Effects of the composition and low-temperature thermomechanical treatment on the mechanical properties of structural steels

Conclusions The investigation of the effect of thermomechanical treatment on the mechanical properties of steels with different compositions makes it possible to put in evidence the effect of alloyed elements. The addition of up to 1.2–1.5% Si (particularly with vanadium) makes it possible to increase the tempering temperature to 350°C without significantly decreasing the strengthening effect of low-temperature thermomechanical treatment. An increase of the concentration of chromium from 1.5 to 3–5% also increases the resistance of the steel. In steel containing 3–5% Cr and also molybdenum, vanadium, and tungsten, the effect of low-temperature thermomechanical treatment is retained after tempering at temperatures up to 500°C, the plasticity remaining rather high. Low-temperature thermomechnical treatment of batches 8 and 10 followed by tempering at 500°C resulted in the following mechanical characteristics: _b=240–255 kg/mm² when =10–13% and =30–35%; after tempering at 350°C _b=255–265 kg/mm², ₅=8–12%, and =28–36%.Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 4, pp. 36–40, April, 1963     

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.     

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.     

Strain-Activated Hydrogen Absorption during Heat Treatment of Al–Zn–Mg–Cu Alloy AA7475

Subsurface porosity due to hydrogen absorption (commonly known as high-temperature oxidation, or HTO) in an Al–5.5% Zn–2.25% Mg–1.5% Cu alloy during heat treatment in undried air at 515°C is accentuated by prior strain. Under the uncontrolled atmospheric conditions used, the critical strain level for the onset of HTO is about 1.5%; increasing strain results in more porosity and surface blistering. If NaBF₄ is added to the furnace atmosphere, no porosity is evident at strain levels up to 5%.     

Austenitic stainless steels strengthened by phase strain hardening and aging

Conclusions Nonmagnetic stainless steels of the Kh12N12T3 and Kh12N14T3 type have good mechanical properties after phase strain hardening and aging (_0.2 = 685 - 785 MPa, _b = 1275 MPa, 20%) as compared with the properties of Fe-Ni-Ti austenitic steels with 26–30% Ni. After phase strain hardening and aging the stability of these steels is high with respect to the transformation during cold treatment.IFM UNTs AN SSSR. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 6, pp. 57–60, June, 1981.     

Peculiarities of the Effect of Perchlorate Ions on Electrodeposition of Cadmium in Aqueous–Acetonitrile Electrolytes

It is shown that, depending on the composition of aqueous–acetonitrile solvent, either acetonitrile (AN) molecules or perchlorate anions predominantly adsorb on the electrode. The highest surface concentration of AN and the lowest rate of cadmium electroreduction are observed in the mixture with the most loosened structure (x ₂ 0.4). The salting-out action of mixed solvent in the domains of its structure stabilization primarily manifests itself in an increase in the adsorption activity of ClO^– ₄ anions and a corresponding promotion of Cd²⁺ discharge as a result of " effect. The maximum process rate is observed in the domain, where the AN structure is ordered by monomeric water molecules.     

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.     

Formation of a Rhenium-Base Coating on a Nb-Base Alloy

To protect Nb–5Mo–15W alloy against high-temperature oxidation a novel coating was developed involving electroplating of a Re–Ni film, followed by pack cementation with Cr and Al. The coating consisted of a duplex-layer structure, an inner (Re–Cr) or Re(Cr) layer and an outer Cr(Al) or NiAl layer. The Re–Ni film containing more than 70at.%Re, developed in the present investigation, is more useful than the conventional low Re–Ni film. The inner (Re–Cr) and Re(Cr) layer acts as a diffusion barrier between the Nb–5Mo–15W alloy substrate and the outer -Cr(Al) or -NiAl layer, which forms a protective -Al₂O₃ scale. The coated Nb–5Mo–15W alloy was oxidized in air at 1373K for up to 360ks, showing very good oxidation resistance.     

Oxidation of Ni–Al-Base Electrodeposited Composite Coatings. II: Oxidation Kinetics and Morphology at 1000°C

The oxidation behavior of nickel-matrix/aluminum-particle composite coat–ings was studied using thermogravimetric (TG) analysis and long-term furnace exposure in air at 1000°C. The coatings were applied by the composite-electrodeposition technique and vacuum heat treated for 3 hr at 825°C prior to oxidation testing. The heat-treated coatings consisted of a two-phase mixture of (Ni)+ (Ni₃Al). During short-term exposure at 1000°C, a thin -Al₂O₃ layer developed below a matrix of spinel NiAl₂O₄, with -Al₂O₃ needles at the outer oxide surface. After 100 hr of oxidation, remnants of -Al₂O₃ are present with spinel at the surface and an inner layer of -Al₂O₃. After 1000–2000 hr, a relatively thick layer of -Al₂O₃ is found below a thin, outer spinel layer. Oxidation kinetics are controlled by the slow growth of the inner Al₂O₃ layer at short-term and intermediate exposures. At long times, an increase in mass gain is found due to oxidation at the coating–substrate interface and enhanced scale formation possibly in areas of reduced Al content. Ternary Si additions to Ni–Al composite coatings were found to have little effect on oxidation performance. Comparison of coatings with bulk Ni–Al alloys showed that low Al -alloys exhibit a healing Al₂O₃ layer after transient Ni-rich oxide growth. Higher Al alloys display Al₂O₃-controlled kinetics with low mass gain during TG analysis.     

Microstructural Evolution of Alumina Layers on an Al–Cu–Fe Quasicrystal during High-Temperature Oxidation

The oxidation of a quasicrystal with the nominal compositionAl₆₃Cu₂₅Fe₁₂ was studied around 800°Cin environmental and synthetic air by means of thermogravimetric analysis,electron microscopy, and analytical electron spectroscopy. In an earlyoxidation stage, -Al₂O₃ formed with an orientational relationship tothe quasicrystal. At the oxide–metal interface, -Al₂O₃transformed into large hexagonal shaped -Al₂O₃grains. The change in surface morphology indicated that at theoxide–gas interface -Al₂O₃ continued togrow as -Al₂O₃. Locally the metastable aluminalayer was transformed thoroughly into -Al₂O₃,which then continued to grow with a nodular morphology. On top of the oxidenodules, several at.% of Cu²⁺ were detected.     

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.     

A solid-state EMF study of the Fe-S-O and Co-S-O ternary systems

The equilibrium oxygen potentials of the two-phase equilibria Fe₃O₄/Fe_1–xS, Co_1–xS/Co₃S₄, Co₃S₄/CoS₂, Co_1–xS/CoO, and CoO/CoSO₄ were measured as a function of temperature. A solid-state emf technique using calcia-stabilized zirconia (CSZ) solid electrolyte was used. These equilibria were studied atP _SO21 atm; the equilibrium Co_1–xS/CoO was also studied atP _SO20.1 atm. Two emf cell designs were used for the measurements atP _SO21 atm andP _SO21 and 0.1 atm, respectively. The homogeneity range of FeS in equilibrium with Fe₃O₄ and that of Co_1–xS in equilibrium with CoO at 1073 K andP _SO21 atm were measured by electron microprobe analysis.     

Structural parameters of structural steel determining its resistance to hydrosulfuric cracking

Conclusions To attain high resistance to hydrosulfuric cracking of steels for drive pipes, it is necessary after heat treatment to attain a structure with the following parameters: size of the coagulated carbide (M₃C) particles d0.05 m to eliminate the possibility of nascent hydrogen accumulating on the carbide-matrix interfaces; subgrain size d>0.30 m to ensure relief of internal stresses, and dislocation density p<-10⁹ cm^–2 to eliminate places of possible localization of hydrogen.I. P. Bardin Central Research Institute of Ferrous Metallurgy. Siberian Branch of the Special Design Bureau of the Scientific and Production Association Soyuzgazavtomatika, Saratov. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 11, pp. 19–20, November, 1991.     

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.     

Dynamic recrystallization of beta-phase in titanium alloy

Conclusion Dynamic recrystallization of cast -grain in alloys type VT-6S, which proceeds most actively at high temperatues (1200°C) and high rates of deformation (10 sec^–1), causes refinement of cast grain and reorientation of crystallites.DeceasedA. A. Baikov Institute of Metallurgy. TsNIIKM Prometei. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 9, pp. 34–36, September, 1991.     

Formation of Recrystallized Structure in Deformed Semiproducts from Titanium Alloys of Transition Class Obtained by Isothermal Die Forming

Alloy VT22 is used for studying the regular features of formation of recrystallized (grain) structure in die-formed preforms of titanium alloys of the transition class with coefficient of -stabilization K = 1.0 – 1.3 in thermomechanical treatment involving deformation under isothermal conditions. The temperature and rate regimes of isothermal die forming and modes of thermomechanical treatment with the use of static, spontaneous, and dynamic recrystallization are determined with the aim of providing a controlled structure with -grains 10 – 100 m in size. It is shown that the formation of a recrystallized structure with b-grains 10 – 30 m in size in deformed semiproducts from alloy VT22 makes it possible to raise the fracture toughness K _Ic .     

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.     

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     

Strengthening heat treatment of alloy VT16 in vacuum

Conclusions Alloy VT16 can be strengthened by heat treatment in vacuum under the following conditions: heating at 775–800° for 2 h, cooling in the container in water, and aging at 500° for 8 h.The alloy subjected to this treatment has the following properties; _b = 103–107 kgf/mm², =59–63%, ₅ = 15.1–16.1%.Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 5, pp. 65–67, May, 1978.     

Role of catastrophic oxidation in the embrittlement of steel ÉI395 and ÉI981A blooms

The causes of internal failures during the hot rolling of ingots formed from austenitic high-temperature steels are investigated.Physicotechnical Institute, Ural Branch, Russian Academy of Sciences. Production Union Izhstal. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 11, pp. 20–24, November, 1994.