Corrosion of steels due to the action of microorganisms

The susceptibility of variously alloyed structural steels to microbiological corrosion in media enriched with hydrogen sulfide and favorable for reproduction of sulfate-reducing bacteria is studied. It is shown that stainless steels 05Kh17N4DB and especially nitrogen-alloyed steel 05Kh13A possess a higher anti-adhesive capacity with respect to corrosion-active microorganisms and resistance to microbe fouling and formation of corrosion-active biofilms than the conventional structural steel 38KhGM. It is assumed that the action of nitrogen can be connected with formation of biocide substances.     

Corrosion stability of austenitic steels 05Kh22AG15N8M2F and 12Kh18N10T in chloride-containing media

Protection of Metals and Physical Chemistry of Surfaces - Comparative corrosion tests are performed of doped stainless steels: conventional stainless steel 12Kh18N10T and new high-tension...     

Relation Between Parameters of Cavitation Resistance and Structure of Steels

The cavitation resistance of steels with different initial structure and hardness (05Kh13, Kh18N10T, St 3, VNS17, 07Kh14AG12M, 12Kh13N3G5, 30Kh13, 03N18K8M5T, 30Kh10G10, 95Kh18, 150Kh12M) is studied. Laws of variation of parameters of cavitation resistance are determined as a function of the level of ultimate hardening of the cavitation-affected surface in the final stage of the incubation period under microimpact loading of the studied steels.__________Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 1, pp. 15 – 19, January, 2005.     

Structure and hardness of corrosion-resistant ferritic steels subjected to high-temperature nitriding

A comparative study of the effect of high-temperature internal nitriding (at above 1000°C) on the structure formation and hardening of thin-sheet samples of 08Kh17T (0.06% C-17.0% Cr-0.5% Ti) and 15Kh25T (0.10% C-25.0% Cr-0.5% Ti) steels was performed. The high-temperature internal nitriding of the 08Kh17T steel leads to the formation of martensite structure with Cr₂N precipitates. The nitriding of 15Kh25T steel results in the formation of a layered structure; in this case, individual layers consist of a mixture of the α and γ phases and Cr₂N particles, which are present in different proportions. It was shown that the internal nitriding of both steels with their subsequent annealing leads to their substantial uniform hardening.     

核级316NG控氮奥氏体不锈钢的局部腐蚀行为

采用电化学测试法、点腐蚀试验法、盐雾腐蚀试验法和慢应变速率测试法,分别对比研究了核级316NG控氮奥氏体不锈钢和321奥氏体不锈钢的局部腐蚀行为,并利用扫描电子显微镜、光学显微镜等分别观察腐蚀后不锈钢的表面形貌。结果表明:316NG和321不锈钢晶间腐蚀再活化率分别为3.83%和4.47%,点腐蚀速率分别为10.74g/(m2·h)和45.97g/(m2·h),盐雾腐蚀速率分别为2.14×10-2 g/(m2·h)和12.32×10-2 g/(m2·h),应力腐蚀开裂敏感指数分别为0.078和0.10;316NG不锈钢中N和Mo元素提高了其耐局部腐蚀性能,因此其耐局部腐蚀性能均优于核电站结构材料321不锈钢的。     

Estimating resistance of <Emphasis Type="Italic">12Kh18N10T</Emphasis> steel against pitting corrosion in solution modeling steaming condensates of oil refineries

The resistance of sensitized 12Kh18N10T steel in aqueous electrolyte solutions, which model steaming condensates of the main refinery plants, namely, primary oil processing, reforming, and heavy fraction hydrorefining, is studied using chemical and electrochemical methods according to the Russian State Standard GOST 9.912. Condensate models were proposed based on many years of analyzing the steaming condensates of the Kirishi refinery plants. The main parameters of the steel susceptibility to pitting corrosion (pitting factor and electrochemical bases of pitting resistance) of the austenitic steels of Kh18N10T grade are shown to depend on the concentration of corrosive anions and their ratios in the solution. A system of correlation dependences is proposed for forecasting the probability of pit formation in the solutions.     

等离子体冶炼的N─Cr─Mn钢的耐腐蚀性能

用等离子氮弧冶炼不同氮含量的铬锰不锈钢,其耐腐蚀性能用动电位扫描、电化学阻抗等方法测试,并与1Cr18Ni9不锈钢作比较,结合显微组织分析耐蚀原因。实验结果表明含氮钢的耐蚀性普遍好于1Cr18Ni9不锈钢。随钢中含氮量增加,奥氏体组织扩大,耐腐蚀性能提高。当含氮量达0.74%时形成完全的奥氏体相。经阳极极化后,含氮钢表面的腐蚀层中奥氏体相比原基体的扩大,膜致密,耐腐蚀性能远远高于原基体。     

New high-silicon corrosion-resistant steel 02Kh8N20S6

Conclusion The large silicon and relatively low chromium concentrations in steel 02Kh8N20S6 (as compared with standard stainless steels) make it possible to obtain high corrosion resistance and resistance to intercrystalline corrosion in highly concentrated nitric acid.I. P. Bardin Central Scientific-Research Institute of Ferrous Metallurgy. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 5, pp. 30–32, May, 1976.     

三种不锈钢在含硫酸的水砂介质中的耐腐蚀磨损性能

利用自行设计的腐蚀磨损试验装置研究了三种不锈钢在不同固液比、硫酸浓度和线速度的条件下的耐腐蚀磨损性能；结果表明，在低硫酸浓度、高固液比和高线速度的条件下，沉淀硬化马氏体不锈钢具有良好的耐腐蚀磨损性能：而在腐蚀性较强、线速度较大的条件下，双相不锈钢的耐腐蚀磨损性能优于沉淀硬化马氏体不锈钢和奥氏体不锈钢；第二相强化奥氏体不锈钢在腐蚀性较强、耐磨性较弱的环境中耐腐蚀磨损性能较好。     

含铌沉淀硬化不锈钢的耐蚀性评估

应航空航天工业的需求,沉淀硬化不锈钢自1945年起即开始研发。这类钢具有置换型马氏体组织,随后能产生沉淀硬化。本文研究了两种含沉淀相形成元素铌的钢的力学性能和耐蚀性,并与PH13．8Mo钢进行了比较。结果表明,一种钢的耐蚀性与PH13—8Mo钢类似,另一种钢的力学性能与PH13—8Mo钢相近。     

Corrosion behaviour of Lotus-type porous high nitrogen nickel-free stainless steels

Corrosion behaviour of three austenitic Lotus-type porous high nitrogen Ni-free stainless steels exposed to an acidic chloride solution has been investigated by electrochemical tests and weight loss measurements. Polarization resistance indicates that the corrosion rate of Lotus-type porous high nitrogen Ni-free stainless steels is an order of magnitude lower than that of Lotus-type porous 316L stainless steel in acidic environment. The localised corrosion resistance of the investigated high nitrogen Ni-free stainless steels, measured as pitting potential, E_b, also resulted to be higher than that of type 316L stainless steel. The influences of porous structure, surface finish and nitrogen addition on the corrosion behaviour were discussed.     

Effectiveness of thermal shotblasting for casehardened steels

The shotpeening process that is used in industry has an ambiguous influence on the contact surface fatigue life of the casehardened steels: it improves this characteristic of the steels 12Kh2N4A and 12Kh2NVFA when using the rational hardening regime and reduces the contact surface fatigue life for any regimes of shotpeening of the temperature-resistant steel 16Kh3NVFMB-Sh. Low-temperature post-deformation annealing improves the contact surface fatigue life of both steels, but it limits their operating temperature. We can broaden the operating temperature range by the use of thermal shotblasting, which involves strain hardening of the casehardened surface that is heated to 250 °C. This is shown in the present work.Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 5, pp. 21–24, May, 1994.     

Corrosion‐technical properties of high‐strength stainless steels for the application in prestressed concrete structures

Experience with prestressed concrete over about half a century has indicated that the corrosion resistance of conventional prestressing steel does not always satisfy, especially the prestressing steels are susceptible to chloride attack (de‐icing salts) and hydrogen (hydrogen‐induced stress corrosion cracking). On the other hand corrosion agents, such as chloride, condensation water, can penetrate in the concrete and arrive at the surface of steels. Hence, corrosion damage of prestressing steels can happen and, in the extreme cases, the prestressed concrete structure collapsed resulting from the failure of the tendon. In this paper, consideration is made to use high‐strength stainless steels as prestressing tendon with bond in concrete. The high‐strength stainless steels of qualities 1.4301 (X5CrNi18‐10), 1.4401 (X5CrNiMo17‐12‐2), 1.4436 (X3CrNiMo17‐13‐3) and 1.4439 (X3CrNiMoN17‐13‐5) with sequence of increasing austenite stability were investigated. For application in prestressing tendon with bond in concrete the cold‐drawn high‐strength stainless steel of quality 1.4401 is an optimal proposition regarding its satisfactory resistance against pitting corrosion and stress corrosion cracking (SCC) in structure‐related corrosive conditions. The lower alloyed steel 1.4301 has an insufficient resistance against the chloride‐induced corrosion because of the lack of molybdenum and the content of deformation martensite due to the strong cold‐drawing of its unstable austenitic structure.     

Structural transformations,strengthening, and wear resistance of titanium nickelide upon abrasive and adhesive wear

Wear resistance and structural transformations upon abrasive and adhesive wear of titanium nickelide Ti49.4Ni50.6 in microcrystalline (MC) and submicrocrystalline (SMC) states have been investigated. It has been shown that the abrasive wear resistance of this alloy exceeds that of the steel 12Kh18N9 by a factor of about 2, that of the steel 110G13 (Hadfield steel), by a factor of 1.3, and is close to that of the steel 95Kh18. Upon adhesive wear in a testing-temperature range from −50 to +300°C, the Ti49.4Ni50.6 alloy, as compared to the steel 12Kh18N9, is characterized by the wear rate that is tens of times smaller and by a reduced (1.5–2.0 times) friction coefficient. The enhanced wear resistance of the Ti49.4Ni50.6 alloy is due to the development of intense strain hardening in it and to a high fracture toughness, which is a consequence of effective relaxation of high contact stresses arising in the surface layer of the alloy. The SMC state produced in the alloy with the help of equal-channel angular pressing (ECAP) has no effect on the abrasive wear resistance of the alloy. The favorable effect of ECAP on the wear resistance of the Ti49.4Ni50.6 alloy takes place under conditions of its adhesive wear at temperatures from −25 to +70°C. The electron-microscopic investigation showed that under conditions of wear at negative and room temperatures in the surface layer (1–5 μm thick) of titanium nickelide there arises a mixed structure consisting of an amorphous phase and nanocrystals of supposedly austenite and martensite. Upon friction at 200–300°C, a nanocrystalline structure of the B2 phase arises near the alloy surface, which, as is the case with the amorphous-nanocrystalline structure, is characterized by significant effective strength and wear resistance.     

Biological corrosion of construction materials at nuclear power engineering enterprises

The research data concerning the biological corrosion of construction materials for nuclear power plants (NPPs) are submitted in this article. The corrosion kinetic features of 08Kh18N10T and 20 steels in industrial neutral electrolyte are analyzed before and after the above steel types are contaminated with microorganisms. The effects of microorganisms and the products of their metabolism on the corrosion of biocide component-protected steels are evaluated.     

Enhanced corrosion resistance of interstitially hardened stainless steel: Implications of a critical passive layer thickness for breakdown

Immense interstitial hardening of 316L austenitic stainless steel via low-temperature paraequilibrium carburization also leads to greatly improved corrosion resistance. Both the hardening and the improved corrosion resistance owe their origin to a “colossal” supersaturation of interstitial carbon. The corrosion resistance of stainless steel involves a Cr₂O₃-rich passive film, and the composition and thickness of the passive film developed during anodic polarization at various potentials were determined for both carburized and non-treated steels using grazing incidence X-ray photoelectron spectroscopy. Passive oxide film breakdown is a necessary step in pitting corrosion, and appears to occur in these steels at a critical film thickness of ≈3 nm. We suggest that this breakdown is of chemomechanical origin. Long wavelength thickness perturbations occur during film growth to reduce the strain energy density in the passive film arising from intrinsic and electric field-induced stresses. At the critical thickness, the localized thinning is sufficient to lead to dielectric breakdown and nucleation of pitting corrosion. The improved corrosion resistance for the carburized material results from thinner passive films at a given potential and hence a delay in the detrimental effect of the thickness perturbations.     

940X新型不锈钢的耐蚀性能

通过盐雾试验和点腐蚀电位测试,对比了新型940X不锈钢和9Cr18不锈钢的耐蚀性能.结果表明,在NaCl溶液中940X不锈钢的耐全面腐蚀和耐点腐蚀的性能比9Cr18的高.并结合化学成分及金相能谱分析了940X不锈钢的耐蚀机理.     

不锈钢海水潮汐区16年腐蚀行为

在青岛、厦门和榆林3个试验站的潮汐区对5种不锈钢暴露16年，总结其腐蚀行为和规律。在潮汐区暴露的不锈钢受点蚀和缝隙腐蚀破坏。不锈钢在潮汐区暴露1至4年的点蚀速度较大，以后点蚀速度减慢。耐点蚀性能较好的不锈钢，耐缝隙腐蚀性能也较好。不锈钢在潮汐区的腐蚀随暴露地点的海水温度升高而加重。增加Cr含量、添加Mo能明显提高不锈钢在潮汐区的耐蚀性。Ni对提高的耐蚀性有效，但影响效果较小。海生物污损能引起不锈钢的局部腐蚀，它对不锈钢在潮汐区的腐蚀有显著影响。     

Effect of Periodic High-Voltage Discharge in a Flow of Liquid on the Surface Layers of Structural Steels and Titanium Alloys

Results of a study of the effect of electric pulse treatment with the use of high-voltage periodic discharge in a flow of water on the structure and hardness of surface layers of specimens of steels 45KhN2MFA, 30Kh3NMAF, 12Kh18N10T and titanium alloys OT4-1 and VT6 are described. It is shown that the structure and properties of the surface in the zone of the action of electric discharge change due to the rapid fusion, crystallization, and rapid hardening of microvolumes of specimens subjected to the highly concentrated energy action. The microhardness of the surface of specimens of pearlitic steels after such a treatment is higher than after volume quenching. The microhardness of the surface layers of specimens of austenitic steel 12Kh18N10T decreases. Hardening of the surface layers of titanium alloys under the action of high-voltage discharge is substantially higher than in the case of quenching, which seems to be connected with their saturation with oxygen and nitrogen from the ionized ambient. Some regular features of the influence of the conditions of periodic discharge on the structure and properties of surface layers of the studied materials are described.     

Analysis of alloying systems of clad stamping tools for cold deformation of metal (review)

Two alloying systems of stamping tools (with intermetallic and carbide hardening) are analysed. Analysis shows the high characteristics of the metal with different alloying systems. The heat resistance of the 100Kh4M5F2(Zr) alloy is not inferior to the R18 high-speed tool steel, and the hardness equals 58–62 HRC as a result of carbide hardening. The relative wear resistance of the 8Kh4GSV2M5F2T alloy was (ε = 2.65), impact toughness (0.28 MJ/m²) and hardness (55 HRC). The highest wear resistance was recorded for the K15M15N5Kh3B2 alloy with the following properties after heat treatment: impact toughness (0.1 MJ/m²) and hardness (39 HRC). The wear resistance is 2–2.5 times higher than that of the R18 high-speed tool steel and 6–6.5 times higher than that of Cr12 and Cr12Mo steels.