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.     

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.     

A Study of the Effects of Motion on Mass Transfer in Pits in a Two-Disk Hydrodynamic System

Effects of medium motion on the mass transfer in model pits in a two-disk hydrodynamic system are studied. Steel 121810 in sodium chloride solutions at 293 to 333 K was an object of the study. The dependences obtained allow evaluating the effects of medium motion on mass transfer in a model pit, depending on its geometrical parameters.     

Optically Scanning the Morphology of Protective Layers and Forecasting the Corrosion Resistance of Thermally Oxidized Steel

The results of investigating the morphology and protective properties of surface layers obtained on chromium steel 1810 by oxidizing in air at a temperature of 140 to 950°C are considered. After a special digital treatment, the scanned optical images of a small surface area probed allow one to introduce and determine those parameters of the morphological nonuniformity of the thermal oxide layer which affect its protective ability. Corrosion tests of oxidized specimens confirmed the applicability of the scanner morphological control to predicting the protective properties of thermal coatings against pit corrosion in chloride-containing electrolyte solutions.     

Thermal Resistance of Low-Alloyed Chromium Alloys

The oxidation kinetics of low-alloyed -2 and 1-17 chromium alloys is investigated at a temperature from 1273 to 1673 K for 1000 h. It is shown that even at a temperature from 1473 to 1673 K the heat resistance of these alloys is higher than that of the 648 nickel-containing alloy at a temperature from 1273 to 1373 K. This allows to recommend the alloys as heat-resistant materials operating at a temperature up to 1573 K.     

Protection of Sintered Steels against Corrosion in Neutral Media with an N-M-1 Inhibitor

The effect of an N-M-1 inhibitor (a salt of cyclohexylamine and C₁₀ to C₁₆ aliphatic acids) on the corrosion of sintered powder steels 13 and 141 (with the 14 to 17% porosity) in distilled or tap water at 20 to 80°C, as well as in 0.05 M Na₂SO₄ solution, is studied by gravimetric and electrochemical methods. The protective concentration of the inhibitor is lower in distilled, than in tap water or sodium sulfate solution. The protective action decreased with an increase in temperature. In tap water or sodium sulfate solution, the corrosion-inhibiting effect is weaker for 13 than for 141.     

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.     

The Effect of Silicon on the Electronic Structure and Corrosion–Electrochemical Behavior of Boron-Containing X20H20 Steels

The effect of silicon (0.06 to 4.89%) on the electron density distribution around ⁵⁷Fe nuclei in quenched boron-containing X20H20 steels is studied with the use of -resonance spectroscopy. Computer treatment of the spectra provided the estimates of the isomeric (chemical) shifts (mm/s) and half-widths (mm/s) of the singlet and doublet spectral lines, as well as the area parts S (%) of each constituent in the summary spectrum and the quadrupole electric splitting eq (mm/s) of the doublet. On the basis of these estimates, both new and earlier obtained experimental data on the peculiarities of the corrosion–electrochemical behavior of silicon-containing austenitic stainless steels are discussed.     

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.     

Peculiarities of a Unified Environmentally Clean System of Etching and Bright Pickling α- and α + β-Titanium Alloys

The kinetics of dissolution, hydrogenation, and bright pickling of titanium alloys in either still or stirred solutions, or under the effect of ultrasound is investigated. In solutions containing H₂O₂ or K₂S₂O₈ as an oxidizer, under ultrasonic treatment, the hydrogenation is practically absent due to stable positive electrode potential, while the dissolution rate can be increased by a factor of 2 to 2.5. A unified environmentally clean solution system for etching and bright pickling of 1-0, 4200, and T6 alloys is developed instead of nitric acid solutions.     

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.     

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.     

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.     

Effect of lamellar structure parameters on the properties of titanium alloy VT3-1

Conclusion An increase in the ultimate breaking strength, stress-rupture strength, and fatigue limit of alloy VT3-1 with a lamellar structure may be achieved as a result of refining any parameter of the structure, particularly -phase platelet thickness, and increasing the volume fraction of secondary -phase. An increase in ductility characteristics, toughness, and creep resistance may be provided by increasing the dimensions of -colonies and primary -phase particles (up to 2.5–3.5 m) and reducing the volume fraction and dispersivity of secondary -phase lamellar precipitates. Coarsening of -grains leads to an increase in a_c, k_Q, and refinement leads to an increase in and a_n.Qualitative dependences for mechanical properties of alloy VT3-1 on lamellar structure parameters made it possible to isolate those structural parameters which have the most marked effect on properties.The properties of alloys with a finely lamellar structure (d25 m, b_{I, II}<2 m) are most sensitive to structure. In this case a change in -colony size by 10 m and -platelet thickness by 1 m affects the properties 3–20 times more strongly than a change in -grain size by 100 m. The effect of finely dispersed secondary -phase precipitates is greater, the coarser the primary -phase structure. Refinement of primary -phase structure with an increase in secondary phase platelet thickness to 1 m or more reduces the sensitivity of alloy mechanical properties to the effect of secondary -phase.With coarsening of the intragranular structure (d>25 m, b_{I, II}2 m) the effect of structural parameters d and b on properties is markedly weakened: on strength properties (_f, ₁₀₀ ⁴⁵⁰ ) by a factor of 100, on ductility (, ), by a factor of 10 to 20, and on impact strength and fracture toughness (a_n, a_c, K_Q) by a factor of five.The qualitative relationships obtained between structure and mechanical properties of alloy VT3-1 are fundamental for controlling the structure of semifinished titanium alloy products.Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 7, pp. 52–55, July, 1986.     

Normalizing of castings in a water-air cooling chamber

The results of modernizing a water-air cooling chamber for normalizing castings of complex shape and steel of different classes are considered. It is economically desirable to modernize existing units with the aim of providing regular water-air cooling schedules which replace the ecologically harmful and fire hazard operation of oil quenching for large articles (dies, shafts, body castings, etc.)AOZT Firm TERMOSTAL. AO Nevskii Zavod, St. Petersburg. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 11, pp. 2–4, November, 1994.     

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.     

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     

High-resolution SIMS and analytical TEM evaluation of alumina scales onβ-NiAl containing Zr or Y

High-resolution SIMS and TEM have been used to evaluate growth processes and interfacial segregation occurring in -Al₂O₃ scales grown at 1200°C on -NiAl containing zirconium or yttrium.¹⁸O/SIMS shows that the extent of aluminum diffusion occurring during -Al₂O₃ growth is reduced by the presence of these alloying elements, which are seen by SIMS imaging as oxide particles within the scale. STEM/EDS of the same oxide scales show that zirconium and yttrium also segregated to the oxide-alloy interface to the extent, respectively, of 0.15 and 0.07 of a monolayer and to oxide grain boundaries (0.2 monolayer). The complementary information provided by SIMS, TEM, and STEM provides a better understanding of the role of reactive elements in modifying scale-growth processes.     

Effect of nitrogen and chromium on the mechanical properties of austenitic steels at −196°C

Conclusion Nitrogen lowers and chromium raises (with >3% N) the strength (_b0.2), ductility (, ), and fracture toughness of austenitic stainless steel of the Kh(18-24)N20 type in the aged condition. The effect of chromium on the properties is due to a change in the solubility of nitrides.I. P. Bardin Central Scientific-Research Institute of Ferrous Metallurgy. Translated from Metallovedenie Termicheskaya Obrabotka Metallov, No. 8, pp. 6–8, August, 1979.