Надійність залізничних коліс, виготовлених різними способами виробництва

• Datum: 2023
• Hauptverfasser: Бабаченко, О.І., Кононенко, Г.А., Подольский, Р.В., Дементьєва, Ж.А., Шпак, О.А., Клинова, О.П.
• Format: Artikel
• Sprache: Ukrainisch
• Veröffentlicht: Physico-technological Institute of Metals and Alloys 2023
• Schlagworte: залізничне колесо; неметалеві включення; інтенсивність напружень; механічні властивості; мікроструктура
• Online Zugang: https://www.metalsandcasting.com/index.php/mcu/article/view/154
• Назва журналу: Metal and Casting of Ukraine

Different indicators of reliability of cast and solid rolled railway wheels are investigated. It has been found that cast wheels (class C by AAR M-107/M-208), having high values of strength characteristics (temporary resistance and hardness), on such important reliability indicators as relative reduction, relative elongation, impact strength and fracture toughness considerably inferior to solid rolled railway wheels (mark T and 2 according to DSTU GOST 10791: 2016), while the level of relative elongation, impact strength and viscosity of casting wheels do not meet the requirements of DSTU GOST 10791: 2016. It has been established, that the presence of a large number of large nonmetallic inclusions of an unfavorable (tapeworm) shape can lead to a crack, which, in combination with cast, directed structure at the intersection of railway wheels, contributes to the spread of the resulting cracks. From the position of fracture mechanics, nonmetallic inclusions are stress concentrators, such as microcracks. The maximum tension at the top of the tape or eutectic sulfide inclusion which is characteristic of a cast wheel, whose length is about 0.05 mm, at a thickness of 0.005 mm at a tension in the wheel rim of 500 MPa can reach values of about 3200 N/mm3/2, which exceeds the allowable level of stress intensity factor for these wheels by 2 times. Solid rolled wheel is characterized by a dense homogeneous macrostructure; the microstructure of the whole wheel is uniform, and nonmetallic inclusions have a rounded shape. Also low values of impact strength, which characterizes the ability of the material to absorb mechanical energy in the process of deformation and fracture under the action of shock load, especially at minus temperatures, increase the likelihood of uncontrolled destruction of products during operation. It has been established that at lower temperatures the cast wheel has a value of impact strength a few times lower than the solid rolled wheels. Determining the scope of the possible use of cast wheels requires further research.