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Previous standards for the manufacturing inspection of railroad wheels using ultrasound, such as UIC 812, have been replaced by new standards, for example EN 13262 and RD32.144-2000, both requiring ultrasonic testing in immersion technique. These new standards require the development of an ultrasonic technique for 100% coverage of the wheel rim and wheel hub, and in special cases for both straight and curved wheel disks. In order to encompass a large variety of railroad wheel designs, inspection and handling techniques should be capable of dealing with wheel diameters ranging from 600 mm to 1300 mm (23" to 51") at testing cycles from 1 to 4 minutes per wheel. The current requirement for the minimum detectable flaw size is DSR 1 mm (disc shape reflector, DSR, 1 mm diameter) for high-speed train wheels rims and DSR 2mm for all other wheel rims. The minimum detectable flaw size for all other wheel areas (hub and disk areas) is DSR 3 mm. To meet all these criteria, the Rail Wheel Inspection (RWI) System was developed by IZFP and their partners. The system consists of an ultrasonic testing sub-system, immersion tank and transportation/handling sub-systems. Test cycles of 1 minute per wheel require two immersion tanks and two transportation/handling subsystems. The ultrasonic sub-system features modular computer-aided 6 to 16- channel UT electronics (PCUS 11) to employ 6 to 16 ultrasonic transducers (the precise number is determined by the testing procedure). This presentation paper offers descriptions of, and results from three of these systems that have been integrated into manufacturing processes at German and Russian wheel manufacturers, and provides details on the following topics: Wheel rim inspection, single-tank immersion technique, 4 minutes inspection cycle per wheel (Bochum, Germany) Wheel rim, hub and disc inspection, single-tank immersion technique, 2 minutes inspection cycle per wheel (Ilsenburg, Germany) Wheel rim, hub and disc inspection, dual-tank immersion technique, 1 minute inspection cycle per wheel (Nishny-Tagil, Russia

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Dependences of the coercive force, the relaxation magnetization, the hardness, and the strength and plastic properties of steel å 74, intended for manufacturing railroad rails, on its tempering temperature were studied. Hardened specimens have the martensite structure as well as the sorbite structure of different dispersity. Analogous dependences of critical fields, which correspond to the displacement of 180 ° and 90 ° domain walls during the magnetization reversal, and of the induced magneticanisotropy field were also analyzed. An åë-2 àîå magnetic structure analyzer was shown to be suitable for the nondestructive testing of the mechanical properties of finished rails. The correlation model is two-parameter; i.e., analyzer readings are used that were recorded after successive magnetization reversals of inspected sections of rails to magnetic fields corresponding to two different currents in the electromagnetic coils. INTRODUCTIONHeavy railroad rails of the ê 65 type are made of high-carbon high-manganese steels, steel å 74 being among them. In compliance with GOST (State Standard) 24182-80, it has the following chemical composition: 0.69-0.80% C, 0.75-1.05% Mn, 0.18-0.4% Si, ≤ 0.035% P, ≤ 0.035% S, and ≤ 0.15% As.During production at Nizhni Tagil Iron and Steel Works (NTMK), hot-rolled rails are subjected to heattreatment hardening at the austenitization temperature T a = 840 ± 10 ° C followed by oil cooling. Because of the low hardness penetration (4-6 mm), sorbite-like plate-type pearlite with a grain size that corresponds to the 7th to 8th number according to GOST 5639-82 [1] is usually present in the body of the rail after the hardening. The tempering temperature is T temp = 450 ± 15 ° C; the holding time is 2 h.In compliance with GOST 18267-83, fully hardened ê 65 rails should exhibit hardness HB 331-388 whose variations along the rail length should not exceed HB 30, an ultimate breaking strength of σ b ≥ 1170 MPa, a yield strength of σ y ≥ 750 MPa, a relative elongation of δ 5 ≥ 6%, and a relative reduction of area ψ ≥ 20%. Standards for rails and methods for improving their quality are described in [2][3][4][5].In compliance with GOST 18267-83, magnetic methods may be used to test the hardness of railroad rails subjected to bulk hardening and tempering. Earlier, two magnetic methods were approbated at NTMK. One of these was based on measurements of the residual magnetization field induced in a section of rail by an attached electromagnet [6]. The other method was based on analogous measurements performed at temperatures above the Curie temperature of cementite ( Θ c = 217 ° C); this allowed extension of the tempering-temperature range within which a one-to-one correlation between the hardness and readings is provided [7]. Tests showed that the first method does not provide a statistically significant correlation between the readings and the hardness of rails subjected to bulk hardening in accordance with the process used at NTMK. A disadvantage of the second method is the necessity to perform additional ...

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