Corrosion of High-Strength Cr–Mn Steels in Chloride Solutions

High-nitrogen Cr-Mn steels 12X18A18 and 05X18A19 are attacked by pitting in NaCl solutions at > 0.1 g-ion/l and T > 313 K because the protective properties of their passive surface films deteriorate (their resistance decreases by a factor of three to six). The passivity range of these steels narrows to 87 and 90 mV at their corrosion depth indices of 1.2 × 10^–3 and 8 × 10^–4 mm/year, respectively. Pitting of 60X38H8B Cr-Mn-Ni steel exposed to NaCl solutions was observed at > 0.3 g-ion/l and T > 303 K. Its corrosion depth index increases to 1.48 mm/year. At < 0.1 g-ion/l, all the steels studied are highly resistant to corrosion.     

The Influence of Ozone on the Electrochemical and Corrosion Behavior of Metals in Acid Media

The corrosion–electrochemical behavior of 092, 0817, 1017132 steels, 0628 alloy, and such metals as aluminum, chromium, and nickel are investigated in ozonized acid media. The effect of ozone on the corrosion–electrochemical properties of these metals are shown to be ambiguous.     

Formation, Structure, and Corrosion Properties of Carbo-Nitrided High-Chromium Steels

Structure and properties of carbidized surface zones on 43, 45, and 2013 steels upon high-temperature nitro-cementation in atmospheres of common or vacuum pyrolysis of nitrogen- and carbon-containing components and charcoal mixtures are discussed.     

On the Similarity Criteria for the Processes of High-Temperature Sulfur Corrosion of Heat-Resistant Alloys

A similarity parameter for the high-temperature sulfur corrosion of heat-resistant alloys is suggested. This parameter allows to put in order published experimental data of different authors. Original data on the weight loss by 826, -70, 26, and several materials for protective coatings also correlate with the similarity parameter. The dependences thus obtained allow to predict the operation life of materials (by their weight loss) and to rank nickel-based alloys by their corrosion resistance, depending on their elemental composition.     

Multicomponent Heat-Resistant Coatings for Blades Produced Using Ion-Plasma Method

It is shown that the ion-plasma method can be combined with the diffusion methods for the formation of complex heat- and corrosion-resistant coatings on blades of C6 alloy. The complex method enables one to apply metal layers, for example, Ni–Cr–Zr, and to produce surface ceramic film based on fcc ZrO₂. A version of the coating satisfied the imitative tests and, as a part of an article, the pilot-industrial tests.     

On the Removal of Aluminide Coating from Blades of Gas Turbin Engine

The peculiarities of removing -11 coating from 32 type alloy in an acidic etching bath depending on the concentration and ratio between the amounts of potassium bichromate and ammonium heptamolybdate additives are studied with gravimetrical and electrochemical methods. The results are explained by the peculiarities of bichromate and molybdate ions adsorption at the surface and their oxidizing properties. Baths providing sufficiently quick removal of the coating at a minimum alloy surface etching are recommended.     

Corrosion Behavior of Copper–Nickel Alloys in Neutral Chloride and Sulfide Containing Solutions

The corrosion behavior of Cu30Ni and 30-1-1 alloys in oxygen-containing chloride solutions (0.1–0.5 N NaCl) with and without Na₂S additive (2–1000 mg/l) is studied with radiometric and electrochemical methods by taking into account the amount of oxygen sorbed in the course of corrosion. In blank solutions, a film of corrosion products is formed on the alloy surface; the thickness and copper content of the film increase with a decrease in chloride concentration. The corrosion rate in sulfide-containing solutions is higher than in sulfide-free ones. In the initial corrosion period, nickel compounds are accumulated in the film. With an increase in sodium sulfide concentration, corrosion accelerates. Additionally alloying the Cu30Ni alloy with manganese and iron reduces its rate by half.     

Metastable manganese austenite as a structural base of high-stability steels conditions of dynamic contact loading

Important regular features of the structure and special features of the behavior of metastable manganese austenite under conditions of quasistatic deformation and dynamic contact loading are considered. Based on the correlation of the energy of packing defects of manganese austenite with the kinetics of deformation martensitic transformations { , } and the capacity for deformation strengthening and relaxation of stresses, principles for choosing the base composition of metastable austenitic steels with a high operating stability for different conditions of dynamic contact loading are established.     

Structure-Selective Dissolution of Al–Fe–Ni Bronze in Chloride Electrolyte

The selectivity of the anodic dissolution of the iron-rich phases of . 9-4-4-1 cast bronze in 0.5 N NaCl + 0.01 N HCl was studied. X-ray diffraction analysis revealed that the Fe₃Al and ₁-phases present at the surface of the initial bronze become predominantly etched during the early period of anodic dissolution at E = –0.12 V (NHE). According to electrochemical and analytical data, the above phases dissolve at this potential most rapidly. The x-ray diffraction data agree well with the results obtained by atomic absorption analysis of the solution.     

General laws governing variation in properties of cast alloys of the Al-Zn-Mg system

Among existing high-strength corrosion-resistant aluminum alloys, those of the Al-Mn-Zn system are most promising. They have a different phase composition, depending on the content of magnesium and Zinc: + (Al₃Mg₂), + + T(Al₂Mg₃Zn₃), + T, + T + (MgZn2) and + The majority of industrial Al-Mg-Zn alloys correspond to the phase regions + T and + T + with respect to composition. A high level of strength and satisfactory overall corrosion resistance are characteristic for these alloys. Al-Mg-Zn alloys may, however, tend to the most dangerous form of corrosion - stress-induced corrosion cracking. Using methods of experiment planning in the study, we investigated Al-Zn-Mg alloys of various compositions for the purpose of selecting alloy compositions with a high level of mechanical properties and stress-induced corrosion cracking.All-Union Scientific-Research Institute of Aviation Materials. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 12, pp. 24–28, December, 1994.     

Resistance of 1201 aluminum alloy to plastic deformation at various strain rates

Conclusion With an increase in the rate of plastic strain there is a change in the resistance of 1201 alloy to plastic deformation, which is revealed in a nontraditional decrease in _0.2 and increase in , and A_p. The characteristics _k and _t increase nonlinearally.Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 8, pp. 56–61, August, 1989.     

X-ray topographic study of β-NiAl upon growth of an α-Al2O3 film

The Berg-Barrett X-ray topographic method was employed as a microstructural technique to seek correlations of the metal substructure to the morphological features of -Al₂O₃ films grown on -NiAl. An analysis of diffraction micrographs using {112} and {002} reflections from individual grains in -NiAl revealed its subgrain structure to a depth of 30 . The dimensions of these subgrains were directly related to the density of oxide ridges in the -Al₂O₃ films and to the dimensions and shapes of cavities at the NiAl-Al₂O₃ interface.     

Structural conversions in VT22 titanium alloy during aging

Conclusion For two-phase high-strength alloys of the VT22 type, as for -alloys of titanium, the presence of an incubation period for the formation of -phase during aging is characteristic. The signs for this process are the following: enchanced etchability of the surface of thin sections; formation of zones which do not have an interface with the matrix but differ from it in etchability (zones of presegregation of -phase); a change in the intensities of the -phase lines on the x-ray diffraction patterns. Decomposition of the -solid solution in titanium alloys of the VT22 type is a multistep process, including formation of segregates (onset of stratification of the -solid solution), regions of the Guinier—Preston zone type, various intermediate states, coherent states of the formed -phase, and finally the appearance of isolated -phase, having an interface with the matrix -solid solution.Pskov Filiate of St. Petersburg State Technical University. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 8, pp. 33–37, August, 1992.     

Two-phase ferritic-martensitic steels

Conclusions The results of laboratory and production experiments showed that the main condition for providing the necessary combination of properties of two-phase ferritic-martensitic steels (high tensile strength, low yield strength, high plasticity and work hardenability) is obtaining the specified quantity of the hardening phase (martensite) in the structure (20–28% M to obtain _t 550 MPa or 10–18% M for _t 450 MPa). The specified ratio of the structural constituents under conditions of mass production of two-phase ferritic-martensitic steels may be guaranteed only with the use of steels containing carbon and alloy elements within the necessary limits and also with strict observance of the heat-treatment cycle. Without the use of metallographic measurements as the criteria for obtaining the optimum structural condition in addition to the required values of strength and plasticity it is necessary to use the _0.2/_t ratio, which must not be greater than 0.5–0.6 with the absence of yield points on the tensile curve (without special temper rolling).As the result of the combination of work done in the Central Scientific-Research Institute of Ferrous Metallurgy together with plants of the Ministries of Ferrous Metallurgy and of the Automobile Industry at present the production is being introduced and experimental production lots of heat-treated two-phase steels of the following types with guaranteed mechanical properties are being supplied:At the Novolipetsk Metallurgical Combine cold-rolled 0.7–2.0-mm sheet of 06KhG(S)Yu and 06G2SYu steels with _0.2 = 260–320 MPa, _t 550 MPa, ₄ 30%, and _0.2/_t 0.5–0.6.At the Cherepovets Metallurgical Combine hot-rolled 2–6-mm sheet of 09G2(S) steel with _0.2 = 260–320 MPa, _t 550 MPa, ₄ 25%, and _0.2/_t 0.5–0.6.At the Beloretsk Metallurgical Combine (billets melted and rolled at the Cherepovets Metallurgical Combine) heat-treated cold-drawn wire up to 10.5 mm in diameter of 06KhGR steel with _0.2 250 MPa, _t 530 MPa, and ₁₀ 30%.For successful development of the production and use of two-phase ferritic-martensitic steels the combined work of the designers of machine building plants on determination of the most effective types of parts, of engineers on correction of the method taking into consideration the specifics of the properties of two-phase ferritic-martensitic steels, and of users on determining the service properties of parts of these steels is necessary. The fulfillment of such a combination of work will make possible th timely formulation of the further work of the metallurgical industry and determination of the required volume and product range of rolled products of two-phase ferritic-martensitic steels.I. P. Bardin Central Scientific-Research Institute of Ferrous Metallurgy. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 11, pp. 25–29, November, 1984.     

The Corrosion of Alloy Steels under Antirust Compounds in the Presence of Microbes

The kinetic corrosion characteristics of 352-, 302, and 30 steels with rust-preventive compounds applied are investigated in an industrial neutral electrolyte, depending on whether a compound is infected with microorganisms or not. The effect of microorganisms and their metabolites on the corrosion of steels greased with the compounds are assessed.     

Solubility of β-stabilizers in α-titanium

Conclusions We have determined the solubilities of iron, chromium, manganese, silicon, copper, molybdenum, vanadium, and tantalum in -titanium (Table 1) and in the -solid solution of Ti+6% Al (Table 2).Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 2, pp. 13–16, February, 1963     

Mechanisms of the effect of vanadium,niobium, and titanium doping on the structure and properties of low-pearlite steels

Conclusions The favorable effect of doping with carbonitride-forming elements-vanadium, niobium, and titanium — on the structure and properties of low-pearlite steels subjected to controlled rolling is due to the change of the structural state of hot-deformed austenite, of the temperature range and nature of the -transformation, of the phase composition of the steel, and of the state of the -solid solution caused by the alloying with these elements.The ambiguous effect of doping with vanadium, niobium, and titanium on the strength and ductile properties of low-pearlite steel is due to the different degree of dispersion hardening, refinement of the ferrite grain, refinement of the solid solution, the ratio of the structural components, and the nature of the products of the -transformation.The newly devised economically alloyed low-pearlite steel 09G2FB for gas pipes with large diameter after controlled rolling with deformation at the concluding stage in the biphase +-region has a unique complex of mechanical properties satisfying the stringent requirements concening pipes intended for operation under conditions of the Far North.I. P. Bardin Central Scientific-Research Institute of Ferrous Metallurgy. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 11, pp. 13–22, November, 1984.     

Effect of rapid cyclic electrothermal treatment on the structure of nickel steel

Conclusions The high dislocation density of austenite undergoing the transformation is due to the influence of fresh dislocations that occur during the transformation in virtue of its martensitic character and to dislocations inherited from the original phases.Since the increase of the dislocation density in austenite causes an increase in the number of martensite crystals, it can be assumed that the increase in the number of phase nuclei is due to an increase in the density of fresh dislocations. In this case the refining of martensite is due to an increase in the number of nuclei and to the barrier effect of elements of the substructure. The formation of atmospheres of impurity atoms at dislocations in alloys with carbon stabilizes the austenite and intensifies recrystallization processes. Cementite particles in phase are not inherited by austenite with heating to the transformation temperature.Institute of Metal Physics, Academy of Sciences Ukrainian SSR. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 1, pp. 20–23, January, 1975.     

Phase and structural transformations in deformation and heat treatment of 08Kh15N5D2T steel tubing

Conclusion Annealing in the intercritical area of the -transformation or hardening from a continuous furnace with subsequent tempering in the -transformation range included in the production plan for cold-rolled 08Kh15N5D2T tubing do not restore the original workability of the steel since the residual austenite is stabilized toward the -transformation in deformation. Annealing at 650°C does not lead to complete recrystallization and detexturing of the metal. To obtain this it is recommended that rapid electric heating for hardening with subsequent tempering be introduced into the production plan for rolling of tubing.Ural Polytechnic Institute. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 8, pp. 7–11, August, 1990.     

Isothermal formation of the ε-phase after phase hardening in ferromanganese alloys

Conclusions The investigations carried out show that isothermal formation of the -phase can be controlled not only by alloying, but also by means of repeated phase transitions. Reduction of the temperature at which the formation of the -phase commences intensifies the isothermal transformation near the martensite point and at room temperature. The latter is valid if the -transformation during continuous cooling begins not lower than the temperature at which the isothermal soaking is carried out, otherwise the intensity of the isothermal process decreases, and the lower the commencement of the -transformation with respect to the temperature isothermal line, the more the intensity drops. It was found that if the -phase forms at –60, –70°C, there is a complex dependence between the rate of the isothermal process and the temperature.It was demonstrated that when the -transformation temperature is fairly low, austenite can be supercooled by rapid cooling and the -phase may form during heating. Given the same supercooling rate, the transformation of austenite into -phase during heating is more complete when the heating rate is slow.It was noticed that if in continuous cooling the -phase forms at –60, –70°C, preliminary supercooling broadens the temperature range over which the isothermal -transformation is observed. The intensity of the process is influenced by the heating rate after supercooling.It was found that the maximum amount of -phase forming in the alloy G19 during continuous cooling after repeated phase transitions and subsequent isothermal soaking does not exceed 50–55%.It was discovered that isothermal soaking at room temperature in between repeated phase transitions intensifies the stabilization of the austenite.Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 4, pp. 2–8, April, 1965