Process of welding a turbine blade, a process of welding a non-uniform article, and a welded turbine blade

A process of welding an article and a welded turbine blade are disclosed. The process includes fusion welding over a primary symmetry line determined from a center of gravity on a first side of the article or blade and fusion welding over the primary symmetry line determined from the center of gravity on a second side of the article or blade. The fusion treating includes multiple fusion treatments.

FIELD OF THE INVENTION

The present invention is directed to processes of fabricating manufactured articles and a manufactured article. In particular, the present invention is directed to processes for fusion welding and a fusion welded article.

BACKGROUND OF THE INVENTION

The operating temperature within a gas turbine is both thermally and chemically hostile. Advances in high temperature capabilities have been achieved through the development of iron, nickel, and cobalt-based superalloys and the use of environmental coatings capable of protecting superalloys from oxidation, hot corrosion, etc.

In the compressor portion of a gas turbine, atmospheric air is compressed to 10-25 times atmospheric pressure, and adiabatically heated to 700° F.-1250° F. (371° C.-677° C.) in the process. This heated and compressed air is directed into a combustor, where it is mixed with fuel. The fuel is ignited, and the combustion process heats the gases to very high temperatures, in excess of 3000° F. (1650° C.). These hot gases pass through the turbine, where airfoils fixed to rotating turbine disks extract energy to drive an attached generator which produces electrical power. To improve the efficiency of operation of the turbine, combustion temperatures have been raised. Of course, as the combustion temperature is raised, steps must be taken to prevent thermal degradation of the materials forming the flow path for these hot gases of combustion.

Many hot gas path articles are fabricated using welding processes. It is desirable for weld joints in or around such articles to have increased operational properties such as crack resistance. Concentrated and non-distributing thermal and/or residual stress along such welds can result in decreased operational properties.

A process of fusion joining a non-uniform article, such as a turbine blade, to distribute thermal and/or residual stress and a non-uniform article having such features would be desirable in the art.

BRIEF DESCRIPTION OF THE INVENTION

In an exemplary embodiment, a process of welding a turbine blade includes fusion joining a suction side along a first path extending over a primary symmetry line determined from a center of gravity of the turbine blade and fusion joining a pressure side along a second path extending over the primary symmetry line determined from the center of gravity of the turbine blade. The fusion joining includes multiple fusion joining processes.

In another exemplary embodiment, a process of joining a non-uniform article includes fusion welding a first side along a first path extending over a primary symmetry line determined from a center of gravity of the non-uniform article, fusion welding a second side along a second path over the primary symmetry line determined from the center of gravity of the non-uniform article, the first side opposing the second side, and identifying the center of gravity by suspending the template of an exact cross section of the non-uniform article from a first point proximal to the first side and suspending the non-uniform article from a second point proximal to an edge extending between the first side and the second side. The fusion welding includes multiple fusion welding processes.

In another exemplary embodiment, a turbine blade includes a pressure side and a suction side, a first overlap fusion welding region on the pressure side extending over a primary symmetry line determined from a center of gravity of the turbine blade, and a second overlap fusion welded region on the suction side extending over the primary symmetry line determined from the center of gravity of the turbine blade. The first overlap fusion welding region and the second overlap fusion welding region are formed by multiple fusion welding processes.

DETAILED DESCRIPTION OF THE INVENTION

Provided is a joining process and a joined article having distributed thermal and/or residual stress along and near the joining region such as a weld, base metal adjacent to the weld. Embodiments of the present disclosure increase crack resistance, decrease crack propensity, increase crack resistance in areas of non-uniform geometry, increase crack resistance in thick sections of a work piece, reduce residual stresses in weld joints through offsetting of shrinkage forces, decrease distortion, decrease costs by reducing or eliminating the use of random welding trials, and combinations thereof.

Referring toFIG. 1, a welding sequence includes joining an article, such as a turbine blade100, along multiple paths, such as a first joining path102and a second joining path103shown inFIG. 1, along a perimeter, such as a circumference, to join the article. The first joining path102and the second joining path103divide the article into two segments, two being a first overlap joint fusion region122and a second overlap fusion joint region124and two being complex geometry single-pass regions126. In further embodiments, four fusion welding paths or more fusion welding paths are used for larger or more complicated articles. The fusion welding is by laser beam welding, electron beam welding, tungsten arc welding, any other suitable fusion joining method, or combinations thereof. In one embodiment, the article has a non-uniform geometry, such as the turbine blade100for a gas turbine, a steam turbine, or another suitable turbine. In one embodiment, the article has a predetermined thickness, for example, between about 100 mils and about 1000 mils, between about 200 mils and about 800 mils, and about 300 mils and about 700 mils, of about 300 mils, of about 400 mils, of about 500 mils, or of about 600 mils.

The first fusion welding path102and the second fusion welding path103each include a start location104and a stop location106. The joining sequence reduces thermal and residual stress of the turbine blade100based upon the positioning of the start location(s)104and the stop location(s)106. In one embodiment, the start locations104for each of the first joining path102and the second joining path103are on the same side of the turbine blade100. For example, in one embodiment, the start location104is on a suction side114of the turbine blade100. Additionally or alternatively, in one embodiment, the stop locations106for each of the first joining path102and the second joining path103are on the same side of the turbine blade100, for example, a pressure side118of the turbine blade100.

Referring toFIG. 2, a transverse component of a center of gravity112of the turbine blade100is determined, for example, by suspending the template of the exact cross section of turbine blade100from a first point202, such as an opening, proximal to a first edge, such as the suction side114of the turbine blade100, and distal from a second edge, such as the pressure side118of the turbine blade100. Referring toFIG. 3, next, a cross-sectional component of the center of gravity112of the turbine blade100is determined, for example, by suspending the template of the exact cross section of turbine blade100from a second point302proximal to a third edge, such as a leading edge116of the turbine blade100, and distal from a fourth edge, such as a trailing edge120of the turbine blade100. A transverse line204(seeFIG. 2) illustrating the transverse component of the center of gravity112and a cross-sectional line304(seeFIG. 3) illustrating the cross-sectional component of the center of gravity112are extended through the turbine blade100to intersect at the center of gravity112.

Referring toFIG. 4, the leading edge116and the trailing edge120of the turbine blade100are used to determine a primary symmetry line402by extending a leading line404from the leading edge116, extending a trailing line406from the trailing edge120and extending the primary symmetry line402from the intersection of the leading line404and the trailing line406through the center of gravity112. In one embodiment, the trailing edge120and/or the leading edge116include(s) a non-linear geometry, such as curved. In this embodiment, the leading line404and/or the trailing line406extend tangentially to the non-linear geometry. In one embodiment, one or more secondary symmetry lines408are then identified.

The primary symmetry line402corresponds to the position of the start locations104(seeFIG. 1) and/or stop locations106(seeFIG. 1) of the first fusion welding path102and the second fusion welding path103(seeFIG. 1). In one embodiment, the start locations104of the first fusion welding path102and the second fusion welding path103are positioned such that the first fusion welding path102and the second fusion welding path103result in fusion welding of the suction side114and/or the pressure side118over the primary symmetry line402. For example, in one embodiment, one of the first fusion welding path102and the second fusion welding path103extends from the suction side114of the turbine blade100, over the primary symmetry line402on the suction side114, to and along the leading edge116of the turbine blade100, to and along the pressure side118of the turbine blade100, and over the primary symmetry line402on the pressure side118. In another embodiment, one of the first fusion joining path102and the second fusion welding path103extends from the pressure side118of the turbine blade100, over the primary symmetry line402on the pressure side118, to and along the trailing edge120of the turbine blade100, to and along the suction side114of the turbine blade100, and over the primary symmetry line402on the suction side114. Additionally or alternatively, in one embodiment, the start location(s)104and/or the stop location(s)106are positioned along the secondary symmetry lines408.

Referring again toFIG. 1, according to an exemplary embodiment, the turbine blade100formed from the exemplary process includes the pressure side118and the suction side114, a first overlap fusion welding region122on the pressure side118extending over the primary symmetry line402based upon the center of gravity112of the turbine blade100, and a second overlap fusion welded region124on the suction side114extending over the primary symmetry line402based upon the center of gravity112of the turbine blade100. The first overlap fusion welding region122and the second overlap fusion welding region124are formed by multiple fusion welding processes. The first overlap fusion welding region122and/or the second overlap fusion welding region124are defined by the start locations104and the stop locations106. In further embodiments, the first overlap fusion welding region122and/or the second overlap fusion welding region124extend between secondary symmetry lines408, are identifiable based upon single-pass regions126, are on the same side of the turbine blade100, such as the suction side114or the pressure side118, or combinations thereof.

In one embodiment, the turbine blade100is formed of, in whole or in part, a superalloy material. A suitable superalloy material is a nickel-based alloy having, by weight, up to about 15% chromium, up to about 10% cobalt, up to about 4% tungsten, up to about 2% molybdenum, up to about 5% titanium, up to about 3% aluminum, and up to about 3% tantalum. In one embodiment, the superalloy material has a composition by weight of about 14% chromium, about 9.5% cobalt, about 3.8% tungsten, about 1.5% molybdenum, about 4.9% titanium, about 3.0% aluminum, about 0.1% carbon, about 0.01% boron, about 2.8% tantalum, and a balance of nickel.

Another suitable superalloy material is a nickel-based alloy having, by weight, up to about 10% chromium, up to about 8% cobalt, up to about 4% titanium, up to about 5% aluminum, up to about 6% tungsten, and up to about 5% tantalum. In one embodiment, the superalloy material has a composition, by weight, of about 9.75% chromium, about 7.5% cobalt, about 3.5% titanium, about 4.2% aluminum, about 6.0% tungsten, about 1.5% molybdenum, about 4.8% tantalum, about 0.08% carbon, about 0.009% zirconium, about 0.009% boron, and a balance of nickel.

Another suitable superalloy material is a nickel-based alloy having, by weight, up to about 8% cobalt, up to about 7% chromium, up to about 6% tantalum, up to about 7% aluminum, up to about 5% tungsten, up to about 3% rhenium and up to about 2% molybdenum. In one embodiment, the superalloy material has 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, about 0.05% carbon, about 0.004% boron, about 0.01% yttrium, and a balance of nickel.

Another suitable superalloy material is a nickel-based alloy having, by weight, up to about 10% chromium, up to about 8% cobalt, up to about 5% aluminum, up to about 4% titanium, up to about 2% molybdenum, up to about 6% tungsten and up to about 5% tantalum. In one embodiment, the superalloy material has 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, about 0.05% carbon, about 0.004% boron, and a balance of nickel.

Another suitable superalloy material is a nickel-based alloy having, by weight, up to about 10% cobalt, up to about 8% chromium, up to about 10% tungsten, up to about 6% aluminum, up to about 3% tantalum and up to about 2% hafnium. In one embodiment, the superalloy material has a composition, by weight, of about 9.5% cobalt, about 8.0% chromium, about 9.5% tungsten, about 0.5% molybdenum, about 5.5% aluminum, about 0.8% titanium, about 3.0% tantalum, about 0.1% zirconium, about 1.0% carbon, about 0.15% hafnium and a balance of nickel.

FIG. 5illustrates an exemplary process500of welding a non-uniform article such as the turbine blade100. The process includes a step of fusion welding the suction side114(step502), for example, along a path, for example, the first fusion welding path102and/or the second fusion welding path103, extending over the primary symmetry line402determined from the center of gravity112of the turbine blade100. The process500further includes a step of fusion welding the pressure side118(step504), for example, along a path, for example, the first fusion welding path102and/or the second fusion welding path103, extending over the primary symmetry line402determined from the center of gravity112of the turbine blade100. Portions of the fusion welding of the suction side114(step502) and the fusion welding of the pressure side118(step504) each include multiple fusion welding processes.

In one embodiment, the fusion welding of the suction side114(step502) is performed first and the fusion welding of the pressure side118(step504) is performed second. In another embodiment, the fusion welding of the suction side114(step502) is performed second and the fusion welding of the pressure side118(step504) is performed first. In yet another embodiment, the fusion welding of the suction side114(step502) and the fusion welding of the pressure side118(step504) are performed at least partially at the same time.

Referring toFIGS. 4 and 5, in one embodiment, the fusion welding of the suction side114(step502) includes fusion welding from a first start location (substep510), such as the start location104on the suction side114proximal to the trailing edge120, then fusion welding over one or more symmetry lines (substep512), such as one or more of the secondary symmetry lines408and/or the primary symmetry line402on the suction side114, and then fusion welding toward the leading edge (substep514) and/or onto the leading edge116. In one embodiment, these substeps are all performed along the first fusion welding path102(seeFIG. 1).

The fusion welding of the suction side114(step502) further includes fusion welding from a second start location (substep516), such as the start location104on the suction side114proximal to the leading edge116, then fusion welding over one or more symmetry lines (substep518), such as the one or more of the secondary symmetry lines408and/or the primary symmetry line402on the suction side114, and then fusion welding toward the trailing edge (substep520) and/or onto the trailing edge120. In one embodiment, these substeps are all performed along the second fusion welding path102(seeFIG. 1).

The fusion welding of the pressure side118(step504) includes fusion welding from the leading edge116(substep522), then fusion welding over one or more symmetry lines (substep524), such as one or more of the secondary symmetry lines408and/or the primary symmetry line402on the pressure side118, and then fusion welding toward the trailing edge (substep526) and/or onto the trailing edge120. In one embodiment, these substeps are all performed along the first fusion welding path102(seeFIG. 1). In another embodiment, these substeps are all performed separate and prior to the fusion welding of the first fusion welding path102.

The fusion welding of the pressure side118(step504) further includes fusion welding from the trailing edge120(substep528), then fusion welding over one or more symmetry lines (substep530), such as the one or more of the secondary symmetry lines408and/or the primary symmetry line402on the pressure side118, and then fusion welding toward the leading edge (532) and/or onto the leading edge116. In one embodiment, these substeps are all performed along the second fusion welding path102(seeFIG. 1). In another embodiment, these substeps are all performed separate and prior to the fusion welding of the first fusion welding path102.

Alternatively, the fusion welding of the suction side114(step502) and the fusion welding of the pressure side118(step504) are reversed. In other embodiments, third fusion welding paths (not shown), fourth fusion welding paths (not shown), or additional or preliminary fusion treatment paths extend in either of these directions to fusion welding the suction side114and/or the pressure side118.

In one embodiment, the process500further includes steps prior to the fusion welding. For example, in one embodiment, the process500includes identifying the center of gravity112(step506), for example, by suspending template of the exact cross section of the turbine blade100from the first point202proximal to the suction side114and suspending template of the cross section of the turbine blade100from the second point302proximal to the leading edge116or the trailing edge120of the turbine blade100. Similarly, in another embodiment, the process500further includes identifying the primary symmetry line402and/or secondary symmetry lines408(step508), for example, by extending a first line, for example, the leading line404, from the leading edge116of the turbine blade100, extending a second line, for example, the trailing line406, from the trailing edge120of the turbine blade100, identifying the intersection point of the first line and the second line, and extending a line, for example, the primary symmetry line402, from the intersection point through the center of gravity112.