Optimization of modes of plasma treatment crane rails

Abstract

Crane operation is accompanied with wear and tear of rails and crane wheels. Actual direction is the renovation and improvement of efficiency of these parts. Modern technologies of restoration of wheels and rails provide surface deposition or treatment with high-frequency currents. A promising direction is a surface treatment of highly concentrated streams of energy: with a laser beam, plasma jet. It is proposed to increase the efficiency of crane rails of surface plasma treatment. The work was carried out on the selection of treatment regimens. Simulation of the thermal impact of the plasma jet on a solid body of a complex shape was performed. Defined were multiple ranges of plasma hardening regimes that meet the requirements of production. The structural transformation of the material in the crane rails plasma treatment was investigated. It is concluded that in carbon and low alloy crane steels plasma exposure zone is characterized by a high degree of dispersion hardened structure and higher toughness as compared to the quenching with high-frequency current. Both shift (within the upper zone of plasma influence) are realized, and fluctuation (in the lower zone of the plasma effect) mechanisms of phase transformations. With high-speed plasma heating is a major transformation of granular or lamellar pearlite into austenite. The level of operational properties of hardened steel, which is achieved in this case is determined by the kinetics of the completeness and pearlite → austenite transformation. For carbon and low alloy rail steels plasma hardening of achievable properties can effectively replace the bulk hardening, hardening by high-frequency, or surface deposition. The range of conditions for plasma treatment was determined which allows to obtain a surface layer with a certain performance properties.