METHOD OF TREATMENT, TURBINE COMPONENT, AND TURBINE SYSTEM

A method of treatment includes laser-hardening a portion of a component and texturing a treated surface of the portion with a hydrophobic surface texture. In some embodiments, the method includes polishing the treated surface after laser-hardening the portion and prior to texturing the treated surface. A component includes a component body having a portion that is laser-hardened. The treated surface is hydrophobic with a hydrophobic surface texture. In some embodiments, the component is a turbine component. In some embodiments, the portion is a leading edge. A turbine system includes a turbine shaft and a turbine component attached to the turbine shaft. The turbine component includes a component body having a leading edge. The leading edge is laser-hardened and the treated surface of the leading edge is hydrophobic with a hydrophobic surface texture.

FIELD OF THE INVENTION

The present invention is directed to methods for treating components and treated components. More specifically, the present invention is directed to methods for laser treating components and laser-treated components.

BACKGROUND OF THE INVENTION

Gas turbines are often subjected to harsh operating conditions and prolonged operation times, leading to oxidation and corrosion wear of gas turbine components. For gas turbine compressor rotor blades, these factors cause surface finish degradation, adversely affecting the aerodynamic performance of the blades by increasing the coefficient of drag (CD), resulting in reduced performance.

Compressor blades made of precipitation hardened steels and martensitic steels undergo leading edge erosion and corrosion, either as a result of wet compression during operation or as a result of water wash or other forms of corrosion from the atmosphere during service. Both leading edge erosion and corrosion tend to reduce the performance of compression blade very significantly.

Usually during major inspections, which are conducted at predetermined intervals, the rotor blades and stator vanes are manually scrubbed and/or cleaned to partially restore the surface finish of the blades and vanes. The scrubbing and/or cleaning of the rotor blades and vanes improve the surface finish, partially restoring gas turbine output and efficiency.

Manual scrubbing and/or cleaning of the rotor blades is a time-consuming process which results in a less than optimal surface finish on the blade. An alternative to manual scrubbing and/or cleaning of the rotor blades is electro-polishing of the rotor blades.

Electro-polishing of the rotor blades provides an improved surface finish to the blade in comparison to manual scrubbing. However, current electro-polishing practices require disassembly and/or transportation of the gas turbine. Disassembly and transportation increase the gas turbine downtime, resulting in lost productivity. Downtime for transportation of the gas turbine can be up to two months.

Steam turbines extract work from a flow of steam to generate power by converting the energy of high-temperature, high-pressure steam generated by a boiler into rotational energy by supplying the steam to cascades of stationary blades (nozzles) and moving blades (buckets). A typical steam turbine may include a rotor associated with a number of wheels. The wheels may be spaced apart from each other along the length of the rotor to define a series of turbine stages. The turbine stages are designed to extract useful work from the steam traveling on a flow path from an entrance to an exit of the turbine in an efficient manner. As the steam travels along the flow path, the steam causes the buckets to drive the rotor. The steam gradually may expand and the temperature and pressure of the steam gradually may decrease. The steam then may be exhausted from the exit of the turbine for reuse or otherwise. Higher temperature steam turbines may generate increased output as the increased temperature of the steam increases the overall energy available for extraction.

As the pressure and temperature change, the steam becomes wet. As the steam flows through the turbine stages of buckets and nozzles, moisture contained in the steam condenses into fine water droplets on turbine surfaces. The water on the component surfaces may lead to corrosion of the surfaces. These fine water droplets combine into coarse water droplets, which are scattered by the steam flow and collide with downstream components. The collisions damp the torque of the buckets through high speed impacts and thus decrease the total performance of the turbine. The coarse water droplets cause erosion of downstream component surfaces, which decreases the aerodynamic performance and section thickness of the components and thus shortens their useful lifespan.

BRIEF DESCRIPTION OF THE INVENTION

In an embodiment, a method of treatment includes laser-hardening a portion of a component and texturing a treated surface of the portion with a hydrophobic surface texture.

In another embodiment, a component includes a component body having a portion. The portion is laser-hardened. The treated surface of the portion is hydrophobic with a hydrophobic surface texture.

In another embodiment, a turbine system includes a turbine shaft and a turbine component attached to the turbine shaft. The turbine component includes a component body having a leading edge. The leading edge is laser-hardened and the treated surface of the leading edge is hydrophobic with a hydrophobic surface texture.

DETAILED DESCRIPTION OF THE INVENTION

Provided is a method of laser treating a component and a laser-treated component having superior erosion and corrosion resistance.

Embodiments of the present disclosure, for example, in comparison to concepts failing to include one or more of the features disclosed herein, increase the surface hardness of a component, increase the hydrophobicity of a component, reduce or prevent droplet erosion during service operations, reduce or prevent water interaction with the component, reduce or prevent corrosion of the component, increase the longevity of the component without pitting, enhance the performance of the component, increase the efficiency of the component, or combinations thereof.

In some embodiments, the laser-treated component includes a turbine component of a gas turbine or a steam turbine, which may include, but is not limited to, a gas turbine compressor blade, a gas turbine rear stage compressor blade, a gas turbine blade, a steam turbine bucket, a steam turbine nozzle, or a steam turbine casing. In preferred embodiments, the laser-treated item has a laser-hardened leading edge and a hydrophobic surface on the leading edge that is textured. In some embodiments, the turbine component is a new component that has not previously been in service in a turbine. In other embodiments, the turbine component is a used component that has previously been in service in a turbine. In some such embodiments, the treated turbine component is refurbished by the method of treatment.

FIG. 1shows a gas turbine100with a compressor section105, a combustion section130, and a turbine section150. The compressor section105includes rotating compressor blades110and non-rotating compressor vanes115structured to compress a fluid. The compressor section105may also include a compressor discharge casing125. The combustion section130includes combustion cans135, fuel nozzles140, and transition sections145. Within each of the combustion cans135, compressed air is received from the compressor section105and mixed with fuel received from a fuel source. The mixture is ignited and creates a working fluid. The working fluid generally flows downstream from the aft end of the fuel nozzles140, downstream through the transition section145, and into the turbine section150. The turbine section150includes rotating components155and stationary components160. The turbine section150converts the energy of the working fluid to a mechanical torque.

Referring toFIG. 1andFIG. 2, a compressor blade110and a compressor vane115each has a portion10that is the leading edge that has been laser hardened and includes a hydrophobic surface texture12on the treated surface14of the portion10. AlthoughFIG. 1andFIG. 2show one compressor blade110and one compressor vane115with a laser-hardened portion10with a treated surface14having a hydrophobic surface texture12, any number of the compressor blades110and the compressor vanes115may have a laser-hardened portion10having a treated surface14with a hydrophobic surface texture12within the spirit of the present invention.

FIG. 3shows a steam turbine system200with a turbine rotor201that is mounted rotatably about an axis of rotation203. The steam turbine system200includes a high pressure (HP) section205, an intermediate pressure (IP) section207, and a low pressure (LP) section209, each mounted on the rotor201. WhileFIG. 3shows one arrangement of the HP section205, the IP section207, and the LP section209, the present disclosure is not so limited; any suitable arrangement of the HP section205, the IP section207, and/or the LP section209may be utilized. Each of the HP section205, the IP section207, and the LP section209includes blades or buckets231(seeFIG. 4) that are circumferentially mounted on the rotor201in casings210,220,230in each of the HP section205, the IP section207, and the LP section209, respectively. The buckets231are driven by steam fed to the respective section, where the rotation of the buckets231resulting from the steam generates mechanical work. The mechanical work produced in the turbine system200drives an external load204, such as an electrical generator, via the rotor201.

As shown inFIG. 3, high pressure steam is fed via high pressure steam inlets211. The steam is exhausted from the HP section205at a high pressure steam outlet213and fed to a reheater215, in which heat is added to the steam. From the reheater215, the steam is fed to the IP section207via an intermediate pressure steam inlet217. The steam is exhausted from the IP section207at an intermediate pressure steam outlet219and fed to the LP section209via a low pressure steam inlet221. The steam is then exhausted from the LP section209via low pressure outlets223.

Each of the HP section205, the IP section207, and the LP section209are connected along the rotor201via couplings225. The couplings225may be mechanical couplings, such as bolted joints, or they may be welded joints. In one embodiment, the couplings225permit detachment of any of the HP section205, the IP section207, and/or the LP section209for reconfiguration, service, or maintenance.

Referring toFIG. 4, a section of the steam turbine system includes the turbine rotor201implanted circumferentially with buckets231and the casing230supporting nozzles233. The buckets231and the nozzles233are arranged in stages in the axial direction of the turbine rotor201. Generally, the buckets231, casing230, and nozzles233are constructed from suitable known turbine bucket, casing, and nozzle materials, including, but not limited to, steel, stainless steel, precipitation-hardened stainless steel, aluminum, titanium, alloys thereof, or combinations thereof.

A bucket231and a nozzle233each has a portion10that is a leading edge that has been laser hardened and includes a hydrophobic surface texture12on the treated surface14of the leading edge10.

As shown inFIG. 5, a method of treatment includes laser-hardening22a portion10of a component16and laser etching26a treated surface14of the portion10with a hydrophobic surface texture12. In some embodiments, the component16is a turbine component. In some embodiments, the portion10is a leading edge of the component16. The turbine component16may be any turbine component16exposed to a corrosive or an erosive environment, including, but not limited to, a compressor blade110, a gas turbine blade, a compressor vane115, a gas turbine blade, a casing230, a bucket231, or a nozzle233. The method of treatment preferably also includes polishing24the treated surface14of the portion10after laser-hardening22the portion10and prior to laser etching26the treated surface14of the portion10.

Laser hardening22, as used herein, is a process of heating the outer layer of a material to just below its melting temperature with a laser beam and then moving the laser beam around the heated surface to harden the surface.

In some embodiments, the laser hardening22includes heating the outer layer of a material to just below its melting temperature with a laser beam and then moving the laser beam around the heated surface to convert locally from an austenitic state to a martensitic state. When the laser beam moves away from an area of the heated layer in the martensitic state, the heated layer cools very rapidly, by self-quenching with surrounding material, to remain in the martensitic state, thereby forming a hard surface layer at the treated surface12. The depth of the hardening depends on the composition of the material and the strength of the laser. The hardening depth is in the range of about 0.1 mm to about 2.5 mm, alternatively about 0.1 mm to about 1.5 mm, alternatively about 0.3 mm to about 2 mm, alternatively about 1 mm to about 2 mm, or any suitable combination, sub-combination, range, or sub-range thereof. The hardness of the laser-hardened portion10is preferably in the range of about 2 to about 3 times greater than the bulk hardness of the component16.

A hydrophobic surface, as used herein, is a surface having a water contact angle greater than 90 degrees. The water contact angle, as used herein, is the angle, as measured through the water, where the water/air interface of a drop of water meets the solid surface. The water contact angle resulting from the hydrophobic surface texture12is greater than 90 degrees, alternatively greater than 100 degrees, alternatively greater than 110 degrees, alternatively greater than 120 degrees, alternatively greater than 130 degrees, alternatively greater than 140 degrees, alternatively greater than 150 degrees, alternatively in the range of 90 to 170 degrees, alternatively in the range of 100 to 160 degrees, alternatively in the range of 120 to 160 degrees, or any suitable combination, sub-combination, range, or sub-range thereof.

A superhydrophobic surface, as used herein, is a surface having a water contact angle greater than 135 degrees. The water contact angle resulting from the superhydrophobic surface texture12is greater than 135 degrees, alternatively greater than 140 degrees, alternatively greater than 150 degrees, alternatively greater than 160 degrees, alternatively in the range of 135 to 170 degrees, alternatively in the range of 140 to 170 degrees, alternatively in the range of 150 to 170 degrees, alternatively in the range of 160 to 170 degrees, or any suitable combination, sub-combination, range, or sub-range thereof. In some embodiments, the superhydrophobic surface texture12has a roll-off angle/contact angle hysteresis less than 10°. The roll-off angle, as used herein, is the angle of inclination of the surface at which the water drop rolls off the surface.

A hydrophobic surface texture12, as used herein, is any surface texture formed in the surface of a material that changes the topography of the surface to increase the hydrophobicity of the surface such that the treated surface14with the hydrophobic surface texture12is hydrophobic. The changes to the topography may include, but are not limited to, indentations, protrusions, cavities, grooves, ridges, spheres, or rods. In some embodiments, the topography change is a micro-scale change. In some embodiments, the topography change is a nano-scale change. Any method capable of producing a hydrophobic surface texture12may be implemented to change the topography of the surface within the spirit of the present invention. In some embodiments, the treated surface14with the hydrophobic surface texture12is superhydrophobic.

The hydrophobic surface texture12may be formed by any method capable of laser etching26a texture12on the surface at the portion10of the component16to make the surface hydrophobic or more hydrophobic than without the hydrophobic surface texture12. In some embodiments, the hydrophobic surface texture12makes the surface superhydrophobic. In some embodiments, the laser used to laser etch26the hydrophobic surface texture12is a femtosecond laser, also known as a femto laser. In some embodiments, the femtosecond laser forms a three-dimensional texture by laser etching26the surface with high-energy femtosecond-long laser pulses. The laser-etched texture12may have a texturing in the micrometer to nanometer size range.

In some embodiments, the laser etching26creates one or more indentations in a treated surface14that have a micro-rough surface of protrusions, cavities, spheres, rods, or other regularly or irregularly shaped features that increases the hydrophobicity of the treated surface14. The micro-rough features have dimensions in the range of 0.5 to 100 microns, alternatively in the range of 25 to 75 microns, alternatively in the range of 40 to 60 microns, or any suitable combination, sub-combination, range, or sub-range thereof. In other embodiments, the laser etching26creates one or more indentations in the treated surface14that have a nano-rough surface of protrusions, cavities, spheres, rods, or other irregularly-shaped features that increases the hydrophobicity of the treated surface. The nano-rough features have dimensions in the range of 1 to 500 nanometers, alternatively in the range of 100 to 400 nanometers, alternatively in the range of 200 to 300 nanometers, or any suitable combination, sub-combination, range, or sub-range thereof.

In some embodiments, laser etching is accomplished by direct laser ablation, interferometric laser ablation, near-field laser ablation, mask-projection ablation, laser-assisted chemical etching, deposition from a laser ablation plume, or plasmonic nanoablation. In some embodiments, the laser etching26is accomplished using femtosecond duration laser pulses. A femtosecond duration laser pulse, as used herein, is any laser pulse having a duration in the range of 1 to 999 femtoseconds. The laser pulse has a duration in the range of 1 to 999 femtoseconds, alternatively in the range of 100 to 750 femtoseconds, alternatively in the range of 400 to 600 femtoseconds, or any suitable combination, sub-combination, range, or sub-range thereof.

The hydrophobic surface texture12created by the laser etching26may be any regular or irregular texture12that makes the treated surface14hydrophobic or more hydrophobic. In some embodiments, the hydrophobic surface texture12created by the laser etching26makes the treated surface14superhydrophobic. The hydrophobic surface texture12preferably deters water vapor from condensing on the treated surface14and preferably deters water droplets from sticking onto the treated surface14.

In some embodiments, the portion of the component16treated by the laser hardening22is made of an iron-based alloy, which may include, but is not limited to, a martensitic steel, a martensitic stainless steel, or a pressure hardened steel, or a cobalt-based material, which may include, but is not limited to, FSX-414, L-605, or Stellite® 6 (Kennametal Inc., Latrobe, Pa.). In some embodiments, the portion of the component16treated by the laser hardening22may be made of any material capable of being converted to a martensitic state or of undergoing a surface microstructure modification by the laser.

As used herein, “FSX-414” refers to an alloy including a cobalt-based carbide-hardened composition, by weight, of about 29% chromium, about 7% tungsten, about 10% nickel, about 0.25% carbon, and a balance of cobalt.

As used herein, “L-605” refers to an alloy including a cobalt-based carbide-hardened composition, by weight, of about 55% cobalt, about 20% chromium, about 15% tungsten, about 10% nickel, about 0.1% carbon, and a balance of cobalt.

As used herein, “ASTROLOY” refers to an alloy including a composition, by weight, of about 15% chromium, about 17% cobalt, about 5.3% molybdenum, about 4% aluminum, about 3.5% titanium, and a balance of nickel.

As used herein, “DS Siemet” refers to an alloy including a composition, by weight, of about 9% cobalt, about 12.1% chromium, about 3.6% aluminum, about 4% titanium, about 5.2% tantalum, about 3.7% tungsten, about 1.8% molybdenum, and a balance of nickel.

As used herein, “GTD111” refers to an alloy including a composition, by weight, of about 14% chromium, about 9.5% cobalt, about 3.8% tungsten, about 4.9% titanium, about 3% aluminum, about 0.1% iron, about 2.8% tantalum, about 1.6% molybdenum, about 0.1% carbon, and a balance of nickel.

As used herein, “GTD262” refers to an alloy including a composition, by weight, of about 22.5% chromium, about 19% cobalt, about 2% tungsten, about 1.35% niobium, about 2.3% titanium, about 1.7% aluminum, about 0.1% carbon, and a balance of nickel.

As used herein, “GTD444” refers to an alloy including a composition, by weight, of about 7.5% cobalt, about 0.2% iron, about 9.75% chromium, about 4.2% aluminum, about 3.5% titanium, about 4.8% tantalum, about 6% tungsten, about 1.5% molybdenum, about 0.5% niobium, about 0.2% silicon, about 0.15% hafnium, and a balance of nickel.

As used herein, “MGA1400” refers to an alloy including a composition, by weight, of about 10% cobalt, about 14% chromium, about 4% aluminum, about 2.7% titanium, about 4.7% tantalum, about 4.3% tungsten, about 1.5% molybdenum, about 0.1% carbon, and a balance of nickel.

As used herein, “MGA2400” refers to an alloy including a composition, by weight, of about 19% cobalt, about 19% chromium, about 1.9% aluminum, about 3.7% titanium, about 1.4% tantalum, about 6% tungsten, about 1% niobium, about 0.1% carbon, and a balance of nickel.

As used herein, “PWA1480” refers to an alloy including a composition, by weight, of about 10% chromium, about 5% cobalt, about 5% aluminum, about 1.5% titanium, about 12% tantalum, about 4% tungsten, and a balance of nickel.

As used herein, “PWA1483” refers to an alloy including a composition, by weight, of about 9% cobalt, about 12.2% chromium, about 3.6% aluminum, about 4.1% titanium, about 5% tantalum, about 3.8% tungsten, about 1.9% molybdenum, and a balance of nickel.

As used herein, “PWA1484” refers to an alloy including a composition, by weight, of about 5% chromium, about 10% cobalt, about 2% molybdenum, about 5.6% aluminum, about 9% tantalum, about 6% tungsten, and a balance of nickel.

As used herein, “René N2” refers to an alloy including a composition, by weight, of about 7.5% cobalt, about 13% chromium, about 6.6% aluminum, about 5% tantalum, about 3.8% tungsten, about 1.6% rhenium, about 0.15% hafnium, and a balance of nickel.

As used herein, “René N4” refers to an alloy including a composition, by weight, of about 9.75% chromium, about 7.5% cobalt, about 4.2% aluminum, about 3.5% titanium, about 1.5% molybdenum, about 6.0% tungsten, about 4.8% tantalum, about 0.5% niobium, about 0.15% hafnium, and a balance of nickel.

As used herein, “René N5” refers to an alloy including a composition, by weight, of about 7.5% cobalt, about 7.0% chromium, about 6.5% tantalum, about 6.2% aluminum, about 5.0% tungsten, about 3.0% rhenium, about 1.5% molybdenum, about 0.15% hafnium, and a balance of nickel.

As used herein, “René N6” refers to an alloy including a composition, by weight, of about 12.5% cobalt, about 4.2% chromium, about 7.2% tantalum, about 5.75% aluminum, about 6% tungsten, about 5.4% rhenium, about 1.4% molybdenum, about 0.15% hafnium, and a balance of nickel.

As used herein, “René 65” refers to an alloy including a composition, by weight, of about 13% cobalt, up to about 1.2% iron, about 16% chromium, about 2.1% aluminum, about 3.75% titanium, about 4% tungsten, about 4% molybdenum, about 0.7% niobium, up to about 0.15% manganese, and a balance of nickel.

As used herein, “René 77” refers to an alloy including a composition, by weight, of about 15% chromium, about 17% cobalt, about 5.3% molybdenum, about 3.35% titanium, about 4.2% aluminum, and a balance of nickel.

As used herein, “René 80” refers to an alloy including a composition, by weight, of about 14% chromium, about 9.5% cobalt, about 4% molybdenum, about 3% aluminum, about 5% titanium, about 4% tungsten, about 0.17% carbon, and a balance of nickel.

As used herein, “René 88DT” refers to an alloy including a composition, by weight, of about 16% chromium, about 13% cobalt, about 4% molybdenum, about 0.7% niobium, about 2.1% aluminum, about 3.7% titanium, about 4% tungsten, about 0.1% rhenium, a maximum of about 4.3% rhenium and tungsten, and a balance of nickel.

As used herein, “René 104” refers to an alloy including a composition, by weight, of about 13.1% chromium, about 18.2% cobalt, about 3.8% molybdenum, about 1.9% tungsten, about 1.4% niobium, about 3.5% aluminum, about 3.5% titanium, about 2.7% tantalum, and a balance of nickel.

As used herein, “René 108” refers to an alloy including a composition, by weight, of about 8.4% chromium, about 9.5% cobalt, about 5.5% aluminum, about 0.7% titanium, about 9.5% tungsten, about 0.5% molybdenum, about 3% tantalum, about 1.5% hafnium, and a balance of nickel.

As used herein, “René 125” refers to an alloy including a composition, by weight, of about 8.5% chromium, about 10% cobalt, about 4.8% aluminum, up to about 2.5% titanium, about 8% tungsten, up to about 2% molybdenum, about 3.8% tantalum, about 1.4% hafnium, about 0.11% carbon, and a balance of nickel.

As used herein, “René 142” refers to an alloy including a composition, by weight, of about 6.8% chromium, about 12% cobalt, about 6.1% aluminum, about 4.9% tungsten, about 1.5% molybdenum, about 2.8% rhenium, about 6.4% tantalum, about 1.5% hafnium, and a balance of nickel.

As used herein, “René 195” refers to an alloy including a composition, by weight, of about 7.6% chromium, about 3.1% cobalt, about 7.8% aluminum, about 5.5% tantalum, about 0.1% molybdenum, about 3.9% tungsten, about 1.7% rhenium, about 0.15% hafnium, and a balance of nickel.

As used herein, “René N500” refers to an alloy including a composition, by weight, of about 7.5% cobalt, about 0.2% iron, about 6% chromium, about 6.25% aluminum, about 6.5% tantalum, about 6.25% tungsten, about 1.5% molybdenum, about 0.15% hafnium, and a balance of nickel.

As used herein, “René N515” refers to an alloy including a composition, by weight, of about 7.5% cobalt, about 0.2% iron, about 6% chromium, about 6.25% aluminum, about 6.5% tantalum, about 6.25% tungsten, about 2% molybdenum, about 0.1% niobium, about 1.5% rhenium, about 0.6% hafnium, and a balance of nickel.

As used herein, “CM247” refer to an alloy including a composition, by weight, of about 5.5% aluminum, about 0.15% carbon, about 8.25% chromium, about 10% cobalt, about 10% tungsten, about 0.7% molybdenum, about 0.5% iron, about 1% titanium, about 3% tantalum, about 1.5% hafnium, and a balance of nickel.

As used herein, “IN100” refers to an alloy including a composition, by weight, of about 10% chromium, about 15% cobalt, about 3% molybdenum, about 4.7% titanium, about 5.5% aluminum, about 0.18% carbon, and a balance of nickel.

As used herein, “INCONEL 700” refers to an alloy including a composition, by weight, of up to about 0.12% carbon, about 15% chromium, about 28.5% cobalt, about 3.75% molybdenum, about 2.2% titanium, about 3% aluminum, about 0.7% iron, up to about 0.3% silicon, up to about 0.1% manganese, and a balance of nickel.

As used herein, “INCONEL 738” refers to an alloy including a composition, by weight, of about 0.17% carbon, about 16% chromium, about 8.5% cobalt, about 1.75% molybdenum, about 2.6% tungsten, about 3.4% titanium, about 3.4% aluminum, about 0.1% zirconium, about 2% niobium, and a balance of nickel.

As used herein, “INCONEL 792” refers to an alloy including a composition, by weight, of about 12.4% chromium, about 9% cobalt, about 1.9% molybdenum, about 3.8% tungsten, about 3.9% tantalum, about 3.1% aluminum, about 4.5% titanium, about 0.12% carbon, about 0.1% zirconium, and a balance of nickel.

As used herein, “UDIMET 500” refers to an alloy including a composition, by weight, of about 18.5% chromium, about 18.5% cobalt, about 4% molybdenum, about 3% titanium, about 3% aluminum, and a balance of nickel.

As used herein, “Mar-M-200” refers to an alloy including a composition, by weight, of about 9% chromium, about 10% cobalt, about 12.5% tungsten, about 1% niobium, about 5% aluminum, about 2% titanium, about 10.14% carbon, about 1.8% hafnium, and a balance of nickel.

As used herein, “TMS-75” refers to an alloy including a composition, by weight, of about 3% chromium, about 12% cobalt, about 2% molybdenum, about 6% tungsten, about 6% aluminum, about 6% tantalum, about 5% rhenium, about 0.1% hafnium, and a balance of nickel.

As used herein, “TMS-82” refers to an alloy including a composition, by weight, of about 4.9% chromium, about 7.8% cobalt, about 1.9% molybdenum, about 2.4% rhenium, about 8.7% tungsten, about 5.3% aluminum, about 0.5% titanium, about 6% tantalum, about 0.1% hafnium, and a balance of nickel.

As used herein, “CMSX-4” refers to an alloy including a composition, by weight, of about 6.4% chromium, about 9.6% cobalt, about 0.6% molybdenum, about 6.4% tungsten, about 5.6% aluminum, about 1.0% titanium, about 6.5% tantalum, about 3% rhenium, about 0.1% hafnium, and a balance of nickel.

As used herein, “CMSX-10” refers to an alloy including a composition, by weight, of about 2% chromium, about 3% cobalt, about 0.4% molybdenum, about 5% tungsten, about 5.7% aluminum, about 0.2% titanium, about 8% tantalum, about 6% rhenium, and a balance of nickel.

In some embodiments, a carbon dioxide laser is used for the laser hardening22. In other embodiments, a high power direct diode laser is used for the laser hardening22. The high power direct diode laser has a power of at least 1 kW, alternatively 1-20 kW, alternatively 2-6 kW, or any suitable combination, sub-combination, range, or sub-range thereof.

The laser-hardened portion10of the turbine component16preferably includes the leading edge of the component. A leading edge, as used herein, is the upstream edge of the component with respect to the direction of flow in the turbine, which is the first portion contacted by the flowstream. The laser hardening22of the leading edge portion10of the turbine component16preferably increases the erosion resistance of the turbine component16in comparison to the corrosion resistance of the turbine component16prior to the laser hardening22.

After the leading edge portion10of the turbine component16has been laser-hardened22, at least a portion of the leading edge portion10is preferably polished24before being laser etched26to increase the hydrophobicity of the treated surface14at the leading edge portion10. In some embodiments, the polishing24includes fine grinding and polishing of the leading edge portion10to a surface roughness (Ra) less than about 0.5 microns, alternatively less than about 1.0 microns, alternatively less than about 0.3 microns, alternatively in the range of 0.4-0.6 microns, alternatively in the range of 0.3-1.0 microns, alternatively in the range of 0.3-0.5 microns, alternatively in the range of 0.5-1 microns, or any suitable combination, sub-combination, range, or sub-range thereof.

The laser etching26on the leading edge portion10increases the corrosion resistance of the turbine component16in comparison to the corrosion resistance of the turbine component16prior to the laser etching26. When used in combination, the laser hardening22of the leading edge portion10of the turbine component16followed by the laser etching26on the laser-hardened surface provides increased erosion resistance and corrosion resistance of the turbine component16in comparison to the properties of the turbine component16prior to the process.

When used in combination, the laser hardening22of a portion10of a component16followed by the laser etching26on the laser-hardened surface provides increased erosion resistance and corrosion resistance of the component16in comparison to the properties of the component16prior to the process.

In certain embodiments, the hydrophobic surface texture12on the treated surface14of the turbine component16is textured such that any water droplets that form on and are released by the turbine component16are less than a predetermined size to minimize or eliminate erosion downstream by the water droplets impacting a downstream turbine component16. The predetermined size may be 200 microns, alternatively 150 microns, alternatively 100 microns, or any suitable combination, sub-combination, range, or sub-range thereof. In a preferred embodiment, the predetermined size is the critical size, below which a water droplet does not cause any downstream erosion by impact. Although this critical size depends upon the operating conditions of the turbine, it is usually in the range of 100 to 200 microns.

The laser etching26to prevent the release of droplets larger than a predetermined size may be accomplished in any of a number of different ways. In some embodiments, the laser etching26provides a degree of hydrophobicity and an area of surface coverage that inhibit water vapor condensing and coalescing to a degree such that any water vapor condensing and coalescing on the surface releases from the surface before reaching the predetermined size. In other embodiments, the laser texturing provides patterns of areas of varying hydrophobicity on the surface to direct the condensing and coalescing water along the surface in a controlled direction and manner that prevents sufficient coalescence of water to reach the predetermined size before the water droplet is released.

Although the process has been described primarily for a turbine component16, the process may be applied to any component16capable of undergoing laser hardening, laser texturing, or laser hardening and laser texturing and located in a system where erosion, corrosion, or erosion and corrosion are issues.

While the invention has been described with reference to one or more embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims. In addition, all numerical values identified in the detailed description shall be interpreted as though the precise and approximate values are both expressly identified.