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.     

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.     

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 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.     

Structure formation in nitrided layers of titanium alloys

Conclusions Nitriding of -, pseudo-- and +-Ti alloys forms diffusion layers consisting of a nitride layer and a gas-saturated layer. In +-Ti alloys, a third additional transient zone forms. During the nitriding process, redistribution of the alloying elements present in the alloys takes place, which is caused by their differing affinities for nitrogen.Nitriding schedules also have an effect on the alloying element redistribution. Nitriding temperature or time increase causes either thickening of the diffusion layer zones or formation of a qualitatively new structure in them.Lvov Physicomechanical Institute. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 6, pp. 11–14, June, 1986.     

Formation of austenite in steels

Conclusions On heating of steel austenite is formed in two stages: a) a diffusionless transformation, leading to the formation of low-carbon austenite; 2) subsequent saturation of the austenite with carbon [8]. In this case the austenite forms first in those places where, for whatever reason (the existence of an interface, differences in concentration, lattice defects), the free energy is larger, which facilitates the nucleation of austenite.Kharkov Highways' Institute. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 9, pp. 2–5, September, 1968.     

Recrystallization of maraging alloys

Conclusions In the maraging alloys investigated the transformation is not accompanied by refining of the original grains. The coarse-grained structure is eliminated by recrystallization of austenite at 900–1000°C, which occurs mainly by means of grain boundary migration.Physics of Metals Institute. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 4, pp. 10–12, April, 1969.     

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.     

Evaluation of the Brittleness of Titanium Alloys in Terms of Mechanical Properties and Fracture Patterns

The phenomena of brittleness of structural -pseudo-- and ( + )-titanium alloys are analyzed and generalized using the results of tests of rupture specimens and various parts. The characteristics of ductility (elongation and contraction ) are used for evaluating the macroscopic manifestations of embrittlement, and the appearance of fracture surfaces as observed in electron microscopic diffraction patterns is used for estimating the micromanifestations of embrittlement.     

Stability of austenite in chrome-nickel stainless steel and susceptibility to corrosion cracking

Conclusions The susceptibility to corrosion cracking of austenitic chromium-nickel steels does not depend on the occurrence of the transformation in the process of deformation.Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 3, pp. 73–75, March, 1967.     

Control of the structure of two-phase titanium alloys in thermomechanical working

Conclusions The embryos of - and -phases obtained in +-titanium alloys in hardening and aging are preserved in cold working and become centers of growth of these phases in subsequent aging. As a result it is possible to obtain -phase or more uniformly distributed -phase in cold-worked and aged alloys.Moscow Institute of Electronic Machine Building. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 5, pp. 53–55, May, 1984.     

High-temperature X-ray studies of austenitizing processes in steels

Conclusion In the temperature range between Ac₁ and Ac₃ the chemical composition of the and phases is not identical not only in carbon but also in alloying elements—the concentration of stabilizers (aluminum, silicon) is higher in ferrite than in austenite, and the concentration of stabilizer (nickel) is higher in austenite than in ferrite.Deceased.Perm' Polytechnical Institute. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 1, pp. 6–8, January, 1972.     

Special features of the α → γ transformation in powder carbon steels

The structural state of powder steels after sintering depends on the technological regimes of their production and can markedly affect the transformations in subsequent heat treatment. The effect of the technological regimes on the nature of the transformation is investigated.Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 3, pp. 14–16, March, 1996.     

Effect of austenitizing conditions on structural transformations in phase cold-worked austenite and the properties of high-strength structural steel with carbide-intermetallide hardening

In many alloy steels, the reverse transformation occurs upon heating under conditions when complete structural inheritance is realized, and it is accompanied by formation of phase cold-worked austenite. The phase cold-working effect is a type of uniform and significant plastic deformation of the austenite, and so can actively affect structure formation processes in steels during austenitizing. Accordingly, it is of interest to use phase cold-working of austenite to improve the structure and properties of high-strength structural steels. We present the results of investigations of the effect of the quench heating conditions on structural transformations in phase cold-worked austenite and the properties of 25N12M6K10 steel with carbideintermetallide hardening.Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 5, pp. 15–21, May, 1994.     

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.     

Effect ofθ-alumina formation on the growth kinetics of alumina-forming superalloys

Alumina-forming ODS superalloys are excellent oxidation-resistant materials. Their resistance relies upon the establishment of a stable, slow-growing, and adherent -alumina. In the present investigation, these alloys exhibited unstable and relatively less adherent -alumina phase, which increased the oxidation rate in the transient stage and converted into -alumina in the later part of the exposure. The oxide-growth process was found to depend upon various parameters such as temperature, time, and presence of an active elecment in the superalloy. Characterization carried out by XRD, SEM/EDAX, and AES on oxidized ODS and non-ODS alloys demonstrated a significant influence of the active element, Y, on the transformation of - to -alumina. SIMS analysis of two-stage oxidation at 900°C for two different durations evidently showed that the change in the transport process is due to -to--alumina transformation. On the basis of these results, a new and consistent mechanism is proposed to explain the influence of -alumina and its transformation on growth kinetics and the effect of yttrium on the transformation leading to good scale adherence and oxidation resistance.     

Effect of preliminary heat treatment on phase transformations and properties of steel Kh15N5D2T (VNS-2)

Conclusions Preliminary heat treatment has a substantial effect on the kinetics of the transformation, the amount of retained austenite, the grain size, and the work of crack propagation in steel Kh15N2D2T after final heat treatment.N. I. Lobachevskii Gorki Physicotechnic Institute of Gorki State University. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 5, pp. 63–64, May. 1978.