L. Kh. Kogan

Effect of the carbon content on the magnetic and electric properties of thermally treated carbon steels and the possibilities of testing the quality of tempering of articles produced from them via the eddy-current method

The magnetic and electric characteristics of 4.7-, 2.2-, and 1.5-mm-thick hardened and tempered carbon-steel specimens with a carbon content of 0.35–1.02% have been studied. The relations of these characteristics to the carbon content, structure, and hardness of the studied specimens are analyzed. The structural state, the thickness, and the acceptable limits of the carbon-content variation in carbon-steel articles, properties that allow the quality of medium-temperature tempering to be tested with the use of the eddy-current method, have been determined.

Features of electromagnetic methods for testing the wear resistance of medium-carbon structural steel subjected to laser or bulk hardening and tempering

Features of applying attachable eddy-current transducers of two types (with a flat end surface and a protruding ferrite rod core with localities 5–6 and 3–4 mm in diameter, respectively) for testing the structural state, hardness, and abrasive wear resistance of structural steel 45X (0.45 mass % C and 0.85% Cr), which was hardened under the action of continuous laser radiation, have been studied. The feasibilities of the eddy-current and coercimetric techniques for evaluating the wear resistance of a medium-carbon steel subjected to laser or bulk hardening and tempering in the temperature range 75–600°C have been studied.

Effect of friction-induced hardening on the features of magnetic and eddy-current behavior of an annealed structural steel under cyclic loading conditions

The effect of friction processing on the mechanical properties in uniaxial tension, the magnetic properties, and the electromagnetic characteristics of an annealed Steel 3 (St3) grade structural steel has been studied. It is established that the coercive force, residual magnetic induction, initial magnetic permeability, and eddy-current characteristics can serve as parameters for monitoring the quality of steel hardened by friction processing. Features of friction-induced changes in the strength, magnetic properties, and electromagnetic characteristics of St3 grade steel loaded in the region of low-cycle fatigue are revealed. It is shown that magnetic and eddy-current techniques can be used for monitoring the state of a friction-hardened surface layer of steel samples in the course of their cyclic loading.

Eddy-current testing of the hardness, wear resistance, and thickness of coatings prepared by gas-powder laser cladding

The possibility of applying the eddy-current method to estimate the composition, hardness, abrasive wear-resistance, and wear resistance under sliding friction conditions of chromium-nickel and chromium-nickel-cobalt coatings prepared by gas-powder laser cladding was studied. Variations in the readings of an eddy-current instrument along the depth of the surface cladding layer and with changing thickness of coatings, which are due to the distribution of structural components in coatings and large differences between the electromagnetic characteristics of cladding layers and the ferromagnetic steel base of specimens, were determined. A technique of the eddy-current testing of the thickness of Cr-Ni and Cr-Ni-Co cladding coatings on a ferromagnetic steel base is proposed. It allows one to estimate the quality of the strengthening laser cladding and subsequent grinding, monitor the state of coatings under service conditions, and forecast the residual life of cladding elements subjected to intense wear.

Application of an Eddy-current method for the assessment of stored plastic deformation and residual mechanical properties after cyclic loading of an annealed medium-carbon steel

The effect of cyclic loading of annealed steel 45 during low-cycle fatigue on changes in its electrical characteristics is studied. In the region of both small and mediate strains, an eddy-current transducer signal is found to be highly sensitive to the plastic deformation stored during cyclic loading. Correlations between readings of an eddy-current instrument and the residual mechanical properties of the material after cyclic loading are obtained. The possibility of assessing the residual mechanical properties of the material during its cyclic loading is considered.

Possibilities of Nondestructive Testing of Physico-Mechanical Characteristics of Hypereutectoid Carbon Steels with the Structures of Isothermal Austenite Decomposition

The possibilities of estimating the hardness, the wear resistance under abrasive action and sliding friction, the impact strength, and the internal stresses of the U9 steel (with 0.94% of carbon) with the initial fine-lamellar pearlite structure annealed at 650°C during 2–600 min on the basis of magnetic and electrical characteristics, readings of an eddy-current instrument, and parameters of electromagnetic-acoustic conversion are studied. A comparative analysis of the magnetic, electromagnetic, strength, and tribological characteristics of the U10 and U15 hypereutectoid steels (with 1% and 1.53% of carbon, respectively) subjected both to isothermal treatment at 330–650°C (with formation of pearlite and bainite structures) and to additional short-time annealing at 650°C is carried out.

Eddy-Current Evaluation of Wear Resistance of Case-Hardened Chromium–Nickel 20KhN3A Steel

The paper considers feasibility of eddy-current evaluation of the wear resistance of the quenched and tempered (100–400°C) case-hardened 20KhN3A steel under conditions of abrasive wear and sliding friction. The effect of cold processing on the susceptibility of the eddy-current method to the wear resistance of a hardened layer has been studied. The effect of the carbon content in the martensite prior to tempering over the range of 0.3 to 0.9 mass % on eddy-current measurements is discussed.

The peculiarities of magnetic and eddy-current testing of quenched structural steel hardened by nanostructuring frictional treatment

This paper deals with the study of the potential of the magnetic and eddy-current methods for the assessment of the structural state of hardened wear-resistant layers on the surface of quenched medium-carbon structural steel 50 (0.51 wt % C) that is subjected to frictional treatment by a sliding hemispherical hard-alloy indenter. It is found that the presence of a thin ∼220 μm hardened wear-resistant layer on the surface of quenched steel 50 can be verified by readings of an eddy-current instrument, as well as by values of the coercive force (for major and minor magnetic hysteresis loops) and the residual magnetic induction (for minor magnetic hysteresis loops if measurements are carried out in weak magnetic fields). The eddy-current method has the highest susceptibility to the structural transformations caused by frictional treatment.

Estimation of the quality of strengthening frictional treatment and subsequent tempering of eutectoid steel by the eddy-current method

The possibilities of the electromagnetic eddy-current method for evaluating the structural state and depth of strengthened layers on the surface of hardened and low-tempered steel U8 subjected to plastic straining using a hard-alloy indenter and subsequent heat treatment (tempering at T = 100–600°C) have been studied.

Application of the eddy-current method for estimating the wear resistance of hydrogen-alloyed β-titanium alloy BT35

The availability of the eddy-current method for the estimation of the wear-resistance under different wearing conditions and at different hydrogen contents in β-titanium alloy BT35 is studied. The alloy is hydrogenated to a hydrogen content of 0.10–0.38 wt % in a hydrogen atmosphere. The effect of the hydrogen content on the electrical resistivity of the alloy is studied. The peculiarities of using two types of eddy-current transducers (with a flat end surface and with a prominent ferrite rod-type core) for the analysis of electropolished surfaces and worn surfaces of titanium-alloy specimens are considered.