RU2318121C1 - Method of strengthening surface of steam turbine blade - Google Patents

Abstract

FIELD: power engineering.

SUBSTANCE: method comprises setting at least one protecting lining on the surface of the blade, shaping the end parts of each lining set on the surface of the blade, riveting the surface of each lining, and coating the surface with the erosion proof material by means of electric spark alloying.

EFFECT: enhanced strength.

Description

The invention relates to steam turbine construction and can be used in wet-steam turbines in the manufacture and repair of the inlet and outlet edges of the blades subjected to erosion destruction or other types of operational damage.

A known method of hardening the surface of the working blades of a wet-steam stage of a steam turbine by installing on the surface subjected to erosion, the protective lining [1] - analogue. The disadvantages of the method [1] can be attributed, firstly, that it provides protection only for the frontal part of the blade, and secondly, the presence of the lining does not provide sufficient protection due to the lack of material for the manufacture of lining, which would be both inexpensive and durable thirdly, the installation of pads on the surface of the blade leads to a noticeable deterioration in its aerodynamic properties.

There is also known a method of hardening the surface of a working blade of a wet-steam stage of a steam turbine by installing on the surface subjected to erosion at least one protective lining, followed by applying by electrospark alloying a coating of erosion-resistant material over the lining and the adjacent boundary zone of the surface of the blade [2] is a prototype. Compared with the method [1], the method [2] allows to increase the wear resistance of the scapula due to the installation of overlays not only in its frontal, but also in the rear part of the root zone of the feather of the scapula, as well as by applying a coating of wear-resistant material over the overlays. In addition, the method [2] allows to slightly improve the aerodynamic properties of the blades by smoothing the protrusions between the edges of the plates and the surface of the blade not covered by the plates. However, this method improves the aerodynamic properties of the blades with the protective pads installed on it is not significant, and its wear resistance is still not high enough.

Achievable result of the invention is to improve the aerodynamic qualities of the working blades, equipped with protective pads and applied by electrospark alloying with a wear-resistant coating, as well as increasing the strength of these protective agents.

This result is ensured by the fact that in the method of hardening the surface of the working blade of a wet-steam stage of a steam turbine by installing on the surface subjected to erosion, at least one protective lining, followed by applying an electrospark alloying coating of erosion-resistant material over the lining and adjacent to him the boundary zone of the surface of the blade, according to the invention after installing the lining the edge sections of each lining adjacent to not covered by lining the surface of the blade is sampled according to the aerodynamic profile to its working surface, after which the surface of each patch is subjected to hardening, and the coating is applied after completion of the indicated operations, or after the specified sampling, the coating is applied first and then the surfaces of the pads are hardened over the applied coating.

Example 1. On a stainless steel turbine blade of a wet-steam turbine in the frontal part and the rear part of the root zone, protective plates of cobalt stellite of the VZK brand were soldered. Then, the edge sections of each patch adjacent to the surface of the blade not covered by the overlays were sampled according to the aerodynamic profile to its working surface, after which the surface of each patch was subjected to hardening, and then, by spark doping on the patch and the adjacent boundary zone of the blade surface with a width of 5. ..10 mm applied a protective coating. The tests of the working blade for 3 months in a humid-steam environment showed a complete absence of traces of erosion on its surface.

Example 2. On a stainless steel turbine blade of a wet-steam turbine in the frontal part and the back of the root zone, protective linings of cobalt stellite grade V3K were soldered. Then, the edge sections of each patch adjacent to the surface of the blade not covered by the overlays were sampled according to the aerodynamic profile to its working surface, after which a protective coating was applied to the covers and the adjacent boundary region of the surface of the blade with a width of 5 ... 10 mm. Then, the surface of each patch over the coating was subjected to hardening. The tests of the working blade for 3 months in a humid-steam environment showed a complete absence of traces of erosion

Information sources

1. USSR Copyright Certificate No. 1278469, 4 F01D 25/28, 1985.

2. Patent No. 52104 RU for utility model, F01D 5/28, 2005.

Claims (1)

The method of hardening the surface of the working blade of a wet-steam stage of a steam turbine by installing at least one protective lining on the surface subjected to erosion, followed by electrospark alloying of a coating of erosion-resistant material on top of the lining and the adjacent boundary area of the blade surface, characterized the fact that after installing the pads, the edge sections of each pads adjacent to the surface of the blade that are not covered by pads are subjected to aero sampling dynamic profile to its working surface, whereupon the surface of each pad is subjected to cold working, and the coating is applied after completion of such operations, or after said first sample is coated and then subjected to cold working surface overlays on top of the coating.