1. Pitting corrosion on highly alloyed stainless steels in dilute sulphuric acid containing sodium chlorideElina Huttunen-Saarivirta, Elisa Isotahdon, Zaiqing Que, M. Lindgren, Ahmad Mardoukhi, Jean-Baptiste Jorcin, Petra Močnik, Tadeja Kosec, Yassine El Ouazari, Sukanya Hägg Mameng, Lena Wegrelius, 2023, izvirni znanstveni članek Povzetek: Stainless steels are widely used in industrial assets and equipment. Despite their good corrosion resistance under a wide range of operating conditions, there is the possibility of pitting corrosion in the presence of chlorides. However, very few studies have identified the safe operating conditions for various high-alloyed stainless steel grades by comparing their pitting susceptibility. In this research, the susceptibility to pitting attack of five stainless steels with austenitic and duplex microstructures was examined in dilute sulphuric acid solution with varying amounts of NaCl at the temperatures of 50, 90 and 130◦C. Based on potentiodynamic polarization scans, none of the test materials underwent pitting corrosion at 50◦C, but differences in susceptibility to pitting attack were clear between the test materials and NaCl concentrations at the temperature of 90◦C, and further tem- perature increase facilitated uniform corrosion. 28-day immersion tests at 90◦ C confirmed the pitting suscepti- bility of duplex grades 1.4662 (PREN 33) and 1.4462 (PREN 35) in the presence of at least 2000 mg/L NaCl, but not the susceptibility of a corresponding austenitic grade 1.4539 (PREN 34). The grades 1.4547 (PREN 43) and 1.4410 (PREN 44) were not susceptible to pitting corrosion under any of the studied conditions. The results from materials microstructural and electrochemical characterization are presented and discussed in this paper.
Ključne besede: stainless steel, austenitic stainless steel, duplex stainless steel, pitting atttack
Objavljeno v DiRROS: 12.07.2023; Ogledov: 304; Prenosov: 380
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2. Sensor development for corrosion monitoring of stainless steels in H2SO4 solutionsMiha Hren, Tadeja Kosec, Mari Lindgren, Elina Huttunen-Saarivirta, Andraž Legat, 2021, izvirni znanstveni članek Povzetek: Equipment made of different stainless steels is often used in the hydrometallurgical processing industry. In this study, an electrical resistance sensor was developed for monitoring corrosion in acidic solutions at high temperature. Two types of stainless steel were used as the electrode materials, namely grade 316L stainless steel (EN 1.4404) and grade 2507 duplex stainless steel (EN 1.4410). The materials and sensors were exposed to a 10% H2SO4 solution containing 5000 mg/L of NaCl at various temperatures. Results from the sensors were verified using electrochemical techniques and postexposure examination. Results showed that the microstructure played an important role in the interpretation of corrosion rates, highlighting the importance of using an appropriate stainless steel for the production of sensors. Electrochemical tests and postexposure examination both showed that the grade 2507 had a significantly lower corrosion rate compared to the grade 316L. Under industrial‑process conditions, the results for the grade 2507 sensor were promising with respect to sensor durability and performance, despite the extremely harsh operating environment.
Ključne besede: stainless steel, hydrometallurgical industry, sulphuric acid, electrical resistance sensor, corrosion
Objavljeno v DiRROS: 05.07.2023; Ogledov: 320; Prenosov: 181
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