B. N. Grgur Corrosion of the stainless steel 316Ti in 10% hydrochloric and sulfuric acid ZASTITA MATERIJALA 61 (2020) broj 4 339 Branimir N. Grgur* Faculty of Technology and Metallurgy University of Belgrade, Belgrade, Serbia Scientific paper ISSN 0351-9465, E-ISSN 2466-2585 UDC:691.714.018.8:669.295:54‑145.15 doi: 10.5937/zasmat2004339G Zastita Materijala 61 (4) 339 - 345 (2020) Corrosion of the stainless steel 316Ti in 10% hydrochloric and sulfuric acid ABSTRACT The corrosion of the austenitic stainless steel 316Ti is investigated in 10% hydrochloric and 10% sulfuric acid, by the means of linear polarization, electrochemical impedance spectroscopy, polarization, and weight loss measurements. It is concluded that 316Ti is unstable in 10% hydrochloric acid and passive in 10% sulfuric acid solution. Keywords: Austenitic stainless steel; Titanium; Weight loss; Micrographs. 1. INTRODUCTION The austenitic stainless steel (SS) 316Ti due to the addition of the titanium has improved mechanical characteristics and improved corrosion resistance in comparisons with similar stainless steels SS 316 and SS 316L grade containing molybdenum. The titanium atoms stabilize the structure of the stainless steel at elevated temperatures above 800°C, avoiding the carbide precipitation at the grain boundaries and protects the metal from corrosion. SS 316Ti is also known as X6CrNiMoTi17-12-2; AISI/SAE 316Ti; UNS S31635 or EN 1.4571 [1]. The SS 316Ti has a broad range of uses, like equipment for the food processing, brewery, vine, chemical and petrochemical equipment, laboratory benches and equipment, seaside architectural paneling and balustrading, boat fittings, chemical transportation containers, heat exchangers, medical implants, etc. [1]. The corrosion behavior of SS 316Ti is less studied than SS 316, 316L, and 304 [2-10]. The corrosion behavior of SS 304, 316, and 316Ti in aqueous solutions of methanesulfonic acid is investigated by Finšgar and Milošev [11]. *Corresponding author: Branimir N. Grgur E-mail: BNGrgur@tmf.bg.ac.rs Paper received: 05. 10. 2020. Paper accepted: 22. 10. 2020. Paper is available on the website: www.idk.org.rs/journal They find comparable corrosion behavior for all three grades. Loto [12] investigated the corrosion resistance of austenitic 316Ti, martensitic GX4CrNiMo16-5-1 (EN 1.4405), and ferritic 444 stainless steel in 1 M sulfuric acid solution with the addition of 0%−6% NaCl. He found that 316Ti is less resistant to the acidic solution in the presence of the chloride ions. Lorsbach and Schmitz [13] showed that agitation rate has important influence in the increases of the corrosion rate of SS 316Ti in an acidic (250 ppm Cl − , pH = 4, t = 30°C) and an alkaline (4% Cl − , pH = 9, t = 80°C) electrolytes. Pardo et al. [14] investigated the influence of Ti, C, and N concentration in SS 316Ti and SS 321 on the intergranular corrosion after different heat treatments in the solution of 0.5 M H 2 SO 4 + 0.01 M KSCN at 30 o C. They determined that the addition of titanium promotes improved intergranular corrosion resistance of the stainless steel due to the precipitation of TiC, which reduces the formation of chromium-rich carbides. Besides, they concluded that SS 316Ti retains better intergranular corrosion resistance than SS 321. Zhao et al. [15] investigated stabilizing treatment on microstructure and intergranular corrosion resistance of 316Ti stainless steel in 0.5M H 2 SO 4 + 0.01M KSCN at 25 o C and showed that intergranular corrosion resistance increased with increasing aging temperature. The corrosion of SS 316Ti is sporadically reported; consequently, the aim of this work is to investigate the corrosion resistivity of SS 316Ti in