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1.We established the dependence of modulus of normal elasticity and hardness on the temperature of Fe-Ni alloys.2.By microstructural analysis of Fe-Ni alloy specimens, we established a correspondence with the phase diagram of the given system. The microstructure was brought to light by chemical etching.3.It was shown that the microstructure of a polished surface is substantially different from the structure in the specimen after 3 hours soaking at 1100° followed by cooling in a vacuum of about 5 × 10-5 mm Hg.

1.After aging at 550° the change in the physical properties of austenitic manganese steel is negligible: The precipitation stage occurs slowly.2.Precipitation hardening occurs at a high rate at 650°, the largest changes in the physical properties occurring in the first 0.5 h. In samples from heat 3, with the highest carbon concentration, migration of carbon atoms from the matrix practically ceases after aging for 8 h, although growth of the particles continues (the electrical resistivity decreases) and the stresses that occur in the lattice with precipitation of particles decrease (the modulus of elasticity increases). For samples with a lower carbon concentration (heat 2) the rate of aging is lower, i.e., the rate of the change in the physical properties is proportional to the carbon concentration.3.Aging at 600° for 1–8 h is accompanied by an anomalous increase in the height of the peak damping decrement of internal friction, along with cessation or slowing down of changes in electrical resistivity and modulus of elasticity. The nature of this phenomenon has not been determined and further studies are needed.

1.The rate of uniform creep in the metal at high temperatures is influenced by the crystal structure, melting point, valence and modulus of elasticity. The first three factors are associated with diffusion. Experimental data show that partial dislocations in close packed structure in pure metals do not improve the resistance of these materials to deformation at high temperatures.2.The grain size has a great effect on creep in materials, but at high temperatures the effect is still not entirely clear. To obtain maximum strength at high temperatures, the structure must be fine grain and stable.3.At high stresses the Weertman theory, based on the motion of dislocations seems more valid; at low stresses the Nabarro-Herring theory based on atomic diffusion holds better.4.Heat resistant alloys should have a close packed structure and contain alloying elements which reduce the diffusion rate and ensure a high modulus of elasticity. Alloys should be fine grain, should contain dispersed stable segregations along the grain boundaries in order to stabilize the size of the crystallites.

A comprehensive study of the suitability of sheets of alloy 1441 of the Al – Cu – Mg – Li system for the production of long-life airplane fuselages is described. The alloy has been used in the Be 103 boatplane airframe and is tested for use in the new business-class airplane of the A. N. Tupolev Aircraft Scientific-and-Engineering Company (ANTK). Sheets of alloy 1441 including thin ones with a thickness of 0.5 mm are manufactured by cold coil rolling. As compared to traditional deformable alloys of the Al – Cu – Mg system, alloy 1441 has a diminished density and an elevated modulus of elasticity at a comparable level of strength. Researchers in Russia (GP GNTs VIAM) and in the USA (LaRC, NASA) studied the tensile mechanical properties, the fracture toughness, the impact toughness, the fatigue resistance, and the growth rate of fatigue crack in sheets fabricated from alloy 1441. Researchers of the A. N. Tupolev ANTK fabricated fuselage panels with sheathing from alloy 1441 and stringers from high-strength aluminum alloy V95. The panels were tested in the ANTK and in the LaRC by the method of internal pressure by pulse-cycle simulation of the surface conditions of the airplane.

The article is devoted to composite materials created on the basis of the technology of light alloys and developments of the All-Russia Institute of Aircraft Materials concerning beryllium alloys with a high modulus of elasticity. The competitiveness of such composite materials is determined by the high level of the specific strength properties, which exceed, in some cases, the characteristics of powder materials of a similar composition and approach the properties of titanium alloys and steels.

1.To obtain the minimal values of the characteristics of imperfect elasticity of precipitation-hardening spring steel Kh15N27T3MR we recommend quenching from 1050° and tempering at 750° for 5 h for the steel not strain hardened and at 700° for 5 h, 700° for 2 h, and 700° for 1 h for the steel deformed 17, 30, and 60%, respectively.2.Plastic deformation of steel Kh15N27T3MR after quenching substantially increases its elastic limit and reduces distortion of the elastic aftereffect, especially during subsequent tempering. In this case strain hardening accelerates precipitation hardening processes.3.For the strain hardened steel the elastic limit decreases at a higher rate and the distortion of the elastic aftereffect increases at a higher rate with increasing testing temperatures. The larger the strain hardening, the more notable this effect.4.Plastic deformation does not change the shear modulus of quenched samples; it increases 6% with tempering. The temperature coefficient of the modulus of elasticity remains constant up to 700°.5.From the results of the investigation we recommend the following maximum operating temperatures for elastic elements made of steel Kh15N27T3MR; 600° for the quenched and tempered steel; 500° for the steel deformed 17 and 30% after quenching; 400° for the steel deformed 60%.

1.We investigated the kinetics of hardening in manganese alloys quenched from the ? Mn region — the distinguishing characteristic is the exceedingly sharp increase of the hardness during the first minute of holding (1–10 min) at 450–500°C. The hardness peak after very short holding times is due to the formation of ß1 phase. With holding for longer times secondary hardening occurs due to precipitation of the hard and brittle a Mn phase.2.The maximum hardness with holding for a short time is higher for the alloy with a large palladium content (30%), which is accompanied by the volume effect of the ? ? a1 + a Mn transformation.3.The hardness of ß1 phase is relatively low and varies little with the tempering time.4.The high hardness of Mn-Pd alloys after holding for a short time is evidently due to the particular condition of the ß1 phase at the time of precipitation from the ? Mn solid solution and the internal stresses that occur.5.In the hardened condition the Mn-Pd alloy with 30% Pd is nonmagnetic, has a high modulus of elasticity, and has satisfactory corrosion resistance.

To increase the hardness of products with large cross sections (elastic sensitive elements, parts of measuring apparatus) made of alloy 44NKhMT, while at the same time reducing the temperature coefficient of the modulus of elasticity (to YE ? 9·10-6 deg-1), thermomechanical treatment using plain shear strain may be recommended.

1.We recommend strict observance of the technological parameters in all metallurgical operations affecting the final structure of Fe-Ni-Co Elinvars, since the thermoelastic coefficient of these alloys is effected greatly by the chemical composition of austenite and the texture.2.Plastic deformation before tempering promotes high thermal stability of the modulus of elasticity and its weak sensitivity to magnetic field in alloys with cobalt.3.High-temperature Elinvars are recommended for high-precision elastic sensing elements for prolonged operation up to 300° and briefly at higher temperatures.

1.Cast iron with 2.9% C and 13.6% Cr has the highest (and cast iron with 2.8% C and 29% Cr the lowest) thermal conductivity and the highest modulus of elasticity and electrical resistivity of the alloys investigated.2.In contrast to steels, the a?? transformation temperature (A1) is higher than the Curie temperature (A2) for the cast irons investigated.3.Raising the carbon content from 2.2 to 3.6% in cast irons with around 13.6% Cr has no effect on A2 but reduces the thermal effect and narrows the temperature range of the magnetic transformation.4.With increasing carbon concentrations from 2.2 to 3.6% in cast iron with around 13.6% Cr the a?? transformation temperature decreases and the temperature range of the transformation becomes broader.