Strengthening of the working edges of the blades of steam turbines

Abstract

The working conditions of the blades of steam turbines require increased hardness of the input edges and resistance to impact erosion, high corrosion resistance. In order to increase the service life of the blades, the inlet edges are quenched by high-frequency currents. The hardened layer was formed by electrospark alloying with T15K6 alloy and 15X11MFSh steel. The use of the widely used T15K6 alloy as a hardened electrode is lim-ited due to the presence of cobalt, as an element forming, as a result of activation, long-lived isotopes that reduce the erosion resistance of the blades. Ultra high speed heating and cooling, pulsed effects of temperatures and pressures result lead to the fact that the composition of the alloyed layer can significantly differ from the composition of the starting materials. The micro-structure, microhardness, and thickness of the deposited layer were investigated. The hardened surface was monitored by external inspection, bending tests, microhardness measurements, and microstructure studies. The advantages of 15X11MFSh steel for hardening the input edges of the working blades of steam turbines are substantiated.