JournalTOCs API - articles

The Role of Chloride Ion on the Atmospheric Corrosion of Steel and Corrosion Resistance of Sn-bearing Steel

2012-05-15T23:03:26Z

The Role of Chloride Ion on the Atmospheric Corrosion of Steel and Corrosion Resistance of Sn-bearing Steel

Corrosion Science, Vol. , No. (2012) pp. -
Publication year: 2012 Source:Corrosion Science T. Kamimura, K. Kashima, K. Sugae, H. Miyuki, T. Kudo In order to clarify the role of chloride ion on the atmospheric corrosion of steels, the minute anode chamber simulating local anode sites on steels was set up, and the pH change was measured. The pH was affected by the chloride concentration, and decreased to 1.5 with the formation of β-FeOOH. The role of chloride ion on the corrosion is discussed from the viewpoint of solubility and hydrolysis of Fe3+-species. An atmospheric corrosion model under high chloride content environments is proposed. Based on the model, it was found that Sn-bearing steel exhibits the superior atmospheric corrosion resistance.

Brugal® thin organic coatings: effective and gainful alternative to traditional methods of protection of steels from corrosion

O. Roos — Fri, 09 Dec 2011 06:48:52 GMT

Brugal® thin organic coatings: effective and gainful alternative to traditional methods of protection of steels from corrosion
O. Roos
Metal Science and Heat Treatment, Vol. , No. (2011) pp. 350 - 352
The advantages of the use of thin organic coatings for protecting steels from corrosion are considered. Main applications of steels with such coatings are presented. The considerable economic effect due to the use of steels with thin organic coatings instead of dyed galvanized steel is described.

Corrosion behavior of various steels in a continuous flow of carbon dioxide containing impurities

2012-04-16T08:00:42Z

Corrosion behavior of various steels in a continuous flow of carbon dioxide containing impurities

International Journal of Greenhouse Gas Control, Vol. , No. (2012) pp. -
Publication year: 2012 Source:International Journal of Greenhouse Gas Control, Volume 9 Aki Sebastian Ruhl, Axel Kranzmann Various steels were exposed to a continuous flow of carbon dioxide containing sulfur dioxide, nitrogen dioxide, oxygen, and humidity (water) at different temperatures. At 170°C only slight surface effects were observed. Corrosion effects became more pronounced with decreasing temperatures and increasing humidity. Acidic condensation, mainly consisting of sulfuric acid, was detected during exposure at 5°C that caused severe corrosion effects and material losses on low alloyed carbon steels and slight corrosion effects on carbon containing chromium steels. No corrosion occurred on high alloyed steel 1.4162. Corrosion products revealed low crystallinity both microscopically and by X-ray diffraction. Some phases containing sulfate but no carbonate were indentified.

Effects of Si as alloying element on corrosion resistance of weathering steel

2012-04-25T23:03:31Z

Effects of Si as alloying element on corrosion resistance of weathering steel

Corrosion Science, Vol. , No. (2012) pp. -
Publication year: 2012 Source:Corrosion Science, Volume 59 J.A. Mejía Gómez, J. Antonissen, C.A. Palacio, E. De Grave The corrosion resistance in saline conditions of weathering steel with different concentrations of Si (1, 2 and 3wt.%) exposed to dip dry tests (simulating wet/dry cycles of atmospheric corrosion) was studied by weight loss, X-ray diffraction, Mössbauer spectroscopy and transmission electron microscopy. The results showed that the steels exhibit better corrosion performance with increasing Si concentration. The formation of Fe-oxides such as goethite, lepidocrocite and magnetite was observed. Superparamagnetic goethite is the dominant phase in the rust developed on the Si steels, indicating that Si favors the formation of goethite with small particle size.

Effect of alloying and thermoplastic treatment on the phase composition and properties of corrosion-resistant steels with metastable austenite

Thu, 05 Apr 2012 06:14:56 GMT

Effect of alloying and thermoplastic treatment on the phase composition and properties of corrosion-resistant steels with metastable austenite
L. A. Maltseva V. A. Sharapova ; T. V. Maltseva ; S. V. Gladkovskii ; A. V. Levina
Metal Science and Heat Treatment, Vol. , No. (2012) pp. 1 - 9
Special features of formation of structure and properties of high-alloy corrosion-resistant steels with different contents of the main components are studied after hardening from various temperatures and deformation with various degrees of reduction.

Shortening of the process of nitriding of corrosion-resistant steels

V. A. Aleksandrov A. V. Grachev ; S. I. Barabanov — Tue, 13 Dec 2011 17:05:43 GMT

Shortening of the process of nitriding of corrosion-resistant steels
V. A. Aleksandrov A. V. Grachev ; S. I. Barabanov
Metal Science and Heat Treatment, Vol. , No. (2011) pp. 344 - 346
The microstructure, the thickness of the nitrided layer, and the microhardness of a group of corrosion-resistant steels are studied after diffusion saturation in an ammonia-air atmosphere. It is shown that the use of such an atmosphere makes it possible to reduce the duration of the process of nitriding by a factor of 3.5 – 4 as compared to nitriding in dissociated ammonia.

Effect of preparation method for two-layer corrosion-resistant steels on their production and operating properties

Mon, 19 Mar 2012 17:10:06 GMT

Effect of preparation method for two-layer corrosion-resistant steels on their production and operating properties
I. G. Rodionova O. N. Baklanova ; A. V. Amezhnov ; T. I. Strizhakova ; A. A. Pavlov
Chemical and Petroleum Engineering, Vol. , No. (2012) pp. 1 - 9
Comparative analysis is provided for two-layer steels prepared by different methods. A method is proposed for thermal cycling tests as an evaluation of the operational reliability of equipment made from two-layer steels.

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.

Corrosion fatigue initiation and short crack growth behaviour of austenitic stainless steels under light water reactor conditions

2012-04-25T23:03:31Z

Corrosion fatigue initiation and short crack growth behaviour of austenitic stainless steels under light water reactor conditions

Corrosion Science, Vol. , No. (2012) pp. -
Publication year: 2012 Source:Corrosion Science, Volume 59 H.P. Seifert, S. Ritter, H.J. Leber The corrosion fatigue initiation and short crack growth behaviour of different wrought low-carbon and stabilised austenitic stainless steels was characterised under simulated boiling water reactor and pressurised water reactor primary water conditions by cyclic fatigue tests with sharply notched fracture mechanics specimens. The special emphasis was placed to the behaviour at low corrosion potentials and, in particular, to hydrogen water chemistry conditions. The major parameter effects and critical conjoint threshold conditions, which result in relevant environmental reduction and acceleration of fatigue initiation life and subsequent short crack growth, respectively, are discussed and summarised. The observed corrosion fatigue behaviour is compared with the fatigue evaluation procedures in codes and regulatory guidelines.

Electrodeposition of zinc-doped silane films for corrosion protection of mild steels

2012-04-25T23:03:31Z

Electrodeposition of zinc-doped silane films for corrosion protection of mild steels

Corrosion Science, Vol. , No. (2012) pp. -
Publication year: 2012 Source:Corrosion Science, Volume 59 Lian-Kui Wu, Ji-Ming Hu, Jian-Qing Zhang Organosilane/zinc composite films are prepared by one-step electrodeposition onto cold-rolled steels for corrosion protection. Electrochemical impedance spectroscopy measurement, bulk solution immersion and wet heat tests all show that the composite films have improved corrosion performance. X-ray photoelectron spectroscopy measurement suggests the successful encapsulation of metallic zinc. The embedding of metallic zinc results in negative shift in open-circuit potential of the film-covered electrodes. Such cathodic protection effect given by the metallic zinc provides the improved corrosion resistance of the composite films.

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.

Comparison of hydrogen embrittlement in three pipeline steels in high pressure gaseous hydrogen environments

2012-04-25T23:03:31Z

Comparison of hydrogen embrittlement in three pipeline steels in high pressure gaseous hydrogen environments

Corrosion Science, Vol. , No. (2012) pp. -
Publication year: 2012 Source:Corrosion Science, Volume 59 N.E. Nanninga, Y.S. Levy, E.S. Drexler, R.T. Condon, A.E. Stevenson, A.J. Slifka The tensile properties of X52, X65, and X100 pipeline steels have been measured in a high-pressure (13.8MPa) hydrogen gas environment. Significant decreases in elongation at failure and reduction of area were observed when testing in hydrogen as compared with air, and those changes were accompanied by noticeable changes in fracture morphology. In addition to baseline characterization of the effects of strength and microstructure on the X52, X65, and X100 alloys, the influence of strain rate and hydrogen gas pressure was studied for only the X100 alloy.

Stress-corrosion failures of main pipelines

A. Ya. Krasovskii I. V. Lokhman ; I. V. Orynyak — Thu, 10 May 2012 06:06:46 GMT

Stress-corrosion failures of main pipelines
A. Ya. Krasovskii I. V. Lokhman ; I. V. Orynyak
Strength of Materials, Vol. , No. (2012) pp. 1 - 15
The basic peculiarities of stress corrosion fracture cases of main pipelines are analyzed. The authors consider structure, mechanical properties, Charpy energy, fracture toughness, corrosion fatigue, and fracture mechanisms of steel Kh70 (from transit gas pipeline “Urengoy–Pomary– Uzhgorod”) in three conditions: as received (archive), after 24 and 26 years of service. The service degradation of steel is revealed, which manifests itself in considerable drop of Charpy energy, fracture toughness and resistance to the corrosion fatigue crack growth. The analysis is performed of the resistance of the pipeline steels to the corrosion fatigue crack nucleation and growth and the respective recommendations are provided concerning the avoidance of the stress corrosion failure of transit gas pipelines.

Influence of alloying elements and density on aqueous corrosion behaviour of some sintered low alloy steels

2012-04-30T00:34:19Z

Influence of alloying elements and density on aqueous corrosion behaviour of some sintered low alloy steels

Materials & Design, Vol. , No. (2012) pp. -
Publication year: 2012 Source:Materials & Design, Volume 40 T.K. Kandavel, R. Chandramouli, P. Karthikeyan Low alloy steels produced through powder metallurgy route of sintering followed by forging are promising candidate materials for high strength small components. Porosity in such steels poses a real challenge during acid pickling treatment, which is one of the processing steps during manufacturing. The present research work attempts to investigate the mechanism underlying the acid corrosion behaviour of some sintered low alloy steels under induced acid pickling conditions. Sintered-forged low alloy steel samples containing molybdenum (Mo), copper (Cu) and titanium (Ti) were subjected to aqueous corrosion attack by immersing the samples in 18% HCl (Hydrochloric acid) solution for 25h. Sample weight loss and Fe (Iron) loss were estimated for the corroded samples. The morphology of the corroded surfaces was studied through metallography and scanning electron microscopy. Higher porosity alloys underwent enhanced corrosion rates. Both corrosion rate and iron loss are found to decrease linearly with reduction in porosity in all cases of the alloys. The alloying elements Mo, Ti and Cu, when added in combination, have played a complementary role in the reduction of corrosion rate by almost one order of magnitude compared to unalloyed steel. Presence of carbides of the carbide forming elements Mo and Ti played a positive role on the corrosion behaviour of the low alloy steels.

A comparative study of critical pitting temperature (CPT) of stainless steels by electrochemical impedance spectroscopy (EIS), potentiodynamic and potentiostatic techniques

2012-04-25T23:03:31Z

A comparative study of critical pitting temperature (CPT) of stainless steels by electrochemical impedance spectroscopy (EIS), potentiodynamic and potentiostatic techniques

Corrosion Science, Vol. , No. (2012) pp. -
Publication year: 2012 Source:Corrosion Science, Volume 59 N. Ebrahimi, M. Momeni, A. Kosari, M. Zakeri, M.H. Moayed In this study critical pitting temperature (CPT) of two stainless steels is compared using EIS, potentiodynamic and potentiostatic techniques. Two types of stainless steels including DSS2205 and 20Cr–28Ni were chosen. EIS measurements were carried at anodic potential of 600mV/SCE and the results were compared with those of potentiodynamic and potentiostatic polarisations. The results revealed that the CPT of DSS2205 and 20Cr–28Ni was between 45–55°C and 35–45°C in potentiodynamic polarisation, respectively. It was 60 and 55°C for potentiostatic method and between 55–60°C and 45–55°C in EIS method for DSS2205 and 20Cr–28Ni, respectively.

22Cr High-Mn-N Low-Ni Economical Duplex Stainless Steels

2012-03-16T04:35:25Z

22Cr High-Mn-N Low-Ni Economical Duplex Stainless Steels

Journal of Iron and Steel Research, International, Vol. , No. (2012) pp. -
Publication year: 2012 Source:Journal of Iron and Steel Research, International, Volume 19, Issue 2 Da-wei JIANG, Chang-sheng GE, Xiang-juan ZHAO, Jun LI, Lu-lu SHI, Xue-shan XIAO A new family of economical duplex stainless steels in which N or Mn was substituted for Ni with composition of 22Cr-8.0Mn-xNi-1.0Mo-0.7Cu-0.7W-0.3N (x = 0.5 – 2.0) have been developed by examining the micro-structure, mechanical and corrosion properties of these alloys. The results show that these alloys have a balanced ferrite-austenite relation. In addition, the alloys are free of precipitation of sigma phase and Cr-nitride when solution-treated at 750 to 1300°C for 30 min. The yield strength, tensile strength and fracture elongation values of experimental alloys solution-treated at 1050°C for 30 min are about 500, 750 MPa and 40.0%, respectively. Low-temperature impact properties can be improved distinctly with the increase of nickel content. Among the designed DSS alloys, the alloy with Ni of 2.0% is found to be an optimum alloy with proper phase proportion, better low-temperature impact properties and higher pitting corrosion resistance compared with those of other alloys. The mechanical and corrosion properties and lower production cost of the designed DSSs are better than those of AISI 304.

Effect of electro discharge machining (EDM) on the AISI316L SS white layer microstructure and corrosion resistance

Wed, 02 May 2012 05:48:24 GMT

Effect of electro discharge machining (EDM) on the AISI316L SS white layer microstructure and corrosion resistance
Habib Sidhom Farhat Ghanem ; Tidiane Amadou ; Gonzalo Gonzalez ; Chedly Braham
The International Journal of Advanced Manufacturing Technology, Vol. , No. (2012) pp. 1 - 13
Abstract The localised corrosion resistance of austenitic stainless steels is strongly influenced by the quality of finished surface. EDM machining induces substantial changes by the high thermal gradients generated by electric sparks. Experimental techniques such as roughness measurement, scanning electron microscopy (SEM), energy dispersive microanalysis (EDX) and X-ray diffraction technique, reveal micro-geometrical, microstructural, chemical and mechanical changes. These changes lead to white and heat-affected layers with a depth less than 100 μm. The white layer is a melted material characterised by dendritic structure and constituted by austenite, chromium carbide and ε-carbide. The heat-affected layer is characterised by very large grain size comparatively to the bulk material. Electrochemical test coupled with metallographic examinations using SEM reveals a weakening of the resistance to pitting and intergranular corrosion comparatively to diamond polished surface. This weakening is correlated to differences in structure and chemical composition of white layer. Susceptibility to stress corrosion cracking has been attributed to the field of tensile residual stresses resulting from thermal effects. The removal of the white layer material by polishing or wire brushing restores the corrosion resistance of the AISI316L SS.

Corrosion of ZrO2 treated type 304 stainless steels in high temperature pure water with various amounts of hydrogen peroxide

2012-03-11T03:07:05Z

Corrosion of ZrO2 treated type 304 stainless steels in high temperature pure water with various amounts of hydrogen peroxide

Progress in Nuclear Energy, Vol. , No. (2012) pp. -
Publication year: 2012 Source:Progress in Nuclear Energy, Volume 57 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 ZrO2 treatment. 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 ZrO2 treatment 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 ZrO2 treated 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 ZrO2 treatment was able to deter the reduction rate of hydrogen peroxide on the Type 304 SS surface.

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.

Effect of hydrogen content on the embrittlement in a Fe–Mn–C twinning-induced plasticity steel

2012-04-25T23:03:31Z

Effect of hydrogen content on the embrittlement in a Fe–Mn–C twinning-induced plasticity steel

Corrosion Science, Vol. , No. (2012) pp. -
Publication year: 2012 Source:Corrosion Science, Volume 59 Motomichi Koyama, Eiji Akiyama, Kaneaki Tsuzaki The hydrogen embrittlement of a Fe–18Mn–0.6C austenitic steel (wt.%) was examined using tensile tests under hydrogen charging at various current densities. The tensile properties deteriorated due to the occurrence of intergranular fracture above a specific current density. The work hardening behavior was not affected by the hydrogen charging, indicating that the embrittlement was independent of the change in behavior of slip deformation, martensitic transformation, and twinning deformation. The relationship between the fracture stresses for the intergranular fracture and the diffusible hydrogen content of the austenitic steel was approximated to the power law similarly to ferritic high strength steels.

Failure analysis of a steel tube joint perforated by corrosion in a well-drilling pipe

2012-05-03T23:09:39Z

Failure analysis of a steel tube joint perforated by corrosion in a well-drilling pipe

Engineering Failure Analysis, Vol. , No. (2012) pp. -
Publication year: 2012 Source:Engineering Failure Analysis Peng Cheng-hong, Liu Zheng-yi, WEI Xing-zhao The corroded steel tube joint belonging to an offshore oil well-drilling pipeline was investigated. All of the pits and punctures distributed along the “steps” are formed by off-centre machining on the internal tube surface, and the pits have a horse’s hoof and hemispherical contour. The metallurgical structure of some spots on non-penetrating corrosion pits and penetrating punctures looked markedly curved, i.e., curved deflections in the banded structure (or streamlines) were visible. The pits contour and metallurgical structure indicate that the pits and punctures are characterised by cavitation erosion. The chemical composition of the corroded steel tube joint is similar to 1320, 1330 and L80-1 steels specified in ASTM standards, and the content of non-metallic impurities in the failed steel tube was identified as Grade 1.0 to 1.5, which is within the permitted range. Corrosion pit surfaces and the tube joint showed a deposit layer and a clay-like substance that was rich in Fe, Mn, Ca, Ti, Cu, C, O, S and Cl, and “crystal sugar –like” appearance observed on location of the penetrating puncture, indicating H2S- and CO2-assisted corrosion mechanisms. These investigations indicated that failure of the pipeline occurred by erosion corrosion, cavitations erosion and chemical corrosion, which is from both mechanical and chemical actions.

A failure study of condenser tube manufactured from low nickel stainless steels

2012-03-13T00:11:05Z

A failure study of condenser tube manufactured from low nickel stainless steels

Engineering Failure Analysis, Vol. , No. (2012) pp. -
Publication year: 2012 Source:Engineering Failure Analysis D.N. Wasnik A failure analysis of condenser tubes manufactured from Type 204 stainless steel was conducted to find the root cause of failures. The failures were observed in the parent materials of the tube rather than from welding or heat-affected zones. A detailed metallography, corrosion test and stress analysis study has been carried out to find out the root cause of failure, and it revealed that the parent materials of the tube were highly sensitized, and post-annealing treatment had been not performed by the manufacturers. The condenser tube failed prematurely due to sensitization and the presence of thermal residual stresses exacerbates this. This study emphasizes the metallurgical analysis performed to identify the root cause of failure of condenser tubes manufactured from Type 204 stainless steel.

Nanomechanical evaluation of the protectiveness of nitrided layers against hydrogen embrittlement

2012-05-15T23:03:26Z

Nanomechanical evaluation of the protectiveness of nitrided layers against hydrogen embrittlement

Corrosion Science, Vol. , No. (2012) pp. -
Publication year: 2012 Source:Corrosion Science M. Asgari, A. Barnoush, R. Johnsen, R. Hoel In this work, the nitrided layer on austenitic AISI 316L stainless steels were examined by means of in-situ electrochemical nanoindentation, and the effect of electrochemically charged hydrogen on the mechanical properties were investigated. By using this method, changes in the mechanical properties due to the absorption of atomic hydrogen at different nitride layer depths have been traced. One important finding is that hydrogen charging of the nitriding layer can soften the layer and reduce the layer hardness, and the reduction of the nitrogen concentration in the nitride layer reduces this softening effect. Graphical Abstract Graphical abstract Highlights ► Plasma nitride layer of 316 SS was studied by electrochemical nanoindentation. ► H Effect on mechanical properties of the substrate and nitride layer was studied. ► H increases the hardness of 316 SS and has opposite effect on the nitride layer. ► The H induced softening is advantageous for controlling the H embrittlement. ► The H induced softening is dependent on the N concentration.

High temperature behavior of the metal/oxide interface of ferritic stainless steels

2012-04-25T23:03:31Z

High temperature behavior of the metal/oxide interface of ferritic stainless steels

Corrosion Science, Vol. , No. (2012) pp. -
Publication year: 2012 Source:Corrosion Science, Volume 59 Jérôme Issartel, Sébastien Martoia, Frédéric Charlot, Valérie Parry, Guillaume Parry, Rafael Estevez, Yves Wouters Two grades of ferritic stainless steel, a bi-stabilized (Ti, Nb) AISI 441 and a stabilized (Ti) AISI 439, were oxidized at 1060°C under simulated process atmosphere for durations between 45 and 1800s. Focused Ion Beam (FIB) coupled with Field Emission Gun and Scanning Electron Microscopy (FEG/SEM) was used to investigate the morphology of the oxide layer. Particularly, metallic protrusions localized at the metal/oxide interface and bulging out through the silica layer were observed. A model based on stress assisted diffusion of oxygen was employed to estimate the effects of the heterogeneous distribution of silica in the oxide. The oxide layer is thought to induce non-uniform nucleation of silica at the metal/oxide interface. Further lateral growth of the silica layer then leads to the formation of metallic protrusions.

Cadmium- and chromate-free coating schemes for corrosion protection of 15CDV6 steel

2012-03-09T01:38:48Z

Cadmium- and chromate-free coating schemes for corrosion protection of 15CDV6 steel

Metal Finishing, Vol. , No. (2012) pp. -
Publication year: 2011 Source:Metal Finishing, Volume 109, Issue 3 Indumathi S.N, T. Vasudevan, S. Sundarrajan, B.V. Subba Rao, C.V.S. Murthy, D.R. Yadav Electrodeposits of cadmium- and chromate-based inorganic inhibitor pigments in paint formulations are extensively used in the aerospace industry to provide long-term corrosion protection for high-strength steel hardware. Due to environmental concerns and worker safety issues, there is a pressing need to identify and adopt alternative ecofriendly coatings with equivalent performance. In this work, an ecofriendly cadmium- and chromatefree coating scheme comprised of zinc nickel alloy plating, trivalent chromium- based passivation, followed by a primer based on polyaniline phosphate, is studied for its anticorrosive properties. Long-term performance evaluation studies of this eco-friendly coating scheme were carried out on 15CDV6 steel, an ultra-high- strength steel used in the aerospace industry. For comparative purposes, two extensively used cadmium- and chromate-based schemes complying to aerospace and military specifications comprised of cadmium plating, hexavalent chromium-based passivation followed by two different chromate-based primers were studied on 15CDV6 steel substrate. Electrochemical impedance spectroscopic studies and salt fog exposure tests were carried out to evaluate the anticorrosive properties of the coat- ing schemes. Cadmium- and chromate-free scheme exhibited excellent performance in the long-term corrosion evaluation studies. The results obtained in accelerated tests show the possibility of replacement of cadmium- and chromate-based schemes for corrosion protection of steels with an eco-friendly option.

The monitoring possibility of some mammalian cells for zinc concentrations on metallic materials

Mon, 13 Feb 2012 17:55:44 GMT

The monitoring possibility of some mammalian cells for zinc concentrations on metallic materials
Akiko Ogawa Naoaki Okuda ; Katsuya Hio ; Hideyuki Kanematsu ; Hidekazu Tamauchi
Cytotechnology, Vol. , No. (2012) pp. 1 - 7
Abstract Zinc plating is widely used to protect steels against corrosion. However, the possibility of a high environmental risk for zinc has been recently discussed among advanced countries and more environmentally-friendly substitutes are required urgently. Therefore, monitoring zinc concentration changes on metallic materials such as steel is very important. We chose to measure zinc concentration changes in some mammalian cells and confirmed that V79 cells were highly sensitive to changes in zinc concentrations. In this study, the following process was applied to the proprietary production for tin-zinc alloy films on steel using V79 cells. Specimens were immersed in PBS to produce extracts. Zinc concentrations in the extracts almost corresponded to zinc concentrations on steel surfaces. When extracts were added to a V79 cell culture, colony formation was inhibited, and inhibition increased with increases in zinc concentrations. Changes in zinc concentrations on steel surfaces with heat treatment could be monitored relatively well by V79 cells, even though the results were still semi-quantitative.

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.

Investigation of hydrogen assisted cracking of a high strength steel using circumferentially notched tensile test

2012-04-30T00:34:45Z

Investigation of hydrogen assisted cracking of a high strength steel using circumferentially notched tensile test

Materials Science and Engineering: A, Vol. , No. (2012) pp. -
Publication year: 2012 Source:Materials Science and Engineering: A, Volume 547 N.R. Raykar, R.K. Singh Raman, S.K. Maiti, Lokesh Choudhary The novel circumferentially notched tensile (CNT) test technique is used for the first time for an investigation of hydrogen assisted stress corrosion cracking. Effect of hydrogen on the fracture strength of high strength steel AS-4340 is examined in neutral 3.5% NaCl solution at room temperature and under hydrogen supply from within the material and/or external environment. A progressive drop in the stress intensity factor at the fracture was observed as a result of: (a) increasing span of hydrogen pre-charging (hence increasing internal hydrogen) and (b) decreasing rate of loading (hence increasing external supply of hydrogen). The measured critical stress intensity factors corresponding to varying degrees of supply of internal hydrogen are consistent with the computed hydrogen concentrations ahead of the crack tip. The experimentally determined threshold for hydrogen embrittlement in the regime of slower loading rates are consistent with the published data. The results presented here establish the usefulness of the CNT test technique for the investigation of HASCC in high strength steel over a wider range of loading rate. Graphical Abstract Highlights ► Novel CNT testing was successfully employed for HASCC study of a high strength steel. ► Effects of both internal and external hydrogen were examined. ► Fracture toughness K Ic H relates to theoretical hydrogen distribution at/around crack tip. ► K Ic H for lower loading rates agree with published threshold fracture toughness data. ► Utility of CNT tests for study of HASCC in steels was established.