Investigation of rail wheel steel crystallographic texture changes due to modification and thermomechanical treatment

Abstract

View the article online for updates and enhancements. Abstract. In this work crystallographic texture for a set of rail wheel steel samples with different regimes of thermo-mechanical treatment and with and without modification by system Al-Mg-SiFe-C-Ca-Ti-Ce was measured by neutron diffraction. The texture measurements were carried out by using time-of-flight technique at SKAT diffractometer situated at IBR-2 reactor (Dubna, JINR, Russia). The three complete pole figures (110), (200), (211) of α-Fe phase in 5˚×5˚grid were extracted from a set of 1368 spectra measured for each sample. The samples were cut from rail wheel rim and from transitional zone (between rail wheel hub and wheel disk). It was concluded that the steel modification and some changes in the heat treatment modes of the rail wheels from the experimental (modified) and the conventional (non-modified) steel lead to reorientation of texture component. IntroductionSolid-rolled wheels for railway rolling stock are being currently produced by about fifteen industrial enterprises in different countries (Belgium, the Czech Republic, France, Russia, Ukraine, etc.). According to Railway Wheels and Wheelsets Committee (ERWA), global demand for wheels is about 4.8 million units per year. Passenger rolling stock market in Europe increases annually by 3% (according to the International Union of Railways). It is need about 500 kg of steel to make one rail wheel. The price of a steel increased since 2004 to 2010 by 100 -120%. The rising of a steel price leads to increasing of wheels price. Therefore, the important task for operating companies becomes to prolong life of wheels, and for producers of wheels is to use the most efficient ways of high-quality metal production. That is why the study of a rail wheel steel quality is urgent from both scientific and practical sides. One way to improve the quality of the wheels is a modification of the molten steel. The modification is admixture of small amounts of additives to modify the properties of alloy through a change its microstructure (grains size, grains shape) and prefered orientations, i.e. texture. The modifiers admixture result in grain refinement. Besides, the additional atoms incorporated into crystal lattice leads to its distortion. This process could result in the blocking of dislocations and consequently to alloy hardening. The final operational properties of the wheels depend on several factors, namely the chemical composition, the macro-and microstructure and also the crystallographic texture of the steel. The production technology of the rail wheels includes such operations as forging, press forming and rolling that can result in texture formation. The subsequent temperature treatment (annealing, quenching and tempering for rim) can also influence texture changing. The crystallographic texture can result in brittle cracking in steel products [1][2][3], so it can be one of the rail wheels damage reasons. The aim of this work is to study the impact of the modification and the thermo-mechanical treatmen...

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