JournalTOCs API - articles

Electrochemical corrosion behaviour of innovative mould steels in a chloride‐containing environment

Electrochemical corrosion behaviour of innovative mould steels in a chloride‐containing environment

Materials and Corrosion, Vol. , No. () pp. -
Article URL: http://dx.doi.org/10.1002%2Fmaco.201005794

Effect of microstructure on corrosion resistance of pipelines steels buried in alkaline soil

Souad Brick Chaouche; Azzedine Lounis; Ghania Nezzal — 2011-12-19T23:20:50-05:00

Effect of microstructure on corrosion resistance of pipelines steels buried in alkaline soil
Souad Brick Chaouche; Azzedine Lounis; Ghania Nezzal
International Journal of Microstructure and Materials Properties, Vol. 6, No. 6 (2011) pp. 526 - 542
In this work, we tried to examine the effect of microstructure of low carbon pipeline steels on their behaviour to corrosion when they are buried in alkaline soil. In this environment, the corrosion rate of these steels depends on a number of different parameters. Perhaps the most significant of these parameters, namely, is the formation, evolution and nature of the corrosion products, which are deposited on the metal surface. The laboratory experiments realised from electrochemical measurements and characterisation of corrosion products have shown that the microstructure influences the properties of the corrosion layers, such as morphology, proportion of the various chemical compounds, adherence of the film and the protective properties. The results obtained are striking, not only there was a difference in certain properties of corrosion layers, but also protective power is strongly affected.

A new steel with good low‐temperature sulfuric acid dew point corrosion resistance

A new steel with good low‐temperature sulfuric acid dew point corrosion resistance

Materials and Corrosion, Vol. , No. () pp. -
In this work, new steels (1#, 2#, and 3#) were developed for low‐temperature sulfuric acid dew point corrosion. The mass loss rate, macro‐ and micro‐morphologies and compositions of corrosion products of new steels in 10, 30, and 50% H2SO4 solutions at its corresponding dew points were investigated by immersion test, scanning electron microscopy (SEM) and energy‐dispersive spectrometry (EDS). The results indicated that mass loss rate of all the tested steels first strongly increased and then decreased as H2SO4 concentration increased, which reached maximum at 30%. Corrosion resistance of 2# steel is the best among all specimens due to its fine and homogeneous morphologies of corrosion products. The electrochemical corrosion properties of new steels in 10 and 30% H2SO4 solutions at its corresponding dew points were studied by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. The results demonstrated that corrosion resistance of 2# steel is the best among all the experimental samples due to its lowest corrosion current density and highest charge transfer resistance, which is consistent with the results obtained from immersion tests.

Corrosion of steel by carbonate‐bicarbonate solution for CO2 capture

Corrosion of steel by carbonate‐bicarbonate solution for CO2 capture

Materials and Corrosion, Vol. , No. () pp. -
Hot alkaline solutions, such as potassium/sodium carbonate solutions, have been used for carbon dioxide removal and capture processes. This survey summarizes the available corrosion data of steels in the solution with carbon dioxide dissolved. Plant operating experiences and laboratory testing results are considered. The corrosion mechanisms, important factors, inhibitor effects, and corrosion cracking are analyzed.

Use of corrosion-resistant steels and alloys in sulfuric acid media

A. S. Zholud A. S. Derbyshev ; Yu. N. Dulepov — Thu, 02 Feb 2012 17:57:56 GMT

Use of corrosion-resistant steels and alloys in sulfuric acid media
A. S. Zholud A. S. Derbyshev ; Yu. N. Dulepov
Chemical and Petroleum Engineering, Vol. , No. (2012) pp. 627 - 631
Within the chemical industry, and also in some other branches, there is extensive use of sulfuric acid solutions of different concentration and corrosiveness, containing metal ions of varied valency (Cu2+, Fe3+, Ni2+, Cr3+, etc.), which appear in a medium, for example, as a result of equipment corrosion, etc. In sulfuric acid media, corrosion can be uniform or local, i.e., pitting, spot corrosion, intercrystalline corrosion (ICC). Whereas uniform corrosion develops as a gradual reduction in the thickness of an original vessel, equipment, and machine component elements, whose corrosion rate may be calculated previously from existing data for the corrosion resistance of structural materials in specific production media, it is almost impossible to predict ICC development, and therefore in many cases it leads to sudden structural breakdown. In order to predict corrosion, it is recommended to use for article manufacture corrosion-resistant steels and alloys with alloying providing in sulfuric acid solutions resistance to uniform and local corrosion with the required heat treatment and monitoring for ICC resistance.

Influence of heat treatments at 475 and 400 °C on the pitting corrosion resistance and sensitization of UNS S32750 and UNS S32760 superduplex stainless steels

Influence of heat treatments at 475 and 400 °C on the pitting corrosion resistance and sensitization of UNS S32750 and UNS S32760 superduplex stainless steels

Materials and Corrosion, Vol. , No. () pp. -
Some precipitation reactions of superduplex stainless steels (SDSS) can improve hardness, yield, and ultimate strength, but with substantial decrease of corrosion resistance. One of these reactions is the spinodal decomposition of ferrite into Cr‐rich fine precipitates (α′) and Cr‐depleted matrix during low temperature aging. In this work, the effect of the α′ precipitation on the pitting corrosion resistance was investigated. The results showed that short duration heat treatments at 475 °C do not decrease the pitting corrosion resistance, but increase the hardness of UNS S32750 and S32760 SDSS. The limits of heat treatment duration for both steels were determined.

A practical application of thermal desorption mass spectrometry for studying inhibitors and corrosion products

A. K. Buryak T. M. Serdyuk ; A. V. Ul’yanov — Sun, 09 Nov 2008 10:10:33 GMT

A practical application of thermal desorption mass spectrometry for studying inhibitors and corrosion products
A. K. Buryak T. M. Serdyuk ; A. V. Ul’yanov
Protection of Metals, Vol. , No. (2008) pp. -
In the present review, examples of the practicality of applying thermal desorption mass spectrometry (TDMS) to study inhibitors and corrosion products are given. It is shown that the highly informative aspect of the method allows regularities of the processes occurring in volume, on surfaces, and in near-surface layers of steels and alloys to be established. The TDMS method makes it possible to identify adsorbed and chemisorbed inhibitors and corrosion products, as well as products of their destruction.

Corrosion of aluminium, stainless steels and AISI 680 nickel alloy in nitrogen‐based fuels

Corrosion of aluminium, stainless steels and AISI 680 nickel alloy in nitrogen‐based fuels

Materials and Corrosion, Vol. , No. () pp. -
Nitrogen‐based compounds can potentially be used as alternative non‐carbon or low‐carbon fuels. Nevertheless, the corrosion of construction materials at high temperatures and pressures in the presence of such fuel has not been reported yet. This work is focused on the corrosion of AISI Al 6061, 1005 carbon steel (CS), 304, 316L, 310 austenitic stainless steels (SS) and 680 nickel alloy in highly concentrated water solution of ammonium nitrate and urea (ANU). The corrosion at 50 °C and ambient pressure and at 350 °C and 20 bar was investigated to simulate storage and working conditions. Sodium chloride was added to the fuel (0–5 wt%) to simulate industrial fertilizers and accelerated corrosion environment. Heavy corrosion of CS was observed in ANU solution at 50 °C, while Al 6061, 304 and 316L SS showed high resistance both to uniform and pitting corrosion in ANU containing 1% of sodium chloride. Addition of 5% sodium chloride caused pitting of Al 6061 but had no influence on the corrosion of SS. Tests in ANU at 350 °C and 20 bar showed pitting on SS 304 and 316L and 680 nickel alloy. The highest corrosion resistance was found for SS 310 due to formation of stable oxide film on its surface.

Study of sensitization and different heating cycles on stainless steels used for automotive exhaust components

Study of sensitization and different heating cycles on stainless steels used for automotive exhaust components

Materials and Corrosion, Vol. , No. () pp. -
In order to achieve a reasonable lifetime of automotive exhaust components, a large number of high alloyed ferritic and austenitic stainless steels are used nowadays. It is a common concept that the lifetime of a component is directly related to the performance of steel against corrosion. The components are divided into different sections depending on their service temperatures. High temperature oxidation resistance is one of the properties which are required in different sections. The effect of material sensitization on corrosion resistance of stainless steels is well understood from the literature. Besides, sensitization materials in exhaust systems have to withstand different cyclic heating and cooling phases. The objective of this study was to develop a basic understanding that can determine the influence of different temperature treatments on stainless steels. A fundamental understanding on the interaction of sensitization and cyclic heat impacts are presented in the paper.

Specific features of hydrogen-induced corrosion degradation of steels of gas and oil pipelines and oil storage reservoirs

E. I. Kryzhanivs’kyi H. M. Nykyforchyn — Wed, 16 Nov 2011 16:47:48 GMT

Specific features of hydrogen-induced corrosion degradation of steels of gas and oil pipelines and oil storage reservoirs
E. I. Kryzhanivs’kyi H. M. Nykyforchyn
Materials Science, Vol. , No. (2011) pp. 127 - 136
We analyze general regularities of degradation of the mechanical and corrosion-mechanical properties of steels of oil and gas main pipelines and oil storage reservoirs after 28–40 years of operation. The transported oil product not only causes corrosion damages of the internal surface of pipelines and reservoirs, but also becomes a source of hydrogenation of the metal. As a result, it degrades already under the long joint action of mechanical load and hydrogen. Changes in (degradation of) the mechanical properties of the sections of a pipe or a reservoir that contact with the transported medium during operation indicate this fact. First of all, this manifests itself as embrittlement of the metal, i.e., as decreases in the plasticity and resistance to fracture. Comparison assessment of operated and nonoperated steels showed the high sensitivity of the electrochemical properties to the state of the metal, which offers prospects for the development of electrochemical methods for assessing its in-service degradation.

Modeling steel corrosion under supercritical CO2 conditions

Modeling steel corrosion under supercritical CO2 conditions

Materials and Corrosion, Vol. , No. () pp. -
Corrosion in the presence of CO2 was studied under supercritical conditions (high pressure and moderate temperature) using different carbon steels and various corrosion resistant alloys (CRA's). An objective of this work was, among others, to put the results in perspective relative to various CO2 corrosion models that have been developed and published over the years. In particular, the NORSOK, FREECORP, and OLI models were used for comparison, while others were discussed as well. The systems investigated were (a) supercritical CO2 (SC CO2) saturated with water (no separate water phase), (b) a water mist phase in equilibrium with SC CO2, (c) a water/brine phase in equilibrium with SC CO2. It was found that the OLI model best simulates the experimental corrosion rates observed in system (c) where coupons were corroded in the aqueous phase at high velocities in the rotating cage. The varying susceptibility of different carbon steels to corrosion under these conditions is highlighted. CRA steels are comparatively more resistant.

Physicochemical properties of steel surfaces with titanium nitride ion-plasma sprayed coating

A. I. Kostrzhitskii T. V. Cheban ; R. A. Podolyan — Sun, 09 Nov 2008 10:10:30 GMT

Physicochemical properties of steel surfaces with titanium nitride ion-plasma sprayed coating
A. I. Kostrzhitskii T. V. Cheban ; R. A. Podolyan
Protection of Metals, Vol. , No. (2008) pp. -
Abstract In nutral media, the regularities of the electrochemical corrosion of a steel, that had been sprayed by ionic plasma with titanium nitride, are studied. It is shown that the coating porosity is the principal factor determining its protective properties. Quantitative data on the effect of operation conditions on the coating porosity and corrosion-electrochemical behavior in liquids are given. Empirical formulas describing the kinetics of increasing the number of corrosion craters are obtained. Guidelines concerning the using of the ion-plasma coatings in the protecting of lean alloy steels against corrosion are formulated.

Study on the Corrosion Mechanism of Zn-5Al-0.5Mg-0.08Si Coating

Study on the Corrosion Mechanism of Zn-5Al-0.5Mg-0.08Si Coating

Journal of Metallurgy, Vol. , No. () pp. -
A new type of hot-dip Zn-5Al-0.5Mg-0.08Si and Zn-5Al alloy coatings was performed on the cold rolled common steel. The hot-dip process was executed by self-made hot-dip galvanising simulator. SEM and EDS test results demonstrated that Mg was mainly distributed in crystal boundaries. XRD test results showed that the corrosion product of Zn-5Al-0.5Mg-0.08Si alloy coating was almost Zn5(OH)8C12⋅H2O. The features of Zn5(OH)8C12⋅H2O are low electric conductivity, insolubility and good adhesion.The corrosion resistance of alloy-coated steels was detected by neutral salt spray test. The microstructural characterization of the coating surface after neutral salt spray test and removing the corrosion products revealed that the corrosion process of Zn-5Al-0.5Mg-0.08Si coating was uniform and the coating surface was almost flat. As a result, the corrosion resistance of Zn-5Al-0.5Mg-0.08Si coating has a remarkable improvement with a factor of 9.2 compared with that of Zn-5Al coating.

Corrosion properties of S-phase layers formed on medical grade austenitic stainless steel

Joseph Buhagiar Hanshan Dong — Mon, 12 Dec 2011 17:13:11 GMT

Corrosion properties of S-phase layers formed on medical grade austenitic stainless steel
Joseph Buhagiar Hanshan Dong
Journal of Materials Science Materials in Medicine, Vol. , No. (2011) pp. 1 - 11
Abstract The corrosion properties of S-phase surface layers formed in AISI 316LVM (ASTM F138) and High-N (ASTM F1586) medical grade austenitic stainless steels by plasma surface alloying with nitrogen (at 430°C), carbon (at 500°C) and both carbon and nitrogen (at 430°C) has been investigated. The corrosion behaviour of the S-phase layers in Ringer’s solutions was evaluated using potentiodynamic and immersion corrosion tests. The corrosion damage was evaluated using microscopy, hardness testing, inductive coupled plasma mass spectroscopy and X-ray diffraction. The experimental results have demonstrated that low-temperature nitriding, carburising and carbonitriding can improve the localised corrosion resistance of both industrial and medical grade austenitic stainless steels as long as the threshold sensitisation temperature is not reached. Carburising at 500°C has proved to be the best hardening treatment with the least effect on the corrosion resistance of the parent alloy.

Electrochemical investigations on corrosion protection oils

Electrochemical investigations on corrosion protection oils

Materials and Corrosion, Vol. , No. () pp. -
Tribologically affected surfaces of high‐strength steels often only may be protected against corrosion by the use of specific protecting oils. The protective effectiveness of these products is usually assessed by neutral salt spray test during qualification. As this test method takes a long time and because the reproducibility is poor a new test method was developed based on electrochemistry. It could be shown that a distinction was possible between well and nonprotecting oils based on current density curves and electrochemical impedance spectroscopy.

Influence of microstructure on mechanical properties and corrosion behavior of 3%Cr steel in CO2 environment

Influence of microstructure on mechanical properties and corrosion behavior of 3%Cr steel in CO2 environment

Materials and Corrosion, Vol. , No. () pp. -
Corrosion behavior and mechanical properties of two 3%Cr pipeline steels were studied which have same chemical compositions but different microstructures, bainite‐ferrite and ferrite‐pearlite microstructures. Analysis of chemical compositions and surface morphology of the corrosion scale were performed using X‐ray diffraction and scanning electron microscopy in conjunction with energy dispersive X‐ray spectroscopy. The semi‐passive character of corrosion scale was investigated using polarization curves measurements. The influence of microstructure on the chromium enrichment in the corrosion scale for different test periods was investigated. The microstructure was observed to affect the corrosion behavior even when the steel surface has been covered with corrosion scales and continue to have an effect until the corrosion scale possessing semi‐passive character. Possessing both good strength and corrosion resistance, 3%Cr steel with bainite‐ferrite microstructure was very promising for pipeline steel applications.

Electrochemical corrosion response of a precipitation hardening moulds steel in a NaCl solution

Electrochemical corrosion response of a precipitation hardening moulds steel in a NaCl solution

Materials and Corrosion, Vol. , No. () pp. -
Investigations concerning the electrochemical corrosion behavior of mould steels are scarce and limited. In the present study, the corrosion resistance of a precipitation hardening moulds steel submitted to aging treatments has been assessed in a 0.1 M NaCl aqueous solution by means of potentiodynamic polarization and electrochemical impedance spectroscopy measurements. The electrochemical characterization of the steel not submitted to hardening treatments was also examined and a comparative study was made between the different specimens. Scanning electron microscopy and electron probe microanalysis were used to obtain information about the morphology and chemical composition of the steels surface after the electrochemical tests. Increasing the aging temperature an increase of secondary hardness is observed, attributable to an increase of secondary phases (re‐precipitated carbides and metastable GP zones) amount, positively reflecting on the mechanical properties. However, the electrochemical results show a progressive worsening of the corrosion behavior, the as‐received steel sample exhibiting the best corrosion resistance. The observed decrease of corrosion resistance with increasing the aging temperature is ascribed to enhanced galvanic coupling phenomena between the secondary phases, acting as cathodes, and the surrounding matrix which, consequently, experiences preferential dissolution.

Protection of carbon steels against atmospheric corrosion in a wet tropical climate using gas-plasma metallization with aluminum

R. A. Tupikov Yu. G. Dragunov ; I. L. Kharina ; D. S. Zmienko — Sun, 09 Nov 2008 10:10:34 GMT

Protection of carbon steels against atmospheric corrosion in a wet tropical climate using gas-plasma metallization with aluminum
R. A. Tupikov Yu. G. Dragunov ; I. L. Kharina ; D. S. Zmienko
Protection of Metals, Vol. , No. (2008) pp. -
Results of testing for resistance to atmospheric corrosion in a humid-tropical climate (in experimental chambers and under outdoor conditions) have been performed for templates of ribbed pipes made of a carbon steel with various types of anticorrosion (paint, diffusional, metallic) coatings. An optimum type of coating has been determined, its properties have been investigated, and the optimum thickness was found that proved to be good at corrosion resistance in ribbed pipes and allowed for the specificity of structural and service features of the equipment to be protected.

Acoustic emission monitoring of micro cell corrosion testing in type 304 stainless steels

Fri, 18 Nov 2011 16:47:44 GMT

Acoustic emission monitoring of micro cell corrosion testing in type 304 stainless steels

Strength, Fracture and Complexity, Vol. , No. (2011) pp. -

A new method of acoustic emission (AE) monitoring was proposed to study the corrosion and stress corrosion cracking (SCC) by chloride ion. It is a combination of the small chloride droplet corrosion, SCC testing method and AE waveform measurement system with a high sensitivity AE sensor, all of which have been developed by our group. Three types of corrosion were observed in the corrosion testing, which were the open pitting, the covered pitting and snake-like corrosion, respectively. There were many AE events in the covered pitting and snake-like corrosion. On the contrary, there was no AE event in the open pitting. Meanwhile, the cross section of the snake-like corrosion was analyzed by EBSD. It shows that under the corrosion surface, there were some cracks at the {111} interface of Σ3 coincidence boundary and annealing twins. Based on these experiment results, it indicated that the microstructure generated by the covered pitting and snake-like corrosion during corrosion is the initiation site of stress corrosion cracking. Besides, the micro cell corrosion and SCC testing in thin plate specimens of SUS304 stainless steel by the AE monitoring were effective for evaluation of the progression process of them.

Content Type Journal Article
Pages 71-78
DOI 10.3233/SFC-2011-0125
Authors
- Mitsuharu Shiwa, National Institute for Materials Science, Ibaraki, Japan
- Hiroyuki Masuda, National Institute for Materials Science, Ibaraki, Japan
- Hisasi Yamawaki, National Institute for Materials Science, Ibaraki, Japan
- Kaita Ito, Department of Materials Engineering, School of Engineering, The University of Tokyo, Tokyo, Japan
- Manabu Enoki, Department of Materials Engineering, School of Engineering, The University of Tokyo, Tokyo, Japan

Journal Strength, Fracture and Complexity
Online ISSN 1875-9262
Print ISSN 1567-2069

Journal Volume Volume 7

Journal Issue Volume 7, Number 1 / 2011

On the Stress Corrosion Cracking and Hydrogen Embrittlement Behavior of Austenitic Stainless Steels in Boiling Saturated Magnesium Chloride Solutions

On the Stress Corrosion Cracking and Hydrogen Embrittlement Behavior of Austenitic Stainless Steels in Boiling Saturated Magnesium Chloride Solutions

International Journal of Corrosion, Vol. , No. () pp. -
The stress corrosion cracking (SCC) and hydrogen embrittlement (HE) behaviors for types 304, 310, and 316 austenitic stainless steels were investigated in boiling saturated magnesium chloride solutions using a constant load method under different conditions including test temperature, applied stress, and sensitization. Both of type 304 and type 316 stainless steels showed quite similar behavior characteristics, whereas type 310 stainless steel showed a different behavior. The time to failure (tf) parameter was used among other parameters to characterize the materials behavior in the test solution and to develop a mathematical model for predicting the time to failure in the chloride solution. The combination of corrosion curve parameters and fracture surface micrographs gave some explanation for the cracking modes as well as an indication for the cracking mechanisms. On the basis of the results obtained, it was estimated that intergranular cracking was resulted from hydrogen embrittlement due to strain-induced formation of martensite along the grain boundaries, while transgranular cracking took place by propagating cracks nucleated at slip steps by dissolution.

Corrosion at the urea injection in SCR‐system during component test

Corrosion at the urea injection in SCR‐system during component test

Materials and Corrosion, Vol. , No. () pp. -
The corrosion behaviour of the austenitic stainless steels 304L and 904L was investigated after component testing in diesel exhaust urea environment. Cross‐sectional analyses and depth profiling of corrosion products were performed with Auger electron spectroscopy (AES) and X‐ray photoelectron spectroscopy (XPS). The samples of both materials displayed high amounts of silicon oxide on their surfaces, though this did not appear to have an active role in the corrosion. The higher alloyed 904L exhibited only small signs of corrosion and the inner oxide below the silicon oxide was chromium rich. Substantial nitrogen uptake was detected, presumably due to the presence of NH3, cyanates and similar species. The lower alloyed 304L showed more severe corrosion. The oxide on the 304L samples mainly consisted of iron oxide apart from the silicon oxide present. The nitrogen uptake was less pronounced and possibly connected to presence of nitride precipitates. The most pronounced corrosion was detected at sites where deposits frequently form and decompose. Those deposits are a probable nitrogen source and may also form compounds enabling the breakdown of the oxide.

Corrosion rate of construction materials in hot phosphoric acid with the contribution of anodic polarization

Corrosion rate of construction materials in hot phosphoric acid with the contribution of anodic polarization

Materials and Corrosion, Vol. , No. () pp. -
The paper is focused on selection of a proper material for construction elements of water electrolysers, which make use of a 85% phosphoric acid as an electrolyte at temperature of 150 °C and which might be loaded with anodic polarization up to 2.5 V versus a saturated Ag/AgCl electrode (SSCE). Several grades of stainless steels were tested as well as tantalum, niobium, titanium, nickel alloys and silicon carbide. The corrosion rate was evaluated by means of mass loss at free corrosion potential as well as under various levels of polarization. The only corrosion resistant material in 85% phosphoric acid at 150 °C and at polarization of 2.5 V/SSCE is tantalum. In that case, even a gentle cathodic polarization is harmful in such an acidic environment. Hydrogen reduction leads to tantalum hydride formation, to loss of mechanical properties and to complete disintegration of the metal. Contrary to tantalum, titanium is free of any corrosion resistance in hot phosphoric acid. Its corrosion rate ranges from tens of millimetres to metres per year depending on temperature of the acid. Alloy bonded tantalum coating was recognized as an effective corrosion protection for both titanium and stainless steel. Its serviceability might be limited by slow dissolution of tantalum that is in order of units of mm/year.

A Method for determining safe concentrations of chloride ions in pitting corrosion of steels in nitrate media

V. P. Razygraev M. V. Lebedeva ; I. I. Korchak — Sun, 09 Nov 2008 10:10:33 GMT

A Method for determining safe concentrations of chloride ions in pitting corrosion of steels in nitrate media
V. P. Razygraev M. V. Lebedeva ; I. I. Korchak
Protection of Metals, Vol. , No. (2008) pp. -
Features of how pitting corrosion develops on steels in nitrate-chloride media are analyzed, and the disadvantages of certain well-known electrochemical methods used to determine safe ratios of components under such conditions are found. A principally new approach to determining these parameters is proposed, based on the induction of intense pitting in definitely aggressive media with subsequent suppression of this process by continuously dilution of the solution or by gradual addition of an inhibitor. Equations are obtained for determining safe component concentrations depending on the volume of solution passing through the cell. Using the proposed method, safe ratios of components are determined for 12Kh18N10T chromium-nickel steel at chloride ion concentrations within 0.02–2.0 M.

Corrosion and contact resistance measurements of different bipolar plate material for Polymer Electrolyte Membrane Fuel Cells

Yue Hung, Hazem Tawfik, K.M. El-Khat — 2008-07-21T23:20:50-05:00

Corrosion and contact resistance measurements of different bipolar plate material for Polymer Electrolyte Membrane Fuel Cells
Yue Hung, Hazem Tawfik, K.M. El-Khat
International Journal of Alternative Propulsion, Vol. 2, No. 1 (2008) pp. 72 - 85
Different types of commercial stainless steels (SS316, SS310 and incoloy 800), poco graphite, composite graphite, titanium carbide, zirconium carbide and carbide base coating on aluminum substrate using thermal spray technique were evaluated as metallic bipolar plate in terms of Interfacial Contact Resistance (ICR) and corrosion resistance in a solution simulating the environment of a bipolar plate in a Polymer Electrolyte Membrane Fuel Cell (PEMFC), 0.5 M H_{2SO_{4 and 200 ppm HF at room temperature. In addition, a comparison between graphite composites and carbide-based amorphous metallic coating alloy bipolar plate cost analysis. Results show that stainless steels have a high ICR and undergo corrosion in both anode and cathode due to the passive film formation. Moreover, although carbide-based alloy showed an ICR much less than composite graphite, their behaviour was not satisfactory in corrosive acidic medium.}}

Corrosion of stainless steels in simulated diesel exhaust environment with urea

Corrosion of stainless steels in simulated diesel exhaust environment with urea

Materials and Corrosion, Vol. , No. () pp. -
Laboratory exposures have been performed simulating a selective catalytic reduction (SCR) system with urea injection for NOx reduction in diesel exhaust after‐treatment. The corrosion behaviour of three ferritic and one austenitic stainless steel was examined using X‐ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES). Continuous exposure to condensate did not cause any corrosion. Results show that cyclic interaction between high temperature and condensation aggravates the corrosion compared to isothermal exposure at 450 °C. All ferritic alloys exhibited more or less the same behaviour, while the austenitic steel performed better. In fact, the presence of urea decreased the corrosion compared to the environment without urea. The cyclic samples exposed with urea displayed iron sulphate on the surface. The sulphate appeared to decrease the oxide thickness. A sulphur enrichment in the form of sulphide also occurred in the inner chromium‐rich oxides of all cyclically exposed samples, both with and without urea. Thus, sulphidation is presumed to be involved in the corrosion process.

Fretting corrosion in liquid lead of structural steels for lead-cooled nuclear systems. Preliminary study of the influence of temperature and time

M. Del Giacco, A. Weisenburger, G. Mueller — 2012-01-27T22:09:53Z

Fretting corrosion in liquid lead of structural steels for lead-cooled nuclear systems. Preliminary study of the influence of temperature and time

Journal of Nuclear Materials, Vol. , No. (2012) pp. -
Publication year: 2012 Source: Journal of Nuclear Materials, Available online 25 January 2012 M. Del Giacco, A. Weisenburger, G. Mueller Structural materials development is a key issue for the realization of advanced lead cooled nuclear systems. One specific challenge for fuel claddings and heat exchanger tubes is the so called fretting corrosion by flow induced vibrations. To address this matter, the ferritic-martensitic steel T91and the austenitic steel 1.4970 were submitted to fretting corrosion test in liquid lead. Preliminary indications concerning the role of temperature and time/number of cycles in the fretting corrosion process, were achieved performing fretting corrosion tests at 450 / 500 °C and for 150 / 600 h (5.4·10/ 2.16·10cycles). The interaction between fretting (mechanical wear) and corrosion processes (oxidation/dissolution) in liquid lead was also investigated.The experiments revealed that protective oxide scales that formed on steels surfaces are removed by the fretting action. Thus, dissolution attack can take place. Besides, in the fretted areas, the formation of interposing layers was noticed. Such scales, created by debris retention and compaction, consist of an outer layer of oxidized debris and an inner layer of metallic debris. Due to the high Ni content, fretting corrosion affects more significantly the 1.4970 than the T91. Moreover after the 600 h test, fatigue cracking was observed on the 1.4970. The volume of material removed from the specimens by fretting corrosion, increased with temperature and time respectively number of cycles.

TBM testing in ITER: Requirements for the development of predictive tools to describe corrosion-related phenomena in HCLL blankets towards DEMO

2011-12-14T22:14:57Z

TBM testing in ITER: Requirements for the development of predictive tools to describe corrosion-related phenomena in HCLL blankets towards DEMO

Fusion Engineering and Design, Vol. , No. (2011) pp. -
Publication year: 2011 Source: Fusion Engineering and Design, Available online 14 December 2011 W. Krauss, J. Konys, A. Li-Puma Compatibility testing of RAFM-steels in Pb–15.7Li environment has shown that liquid metal corrosion is always present and dissolution of steel elements in hot areas of non-isothermal systems takes place whereas a transport of the corrosion products and formed precipitates has to be considered in the TBM design.It is clear that for the design of a HCLL breeding blanket system for DEMO and to ensure the safety over a fusion power plant lifetime, a good knowledge of the corrosion behavior including the dominating mechanisms is required. Simulation tools predicting the corrosion behavior of bare and coated Eurofer in Pb–15.7Li must be implemented and validated in a real fusion environment where numerous physical phenomena are additionally present, compared to the state of the art corrosion knowledge, such as neutron flux, H, T permeation, MHD effects, temperature field with steep gradients.The state of the art will be shown and discussed using some of the main fundamental corrosion data selected from own testing campaigns and published literature regarding corrosion behavior of TBMs.On this basis a test matrix for TBM testing in ITER is presented in the paper and the deficits in present knowledge are outlined deviating future development needs in corrosion. Highlights► To collect corrosion data relevant for TBM operation in updated facilities. ► To develop predictive tools (corrosion, transport, precipitation, impurity effects). ► To perform validation of predictive tools. ► To develop/qualify components for TBM tests in ITER.

Effects of silty sand on CO2 corrosion behavior of low-Cr tubing steel

Fri, 06 Jan 2012 16:47:21 GMT

Effects of silty sand on CO2 corrosion behavior of low-Cr tubing steel

Chinese Science Bulletin, Vol. , No. (2012) pp. -

Abstract

An experimental study was carried out to assess the effects of silty sand on the CO₂ corrosion behavior of 1 wt% Cr (1Cr) and 3 wt% Cr (3Cr) tubing steel under 0.5 MPa CO₂ at 100°C and 1.5 m/s flow velocity. The 1Cr and 3Cr specimens both suffered general corrosion, but the surface was coarser in the pure CO₂ corrosion environment. Under silty sand conditions, severe pitting corrosion occurred on the 1Cr specimens and some acicular pitting appeared on the 3Cr specimens. The average corrosion rates of 1Cr and 3Cr steels increased by factors of 3 and 1.6, respectively. The corrosion products were analyzed by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and electrical impedance spectroscopy (EIS). The results show that silty sand acts as an inclusion in corrosion product films and reduces the homogeneity and density of the products, rather than abrading the corrosion film. Ion-diffusion channels may build up around the irregular silty sand; this would degrade the protective capabilities of the product films and aggravate corrosion.

Content Type Journal Article
Category Article
Pages 1-8
DOI 10.1007/s11434-011-4947-4
Authors
- Wei Yan, State Key Laboratory of Petroleum Resource and Prospecting, China University of Petroleum, Beijing, 102249 China
- JinGen Deng, State Key Laboratory of Petroleum Resource and Prospecting, China University of Petroleum, Beijing, 102249 China
- XiaoRong Li, State Key Laboratory of Petroleum Resource and Prospecting, China University of Petroleum, Beijing, 102249 China
- XingLiang Dong, China National Offshore Oil Company, Beijing, 100600 China
- ChunYang Zhang, China National Offshore Oil Company, Beijing, 100600 China

Journal Chinese Science Bulletin
Online ISSN 1861-9541
Print ISSN 1001-6538

Study of the correlation between corrosion resistance and semi‐conducting properties of the passive film of AISI 316L stainless steel in physiological solution

Study of the correlation between corrosion resistance and semi‐conducting properties of the passive film of AISI 316L stainless steel in physiological solution

Materials and Corrosion, Vol. , No. () pp. -
In this work the corrosion resistance of AISI 316L biomedical stainless steel was assessed through electrochemical impedance spectroscopy (EIS) measurements in Hanks' solution at 37 °C. Specimens were immersed in the electrolyte during 21 days. Semi‐conducting properties of the passive film naturally formed on the surface of the metallic material during the test were evaluated through the Mott–Schottky approach. The aim was to investigate the correlation between corrosion resistance and semi‐conducting properties in the physiological solution. The corrosion resistance was found to decrease with the immersion time. The density of defects in the passive film increased accordingly as indicated by the Mott–Schottky plots. The passive film presented a semi‐conducting behavior with a duplex character. Above the flat band potential the behavior was typical of an n‐type semiconductor whilst below such value it was typical of a p‐type semiconductor. The results from EIS measurements and Mott–Schottky were in good agreement, suggesting that the corrosion resistance of biomedical stainless steels may be associated with the semi‐conducting properties of the passive films formed during immersion in physiological medium.

Grit blasting of medical stainless steel: implications on its corrosion behavior, ion release and biocompatibility

Tue, 24 Jan 2012 06:55:00 GMT

Grit blasting of medical stainless steel: implications on its corrosion behavior, ion release and biocompatibility
J. C. Galván L. Saldaña ; M. Multigner ; A. Calzado-Martín ; M. Larrea ; C. Serra ; N. Vilaboa ; J. L. González-Carrasco
Journal of Materials Science Materials in Medicine, Vol. , No. (2012) pp. 1 - 10
Abstract This study reports on the biocompatibility of 316 LVM steel blasted with small and rounded ZrO2 particles or larger and angular shaped Al2O3 particles. The effect of blasting on the in vitro corrosion behavior and the associated ion release is also considered. Surface of Al2O3 blasted samples was rougher than that of ZrO2 blasted samples, which was also manifested by a higher surface area. Compared to the polished alloy, blasted steels exhibited a lower corrosion resistance at the earlier stages of immersion, particularly when using Al2O3 particles. With increasing immersion time, blasted samples experienced an improvement of the corrosion resistance, achieving impedance values typical of passive alloys. Blasting of the alloy led to an increase in Fe release and the leaching of Ni, Mn, Cr and Mo. On all surfaces, ion release is higher during the first 24 h exposure and tends to decrease during the subsequent exposure time. Despite the lower corrosion resistance and higher amount of ions released, blasted alloys exhibit a good biocompatibility, as demonstrated by culturing osteoblastic cells that attached and grew on the surfaces.

Corrosion of materials in hydrochloric acid solutions

A. S. Derbyshev A. N. Suriev ; A. N. Efimov ; I. A. Beresneva ; F. A. Ladygin — Thu, 02 Feb 2012 17:57:57 GMT

Corrosion of materials in hydrochloric acid solutions
A. S. Derbyshev A. N. Suriev ; A. N. Efimov ; I. A. Beresneva ; F. A. Ladygin
Chemical and Petroleum Engineering, Vol. , No. (2012) pp. 632 - 634
Hydrochloric acid solutions, particularly at elevated temperature, are very corrosive media and cause rapid corrosion of the majority of metals, steels, and alloys, and also chemical breakdown of many nonmetallic materials. Under laboratory conditions in 2% hydrochloric acid solution at 20–25°C the corrosion resistance is studied for specimens of steels 12Kh18N10T, 10Kh17N13M3T, alloy 06KhN28MDT, and titanium VT1-0, and also in 20% hydrochloric acid solution at 95–100°C for specimens of nickel-molybdenum alloys N70MFV-VI (EP814A-VI), alloy N65M-VI (EP982), titanium-palladium alloy 4200 (Ti–0.2%Pd), zirconium, and tantalum, as well as nonmetallic materials, i.e., fluoroplastic, glass, porcelain, faolite, graphite, polypropylene, cross-linked polyethylene, acrylic plastic, silicon carbide composite, and vinyl plastic. The test duration is 1000 h. In 2% hydrochloric acid solution at 20–25°C high resistance is exhibited by titanium VT1-0, alloy 06KhN28MDT, and corrosion-resistant chromium-nickel-molybdenum alloy 10Kh17N13M3T, from which it is possible to manufacture equipment and engineering pipelines in contact with low-concentration hydrochloric acid solutions operating at ambient temperature. In hydrochloric acid solution with a weight concentration of 20% at 95–100°C high resistance to uniform and local corrosion is exhibited by zirconium and tantalum, and the rate of corrosion penetration for alloy N70MFV-VI (EP814A) is 0.447 mm/yr, for alloy KhN63MB it is 1.441 mm/yr, for alloy KhN65MV it is 13.931 mm/yr, and for alloy 4200 it is 3.403 mm/yr. Of the nonmetallic materials, alongside fluoroplastic, high chemical resistance is exhibited by polypropylene, and cross-linked polyethylene.

Corrosion of ZrO2treated type 304 stainless steels in high temperature pure water with various amounts of hydrogen peroxide

2011-12-30T02:45:30Z

Corrosion of ZrO2treated type 304 stainless steels in high temperature pure water with various amounts of hydrogen peroxide

Progress in Nuclear Energy, Vol. , No. (2011) pp. -
Publication year: 2011 Source: Progress in Nuclear Energy, Available online 28 December 2011 Tsung-Kuang Yeh, Po-I. Wu, Chuen- Horng Tsai As boiling water reactors (BWRs) age, intergranular stress corrosion cracking (IGSCC) of the structural materials in the reactor piping systems and vessel internals has become a major degradation problem. Several approaches to mitigating IGSCC in the structural components have been developed and investigated. Among them, the technique of inhibitive protective coatings is deemed the most promising one since it is expected to work even in the absence of the well-known hydrogen water chemistry technology.Following our earlier work on exploring the electrochemical characteristics of important oxidizing species on zirconium oxide (ZrO2) treated Type 304 stainless steels (SSs), we targeted on the characteristics of hydrogen peroxide, which is another strongly oxidizing species in the reactor coolant other than oxygen, in this study. Tests were conducted to determine electrochemical parameters such as electrochemical corrosion potential (ECP), corrosion current density, exchange current density and Tafel constant of the reduction reaction of hydrogen peroxide on 304 SS specimens before and after the ZrO2treatment. The surface morphologies of the treated and untreated specimens were examined by scanning electron microscopy, energy dispersive X-ray spectroscopy, and laser Raman spectra. Furthermore, the corrosion mitigation efficiency of ZrO2treatment was evaluated by electrochemical polarization tests in simulated BWR environments. Test results showed that there were no significant differences in ECP between the untreated and ZrO2treated specimens in the test environments of various hydrogen peroxide concentrations. However, it was found via polarization analysis that the exchange current density of the reduction reaction on and the corrosion current density of the treated specimens were markedly lower than those on and of the untreated ones in the same environments. The ZrO2treatment was able to deter the reduction rate of hydrogen peroxide on the Type 304 SS surface.

Effect of a pipe-steel killing technology on the composition and number of nonmetallic inclusions

K. V. Grigorovich T. V. Shibaeva ; A. M. Arsenkin — Sat, 07 Jan 2012 16:42:44 GMT

Effect of a pipe-steel killing technology on the composition and number of nonmetallic inclusions
K. V. Grigorovich T. V. Shibaeva ; A. M. Arsenkin
Russian Metallurgy (Metally), Vol. , No. (2012) pp. 927 - 933
Abstract Pipes made from steels 19G, 17GS, 17G1S, 10G2FBYu, 13G1S-U, and 20KT of various manufacturers and technologies are studied. Electron microprobe and fractional gas analyses are used to determine the main types and number of nonmetallic inclusions (NIs). The effect of a modification procedure on the oxidic cleanness of steel 20KT (produced at JSC “Volzhskii Pipe Works”) is studied. The use of a silicocalcium-filled wire is shown to increase the total contamination of the steel by nonmetallic, in particular, calcium aluminate and magnesium spinel inclusions, which are conditionally related to corrosion-active nonmetallic inclusions (CANIs). Fractional gas analysis is shown to allow the number of oxide inclusions of various types to be accurately determined in pipe steels. No correlation is found between the volume fraction of oxide inclusions determined by fractional gas analysis and the number of CANIs determined by a metallo-graphic method.

Electrochemical investigations on the corrosion behaviour of galvanized reinforcing steels in concrete with chromate‐reduced cements

Electrochemical investigations on the corrosion behaviour of galvanized reinforcing steels in concrete with chromate‐reduced cements

Materials and Corrosion, Vol. , No. () pp. -
The reduction of the chromate contents in cements affects the electrochemical reactions of galvanized reinforcing steels in fresh concrete. By means of electrochemical measurements and bar pull‐out tests the effect of chromates on the formation of protective coatings at the zinc and the bond behaviour have been investigated using chromate‐containing and chromate‐reduced cements. The results have shown that the bond zone was affected as a result of chromate reduction for cement types CEM I and CEM II. The disturbance to the bond zone should be considered as long‐term in relation to the pore structure which is formed. The effects on the bond are largely compensated for as the concrete ages. The results of the related bond strength with displacement paths of 0.1 and 0.5 mm, respectively, are still within the range of expected figures for non‐galvanized reinforcing steel despite the structural disturbance. Under practical aspects it is not necessary that the existing structural disturbance with respect to bond strength is taken into consideration.

Effects of orientation, stress and exposure time on short intergranular stress corrosion crack behaviour in sensitised type 304 austenitic stainless steel

Effects of orientation, stress and exposure time on short intergranular stress corrosion crack behaviour in sensitised type 304 austenitic stainless steel

Fatigue & Fracture of Engineering Materials and Structures, Vol. , No. () pp. -
Intergranular stress corrosion cracking (IGSCC) in austenitic stainless steels occurs at susceptible grain boundaries after sensitisation. In this study, the effects of test duration, static stress (applied and residual) and microstructure orientation on the developed populations of short crack nuclei are reported for a sensitised type 304 austenitic stainless steel in an acidified potassium tetrathionate (K2S4O6) solution. The crack populations were analysed using the Gumbel distribution method, showing an increase in the characteristic crack lengths with increasing time and grain size. There is a weak, but measurable effect of stress on crack length. Tensile stress increases crack growth and compressive residual stresses introduced by surface machining are shown to be beneficial. A significant dependence on sample orientation is observed and this cannot be explained in terms of the bulk microstructure properties or characteristics, which showed no significant variations.

Revisiting Stress Corrosion Cracking of Steel in Caustic Solutions for Developing Cracking Susceptibility Diagrams for Improved Applicability

Sarvesh Pal R. K. Singh Raman ; R. N. Ibrahim — Fri, 27 Jan 2012 06:51:47 GMT

Revisiting Stress Corrosion Cracking of Steel in Caustic Solutions for Developing Cracking Susceptibility Diagrams for Improved Applicability
Sarvesh Pal R. K. Singh Raman ; R. N. Ibrahim
Metallurgical and Materials Transactions A, Vol. , No. (2012) pp. 1 - 12
Abstract Stress corrosion cracking tests were conducted using Bayer solutions of different chemistry at different temperatures for extraction of alumina from bauxite ores. The validity of the commonly used caustic cracking susceptibility (CS) diagram for steels exposed to plain caustic solutions was assessed by testing the notched and precracked specimens. This study presents first results toward the development of a model susceptibility diagram for actual Bayer solutions, and for improved applicability of the traditional plain caustic diagram. For mechanistic understanding of caustic cracking, tests were also carried out under imposed electrochemical conditions.

Characterization of Uncoated Stainless Steel as Proton Exchange Membrane Fuel Cell Bipolar Plates material

Characterization of Uncoated Stainless Steel as Proton Exchange Membrane Fuel Cell Bipolar Plates material

Fuel Cells, Vol. , No. () pp. -
Thanks to their high conductivity, important gas tightness, good corrosion resistance, and low‐cost manufacturing pathways, stainless steels are considered as good candidates for proton exchange membrane fuel cell (PEMFC) bipolar plates materials. In this study, a proprietary alloy was identified as very promising: its initial electrical contact resistance (ECR) with the gas diffusion layer was low, while its corrosion resistance in simulated PEMFC environment was sufficient. Furthermore, the ECR did not increase dramatically during long‐term potentiostatic and potentiodynamic polarizations in simulated PEMFC cathode and anode environments. Finally, the stainless steel was successfully tested for 3,000 h in a commercial system using a 16‐cell stack, without detrimental cell voltage losses.

Sensitization and Intergranular Corrosion Behavior of High Nitrogen Type 304LN Stainless Steels for Reprocessing and Waste Management Applications

Thu, 19 Jan 2012 06:45:51 GMT

Sensitization and Intergranular Corrosion Behavior of High Nitrogen Type 304LN Stainless Steels for Reprocessing and Waste Management Applications
N. Parvathavarthini U. Kamachi Mudali ; Lilyana Nenova ; Chavdar Andreev ; Baldev Raj
Metallurgical and Materials Transactions A, Vol. , No. (2012) pp. 1 - 16
Abstract High nitrogen 304LN stainless steels (SS) intended for chloride and nitric acid environments in spent nuclear fuel reprocessing and waste management applications were evaluated for their sensitization and intergranular corrosion (IGC) resistance. For this purpose, high nitrogen (0.132 pct, 0.193 pct and 0.406 pct) containing, impurity-controlled, vanadium-added 304LN SS alloys were developed. For comparison, 304L SS, which is currently used in reprocessing plants, was also studied. These stainless steels were subjected to heat treatment at 948 K (675 °C) for various durations ranging from 1 to 1000 hours and tested for susceptibility to IGC as per ASTM A262 Practice A and E tests. The degree of sensitization was estimated with the double loop electrochemical potentiokinetic reactivation technique. The increase in nitrogen content resulted in higher hardness and finer grain size. Based on the detailed microstructural and corrosion studies, it was determined that an addition of 0.132 pct and 0.193 pct nitrogen showed better IGC resistance and an additional increase in nitrogen resulted in deterioration resulting from chromium nitride precipitation, which was confirmed by electrochemical phase separation and X-ray diffraction studies. The onset of desensitization was faster for the alloy with 0.132 pct nitrogen as well as 0.406 pct nitrogen because of the lower nitrogen content in the former case and the finer grain size in the latter case. The higher hardness and superior IGC resistance of 0.132 pct and 0.193 pct nitrogen containing Type 304LN SS suggests the suitability of this alloy for nitric acid- and chloride-containing environments of reprocessing and waste management plants.

Using corona and glow discharges for improving strength properties and corrosion resistance of steel

V. F. Vorobyov A. S. Pomel’nikova ; M. N. Shipko ; M. A. Stepovich — Sat, 24 Dec 2011 16:48:14 GMT

Using corona and glow discharges for improving strength properties and corrosion resistance of steel
V. F. Vorobyov A. S. Pomel’nikova ; M. N. Shipko ; M. A. Stepovich
Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques, Vol. , No. (2011) pp. 1208 - 1211
Abstract The effect of glow and corona discharges on the strength and physicochemical properties of steels has been considered. It has been found that the thickness of the hardened layer and the negative potential of the surface of the steel samples depend on the current intensity and the time of treatment in a corona discharge. The variation of the surface potential correlated with changes of the strength characteristics of steel. It has been shown that variation of the strength characteristics of steel after its treatment in a corona discharge was connected with a rearrangement of the defect structure. The variation of the strength characteristics of steel after its treatment in a glow discharge was due to implantation of nitrogen atoms in surface layers of the material.

Using corona and glow discharges for improving strength properties and corrosion resistance of steel

V. F. Vorobyov A. S. Pomel’nikova ; M. N. Shipko ; M. A. Stepovich — Sat, 24 Dec 2011 16:48:14 GMT

Using corona and glow discharges for improving strength properties and corrosion resistance of steel
V. F. Vorobyov A. S. Pomel’nikova ; M. N. Shipko ; M. A. Stepovich
Journal of Surface Investigation. X-ray, Synchrotron and Neutron Techniques, Vol. , No. (2011) pp. 1208 - 1211
Abstract The effect of glow and corona discharges on the strength and physicochemical properties of steels has been considered. It has been found that the thickness of the hardened layer and the negative potential of the surface of the steel samples depend on the current intensity and the time of treatment in a corona discharge. The variation of the surface potential correlated with changes of the strength characteristics of steel. It has been shown that variation of the strength characteristics of steel after its treatment in a corona discharge was connected with a rearrangement of the defect structure. The variation of the strength characteristics of steel after its treatment in a glow discharge was due to implantation of nitrogen atoms in surface layers of the material.

Inhibition of hydrogen sulfide corrosion of steel by catamin AB

L. V. Frolova E. V. Tomina ; L. P. Kazanskii ; Yu. I. Kuznetsov — Sun, 09 Nov 2008 10:10:31 GMT

Inhibition of hydrogen sulfide corrosion of steel by catamin AB
L. V. Frolova E. V. Tomina ; L. P. Kazanskii ; Yu. I. Kuznetsov
Protection of Metals, Vol. , No. (2008) pp. -
The protective properties of a quaternary ammonium salt (dimethyl alkyl benzyl ammonium chloride, or catamin AB) have been studied in wide intervals of concentrations of H2S (from 10 to 2000 mg/l) and of the inhibitor (from 25 to 500 mg/l). It is shown that catamin AB, which effectively slows down the corrosion of steels and preserves their plastic properties in aqueous solutions saturated by hydrogen sulfide to approximately CH2 S = 2000 mg/l, does not possess high protective properties in the same solutions at CH2 S = 0.0−50.0 mg/l. According to the results of XPS studies, this fact is connected to the weak adsorption of this inhibitor on the surface of steel in the absence of a film of iron sulfides on it. Based on the XPS data, it has been shown that, in media containing high concentrations of H2S, a thin (a few nanometers thick) film of iron sulfides is formed on steel. This film is covered with a monomolecular layer of catamin AB, impeding the dissolution of the steel and further growth of the sulfide film.

Phase transformations in a corrosion-resistant high-chromium nitrogen-bearing steel

M. V. Kostina S. O. Muradyan ; M. S. Khadyev ; A. A. Korneev — Sat, 07 Jan 2012 16:42:47 GMT

Phase transformations in a corrosion-resistant high-chromium nitrogen-bearing steel
M. V. Kostina S. O. Muradyan ; M. S. Khadyev ; A. A. Korneev
Russian Metallurgy (Metally), Vol. , No. (2012) pp. 813 - 825
Abstract The structure, phase composition, and mechanical properties of an austenitic corrosion-resistant high-chromium nitrogen-bearing (∼0.5% N) steel are studied in the as-cast state and after homogenizing heat treatment (HT) followed by quenching. The main structural constituents of the as-cast steel are austenite and the σ phase (12%), which forms as an interdendritic metal during solidification, and δ ferrite and M 23C6-type chromium carbides are absent. Homogenizing HT at 1100–1200°C leads to the σ → γ transformation through the stage of the formation of intermediate δ ferrite via the restructuring of the tetragonal into the bcc lattice. Upon long-term homogenizing HT, the chromium concentration in ferrite decreases due to diffusion chromium redistribution and the δ → γ transformation takes place. The austenite in both the as-cast steel and the steel subjected to homogenizing HT followed by water quenching contains numerous (Cr, V)N nanoparticles. The twofold yield strength of this steel (∼400 MPa) as compared to nitrogen-free 18Cr-10Ni-type steels can be explained by not only the solid-solution hardening of austenite by nitrogen but also by precipitation hardening.

Inhibition investigation and determination of some quantum chemical parameters of 1‐(4‐(dimethylamino)benzylidene)thiosemicarbazide on steel alloys in sulfuric acid medium

Inhibition investigation and determination of some quantum chemical parameters of 1‐(4‐(dimethylamino)benzylidene)thiosemicarbazide on steel alloys in sulfuric acid medium

Materials and Corrosion, Vol. , No. () pp. -
The inhibition effect of 1‐(4‐(dimethylamino)benzylidene)thiosemicarbazide (DBT) on the corrosion behavior of 304 stainless steel and mild steel in 0.5 M sulfuric acid solution was investigated using weight loss and potentiostatic polarization methods. The experimental results suggest that DBT inhibits the corrosion of the steels in acid solution. The inhibition efficiencies increased as the concentration of the compound was increased. The calculated inhibition efficiencies from the two investigated methods were in good agreement. Potentiostatic polarization measurements indicate that DBT acts as a mixed type inhibitor for both alloys. The adsorption of inhibitor on the steel surfaces obeys Langmuir adsorption isotherm. The structure of DBT was optimized using PM3 semi‐empirical method. Highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital (LUMO), energy levels, ELUMO − EHOMO (energy gap), dipole moment (µ), and Mulliken charge densities for this molecule were computed and the adsorption mechanism was discussed. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were used to characterize the surfaces of the alloys.

Bioactive Materials for Regenerative Medicine: Zeolite‐Hydroxyapatite Bone Mimetic Coatings

Bioactive Materials for Regenerative Medicine: Zeolite‐Hydroxyapatite Bone Mimetic Coatings

Advanced Engineering Materials, Vol. , No. () pp. -
We report the synthesis and characterization of a novel zeolite‐hydroxyapatite composite coating on titanium alloys and stainless steel. The zeolite‐hydroxyapatite coating is superhydrophilic and outperforms the state‐of‐the‐art Ti6Al4V alloys in corrosion resistance tests in aggressive pitting NaCl media, phosphate buffer solution with BSA protein, as well as highly complex DMEM cell culture media. And the composite coating also eliminates the elastic modulus mismatch between coating and bone. In addition, the composite coating has an osteoconductive and osteoinductive effect on hFOBs, indicating that it may enhance osteointegration of implants and speed up post‐surgical recovery, and thus reduce the need for recurring implant replacement surgeries. Replacing titanium with zeolite‐hydroxyapatite coated steel can also significantly reduce implant cost while improving implant lifespan.The schematic shows a superhydrophilic zeolite‐hydroxyapatite coating which outperforms the state‐of‐the‐art Ti6Al4V alloys in corrosion resistance tests in saline and highly complex biological media. Better osteoconductive and osteoconductive properties along with elimination of the modulus mismatch between bone and the implant surface suggest enhanced osteointegration of implants and a faster post‐surgical recovery for patients. Substituting titanium with zeolite‐hydroxyapatite coated steels can significantly reduce the cost of implants.

Influence of steel shim hardness on the Sliding Hinge Joint performance

2011-12-14T22:09:43Z

Influence of steel shim hardness on the Sliding Hinge Joint performance

Journal of Constructional Steel Research, Vol. , No. (2011) pp. -
Publication year: 2011 Source: Journal of Constructional Steel Research, Available online 14 December 2011 Hsen-Han Khoo, Charles Clifton, John Butterworth, Gregory MacRae, George Ferguson The Sliding Hinge Joint is a flexural connection designed for use at the ends of beams in steel moment resisting frames. It is an asymmetric friction connection, where energy is dissipated through sliding in slotted bolted connections in the beam bottom flange. The friction resistance and the repeatability of the hysteretic force displacement curves are dependent on the type of shim used. Brass or mild steel shims have been researched and used in construction to date. This paper describes tests on the sliding components conducted to investigate the use of steel shims of different hardness. The materials tested were mild steel, high strength quenched and tempered steel, and abrasion resistant steel. The beam and cleats which these shims slid against were Grade 300 mild steel. The specimens were tested dynamically at earthquake rates of loading. The abrasion resistant steel, the hardest material, produced the most stable and consistent sliding characteristics for all displacement cycles on different specimens. It also had the least material wear and the highest friction capacity per bolt. Compared to brass, high strength steels are more readily available, less costly, more easily erected, and less susceptible to corrosion, making them a preferred solution. Highlights► Asymmetric friction connections tested dynamically with different shims. ► Shims were of different steel grade and hardness, sliding on mild steel. ► Performance was evaluated based on material wear and sliding characteristics. ► Abrasion resistant steel, the hardest shim tested, performed the best. ► Abrasion resistant steel had least wear, most stable and highest sliding friction.

ANALYSIS OF METALLURGICAL AND MECHANICAL PROPERTIES OF LASER WELDED SUPER AUSTENITIC STAINLESS STEEL

SATHIYA PAULRAJ M.Y ABDUL JALEEL, B Shanmugarajan — 2012-03-23 00:00:00.0

ANALYSIS OF METALLURGICAL AND MECHANICAL PROPERTIES OF LASER WELDED SUPER AUSTENITIC STAINLESS STEEL
SATHIYA PAULRAJ M.Y ABDUL JALEEL, B Shanmugarajan
Journal of Engineering, Design and Technology, Vol. , No. (2012) pp. -
Abstract

Purpose - Laser welding under high power, high degree of automation and high production rate is extremely advantageous in automotive application. Super austenitic stainless steel is the preferable material for high corrosion resistance requirements. These steels are relatively cheaper than austenitic stainless steel and it is expensive than nickel base super alloys for such applications. The main purpose of this paper is to present the investigations of the microstructure and mechanical properties of super austenitic stainless steel butt joints made by 3.5 kW cooled slab CO2 laser welding using different shielding gases like argon, nitrogen and helium.Design/methodology/approach - The tensile and impact tests were performed and the fractured surfaces were analyzed by scanning electron microscope. The hardness across the joint zone was measured. The X-ray diffraction technique was used to analyze the phase composition. The microstructure of the laser welds were analyzed through optical microscopy.Findings - The tensile sample fractures indicate that the specimen fails in a ductile manner under the action of tensile loading. The impact fracture surfaces of the different shielding gas laser welded joints show mixed mode fractures, that is, ductile and cleavage fractures. The hardness values of the Helium shielded laser joints in the weld metal regions are much higher than the others.Research limitations/implications - There is no limitation, except for the availability of the high beam power laser welding machine. Practical implications - The implication is limited to the laser welding shop hazard during the experiment. Originality/value - The research work is original.

Comparison between symmetric and asymmetric hot rolling techniques performed on duplex stainless steel 2205

C. Mapelli S. Barella ; D. Mombelli ; C. Baldizzone ; A. Gruttadauria — Wed, 11 Jan 2012 17:57:27 GMT

Comparison between symmetric and asymmetric hot rolling techniques performed on duplex stainless steel 2205
C. Mapelli S. Barella ; D. Mombelli ; C. Baldizzone ; A. Gruttadauria
International Journal of Material Forming, Vol. , No. (2012) pp. 1 - 13
Abstract The use of duplex stainless steel represents one possible efficient alternative of austenitic grade and an interesting resources for its high performance against stress corrosion cracking. Unfortunately such material shows some limitations in their use: for instance the sheets or plates of duplex stainless steels present anomalous and poor formability for plastic deformation processes. Such problems are mainly related to an unsuitable normal anisotropy coefficient, which might cause the “necking” and “earing” phenomena, especially during hot rolling. The study deals with the comparison of symmetric and asymmetric rolling technique on stainless steel duplex 2205 specimens. All the experiments were carried out using a laboratory mill, properly equipped with an individual engine for each rolling cylinder. The experimental parameters considered include three different pre-heating temperatures and two asymmetry ratios, while the reduction level is maintained constant for both rolling configurations. Moreover, the study involves also the analysis of the influence of solubilization quenching and the SEM, SEM-EBSD investigation dedicated to establish the microstructure modifications. The specimens were also studied through tensile tests to determine the influence of the rolling techniques on the mechanical properties of the product, focusing on the definition of the average anisotropy coefficient. The results of the experimental trials allow to conclude that the use of asymmetric rolling process induces an improved formability and increases duplex 2205 tensile properties.