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1.
O. G. Zotov Yu. N. Koval' S. Yu. Kondrat'ev B. A. Chaikovskii G. Ya. Yaroslavskii 《Strength of Materials》1989,21(3):401-406
| 1. | The damping capacity and the structure of the -alloys of the Cu–Al–Zn system after quenching in air are determined by the general degree of alloying expressed by the electron concentration and by the ratio of the alloying elements. |
| 2. | The alloys with the electron concentration e/a<1.45–1.48 show=" diffusion=" breakdown=" and=" the=" level=" of=" damping=" capacity=" increases=" with=" the=" increase=" of=" electron=" concentration=" as=" a=" result=" of=" the=" increase=" of=" the=" amount=" of=" martensite=" in=" the=" structure.="> |
| 3. | In the alloys with the electron concentration e/a>1.45–1.48 the damping capacity is determined by the ratio of the two types of martensite present in the structure, 2H and M18R. The amount of M18R martensite increases with the increase of the zinc content and reduces the damping capacity and, conversely, the increase of the aluminum content increases the amount of 2H martensite and also increases the damping capacity. |
2.
V. A. Yartis' A. I. Shtogrin I. Yu. Zavalii M. I. Bartashevich Yu. B. Kuz'ma 《Materials Science》1993,28(4):383-388
| 1. | Solid solutions are formed with the Nd2Fe14B structure type when 10% of the iron atoms in the Nd2Fe14B are replaced by series 1 transition metals (Sc, V, Cr, Mn, Co, Ni) or silicon to give Nd2Fe12.6T1.4B. The tetragonal unit cell of the initial structure is almost unaltered. |
| 2. | The chemical nature of the alloying component affects the activity in the interaction with hydrogen for the initial intermetallides, as well as the adsorption capacity and the thermal stability in the hydrides formed. The highest rate of hydride formation occurs for alloys rich in neodymium, which is due to the catalysis by the solid solution of iron in neodymium. |
| 3. | Hydrogenation is accompanied by a rise in Curie temperture of 70–100 K with a simultaneous slight rise in the specific magnetization and a subtantial reduction in the anisotropy field. |
| 4. | The Nd2Fe12.6T1.4B intermetallides are embrittled by hydrogen saturation, which is due to the expansion of the structure by 2–3%, and which enables one to make fine powders with clean unoxidized surfaces. There are thus appreciable increases in the magnetic characteristics of permanent magnets: coercive force, residual magnetization and magnetic energy, which enables one to make high-quality permanent magnets. |
3.
V. T. Troshchenko V. V. Pokrovskii P. V. Yasnii V. G. Kaplunenko V. V. Burdakov V. P. Leonov Yu. A. Nikonov 《Strength of Materials》1988,20(9):1138-1145
| 1. | On the basis of the experimental investigation of the effect of the test temperature (153–293°K) on the rate of FCG in steels IP-1, IP-2, and IP-3 with a coefficient of load cycle asymmetry R=–2, –1, 0, and 0.5 it was established that lowering of the test temperature has an ambiguous effect on the rate of fatigue crack growth in the mentioned steels. In most cases the rate of FCG is practically insensitive to the test temperature although we can see a general tendency of the coefficient m of the Paris equation increasing with the test temperature being lowered from 293 to 153°K. |
| 2. | A change of the coefficient of load cycle asymmetry in the range –2–0 does not have a substantial effect on the rate of FCG, and in the range 0–0.5 it reduces this rate (in coordinates d/dN-Kmax) at 213 and 293°K, particularly substantially at 213°K. |
| 3. | For the investigated chrome-nickel-molybdenum steels in the temperature range 293-153°K a single dependence was established; it describes the decrease of the coefficient m with rising level of fracture toughness under static loading. |
| 4. | With the test temperature rising from 113 to 153°K, the characteristics of fracture toughness of all the investigated steels increase monotonically under static and cyclic loading, and also in the case of stopping of the crack. |
| 5. | Cyclic loading reduces substantially (to one half) the fracture toughness of steels IP-1 and IP-2 in the temperature range 113–153°K and does not change the values of K1 fc compared with KIc for steel IP-3. |
| 6. | In steels IP-1, IP-2 at temperatures of 113–153°K the fracture toughness under cyclic loading corresponding to final fracture of the specimen practically coincides with the fracture toughness at the instant of stopping of the crack. |
| 7. | In the temperature range 100–183°K of the three investigated steels steel IP-1 has the highest resistance to brittle failure under static loading and at the instant of stopping of the crack, steel IP-2 has the lowest resistance. |
4.
| 1. | Formulas were obtained to permit determination of the steady-state creep rate of a multilayered insulation under isothermal conditions and with a transverse temperature gradient from known parameters of the creep of the composite's components. |
| 2. | A study was made of the creep of insulation made of a ZrO2/ZrC composite in the temperature range 1900–2600 K at a compressive stress of 1–10 MPa. |
5.
| 1. | Formation of a multiphase structure changes the mechanism of the corrosion process of the Fe-Cr-Co-Mo steels: instead of general corrosion typical of the single-phase martensitic structure, pitting corrosion took place. The x-phase whose electrical restivity is higher than that of -ferrite and R-phase, increase the corrosion resistance of the steels. |
| 2. | A reduction of the chrome content of the maraging steels with the Fe-Cr-Co-Mo alloying base from 12.5 to 10% reduces their corrosion resistance. |
6.
| 1. | Steel strengthened by phase work-hardening is distinguished by a ratio of fatigue limit to tensile strength (–1/u=0.55–0.60) significantly greater than that of dispersion hardening steel. |
| 2. | The surface treatment method (grinding, turning, surface plastic deformation to a definite intensity) does not have a significant effect on the fatigue strength of N26T steel strengthened by phase work-hardening. |
| 3. | Combined strengthening of phase work-hardenable steel by surface plastic deformation, which causes the formation of 15–25% phase on the surface, and subsequent aging at 350–400°C is an effective means of increasing life. The use of this method makes it possible to increase the fatigue limit by 20% for uniform cross section samples and by 200% for those with a notch. |
| 4. | The increase in the fatigue limit with the use of combined strengthening (surface plastic deformation and aging) is related to the increase in the strength of the surface layers as a result of the increase in the dislocation density and fixing of them by the particles of Ni3Ti precipitated in aging and also to the decrease in peak microstresses. |
7.
N. M. Grinberg V. A. Serdyuk A. M. Gavrilyako V. A. Zolot'ko E. L. Miloslavskaya L. E. Gorelkova 《Strength of Materials》1989,21(7):859-865
| 1. | In the AMg6 aluminum alloy the fatigue crack growth rate at 293 K decreases as compared with the same value in air and parameters Kth and K* increase in vacuum. |
| 2. | With a temperature drop from 293 to 140 K the fatigue crack growth rate decreases especially at low Kmax values, while the Kth and K* values increase. |
| 3. | Each region of the kinetic diagram of fatigue fracture is characterized by a definite micromechanism of fatigue fracture which for the investigated alloy does not change in vacuum even at temperatures falling to 140 K. |
| 4. | On the basis of the dependence of groove pitches on Kmax for the AMg6 alloy in region II of the kinetic diagram of fatigue failure, coordinates K* and A of the transition point which divides this region into sections IIa and IIb were determined. Ordinate A=SIIa does not depend on the medium and temperature and is for this alloy (1.8–2.0)·10–7 m. |
| 5. | Since K* is an important practical characteristic of cyclic crack resistance, the experimental method of its determination must be based on recording the transitional character of one of the physical processes taking place in this point. |
8.
| 1. | The mechanical properties of niobium and its alloys depenet to a considerable extent on their content of interstitial impurities at both low and high temperatures; this opens up the possibility of alloying with such impurities finished components of niobium and its alloys in order to obtain the best combination of strength and ductility in each particular case. |
| 2. | The results of long-term strength tests on alloy 5VMTsU at 1100°C in vacum of 10–5 and 10–8 mm Hg have shown that the strength of this alloy on a basis of 800 h falls by 49% in a vacuum of 10–8 mm Hg. |
9.
| 1. | The structures of the nodal sections of the dished ends designed in accordance with the compensation principle and design restrictions of the standards are charcterized by the permissable level of the maximum working stresses. |
| 2. | In varying the fraction of the reinforcing metal of the nozzle section situated in the wall of the dished end from 50 to 80% the level of the maximum stresses in the section changes only slightly. |
| 3. | The structures containing 70–80% of reinforcing metal in the wall of the nozzle are more rational from the viewpoint of reducing the metal requirement and have sufficient strength at the same time. |
| 4. | The permissible value of the ratio d/D specified by the standards can be increased from 0.3 to 0.5 without reducing the strength of the nozzle section. |
10.
I. M. Rozenshtein 《Materials Science》1992,28(5):421-424
| 1. | The critical temperature of arrest of brittle cracks can be interpreted as a partial case on the critical temperature of brittleness in crack initiation. |
| 2. | A method of determining the correlation between the CTABC and the critical brittleness temperature at crack initiation was determined. |
11.
T. B. Buzovkina A. N. Sofronkov L. I. Korolenko S. A. Lyaskovskii I. A. Kuznetsova 《Materials Science》1993,28(4):354-358
| 1. | Unstable peroxides are formed when sea water reacts with a nonpassivating steel surface, which results in passivation. |
| 2. | The pH shifts as far as 13 in sea water in a real static crack in 15KhN5 steel, which is accentuated as the stress level increases, the crack lengthens, and the tip is approached. |
| 3. | The alkalinization in sea water above steel turnings is much less than in a crack but the pH dynamics are the same. |
| 4. | Metabolites from aerobic fouling organisms (bicarbonates and oxygen) retard the decomposition of hydrogen peroxide at the surface, which raises the pH and Eh; the metabolites from aerobic bacteria (hydrosulfides) reduce the hydrogen peroxide concentration, which reduces the pH and Eh. |
| 5. | The hydrogen release overvoltage is reduced on peroxide films on steel surfaces of 15KhN5 type, and the cathodic reaction of depolarizer reduction is retarded. |
12.
| 1. | High-temperature thermomechanical treatment and microalloying with 0.1% La raise the fatigue and corrosion-fatigue strength of steel 1Kh17N2. |
| 2. | The rise in the fatigue strength is due to an increase in the resistance to crack growth resulting from changes in the structure and substructure brought about in the steel by the high-temperature treatment and microalloying with the rare earth metal. |
| 3. | High-temperature thermomechanical treatment of steel 1Kh17N2 and its alloying with 0.1% La raise the corrosion resistance of the steel and reduce its tendency to intercrystalline corrosion. |
| 4. | The increase in the corrosion resistance of steel 1KM7N2 after the high-temperature treatment and microalloying with the rare earth metal is caused by the structural changes produced in the steel by the treatment and the microalloying. |
13.
L. V. Kuksa B. I. Koval'chuk A. A. Lebedev V. I. Él'manovich 《Strength of Materials》1976,8(4):393-398
| 1. | Plastic deformation in polycrystalline copper develops unevenly in the microregions in both the linear and the plane stress state (including plane stress under conditions of complex loading). A higher level of microinhomogeneity in deformation was observed in the plane stress state. |
| 2. | The immobilization and duplication of microcenters of increased and reduced deformation in simple loading is a general property of polycrystalline materials and is in independent of the nature of the material and the type of stress state. |
| 3. | The development of deformations in individual microsectors in conditions of complex loading (axial tension—uniform biaxial tension—transverse tension) differs substantially from that in simple loading. The difference lies in the varying degrees of localization of deformation of fixed microsectors. |
| 4. | In a plane stress state, especially under conditions of complex loading, deformation is due to the action of a larger number of slip systems than in a linear stress state; this must indicate more complex deformation conditions in the individual microvolumes. |
14.
J. Davidov 《Materials Science》1993,28(1):62-67
| 1. | With respect to low-cycle fatigue behaviour the increasing of iron quantity from 0.12% to 0.38% results in a decrease of cyclic ductility of AlSi7Mg alloy but this decrease is not very significant. |
| 2. | The alloy with 0.12% Fe shows better low-cycle fatigue resistance then other materials investigated due to its relatively higher cyclic ductility. |
| 3. | The structure with 0.29% Fe shows the best fatigue crack growth resistance which is due to the best combination of its mechanical properties and relatively ductile type of fracture. |
| 4. | With regard to the low-cycle fatigue behaviour and fatigue crack growth resistance investigations carried out in this work have shown AlSi7Mg alloy with 0.29% Fe seems to be the most appropriate material for manufacturing counterpressure cast car wheels of the particular design investigated because the decrease of cyclic ductility for this structure is not very significant. |
15.
| 1. | The kinetics of growth of the diffusion zone, formed in the dynamic powder mixture, differs from the kinetics of growth in the stationary mixture by the value of the parabolic growth constant. The difference in the diffusion constants is reflected in the structure and the phase composition of the borosiliconized layer. |
| 2. | The special feature of formation of the phases of the diffusion layers in the dynamic borosiliconizing mixture is the formation of higher silicide phases and also phases of a more complicated composition. |
| 3. | With all conditions being equal, the rate of saturation in the dynamic mixture in borosiliconizing is 1.5–2.0 times higher in comparison with saturation in the stationary mixture. |
16.
| 1. | The results show that when the temperature is reduced from 293 to 11°K the fatigue crack growth rate in Kh60MVYu nickel alloy decreases only insignificantly and only in the near-threshold region. Under the effect of vacuum the rate decreases to a considerably greater extent and in a wider range. |
| 2. | The threshold stress intensity factor Kth increases under the effect of both the medium and low temperature (11°K). |
| 3. | The size of the plastic zone at the crack tip is independent of the medium and decreases with decreasing temperature. |
| 4. | The size of the plastic zone at the point with the abscissa K* corresponds to 2h=3d, both for 293°K and 11°K. At this point the value m changes abruptly from m2=2 to m1=6. |
17.
| 1. | It has not been possible as yet to determine the relation between ultimate strength and hardness within a wide temperature range which, to a considerable extent, can be explained by the lack of methods for correct determination of the strain rate in hardness tests. |
| 2. | For solving this problem, as a method for determining hardness it is most advantageous to use the method of scratching whose advantage is the simplicity of adjustment and calculation of the rate of strain of the material under the indenter. |
| 3. | It is necessary to create experimental techniques which permit a complex investigation of the mechanical properties of materials, in particular strength and hardness, within a wide range of temperatures and strain rates. |
18.
| 1. | An algorithm was developed which employs a finite-elements method to solve problems characterized by large dimensions. The algorithm makes it possible to determine the stress-strain state of GTE rotors and to evaluate their load-carrying capacity. |
| 2. | The proposed method of formulating boundary conditions from the results of calculations performed for the assembled rotor makes it possible to determine the stress-strain state of the individual elements with allowance for their interaction. |
| 3. | The results of calculations for the assembled rotor can be used to reliably determine the clearances in the seals. |
| 4. | To reduce the bending strains in cantilevered disks, it is recommended not only that sloping disks be used, but also that the body of the disks be offset relative to the rim. |
19.
| 1. | Analytical relations were established which make it possible to determine the temperature Tb for standardized specimens. |
| 2. | It was shown that it is possible to use either of the known relations of(T) or KIc(T) and the value of Tb to find the other relation-say KIc(T). |
| 3. | The analytical expressions obtained in the present study for Tb agree qualitatively with the changes seen in practice in the quantity Tb under the influence of radiation due to a change in loading rate, variation of the geometry of the specimen and CSM, variation of the notch radius, or other factors. |
20.
| 1. | Multiple regression analysis was used to determine a strong correlation between the composition and physicomechanical characteristics of the high-manganese steel alloyed with boron and vanadium. |
| 2. | The correlation of abrasive and impact-abrasive wear resistance with each mechanical characteristic is very weak and in certain cases does not exist at all. |
| 3. | A correlation was found between each type of wear and the remaining characteristics. Abrasive resistance can be increased only by increasing hardness and impact-abrasive wear resistance can be increased by increasing hardness and bending strength. Impact toughness has no effect on wear resistance in both types of wear. |