Laser surfacing of hardening stelite coatings on the blades of steam turbines for repair and protection against vapor-droplet erosion

As the steam cools during the operation of the turbine, water drops are condensed in it. Steam turbine blades are attacked by these droplets, leading to vapor-droplet erosion. Soldering of the stellite plates was considered a common method of protecting the blades, but this solution has serious drawbacks. First, the use of soldered plates reduces the efficiency of the turbine due to the distortion of the geometry of the blades and their unnecessary weighting. Secondly, the soldered blades tend to premature detachment, and the escaping plates can damage other blades. In addition, the loss of the plates worsens the balancing of the turbine.
JSC Plakart uses stellite laser welding both for protection against wear of new blades and for repairing damaged ones. Of course, surfacing stellite new, specially designed for this blade, gives much more advantages. Since the laser deposited stellite hardly mixes with the base, the surfacing layer is made much thinner than the plate, which reduces the weight and improves the aerodynamics of the blade.
When repairing, the stellite plates are removed, in their place a layer of stellitic coating is deposited. At the same time, the repair of the blade, on which the stellite plates were previously installed, is usually more complicated than the surfacing of a new blade, and therefore requires high costs. Repair of blades with a deposited stellite layer is usually not required, since the life of a thin layer of stellite is longer than the resource of the blade.