Materials and Corrosion-werkstoffe Und Korrosion最新文献

RETRACTION: Lkhagvaa Telmenbayar, Tumur-Ochir Erdenebat, Minjung, Daejeong Yang, Ramu Adam Gopal, Dongjin Choi Fabrication of a superhydrophobic surface on Al alloy 5052via combined anodic oxidation and fluorination treatment, published in Materials and Corrosion, DOI 10.1002/maco.202012190. The above article, published online on 03 March 2021 in Wiley Online Library (wileyonlinelibrary.com), has been withdrawn by agreement between the journal JPM Regina Hagen, Author Dongjin Choi, and Wiley-VCH. The withdrawal has been agreed upon following that there was a minor problem with the materials authors used and they plan to resubmit after additional experiments. wileyonlinelibrary.com/journal/maco Materials and Corrosion. 2021;1–9.

The study investigates salt chemistry and corrosion behavior of SS 316H and Alloy 617 in thermally purified molten NaF-KF-UF₄-UF₃ salts (UF₄/UF₃ initial ratio 12–14) at 800°C for 120, 72, and 32 h. UF₄/UF₃ ratio increases after corrosion tests. Cr species concentration in salts keeps increasing. Fe, Co, Ni, and Mo species increase first, then decrease. Cr/Mn oxides are formed along grain boundaries in SS 316H. Cr near the surface of Alloy 617 is completely depleted. A thin layer composed of Fe, Co, Ni, and Mo is observed on the Alloy 617 surface in 72-h and 32-h tests.

The effects of rare earth elements (REEs) on the corrosion behavior of weathering steels under a simulated immersion environment and a real atmospheric environment have been investigated in this paper. Although the corrosion rate of the indoor accelerated corrosion experiment (0.01 mol/L NaHSO₃) is much higher than that of the real atmospheric exposure experiment, the addition of REEs can highly improve the corrosion resistance of test steels under both conditions. The improvement of the corrosion resistance can be attributed to the quick transformation of γ-FeOOH into α-FeOOH and the accelerated formation of a stable rust layer by REEs. Furthermore, the segregation of the REE inner rust layer increases the density of the rust layer and prevents corrosive particles from eroding the matrix. REEs can also promote the segregation of Cu, Cr, and other alloying elements in the rust layer, thus blocking the cracks and holes and enabling the formation of a continuous rust layer with good adhesion.

Owing to their excellent properties, duplex stainless steels (DSSs) may be selected for the H₂S environment. Operational limits are not defined and depend on fabrication processes. In this work, the susceptibilities of two DSSs 2205 to sulfide stress corrosion (SSC) in saline solutions with three pH levels were investigated. The difference between materials is the fabrication route: hot rolled (HR) tubes and powder metallurgy with compacting and sintering final operations by hot isostatic pressing (PM-HIP). The susceptibility parameters were evaluated by slow strain rate tensile tests (SSRT). Both materials suffered embrittlement in solutions with pH 3.5 and 4.5, but the susceptibility was slightly better in the HR. In the solution with pH 5.5, the HR fractured with ductile behavior, while the PM-HIP was brittle. The better resistance of HR to SSC can be explained by microstructural features, such as the lower grain size and austenite island interspace.

Although copper (Cu) pipes are widely used in refrigerant piping owing to their high thermal conductivity and weathering resistance, there are concerns regarding the increasing price and limited supply of Cu. Consequently, our focus has shifted to aluminum (Al), which is relatively abundant and inexpensive, to investigate its application in refrigerant piping. We previously examined corrosion factors on both the internal and external surfaces of straight piping and conducted accelerated degradation tests, showing that Al has a durability comparable to that of Cu. However, bending sections are always used in addition to straight pipes, and bending induces tensile stress on the outer side of the bending curvature and compressive stress on the inner side. Notably, stress corrosion cracking may occur under tensile stress in corrosive environments. Herein, we investigate the mechanical, electrochemical, and weather resistance properties of bent Al and Cu pipes to evaluate the practicality of Al refrigerant piping.

In this study, the intergranular corrosion (IGC) susceptibility of AA2098-T351 welds, fabricated through friction stir welding (FSW), was systematically evaluated. The evaluation employed American Society for Testing and Materials (ASTM) G110-92 practice and electrochemical impedance measurements, with comparative analyses against unwelded alloys (BS). The key findings depicted that FSW-induced microstructure changes significantly influenced IGC susceptibility across different zones. Zones affected by FSW presented distinct susceptibilities compared with the base metal (BM). The ASTM G110-92 test effectively differentiated the heat-affected zone (HAZ) into segments with changing corrosion resistances based on welding temperature gradients. Cross-sectional analyses using scanning electron microscopy (SEM) techniques correlated corrosion characteristics with microstructural features identified by transmission electron microscopy (TEM). Overall, FSW-induced microstructural alterations emerged as a predominant factor influencing the varying susceptibilities of different zones to IGC, and electrochemical impedance measurements (EIS) validated the findings from ASTM G110-92 practice.

In the construction area, as well as in the restoration of old and historical buildings, different metallic materials are frequently in contact with gypsum plaster. Due to the high porosity of gypsum plaster, and particularly in high relative humidity environments, the risk of corrosion exists. In the present work, carbon, galvanized and stainless steel, as well as copper, were embedded in gypsum plaster (with varying water/gypsum ratios) and exposed to different environmental conditions, and the corrosion rate was assessed by electrochemical techniques. Stainless steel showed very low corrosion rates, carbon and galvanized steel showed considerable corrosion rates, and copper showed moderate corrosion rates. The higher the humidity, the higher the corrosion rate, independently of the water/gypsum ratio. A comparison with results obtained for the same materials embedded in mortar was performed. Except for stainless steel, the corrosion rates obtained in gypsum are higher than those obtained in mortar, being this difference up to two orders of magnitude. The differences in the pH of both matrices explained the lower corrosion rates measured in mortar.