Fugivara, D.L. The Authors (1963), A.R. The obtained spectra were corrected based on the carbon peak (C1s) position to 284.8 eV and analysed using CasaXPS software (Version 2.3.17). Payne, A.P. The presence of this film is believed to be key to understand the corrosion performance and passivity of type 316 stainless steel in caustic environments. The polarization curves for the aerated and de-aerated systems show very similar electrochemical behavior. Google Scholar, A. Bhattacharya, P.M. Singh, Electrochemical behaviour of duplex stainless steels in caustic environment. Type 316L stainless steel exposed to aerated 50 wt% NaOH solution at 25 °C shows corrosion rates of 0.023 mm/year. The role of temperature on the stability of NiO and Ni(OH)2 is currently subject of further investigations, since it is not clear why higher corrosion rates are observed when this film is present. The pristine reference sample contains iron metal (12.7%) and iron oxide/hydroxide peaks (46.7%), with the presence of iron oxide/hydroxides related to the passive film on stainless steels [36, 37]. GI-XRD analysis of the black surface film after immersion in 50% NaOH at 90 °C. Sol. Pitting corrosion of a stainless steel is illustrated in the Figure 1. Films 33(5), 05E122 (2015), M.C. Gittos, D.L. Austenitic stainless steels generally show high corrosion rates when exposed to concentrated, de-aerated alkaline aqueous environment at temperatures above 60 °C, with typical corrosion rates of 0.05–2 mm/year. However, with some chemicals, mainly acids, the passive layer may be attacked uniformly depending on concentration and temperature and the metal loss is distributed over the entire surface of the steel. Very dilute caustic solutions show reduced corrosion susceptibility, for example, with exposure to mildly caustic environment up to pH 12, resulting in corrosion rates of 0.01 mm/year [12,13,14]. Sci. Lett. This behavior seems to be related to the diminution in the length of the passive region mentioned before in Fig. Therefore, the use of basic forms of stainless steel is not recommended in more hostile conditions. Ameer, A.M. Fekry, A.A. Ghoneim, F.A. The graph clearly shows the effect of temperature on passivity. Raul Davalos Monteiro. The surface of a sample exposed for 4 months in 50% NaOH at 90 °C was analysed by GI-XRD, with the spectrum of the dark surface film shown in Fig. McIntyre, M.G. 205, Appleton, WI, USA (1986), F.A. Correspondence to LPR was conducted in the range from − 10 to + 10 mV versus Ecorr, using a scan rate of 1 mV/s. Corrosion rate versus temperature of Type 316L stainless steel in aerated and de-aerated 30%, 40% and 50% NaOH solutions From the highest active peak of the polarization curve. Based on the Pourbaix diagrams of Iron, Chromium and Nickel, the possibility of forming a passive film with exposure to caustic pH supports the argument of using stainless steel in these media. Bringas, Corrosion Control, vol. The effect of oxygen in 30 wt% NaOH solution is shown in Fig. NaOH at temperatures up to 90 °C has been elucidated. Fig. The reference surface condition also contained 4.2% chromium metal and 27.4% chromium oxide/hydroxides. Nickel alloy 200 shows no activation peak at this potential. J. Electrochem. Biesinger, B.P. Here is a quick explanation of some of the things that can corrode stainless steel: 1: Strong Chlorides Can Cause Pitting Corrosion in Stainless Steel. General Corrosion on stainless steel Normally stainless steel does not corrode uniformly like ordinary carbon and alloy steels. 2d. The effect of solution de-aeration on the electrochemical behavior in 40 wt% and 50 wt% NaOH is summarized in Fig. 19(4), 261–281 (1979), J.R. Davis (ed. Basic types of stainless steel like 304 and 316 may corrode easier in certain environments and then a more highly alloyed stainless steel can be used. Engelberg, Reduction of austenite-ferrite galvanic activity in the heat-affected zone of a Gleeble-simulated grade 2205 duplex stainless steel weld. Montemor, The passive behaviour of AISI 316 in alkaline media and the effect of pH: a combined electrochemical and analytical study. Sci. 2. NaOH at temperatures up to 90 °C has been elucidated. After exposure to concentrated caustic solutions at temperature above 50 °C, stainless steel surfaces are covered by a black surface film predominantly made of nickel oxide and hydroxides. The obtained Ni 2p spectra is shown in Fig. At potentials more positive than the 1st passivation region (Epass-1), a thick (> 100 nm) partially protective Ni(OH)2 layer has also been reported, associated with the formation of thin de-alloyed layers, approaching compositions of binary 50–50 Fe–Ni alloys [30]. This is also described in an investigation on the electrochemical behavior of Nickel [32]. 304 stainless steel, whose chromium content is equal to 18%, has been chosen in this study because of its frequent use and its relatively weak resistance to corrosion (in comparison with the other stainless steels), allowing to assess more easily the influence of the environment on corrosion. However, when the temperature is increased above 50 °C and the system is de-aerated the corrosion rates even at the free corrosion potential reach up to nearly 0.5 mm/year, 21 times the value at room temperature. Eng. 142, 93–101 (2018), H. Feng et al., Corrosion behavior of super duplex stainless steel S32750 in white liquor. https://doi.org/10.1590/1980-5373-mr-2017-0148, Article Corrosion of unprotected carbon steel occurs even inside reinforced J. Electrochem. (2018). The temperature was altered approximately 4 times per week. Corrosion 33(2), 60–67 (1977), V.S. Galvanic corrosion can be prevented: None. Trans. All electrochemical potentials were converted to the normal hydrogen electrode (Red-rod +129.5 mV vs. NHE). All obtained parameters and associated values are summarized in the “Appendix” section. a Electrochemical response of type 316L in 50% aerated NaOH at 90 °C with potential regions describing the stainless steel behaviour in this environment, and b potentio-dynamic polarization curves of austenitic stainless steel types 316, 304 and 204, duplex stainless steel type 2205, and Ni alloy 200 in 50% NaOH at 90 °C aerated solution. 46(9), 2117–2133 (2004), B. Krawczyk, P. Cook, J. Hobbs, D. Engelberg, Corrosion behavior of cold rolled type 316L stainless steel in HCl containing environment. A noticeable dark film can be recognized after an immersion of the sample in caustic solutions at temperatures between 50 and 90 °C. Sastri, E. Ghali, M. Elboujdaini, Corrosion Prevention and Protection: Practical Solutions (Wiley, New York, 2007), M.A. Figure 8a shows weight loss measurements at room temperature with exposure up to 4 months. … J. Cook, X-ray photoelectron studies on some oxides and hydroxides of cobalt, nickel, and copper. Sci. NaOH presented corrosion rates of up to 0.5 mm/year at open circuit potential, with maximum corrosion rates under polarisation of up to ≈ 18 mm/year. Pitting corrosion, or pitting, is a form of extremely localized corrosion that leads to the creation of small holes in the metal. No decay: Mitigating actions. A second weight loss test by including changes in temperature of the environment was performed, to simulate heat exchanger temperature perturbations. The different domains in Fig. Smart, Resolving surface chemical states in XPS analysis of first row transition metals, oxides and hydroxides: Cr, Mn, Fe, Co and Ni. Previous work has also revealed the negative influence of Molybdenum on the corrosion resistance of stainless steel in white liquor, facilitating high dissolution rates in the form of MoO24-ion formation [31].
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