Papers by Keyword: Rings

Abstract: The article presents the application of computed tomography (CT) for the detection of internal material defects in roller bearing rings made of steel. The tests were conducted using a set of four rings with different defects created artificially by means of electric discharge machining. In each test ring, several defects of the same type could be observed; however, they differed in terms of their size and geometry. The defects analysed had the form of internal blind holes with axes transverse or parallel to the surface of the track of the bearing – internal blind rectangular holes, and through slits in the inner cylindrical surface. The tests were conducted using a “V|tome|x s” X-ray CT scanner (tomograph) by GE. The roentgenograms of test objects were taken and then reconstructed in 3D. Each defect was visualised in different section planes of a reconstructed ring. Selected defects were represented in a solid form, and the measurements were taken in order to determine their geometry and volume. The tests confirmed that CT can be used in studies on such internal material defects in roller bearing rings as subsurface voids. All artificially made model defects were detected.

Abstract: 0.3C-CrMoV(ESR) steel is an ultra-high strength low alloy steel indigenously developed by ISRO for space applications. The steel is used in the form of rings of 2.8 m diameter also. In this paper, the effect of tempering temperature on ring rolled steel for the best combination of fracture toughness and strength properties is studied. The tensile properties and fracture toughness of the steel were evaluated in the as quenched and tempered conditions through the specimens drawn in radial direction of the ring segment. Five tempering temperatures were used in the study: 200, 450, 475, 500 and 510°C. Tensile strength of the steel showed continuous decrease with increasing tempering temperature, but yield strength increased reaching maximum when tempered at 450°C and further decreased with increasing tempering temperature. The elongation was higher for higher tempering temperature. The strain hardening exponent decreased with increasing tempering temperature. The fracture toughness test results showed that tempering between 475 and 510°C exhibited better combination of fracture toughness and strength.