Comparative Analysis of Wheelsets Tyres, Hardened Using a Laser or Plasma Heat Source
Lateral wear of the locomotive wheel flange is one of the main types of wear that occurs during rolling stock operation. An important characteristic of a rail wheel rim is its wear resistance, which directly depends on the carbon content in steel. The carbon content in wheel steel of group 2 in the amount of 0,55-0,65 is due to the fact that at its lower concentration, the proportion of grain boundary ferrite increases, which leads to a decrease in the contact strength of wheels, and a higher one leads to a tendency to brittle fracture. The increased carbon content makes it possible to harden the surface of steel. Plasma and laser hardening technologies can be used to reduce tyre flange wear and increase the service life of locomotive wheelsets. The objective of this work is to determine advantages and disadvantages of technologies for laser and plasma hardening of working surfaces of tyres of wheelsets of railway rolling stock. The comparative analysis related to microstructure and microhardness of wheelsets tyres of the 2TE25KM diesel locomotive which are made of wheel steel of group 2 according to GOST 398-2010 state standard and hardened respectively by plasma and laser hardening. The tasks set were solved using theoretical and experimental research methods. The preparation and study of hardened samples was carried out using the equipment of the testing laboratory of LLC Scientific and Technical Association «IRE-Polus». A study referred to hardened zones in various areas and sections of the tyre. Tribological tests concerned wear resistance of specimens hardened with a high-power fiber laser. The main advantages and disadvantages of laser and plasma hardening processes are revealed. The conducted studies allow making a conclusion that the use of laser hardening technology for hardening wheelsets tyres, as an alternative to the plasma hardening process, is highly promising. The text of the article originally written in Russian is published in the first part of the issue.