalc® simulation, probably due to texturing effect of previous rolling process. Values obtained by quantitative metallography look more assertive as it is a direct measurement method but the ferritoscope technique should be considered mainly for in loco measurement.