Yu. M. Kolobylin

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.

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.

The influence of a combined strain-heat treatment on the features of electromagnetic testing of fatigue degradation of quenched constructional steel

The possibilities of the magnetic and eddy-current methods for testing fatigue degradation during low-cycle loading of quenched steel 50 (0.51% C) that was subjected to a combined strain-heat treatment according to an optimal regime that included friction treatment with subsequent tempering at T = 350°C, were investigated. It is shown that for steel that was subjected to a combined nanostructuring treatment, the accumulation of a plastic strain under “hard” cyclic loading can be tested using the coercimetric method and values of the residual magnetic induction on the major and minor magnetic-hysteresis loops, values of the maximum and initial magnetic permeabilities, and readings of an eddy-current instrument at a low excitation frequency of the eddy-current transducer. The appearance of surface fatigue cracks can be tested via eddy-current measurements at high frequencies, when the contribution of the crack formation in the hardened layer to the eddy-current characteristics is considerable.

Magnetic and eddy-current testing of hardened constructional steel subjected to combined strain-thermal treatment

The potentialities of magnetic and eddy-current methods for testing a structural state, wear resistance, and mechanical properties of steel 50 (0.51 wt. % C) subjected to quenching from 850°C, nanostructurizing frictional treatment with a hard alloy indenter, and tempering at the temperatures of 100–600°C are studied. It is shown that the structural state of constructional steel 50 that is subjected to combined strain-thermal treatment can be tested using the eddy-current method upon low temperature (to 250°C) tempering and in the tempering temperature range of 250–450°C, the coercitimetric method and based on the maximum permeability in the temperature range of 100–350°C, based on the residual magnetic induction for major and minor magnetic hysteresis loops in the temperature ranges of 100–400°C and 250–600°C, respectively, and based on the specific resistivity in the temperature range of 100–300°C. Correlations between electromagnetic parameters and hardness, mechanical properties, wear intensity under the conditions of dry frictional that point to the possibility of using eddy-current and magnetic testing of the quality of optimized strain-thermal treatment, which provides a good complex of wear resistance and mechanical characteristics of constructional steel, were established.

Eddy-current and coercive-force testing of abrasion-resistant ball bearing steel IIIX15 subjected to laser and bulk thermal processing

The possibility of using the eddy-current and coercive-force methods for assessment of the structural state and the abrasion resistance of ball-bearing steel IIIX15 (1.00% C and 1.42% Cr) is studied. The steel was subjected to laser and bulk quenching, subzero treatment, and tempering in the temperature range 75–600°C. The presence of residual austenite (in an amount of up to 45 vol %) in the quenched structure is shown to affect the sensitivity of the coercive-force and eddy-current methods used to test the abrasion resistance of steels tempered at low temperatures. Variations in hardness, abrasion resistance, and the parameter of the electromagnetic eddy-current testing as a function of the depth of the laser-irradiated zones in steel IIIX15 subjected to preliminary thermal strengthening is considered.

Eddy-current testing of the wear resistance of laser-hardened carburized chromonickel steel and the quality of laser hardening of drill bits

Features of eddy-current testing of carburized chromonickel steel 30XH3A subjected to processing with continuous laser radiation, subsequent treatment with cold at s-196°C (reducing the content of retained austenite in the carburized layer from 25–40 to 5–10 vol %), and tempering in the temperature range 100–400°C are studied. It is shown that the eddy-current method can be used to detect the presence of a laser-hardened wear-resistant layer on the steel surface and evaluate an abrupt decrease in the abrasive wear resistance of steel hardened with laser radiation, additionally treated with cold, and then exposed to low-temperature tempering. The possibility of eddy-current testing of the quality of laser hardening of roller paths of the bearing unit of rock-drilling bits manufactured from carburized steel 20XH3A using an attachable transducer with a protruding rod core is established.

Coercive-force and eddy-current testing of the abrasive wear resistance of quenched and tempered hypereutectoid carbon steels: II. Steels subjected to different quenching regimes, subzero treatment, and tempering after high-temperature quenching

The effects of the carbon concentration in martensite from 0.70 to 1.35 wt %, the presence of up to 70 vol % residual austenite, the degree of coagulation, and the volume fraction of tempering carbides on the specific features of the application of eddy-current and magnetic methods for testing abrasive wear resistance are studied. The case of high-carbon (0.83–1.53 wt % C) steels quenched from 790–1200° C, treated with cold at −196°C, and tempered in the temperature range 75–700°C is considered.