On the Effect of Loading System Rigidity on Strain Resistance and the Fracture of Alloy Specimens on Deep Cooling

The results of investigating the effect of loading system stiffness on the parameters of low-temperature intermittent yield and the mechanical characteristics of the steels 03Kh20N16AG6 and 12Kh18N10T and the titanium alloy 3M at 4.2 K at different development stages of plastic strain instability are presented. Criteria of fracture by the adiabatic-shear mechanism are considered. An analysis of the stiffness components of an electrohydraulically driven testing machine is given. The necessity of laying down stiffness regulations for conventional mechanical tests of materials has been shown.     

Dynamic Compression of High-Strength Steel and Titanium Alloy

We describe a procedure of impact compression of 20Kh2N4A high-strength steel and VT-8 titanium alloy and present some experimental results accumulated for these materials. The analysis of these data demonstrates that compression strength significantly increases as the investigated range of strain rates becomes larger by an order of magnitude. Moreover, the compression strength of the studied materials strongly increases with the strain rate.     

Investigation of the regularities of deformation of heat-resistant steels under conditions of creep in the complex stressed state

We study the regularities of deformation of 1Kh18N9T steel under long-term static loading along different paths of radial loading with regard for the influence of the type of stressed state. The viscoplastic properties of 08Kh18N10T-VD steel subjected to stepwise static loading under conditions of complex stressed state are analyzed.     

Specific features of the deformation of steels in hydrogen

We have studied the effect of hydrogen on the mechanical properties of foils made of 08Kh18N12T steel under uniaxial tension. The initial stages of deformation in hydrogen require forces smaller by a factor of 3–5. In the case of biaxial tension of membranes made of this steel, their deformation ability also increases. The effect of hydrogen on the axial residual stresses of the first kind in 08Kh18N12T, 40Kh, and ShKh15 steels manifests itself in the activation of tensile deformation (inducing of compressive stresses). We have recorded a 30% increase in the fatigue limit of an austenitic alloy in hydrogen with a pressure of 30 MPa (the reference medium is air). __________ Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 44, No. 4, pp. 84–88, July–August, 2008.     

Effect of technological factors on low-cycle fatigue of 12Kh18N10T and 20 steels

Conclusions 1. No large differences were detected in the fatigue strength for finite life of 12Kh18N10T steel after different turning conditions.2. The reduction of the resistance to low-cycle fatigue of 12Kh18N10T and 20 steels after single plastic deformation, determined by experiment and calculations, is in quantitative agreement.Scientific Research and Design Institute of Power Engineering Moscow. Translated from Fiziko-Khimicheskaya Mekhanika Materialov, Vol. 29, No. 2, pp. 122–124, March–April, 1993.     

Crack resistance of chromium-nickel steels with impact loading under cryogenic temperature conditions

Results are presented for an experimental study of the effect of cooling to 77 K on resistance to crack development of chromium-nickel steels 12Kh18N10T and 03Kh20N16AG6 with impact loading. The crack resistance characteristics with a rate of crack growth of 1.5 m/sec were determined from the deformation diagram recorded during testing. Features are noted for crack advance with cooling under conditions of a dynamically applied load.Translated from Problemy Prochnosti, No. 7, pp. 26–29, July, 1992.     

Microcrack initiation and growth in heat-resistant 15Kh2MFA steel under cyclic deformation

This paper presents the results of investigation of a nuclear reactor pressure vessel steel 15Kh2MFA of two strength levels under cyclic loading. The mechanism of microcrack formation on the surface and in the bulk of 15Kh2MFA steel under cyclic deformation was investigated. Analysis of the specimen surfaces has shown that microcracks are caused by cyclic sliding in grains most favourably oriented with respect to the direction of the maximum shear stresses. Transmission electron microscope investigations show that microcracks in the material inside the grains are formed mainly along the band‐type dislocation structure parallel to the dislocation subboundary. During cyclic deformation, the dislocation density on the subboundaries increases, in the local areas the dislocation density becomes limiting and it reaches the plasticity limit and causes microcrack formation. The interrelation of the average length of microcracks and their surface density with the energy density of inelastic deformation has been found.     

The Influence of the Cyclic Loading Rate on the Plastic Zone Depth in VNS-25 Alloy

We have studied the plastic zone depth at the fatigue crack tip in VNS-25 (03Kh12N10MT) alloy specimens, previously subjected to the cyclic fracture toughness tests under symmetrical push-pull loading with a frequency of 20, 170, 600 Hz, 3 and 10 kHz. For the same values of the stress intensity factor, an increase in the loading frequency is shown to slow down the fatigue crack growth and reduce the plastic zone depth under the fracture surface. However, the dependence of the plastic zone depth on the crack growth rate is invariant with respect to the loading frequency.     

Corrosion-Fatigue Strength of Corrosion-Resistant Steels with Welded Joints

We consider the influence of argon-arc welding and the type of a weld on the corrosion-fatigue strength of specimens (d = 50 and 200 mm) made of 08Kh17N6T, 10Kh26N5M2, and 08Kh18G12N5AB stainless steels. We established that fatigue cracks are initiated from near-surface welding defects and fracture occurs along the weld. We showed that the use of surface plastic deformation is more efficient for enhancement of the corrosion-fatigue strength of welded specimens than cathodic protection.     

Effect of lithium-lead eutectic and hydrogen on the fatigue behavior of some austenitic alloys

We investigate low-cycle and high-cycle fatigue of 04Kh16N11M3T and 03Kh20N45M4BCh austenitic alloys under rigid loading by pure bending in air, hydrogen, and lithium-lead eutectic at 80, 250, and 350°C. The amplitude of deformation did not exceed ±3%. We discovered a decrease in durability at 250 and 350°C in the presence of lithium-lead eutectic under low-cycle loading and under high-cycle loading in the stage of limited endurance. The greater the amplitude of loading, the sharper the decrease in durability, and this effect is more pronounced at 250°C than at 350°C. Under the action of gaseous hydrogen, the durability of 04Kh16N11M3T alloy increases under low-cycle loading as compared to that in air. In the same situation, the durability of 03Kh20N45M4BCh alloy decreases. Under high-cycle loading, no influence of hydrogen on the limited endurance of these alloys was detected. Both in hydrogen and in lithium-lead eutectic, we observed a decrease in the amplitude of deformation at the fatigue limit on a base of 10⁷ cycles.Translated from Fiziko-Khimicheskaya Mekhanika Materialov, Vol. 31, No. 1, pp. 101–106, January – February, 1995.     

Effect of the Specimen Geometry on Strength and Plasticity Characteristics of Steels on Subzero Cooling

We present the results of investigations into the deformability and strength of conical and tubular specimens of 03Kh20N16ÀG6 and 12Kh18N10Ò steels in uniaxial tension over a temperature range of 293–4.2 K. It is demonstrated that the deformability of the above steels is related to the geometry of the test object, whereas the character of this relation is determined by the test temperature and class of steel. At a temperature of 4.2 K, a qualitative change in the deformation mechanisms occurs, as a result of which the influence of the design factors changes significantly. A drop in the plasticity for both types of the specimens and a considerable hardening of the 03Kh20N16ÀG6 steel thin-walled tubular specimens are noted.     

Monitoring the State of Stainless Steel under Cyclic Deformation by the Acoustic and Eddy Current Methods

Measurement Techniques - The effect of the amplitude of deformation on the intensity of the change of the elastic and magnetic properties of austenitic stainless steel 12Kh18N10T was studied. It is...     

Material deformation and fracture under impulsive loading conditions

Engineering structures experience impulsive loads during the time of natural disasters like earthquakes, cyclones and collisions. The design of structures resistant to such natural disasters requires an understanding of the deformation and fracture behaviour of the materials constituting the structure under impulsive loading conditions. In this paper the various aspects of dynamic plastic deformation and fracture of common engineering materials are reviewed and contrasted with their behaviour under static loading conditions.     

Mathematical Modeling of the Monotonic and Cyclic Loading Processes

Strength of Materials - Based on experimental studies of specimens of 12Kh18N10T stainless steel under a rigid (strain-controlled) deformation process, which includes a sequence of monotonic and...     

Inelasticity monitoring of structural materials by the resonance method

We have developed a method which provides monitoring of the inelasticity kinetics of polycrystal materials by variation of the stress-strain phase-shift angle in the locally loaded surface zone of the material under study. The proposed method allows one to determine current value of damage of investigated aluminum alloy under laboratory conditions of cyclic deformation by variation of statistical characteristics of phase-shift angle distribution. AMg6N aluminum alloy, which is a cyclically hardening material, was used in this study. Translated from Problemy Prochnosti, No. 3, pp. 124–133, May–June, 2009.     

Effect of microalloying with rare-earth metals on the resistance of steels to deformation and failure under an alternating elastoplastic load

Results of experimental investigation of the resistance of steels OKh16N15M3B and Kh13N13T3 to cyclic alternating deformation and failure at T=923K after microalloying with Sc are presented. It is established that microalloying enhanced the characteristics investigated. Radiation-induced damage(=4.5·10¹⁷ neutrons/(m²·sec), E0.1 MeV) during the loading of microalloyed steel 00Kh16N15M3B lowered resistance to cyclic deformation while increasing the strain-hardening factor and cyclic longevity as compared with similar characteristics under normal conditions.Translated from Problemy Prochnosti, No. 1, pp. 12–17, January, 1994.     

Loss of stability for the process of plastic deformation with a complex stressed state

Basic preconditions are presented for considering the stability of the plastic deformation process in evaluating the ultimate deformation and strength properties of structural materials in tubular specimens under conditions of a complex stressed state. Calculated dependences are provided for calculating these characteristics. Results of experimental studies are analyzed for heat-resistant steels 15Kh2MFA, 15Kh2NMFA, and VK-2 (KP-100) (the latter simulates radiation embrittled steel 15Kh2NMFA) with different principal stress ratios in the temperature range 20–350°C. Calculated values of ultimate stresses and strains are compared with experimental data. The possibility of using the results of experiments carried out with stepwise loading as a basis for calculating the endurance under cyclic loading conditions with a complex stressed state is substantiated.Translated from Problemy Prochnosti, No. 10, pp. 3–8, October, 1991.     

Studying the rate of heat dissipation at the vertex of a fatigue crack

The thermodynamics of the process of fatigue-crack propagation in plastic materials is analyzed by the example of chromium-nickel steel of 8Kh18N10 grade. An original device has been developed that is capable of measuring the rate of dissipation of the plastic deformation energy at the crack vertex during its propagation. Experimental results showed that, at a constant stress amplitude, the rate of fatigue-crack propagation is a linear function of the product of the energy-dissipation rate and crack length.     

爆炸加载条件下工业纯铁的冶金效应

针对内部爆炸加载的工业纯铁圆管和爆炸成形弹丸非常高的宏观塑性变形,对相应的微观组织进行了观察。结果表明：塑性变形时纯铁内发生动态回复和动态再结晶。这与冲击波引起的绝热温升和塑性变形功产生的绝热温升有关;动态回复和动态再结晶的软化作用使纯铁具有较高的塑性变形能力。