Austenitic stainless steels, corrosion behavior

Although Hitec is nonflammable, it is a strong oxidizer and supports the combustion of other materials. Consequendy, combustible materials must be excluded from contact with the molten salt. Hitec is compatible with carbon steel at temperatures up to 450°C. At higher temperatures, low alloy or austenitic stainless steel is recommended. Adding water to Hitec does not appreciably alter its corrosion behavior. 

Assis SL, Rogero SO, Antunes RA, Padilha AF, Costa I. A comparative study of the in vitro corrosion behavior and cytotoxicity of a superferritic stainless steel, aTi-13Nb-13Zr alloy, and an austenitic stainless steel in Hank s solution. Journal of Biomedical Materials Research B 2005, 73, 109-116. 

Localized biological corrosion of stainless steels. There are three general sets of conditions under which localized biological corrosion of austenitic stainless steel occurs (Figure 6.29). These conditions should be examined for metals that show active-passive corrosion behavior. Microbiological corrosion in austenitic steel weldments has been documented. (Wahid)61, (Krysiak)14... 

Austenitic stainless steels like 31 OS, 316, or 316L are typically used for the construction of cathode and anode current collectors and bipolar separator plates. Corrosion of these steel components is a major lifetime-limiting factor in MCFC. The corrosion behavior of stainless steel components in molten carbonate conditions has been studied extensively during the past decade. Research is being aimed at increasing the corrosion resistance of these components by altering the alloy composition or by surface modification techniques. ... 

W.Y.C. Chen and J.R. Stephens, Anodic Polarization Behavior of Austenitic Stainless Steel Alloys with Lower Chromium Content, Corrosion, Vol 35, 1979, p 443-450... 

Ferritic stainless steel has the reputation of being less sensitive to intergranular corrosion than austenitic stainless steel. This type of corrosion can nevertheless take place under certain conditions of thermal treatment [20]. The diffusion coefficients of both carbon and chromium in ferrite are larger than in austenite. Grain boundary precipitation of carbides and nitrides of chromium can therefore occur at temperatures of 540-600 °C already. The behavior differs from that of austenitic stainless steel, which becomes sensitized at higher temperatures only. Because of the larger diffusion... 

Brown, M. H., Behavior of Austenitic Stainless Steels in Evaluation Tests for the Detection of Susceptibility to Intergranular Corrosion, Corrosion, Vol. 30, No. 1, January 1974,... 

Well-documented studies have been performed to compare the fatigue behavior in air and under vacuum at low or moderate temperature of copper (Wang et al., 1984 Bayerlein and Mughrabi, 1992) and austenitic stainless steels (Gerland et al., 1988 Mendez et al., 1993). As an example. Fig. 5-12 shows the marked effect of an air environment at room temperature, even for a corrosion-resistant alloy. High cumulative plastic strain amplitudes can be reached under vacuum. The oxygen partial pressure controls the nature of the surface oxide and localization of the crack initiation process in persistent slip bands formed by cyclic straining. 

Commercial phosphoric acid contains fluorides, chlorides, sulfates, and heavy metal ions as impurities, however, which significantly increase its corrosivity and makes its corrosion characteristics unpredictable. Chloride contamination significantly increases acid corrosion of austenitic stainless steels and requires the use of nickel-based alloys. Very good corrosion behavior is reported for the superferrite XlCrNiMoNb28-4-2, Fig. 1-44 (Thyssen Edelstahl, 1979). 

H. Leinonen, 1. Virkkunen, H. Hanninen, Stress corrosion cracking and life prediction of austenitic stainless steels in calcium chloride solution, in Hydrogen Effects on Material Behavior and Corrosion Deformation Interactions, Proc. Int. Conf, Moran, WY, USA, 22-26 Sept. 2002 (2003) 673-682. 

The conventional solution to the poor biocompatibility of metallic materials is to select the materials inert in the human body. Stainless steel, for example, has nice resistance to corrosion due to the addition of Cr, which results in its broad clinical uses. The only implant material entering clinical treatments is 316L stainless steel, an austenitic stainless steel (Niinomi, 2008). Co-based alloys have favorable behavior for fabricating wear-bearing devices (Niinomi, 2008). Co alloys often need addition of Ni to increase the processibility (Niinomi, 2008), which remains a challenge. 

This section deals with the corrosion behavior of duplex stainless steel, some high austenitic stainless steels, and a nickel-based alloy in 28% HCl acidizing solutions, either in inhibited or uninhibited conditions, at 130 °C. Weight loss, crevice corrosion, and stress corrosion cracking tests were carried out for 6 and 24 hours, with amine-based commercial corrosion inhibitors, originally formulated for carbon steel. 

J. Moon, H.-Y. Ha, T.-H. Lee 2013. Corrosion behavior in high heat input welded heat-affected zone of Ni-free high-nitrogen, Fe-18Cr-10Mn-N austenitic stainless steel. Materials Characteriza-tion l, 113-119. 

CF tests on smooth specimens were performed at room temperature on a 316 L austenitic stainless steel in a 0.5 N H2SO4 solution at different electrochemical potentials and for a prescribed plasfic strain amplitude of 4 x 10 (s = 10 s ). The depassivation-repassivation process occurs in a very regular way, well before any microcracks can form [11]. It is of particular interest to follow the evolution of the maximum flow stress in the corrosive solution at free potential and at imposed cathodic potential and to compare this evolution with that observed in air (Figure 12.9). It clearly appears that (a) a cyclic softening effect occurs at the free potential in comparison with the behavior in air (b) this softening effect disappears when the cathodic potential is applied (and the anodic dissolution is markedly reduced), after about 150 cycles (c) the softening effect then occurs in the same way when... 

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