FERRITE CONTENT DETERMINATION. METHOD VALIDATION FOR USE IN DUPLEX STAINLESS STEELS: TRADITIONAL VERSUS DIGITAL APPROACHES
Joana Leal, Paulo Duarte, Cláudia Fernandes
Pages: 106-116
Published: 16 Nov 2022
Views: 492
Downloads: 48
Abstract: The use of duplexes has expanded widely across an extensive number of industries e.g. oil, gas, petrochemical, pulp and recycling, as a structural and engineering material. These steels are mainly used in aqueous environments containing chlorides and as replacements for austenitic stainless steels that have suffered pitting or stress corrosion in service. The properties of these duplex steels depend on the volume fraction (VF) between austenite and ferrite, which is provided by high temperature heat treatment. Duplex stainless steels are intended to present a microstructure composed of similar VF of austenite and ferrite; this is the phase composition leading to the best compromise of mechanical and corrosion properties. The characterization of this volume content is done by readily available metallographic means, as described in the standard ASTM E562 for the measurement of ferrite content by point counting over a significant number of micrographs. This is, however, an outdated and time-consuming approach. The aim of this work is to validate the VF determination method that is more suitable for industrial use, knowledge creation and transfer. Two duplex stainless steels were analysed by two different metallographic approaches (ASTM E562, ASTM E1245), by varying magnification and the number of fields used. Ferrite content and its variability within techniques due to the analytical variables are discussed. Finally, comparison is made between the final values for the ferrite content determined by each metallographic approach. The results highlight the recommendation for the use of the digital automatic image analysis, over the common traditional manual counting point approach. Since the digital approach allows a more efficient and comprehensive process in terms of practical results, simplicity, time and output representativeness of the total volume of the material. Digital automatic image analysis approach can be nowadays more efficiently and accurately used to perform the same analysis.
Keywords: duplex stainless steel, ferrite content, method validation, digital automatic image analysis, knowledge transfer
Cite this article: Joana Leal, Paulo Duarte, Cláudia Fernandes. FERRITE CONTENT DETERMINATION. METHOD VALIDATION FOR USE IN DUPLEX STAINLESS STEELS: TRADITIONAL VERSUS DIGITAL APPROACHES. Journal of International Scientific Publications: Materials, Methods & Technologies 16, 106-116 (2022). https://www.scientific-publications.net/en/article/1002512/
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