Diagnostics of fracturing of structural materials based on parameters of electromagnetic radiation signals

The methodological aspects and results of experimental studies allowing for remote evaluation of the integrity of structural materials under loading using the method of electromagnetic emission (EME) are considered. It is known that in the process of loading different materials systems of cracks that are formed in them emit acoustic and electromagnetic signals. Based on signal parameter variations, it is possible to predict an oncoming moment of disruption of their integrity. The EME is a remote method and does not require direct contact with an object under study, be it rock specimens or metal articles. It is proposed to use it for testing the integrity of metal articles. The first results of diagnostics of the integrity of metal rings made of different materials (steels, duraluminum, zirconium, and copper) using sensing devices, namely antennas of electrical and magnetic types, are presented. It is shown that when loaded different types of materials emit EME signals of different amplitudes whose level substantially exceeds the level of external disturbances and internal equipment noises. It is proposed to evaluate the integrity of different metal articles, especially those in nooks, based on increased amplitudes of EME signals.     

Problem of unexpected failure of steel parts

Examples of unexpected (brittle) fracture that occurs in the production of parts or the operation of parts and machines despite of the fact that the mechanical properties of the metal (steel) satisfy the standards for metal products are considered. Solutions to the problem are suggested on the basis of earlier works of the author. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 3, pp. 31–34, March, 1998.     

Use of carbonitriding for self-sharpening of tools in service

Conclusions  

Effect of temperature on the fracture behaviour of heat‐treated Al–Cu–Li alloy laser welds under low‐cycle fatigue loading

The paper presents the results of the studies of the effect of temperature on the fracture behaviour of Al–Cu–Li alloy laser welds under low‐cycle fatigue loading. The mechanical properties and the microstructure of the welded joints without and after postweld heat treatment (PWHT) were investigated. The tensile strength and the low‐cycle fatigue resistance of the welded joints were studied at various test temperatures (20°C, 85°C and ? 60°C). It was been found that heating up to 85°C and cooling down to ?60°C reduced the maximum number of loading cycles of the welded joints after PWHT by 1.5–2.0 times compared with that at a test temperature of 20°C.     

Non‐reflecting boundary conditions for atomistic,continuum and coupled atomistic/continuum simulations

We present a method to numerically calculate a non‐reflecting boundary condition which is applicable to atomistic, continuum and coupled multiscale atomistic/continuum simulations. The method is based on the assumption that the forces near the domain boundary can be well represented as a linear function of the displacements, and utilizes standard Laplace and Fourier transform techniques to eliminate the unnecessary degrees of freedom. The eliminated degrees of freedom are accounted for in a time‐history kernel that can be calculated for arbitrary crystal lattices and interatomic potentials, or regular finite element meshes using an automated numerical procedure. The new theoretical developments presented in this work allow the application of the method to non‐nearest neighbour atomic interactions; it is also demonstrated that the identical procedure can be used for finite element and mesh‐free simulations. We illustrate the effectiveness of the method on a one‐dimensional model problem, and calculate the time‐history kernel for FCC gold using the embedded atom method (EAM). Copyright © 2005 John Wiley & Sons, Ltd.     

Effect of preliminary and repeated heat treatment on the plasticity and structure of 25Kh17N2B-Sh steel

An investigation of prematurely damaged high-pressure pipelines from steel 25Kh17N2B-Sh showed that the microstructure of their parts contains a carbide network and coarse austenite grains, which are known to worsen the mechanical properties. The possibility of improving the structure and plasticity of parts of high-pressure pipelines from martensitic steel 25Kh17N2B-Sh by preliminary quenching with subsequent subcritical tempering or cyclic heat treatment before final vacuum quenching is discussed below, The capacity for grain growth in the quenching of parts from rods of different heats and the effect of double quenching to improve the coarse-grain structure are investigated.Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 8, pp. 9–11, August, 1995.     

On the critical quenching rate

Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 12, pp. 3–5, December, 1992.