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.     

Effect of Structure and Phase Composition on Coercive Force and Saturation Magnetization of Mechanically Alloyed Fe100 – xCx (x = 25, 32) Powders

Mechanical fracture of iron and graphite powders leads to formation of the amorphous Fe–C phase and subsequent precipitation of the Fe₃C carbide in the Fe(75)C(25) system and Fe₃CFe₇C₃ carbide in the Fe(68)C(32) system, which are in strongly strained states. After annealing, carbides with undistorted structures are formed, and their content is higher. On the initial stage of this mechanical alloying, the magnetic characteristics of these structures are determined by their defectiveness, and on the subsequent stages of fracturing and annealing by the types, quantities, and structural conditions of the resulting carbide phases.     

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.     

Choice of place of magnetic-flux registration in the magnetic core of an attachable electromagnet for inspection of articles using their coercive force

The demagnetizing current I _dc is measured in different areas of an electromagnet-article magnetic circuit at the moment of zero crossing of the magnetic flux as the gap between the electromagnet and article changes. The weaker dependence of the I _dce magnitude measured in close proximity to the article on the gap width and the possibility of using the parameter in measuring the coercive force of the article with an attachable transducer (in particular, with a Hall sensor) are demonstrated.     

Structure and electromagnetic properties of ZhGr-type powder steel deformed by rolling with different porosity and temper

The results of studying the structure and electromagnetic properties of powder construction steels of the ZhGr type with different temper (0.03, 0.45, and 0.95 wt %) and porosity (8, 12, and 18%) after deformation by rolling to the degree of strain ɛ = 30% and a step of 0.5–6.0% are presented. The data of microstructure studies that indicate anisotropy of the structural elements in the direction of rolling are presented, and typical types of pores are identified and described. The porosity value of steels with any composition is halved when the strain is about 30%; here, the maximal magnetization monotonically increases because the volumetric portion of pores decreases.     

The effect of equal channel angular pressing on the mechanical and magnetic properties of 09Γ2C steel

The physical and mechanical properties of 09Γ2C steel that was subjected to strengthening by intense plastic deformation using the method of equal channel angular pressing (ECAP) are studied. An unambiguous interrelationship between the magnetic (coercive force, maximal permeability, Barkhausen magnetic noise parameters) and mechanical (rupture limit, conditional yield strength, relative elongation and narrowing upon damaging) characteristics of 09Γ2C steel, which was strengthened using ECAP following different technological regimes, is demonstrated. Therefore, it is possible to estimate the strength and plasticity characteristics of the analyzed material based on the measurement of its magnetic parameters. It has been revealed that under conditions of uniaxial tension in the range from 0 to (0.2–0.6) of the conditional yield strength (depending on the ECAP regime), it is possible to diagnose changes in the stressed state of items that are made of 09Γ2C steel that is hardened in accordance with the ECAP technique using magnetic structuroscopy methods.     

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.     

Comparison of Magnetic Parameters of Quenched Pipe Steels with X-Ray–Evaluated Residual Macro- and Microstresses

Russian Journal of Nondestructive Testing - Residual micro- and macrostresses have been determined by X-ray diffraction analysis in 22KhG2A, 30KhMA, and 32G2 grade steels quenched and tempered from...     

Measuring the carbon content in sintered steels by the magnetoelastic acoustic-emission method

Conclusions In magnetic reversal of sintered steel specimens the parameters of the magnetoelastic acoustic-emission signals occurring depend upon the carbon content and the degree of porosity. The parameter most sensitive to the structural condition of the sintered steels, the total number of pulses measured per unit of time, is nine times more sensitive in relation to variations in carbon content than to changes in porosity within the tolerance limits for the investigated types of steel, which may be used for nondestructive inspection of the structure of sintered steels.Translated from Poroshkovaya Metallurgiya, No. 3(303), pp. 65–69, March, 1988.     

On Possibility of Nondestructive Testing of the Grain Size in the Intermediate Stages of Manufacturing Electrical Steel

The results of investigation of the relation between the grain size in the intermediate stages of manufacturing electrical steel and various physical characteristics are given. The investigations are carried out for the purpose of clarifying the possibility of using these characteristics for arranging nondestructive testing of the grain size in the process of steel manufacturing. The paper contains the results of tests performed with the use of the methods of measuring the leakage magnetic fields on the grain boundaries by means of yttrium iron garnet films employed for visualization of the magnetic fields, the Barkhausen effect, the ultrasonic and eddy-current methods, the electromagnetic-acoustic conversion (EMAC) method, and the use of the relation between the grain size and the value of the coercive force.