Casting part including a channel and having a surface anti-speckle element in a turning part of the channel, and related removable core and method

Abstract

The present invention provides a cast component (90) including a body (101) and a passage (220) defined within the body. The passage includes a first portion (124), a second portion (126), and a turning portion (122) fluidly coupling the first portion (124) and the second portion (126). The turning portion (122) includes a first surface (232) and a second surface (234). A surface anti-speckling element (240) passes through the turning portion (122) of the passage, extending from the first surface (232) to the second surface (234) of the turning portion (122). The element divides the passage in the turning portion (122) into a first sub-passage (242) and a second sub-passage (244). The element is formed by an opening in a removable core (180) used during casting, the removable core including a surface anti-speckling opening (200) located at the position of the element, the surface anti-speckling opening providing a path for a low density liquid alloy (164) to flow through a core turning portion (182) of the core to reduce surface speckling of the passage (220) in the body (101) of the component.

Description

Technical Field

[0001] The present disclosure relates generally to cast components and, more particularly, to cast components including surface anti-speckling elements in the turning portions of channels. The elements are formed by openings in the core turning portions of removable cores used during casting, the removable cores including openings at the locations of the elements. The openings provide a path for low-density liquid alloy to flow through the core turning portions of the core to reduce surface speckling of the channels in the body of the component. Background Art

[0002] During the casting of components using single-crystal metal alloys, as the molten alloy solidifies, the planar solidification front moves upward through the melt pool. As the solidification front moves upward, the higher-density liquid alloy containing dendrites solidifies first, and the lower-density liquid alloy containing interdendritic material solidifies second. One challenge in casting single-crystal metal alloys includes preventing speckling on the component surface. Speckling includes speckled regions of inferior alloy containing dendrite arms and / or equiaxed grains, which can affect the expected life of the component depending on the location. Due to the impact on the expected life, speckling needs to be avoided at certain locations within high-performance cast components such as superalloy turbine blades compared to the rest of the casting. Surface speckling typically occurs in large amounts of material but can also occur, for example, when the core restricts the flow of low-density liquid alloy as the solidification front moves upward in the casting. Summary of the Invention

[0003] One aspect of the present disclosure provides a cast component including: a body; a channel defined within the body, the channel including a first portion, a second portion, and a turning portion fluidly coupling the first portion and the second portion, the turning portion including a first surface and a second surface; and a surface anti-speckling element passing through the turning portion of the channel, extending from the first surface of the turning portion to the second surface, the surface anti-speckling element dividing the channel in the turning portion into a first sub-channel and a second sub-channel, wherein the channel does not experience surface speckling.

[0004] Another aspect of the present disclosure provides a turbine blade including: a body including an airfoil, a tip, and a root; a cooling channel defined within the body, the cooling channel including a first portion, a second portion, and a turning portion fluidly coupling the first portion and the second portion, the turning portion including a first surface and a second surface; and a surface anti-speckling element passing through the turning portion of the cooling channel, extending from the first surface of the turning portion to the second surface, the surface anti-speckling element dividing the cooling channel in the turning portion into a first sub-channel and a second sub-channel, wherein the turning portion defines a cooling channel turn in at least one of the tip and the root and does not experience surface speckling, and wherein the surface anti-speckling element is non-load-bearing.

[0005] Another aspect of the present disclosure provides a removable core for casting a turbine blade in a mold. The removable core includes: a core body configured to define a cooling passage in a body of the turbine blade, the core body including a first core portion, a second core portion, and a core turning portion connecting the first core portion and the second core portion, the core turning portion including an inner surface and an outer surface; and a surface anti-pitting opening passing through the core turning portion and extending from the inner surface to the outer surface of the core turning portion, the surface anti-pitting opening dividing the core turning portion into a first sub-portion and a second sub-portion and providing a path for a low-density liquid alloy to flow through the core turning portion during the casting process to reduce surface pitting of the cooling passage in the body of the turbine blade.

[0006] Yet another aspect of the present disclosure provides a method of casting a turbine blade. The method includes: forming a removable core including: a core body configured to define a cooling passage in a body of the turbine blade, the core body including a first core portion, a second core portion, and a core turning portion connecting the first core portion and the second core portion, the core turning portion including an inner surface and an outer surface; and a surface anti-pitting opening passing through the core turning portion and extending from the inner surface to the outer surface of the core turning portion, the surface anti-pitting opening dividing the core turning portion into a first sub-portion and a second sub-portion; placing the removable core in a mold defining at least a portion of an outer surface of the turbine blade; and casting the turbine blade in the mold, the surface anti-pitting opening providing a path for a low-density liquid alloy to flow through the core turning portion to reduce surface pitting of the cooling passage in the body of the turbine blade.

[0007] Exemplary aspects of the present disclosure are designed to address the problems described herein and / or other problems not discussed. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] These and other features of the present disclosure will be more readily understood from the following detailed description of various aspects of the present disclosure in conjunction with the accompanying drawings depicting the various embodiments of the present disclosure, wherein:

[0009] Figure 1 A perspective view of a cast component in an exemplary form of a turbine blade is shown, and embodiments of the present disclosure may be employed therein.

[0010] Figure 2 Shows an inverted cast component along Figure 1 A schematic cross-sectional view of a portion of the inverted cast component taken along line A-A in the prior art.

[0011] Figure 3 Shows an inverted cast component along Figure 1 A schematic cross-sectional view of a portion of the inverted cast component taken along line A-A in the prior art.

[0012] Figure 4 An enlarged cross-sectional view of a turning portion in a passage of a component including a plaque chain according to the prior art is shown.

[0013] Figure 5 An illustration is provided of a schematic cross-sectional view of a portion of a component formed by inverted casting using a removable core including surface plaque-resistant openings along Figure 1 line A-A in accordance with an embodiment of the present disclosure.

[0014] Figure 6 An illustration is provided of a schematic cross-sectional view of a portion of a component formed by inverted casting using a removable core including surface plaque-resistant openings along Figure 1 line A-A in accordance with an embodiment of the present disclosure.

[0015] Figure 7 A perspective view of a core turning portion of a removable core according to an embodiment of the present disclosure is shown.

[0016] Figure 8 A perspective view of a core turning portion of a removable core according to other embodiments of the present disclosure is shown.

[0017] Figure 9 An enlarged cross-sectional view of a turning portion in a passage of a cast component including a surface plaque-resistant element formed in accordance with an embodiment of the present disclosure and without a plaque chain is shown.

[0018] Figure 10 An illustration is provided of Figure 9 a cross-sectional view of a turning portion in a passage of a cast component taken along line of sight 10-10.

[0019] Figure 11 A cross-sectional view of a turning portion in a passage of a cast component including a surface plaque-resistant element and ribs formed in accordance with an embodiment of the present disclosure and without a plaque chain is shown.

[0020] Figure 12 An enlarged cross-sectional view of a turning portion in a passage of a cast component including two or more surface plaque-resistant elements formed in accordance with an embodiment of the present disclosure and without a plaque chain is shown.

[0021] It should be noted that the drawings of the present disclosure are not necessarily drawn to scale. The drawings are intended to depict only typical aspects of the present disclosure and should not therefore be regarded as limiting the scope of the present disclosure. In the drawings, like numerals represent like elements among the drawings. Detailed Description

[0022] First, to clearly describe the presently disclosed subject matter, it will be necessary to select certain terms when referring to and describing relevant portions within exemplary cast components such as turbine blades. To the extent possible, general industry terms will be used and adopted in a manner consistent with their accepted meanings. Unless otherwise indicated, such terms should be given a broad interpretation consistent with the context of this application and the scope of the appended claims. Those of ordinary skill in the art will appreciate that typically several different or overlapping terms may be used to refer to a particular component. An object described herein as a single part may include multiple components and in another context be referred to as being composed of multiple components. Alternatively, an object described herein as including multiple components may elsewhere be referred to as a single part.

[0023] It is often necessary to describe parts that are disposed at different radial positions relative to a central axis. The term "radial" refers to movement or position perpendicular to the axis. For example, if a first component is closer to the axis than a second component, it will be stated herein that the first component is "radially inward" of or "inside" the second component. On the other hand, if a first component resides farther from the axis than a second component, it may be stated herein that the first component is "radially outward" or "outside" of the second component. The term "axial" refers to movement or position parallel to the axis, such as that of a turbine rotor. Finally, the term "circumferential" refers to movement or position around the axis. It should be understood that such terms may be applied relative to the central axis of a turbine.

[0024] In addition, several descriptive terms may be regularly used herein, as described below. The terms "first," "second," and "third" may be used interchangeably to distinguish one component from another and are not intended to denote the position or importance of the individual components.

[0025] The terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the disclosure. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that when used in the specification, the terms "comprises" and / or "comprising" specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. "Optional" or "optionally" means that the subsequent described event or circumstance may or may not occur, or that the subsequent described component or feature may or may not be present, and the description includes instances where the event occurs or the component is present and instances where the event does not occur or the component is not present.

[0026] When an element or layer is referred to as being "on another element or layer", "engaged to another element or layer", "connected to another element or layer", or "coupled to another element or layer", it can be directly on, engaged to, connected to, or coupled to the other element or layer, or intervening elements or layers can be present. In contrast, when an element is referred to as being "directly on another element or layer", "directly engaged to another element or layer", "directly connected to another element or layer", or "directly coupled to another element or layer", intervening elements or layers may not be present. Other words used to describe the relationship between elements should be interpreted in a similar manner (e.g., "between" versus "directly between", "adjacent" versus "directly adjacent", etc.). As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0027] As noted above, the present disclosure provides a cast component that includes a body and a passage defined within the body. The passage includes a first portion, a second portion, and a turning portion that fluidly couples the first portion and the second portion. The turning portion includes a first surface and a second surface. A surface anti-spotting element passes through the turning portion of the passage, extending from the first surface to the second surface of the turning portion. The element divides the passage in the turning portion into a first sub-passage and a second sub-passage. The element is formed by a removable core used during casting of the component, the removable core including a surface anti-spotting opening located at the position of the element. Spotting can occur when a low-density liquid alloy flows upward and forms a plume that includes dendrite arms that can deposit on the surface of the component and form spots (spot chains). Spotting can be restricted in casting regions that cannot support flow recirculation and thus cannot form a plume. In such cases, the low-density liquid alloy can accumulate at the solidification front. When the layer of low-density liquid alloy encounters a constraint to flow due to a physical obstruction such as a turn in the core, the low-density liquid alloy flows along the surface of the core, thereby forming spots on the first surface of the turning portion of the passage. The surface anti-spotting opening according to an embodiment of the present disclosure provides a path for the low-density liquid alloy to flow through the turning portion of the core and avoid the restricted region, allowing the dendrite arms to reach the main melt pool. Thus, the opening reduces surface spotting in the passage within the body of the component.

[0028] Figure 1A perspective view of an exemplary cast component 90 in the form of a turbine blade 100 is shown. The turbine blade 100 includes a body 101 that includes a root 102 by which the turbine blade 100 is attached to a rotor (not shown) of a turbine. The root 102 may include a dovetail that is configured to be mounted in a corresponding dovetail slot in the periphery of a rotor disk. The root 102 may also include a shank that extends between the dovetail and a platform 104 that is disposed at the junction of an airfoil 106 and the root 102 and that defines a portion of an inner boundary of a flow path through the turbine. It should be understood that the airfoil 106 is the active component of the turbine blade 100 that intercepts the flow of a working fluid and causes the rotor disk to rotate. The airfoil 106 extends from the root 102 to a tip 103. As can be seen, the airfoil 106 of the turbine blade 100 includes a concave pressure side (PS) outer wall 110 and a circumferentially or laterally opposed convex suction side (SS) outer wall 112 that extend axially between opposite leading edges 114 and trailing edges 116, respectively. The outer walls 110 and 112 also extend radially from the platform 104 to the outer tip 103.

[0029] As shown, a cast component 90 such as the turbine blade 100 may also include therein a passage 120 that, for example, traverses the airfoil 106 in a sinusoidal manner. The passage 120 may be a coolant passage for delivering coolant throughout the turbine blade 100 and may thus be referred to herein as a passage or a coolant passage. As shown, the passage 120 may include any number of turn portions 122 in the root 102 and / or the tip 103. The turn portions 122 couple respective first portions 124 and second portions 126 of the passage 120 on opposite sides of the turn portion 122. The first portions 124 and second portions 126 may be referred to as “upper tubes” because they extend radially in the turbine blade 100. Ribs 128 separate the respective portions 124, 126 of the passage 120. While the exemplary turbine blade 100 is a turbine rotor blade, it should be understood that the present disclosure may also be applied to other types of blades and / or hot gas path components within a turbine, including, for example, turbine stator blades, nozzles or vanes, or casing components. Further, while the present disclosure will be described with respect to the turbine blade 100, embodiments of the present disclosure may be applied to any cast component 90 for which spotting on the surface of the component is a problem.

[0030] The cast component 90 (hereinafter referred to as "component 90") is made of a single crystal metal or a metal alloy, such as a superalloy or a columnar grain structure (e.g., a directionally solidified (DS) blade). In one embodiment, component 90 may be made of a metal, which may include a pure metal or an alloy. As used herein, "superalloy" refers to an alloy that has many excellent physical properties compared to conventional alloys, such as but not limited to: high mechanical strength, high resistance to thermal creep deformation, such as Rene N5, Rene N500, Rene 108, CM247, Haynes alloys, Incalloy, MP98T, TMS alloys, CMSX single crystal alloys. In one embodiment, a superalloy that may be particularly advantageous for the teachings of the present disclosure is a superalloy having a high gamma prime (γ') value. "Gamma prime" (γ') is the primary strengthening phase of nickel-based alloys. Exemplary high γ' superalloys include but are not limited to: Rene 108, N4, N5, N500, GTD 444, MarM 247, and IN 738. In a specific embodiment, component 90 may include Rene N4.

[0031] Figure 2 and Figure 3 FIG. shows a schematic cross-sectional view of a portion of an inverted-cast turbine blade according to the prior art. Figure 2 and Figure 3 is taken along line of sight A-A in Figure 1 when casting the turbine blade 100. Figure 2 and Figure 3 FIG. shows a portion of the mold 140, where the airfoil forming portion 142 intersects the platform forming portion 144, and the removable core 146 is positioned to form a cooling channel 120 in the exemplary turbine airfoil 106 ( Figure 1 ). The removable core 146 extends through the airfoil forming portion 142 of the mold 140 and includes a core turn portion 150. In Figure 2 and Figure 3 , the core turn portion 150 would extend out of the page. In a non-limiting example, the core turn portion 150 may be a U-turn in the channel 120 of the turbine blade 100 that joins portions 124, 126 (upper tubes) of the channel 120 ( Figure 1 ). However, it should be emphasized that the core turn portion 150 may be any portion through which the constrained solidification front 160 of the removable core 146 travels. Thus, the constrained region 152 may include a section of the casting where no flow recirculation and patchy plumes can occur within the solidification zone 166. Examples may include rib cavities 127 (between portions of the core 146 in Figures 2 to 3 ), in which ribs 128 are formed that separate the first portion 124 and the second portion 126 (upper tubes) of the cooling channel 120 ( Figure 4); and a space 156, which is located between the core 146 and the inner surface 154 of the mold 140 and is thinner than in adjacent regions to form a thinner wall in the cast part. As will be understood by those skilled in the art, the constrained region 152 can be formed in a variety of alternative situations.

[0032] As Figure 2 shown, as casting occurs, a solidification front 160 forms below the main liquid melt pool 162 of the liquid alloy (the mold is shown as partially filled). As noted, during dendritic growth in the solidification zone 166, heavy elements preferentially segregate into the dendritic structure of the solidified metal alloy 168, leaving a low-density liquid alloy 164 in the spaces between the dendrites. The low-density liquid alloy 164 migrates upward due to buoyancy. When the velocity of the solidification front 160 is lower than the upward velocity of the low-density liquid alloy 164, the casting is prone to mottling. In the constrained region 152, the recirculation path required for mottle plumes cannot form. Instead, the low-density liquid alloy 164 accumulates above the solidification zone 166, forming a layer of low-density liquid alloy 164. The low-density liquid alloy 164 can include dendritic fragments that accumulate during the upward flow of the alloy.

[0033] As Figure 3 shown, when the layer of low-density liquid alloy 164 encounters a constraint to the flow such as a core turn portion 150, it is forced to flow around the obstacle and can deposit dendritic fragments on the surface of the removable core 146 or nucleate small equiaxed grains to form a chain of mottles 170 on one or both surfaces of the channel 120 ( Figure 1 ).

[0034] Once casting is complete, any currently known or later developed removal process (e.g., leaching) can be used to remove the removable core 146. Figure 4 An enlarged view of the turn portion 122 is shown, where the removable core 146 has been removed, and a chain of mottles 170 between the first portion 124 and the second portion 126 of the cooling channel 120 is shown. The rib 128 separates the portions 124, 126.

[0035] Figures 5 to 6 A schematic cross-sectional view of a portion of a turbine blade 100 cast in an inverted manner using a removable core 180 according to an embodiment of the present disclosure is shown ( Figure 1 ). Figure 5 And Figure 6 are taken along Figure 1 the line of sight A-A in Figure 7 shown. A perspective view of the core turn portion 182 of the removable core 180 is shown. The removable core 180 used to cast the turbine blade 100 in the mold 140 can include a body 101 for defining the turbine blade 100 ( Figure 1) the cooling channel 120( Figure 1 ) the core body 184 of. The core body 184 includes a first core portion 186, a second core portion 188, and a core turning portion 182 that connects the first core portion 186 and the second core portion 188. The core turning portion 182 includes an inner surface 192 and an outer surface 194. In one non-limiting example, the core turning portion 182 can be used to form portions 124, 126 (upper tube) of the connecting channel( Figure 1 ) the turbine blade 100( Figure 1 ) the cooling channel 120( Figure 1 ) the U-turn in. However, it should be emphasized that the core turning portion 182 can be any part for the constrained solidification front 160 of the removable core 180 to travel through, thereby forming the constrained region 152. In this non-limiting example, as shown in the figure, the inner surface 192 of the core turning portion 182 constrains the solidification front 198 that travels upward through the rib cavity 127 (to form the rib 128) within the body 101 of the turbine blade 100( Figure 1 ) Compared with a conventional core, the removable core 180 includes a surface anti-splotch opening 200 that passes through the core turning portion 182 and extends from the inner surface 192 to the outer surface 194 of the core turning portion 182. The surface anti-splotch opening 200 (hereinafter referred to as "opening 200") divides the core turning portion 182 into a first sub-portion 202 and a second sub-portion 204.

[0036] As Figure 5 shown, as the casting occurs, the solidification front 198 forms below the main liquid melt pool 162 of the liquid alloy, where the low-density liquid alloy 164 is above the solidification (mushy) zone 166, and this solidification zone is above the solidified metal alloy 168 (the mold is shown as partially filled). As previously pointed out, during dendritic growth in the solidification zone 166, heavy elements preferentially segregate into the dendritic structure of the solidified metal alloy 168, leaving the low-density liquid alloy 164 in the spaces between the dendrites. As Figure 6 shown, the low-density liquid alloy 164 migrates upward due to buoyancy and accumulates at the front 198. Compared with a conventional core, the opening 200 provides a path for the low-density liquid alloy 164 to flow through the core turning portion 182 during the casting process to reduce surface splotching of the cooling channel 120 in the body 101 of the turbine blade 100.

[0037] The opening 200 can have any shape required to reduce the flow resistance of a specific core-mold configuration. In one embodiment, as Figures 5 to 6 shown, the opening 200 has an hourglass-shaped cross-section. In other embodiments, the opening 200 can be cylindrical, frustoconical, etc. The opening 200 can have a smooth surface or a rough surface. As Figure 7As shown, the removable core 180 may also optionally include at least one surface anti-banding groove 210 on the surface 212 of the core turning portion 182. If desired, the groove 210 may be provided to provide additional low-density liquid alloy "traps" where dendrite arms can settle rather than areas where an undesired chain of bands is not desired. The groove 210 may be located at any desired position and have any depth, length, or shape. Notably, the groove 210 may have a shape that forms any desired shape turbulator for the cooling channel 120.

[0038] The opening 200 may be provided in more than one location. For example, the opening 200 may be provided on the removable core 180 regardless of where the flow resistance of the desired low-density liquid alloy 164 is to be reduced. Figure 8 Another embodiment is shown in which two or more surface anti-banding openings 200 are employed.

[0039] Return Figure 5 and Figure 6 , a method of casting a turbine blade 100 ( Figure 1 ) may include forming a removable core 180 that includes a core body 184 for defining a channel 120 (such as a cooling channel in the turbine blade 100) in a body 101 of a component 90. The removable core 180 may include any currently known or later developed removable core material such as, but not limited to, ceramics, etc., and may be made using any technique such as additive manufacturing, etc. The core body 184 includes a first core portion 186, a second core portion 188, and a core turning portion 182 that couples the first and second core portions. The core turning portion 182 includes an inner surface 192 and an outer surface 194. As noted, the removable core 180 also includes a surface anti-banding opening 200 that passes through the core turning portion 182 and extends from the inner surface 192 to the outer surface 194 of the core turning portion 182. The opening 200 divides the core turning portion 182 into a first sub-portion 202 and a second sub-portion 204. The method may include placing the removable core 180 in a mold 140 that defines at least a portion of an outer surface 221 ( Figure 1 ) of a component 90 (such as a turbine blade 100). The removable core 180 may be placed in the mold 140 in any currently known or later developed manner.

[0040] The method may further include, as Figures 5 to 6 shown, casting the turbine blade 100 ( Figure 1 ) in the mold 140. During casting, the surface anti-banding opening 200 provides a path for the low-density liquid alloy 164 to flow through the core turning portion 180 to reduce surface banding in the channel 120 (such as the cooling channel of the turbine blade 100) in the body 102 of the component 90. Here, as Figure 6As shown, the low-density liquid alloy 164 accumulates at the solidification front 198 but flows through the opening 200 in the removable core 180 and is re-incorporated into the body of the main liquid melt pool 162. After removal of the core, the remaining metal forms a surface anti-speckling element 240 that can act as a non-load-bearing turbulator ( Figures 9 to 12 ). In the case where the grooves 210 are provided on the surface 212 of the core 180, they can also trap the low-density liquid alloy 164 and act as a plaque trap that ultimately provides turbulator ribs 250 ( Figure 11 ).

[0041] Figure 1 and Figure 9 FIG. shows a cast component 90 according to an embodiment of the present disclosure. Figure 9 FIG. shows an enlarged cross-sectional view of a turning portion 122 in a channel 220 of a cast component 90 formed according to an embodiment of the present disclosure. The channel 220 (i.e., its surface) has no chain of plaques. The cast component 90 may include a body 101, and the channel 220 is defined within the body. As Figure 9 best shown, the channel 220 includes a first portion 124, a second portion 126, and a turning portion 122 that fluidly couples the first portion 124 and the second portion 126. The turning portion 122 of the channel 120 may have various shapes, such as a curved shape, such as a U-shaped shape. Figure 10 FIG. shows a cross-sectional view of the turning portion 122 of the channel 220 taken along the line of sight 10-10 in Figure 9 . As shown, the turning portion 122 includes a first surface 232 ( Figure 9 and Figure 10 ) and an opposing second surface 234 ( Figure 9 and Figure 10 ).

[0042] The cast component 90 further includes a surface anti-speckling element 240 that passes through the turning portion 122 of the channel 220 and extends from the first surface 232 to the second surface 234 of the turning portion 122. The surface anti-speckling element 240 is formed by an opening 200 ( Figure 6 ) in the removable core 180 ( Figure 6 ). The surface anti-speckling element 240 (hereinafter referred to as "element 240") divides the channel 120 in the turning portion 122 into a first sub-channel 242 and a second sub-channel 244. As noted, the channel 120 has no surface speckling. The element 240 may have any cross-section formed by the opening 200 ( Figure 6 ). For example, as Figure 10As shown, the element 240 may have an hourglass-shaped cross-section. In other embodiments, it may be cylindrical, frustoconical, etc. For example, depending on the desired impingement of the coolant flow, the element 240 may also have a smooth surface or a rough surface. The body 101 comprises a uniform single crystal metal (which may comprise any of the materials listed previously herein) or any columnar microstructure (such as a directionally solidified (DS) blade). (Regarding directional solidification, when the casting is directionally solidified, the microstructure is columnar, having a primary crystal orientation in the direction of the temperature gradient. When a seed selector and / or a seed is added to the base of the casting, a single crystal structure is produced. Both types of castings are prone to pitting). The body 101 has a first porosity. However, due to dendrite arms accumulating in the openings 200 during casting ( Figure 6 ), the element 240 may comprise at least one of equiaxed grains and a second porosity greater than the first porosity. That is, the element 240 may comprise a metal alloy of poorer quality. Thus, the surface pitting resistant element 240 may be designed to be non-load bearing. As described, the body 101 may define a turbine blade 100 comprising a tip 103 and a root 102 ( Figure 1 ). The turning portion 122 may define a turn of the cooling channel 120 located in the tip 103 and / or the root 102.

[0043] Figure 11 An enlarged cross-sectional view of the turning portion 122 in the channel 220 of the cast component 90 formed according to other embodiments of the present disclosure is shown. In these embodiments, at least one surface pitting resistant (turbulator) rib 250 may be provided on the first surface 232 and / or the second surface 234 of the turning portion 122. The rib 250 may be formed by grooves 210 on a removable core ( Figure 7 ), and may provide any desired turbulator shape. Any number of ribs / grooves may be provided.

[0044] Figure 12 An enlarged cross-sectional view of the turning portion 122 in the channel 220 of the cast component 90 formed according to other embodiments of the present disclosure is shown. In these embodiments, two or more surface pitting resistant elements 240 may be provided. Each element 240 divides the channel 120 in the turning portion 122 into a corresponding first sub-channel 242 and a second sub-channel 244. As shown, the first sub-channel 242 and the second sub-channel 244 are fluidly coupled between adjacent pairs of two or more surface pitting resistant elements 240 (sub-channel 246).

[0045] As noted, component 90 may be in the form of turbine blade 100. In this case, as noted, body 101 includes airfoil 106, tip 103, and root 102. Cooling passage 120 is defined within body 102 and includes first portion 124, second portion 126, and turning portion 122 fluidly coupling first portion 124 and second portion 126. Element 240 passes through turning portion 122 of cooling passage 120, extending from first surface 232 of the turning portion to second surface 234. Each element 240 divides cooling passage 120 in turning portion 122 into first sub-channel 242 and second sub-channel 244. Sub-channels 242, 244 are fluidly coupled between adjacent pairs of two or more surface anti-splotch elements 240. Turning portion 122 may define a cooling passage turn located in tip 103 and / or root 102. In any case, turning portion 122 has no splotchy surfaces. Element 240 may be non-load-bearing. Turbine blade 100 may further include ribs 250 located on surfaces 232, 234 of turning portion 122. Element 240 and / or rib 250 may act as turbulators to cause coolant to flow through cooling passage 120.

[0046] Embodiments of the present disclosure provide a removable core and casting method that reduces splotching in cast components (such as root and / or tip turns in cooling passages of hot gas path components such as turbine blades or nozzles) where there are constrained regions. The removable core may include surface anti-splotch openings and / or patch-trapping ribs that subsequently form turbulators or other structures. The openings and / or ribs are used to collect low-density liquid alloy and trap patches in regions of the component that do not affect the component's intended life and may be non-load-bearing.

[0047] As used throughout the specification and claims, approximating language may be used to modify any quantitative representation that can permit variation without resulting in a change in the basic function associated therewith. Thus, a value modified by one or more terms, such as "about," "approximately," and "substantially," is not limited to the specified exact value. In at least some instances, approximating language may correspond to the precision of the instrument used to measure the value. Here and throughout the specification and claims, range limitations may be combined and / or interchanged; unless the context or language indicates otherwise, these ranges are recognized and include all sub-ranges subsumed therein. "About" applied to a particular value of a range applies to both end values of that range and may indicate + / −10% of that value unless otherwise dependent on the precision of the instrument used to measure the value.

[0048] All corresponding structures, materials, acts, and equivalents of the apparatus or steps plus function elements in the following claims are intended to include any structure, material, or act for performing the functions in conjunction with other claimed elements for which protection is claimed. The description of the present disclosure has been presented for purposes of illustration and description, but is not intended to be exhaustive or to limit the present disclosure to the forms disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the present disclosure. The embodiments were chosen and described in order to best explain the principles of the present disclosure and its practical application, and to enable others of ordinary skill in the art to understand the present disclosure in various embodiments with various modifications that are suited to the particular use contemplated.

Claims

1. A cast component (90) comprising: a body (101); channels (120, 220) defined within the body (101), the channels (120, 220) including a first portion (124), a second portion (126), and turning portions (122, 150, 182) fluidly coupling the first portion (124) and the second portion (126), the turning portions (122, 150, 182) including a first surface (232) and a second surface (234); and a surface anti - fouling element (240) passing through the turning portions (122, 150, 182) of the channels (120, 220), extending from the first surface (232) to the second surface (234) of the turning portions (122, 150, 182), the surface anti - fouling element (240) dividing the channels (120, 220) in the turning portions (122, 150, 182) into a first sub - channel (242) and a second sub - channel (244), wherein the channels (120, 220) are free of surface fouling; wherein the surface anti - fouling element (240) includes two or more surface anti - fouling elements (240), each surface anti - fouling element (240) dividing the channels (120, 220) in the turning portions (122, 150, 182) into a corresponding first sub - channel (242) and a corresponding second sub - channel (244), wherein the first sub - channels (242) and the second sub - channels (244) are fluidly coupled between adjacent pairs of the two or more surface anti - fouling elements (240).

2. The cast component (90) according to claim 1, wherein the surface anti - fouling element (240) has an hourglass - shaped cross - section.

3. The cast component (90) according to claim 1, wherein the body (101) comprises a uniform single - crystal metal having a first porosity, and the surface anti - fouling element (240) comprises at least one of equiaxed grains and a second porosity greater than the first porosity.

4. The cast component (90) according to claim 1, wherein the turning portions (122, 150, 182) of the channels (120, 220) have a U - shaped configuration.

5. The cast component (90) according to claim 1, wherein the body (101) defines a turbine blade (100) including a tip (103) and a root (102), and the turning portions (122, 150, 182) define a channel turn located in at least one of the tip (103) and the root (102).

6. The cast component (90) according to claim 1, further comprising at least one surface anti - fouling rib (250) located on the first surface (232) of the turning portions (122, 150, 182).

7. The cast component (90) according to claim 1, wherein the surface anti-pitting element (240) is non-load-bearing.

8. A turbine blade (100) comprising: a body (101) including an airfoil (106), a tip (103), and a root (102); cooling channels (120, 220) defined within the body (101), the cooling channels (120, 220) including a first portion (124), a second portion (126), and turning portions (122, 150, 182) fluidly coupling the first portion (124) and the second portion (126), the turning portions (122, 150, 182) including a first surface (232) and a second surface (234); and a surface anti-pitting element (240) passing through the turning portions (122, 150, 182) of the cooling channels (120, 220) and extending from the first surface (232) to the second surface (234) of the turning portions (122, 150, 182), the surface anti-pitting element (240) dividing the cooling channels (120, 220) in the turning portions (122, 150, 182) into a first sub-channel (242) and a second sub-channel (244), wherein the turning portions (122, 150, 182) define a cooling channel turn in at least one of the tip (103) and the root (102) and are free of surface pitting, and wherein the surface anti-pitting element (240) is non-load-bearing; wherein the surface anti-pitting element (240) includes two or more surface anti-pitting elements (240), each surface anti-pitting element (240) dividing the cooling channels (120, 220) in the turning portions (122, 150, 182) into a corresponding first sub-channel (242) and a corresponding second sub-channel (244), wherein the first sub-channels (242) and the second sub-channels (244) are fluidly coupled between adjacent pairs of the two or more surface anti-pitting elements (240).

9. The turbine blade (100) according to claim 8, wherein the surface anti-pitting element (240) has an hourglass-shaped cross-section.

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