Method for producing additively manufactured graded composite transition joints

Abstract

The present disclosure provides a method for producing an additively manufactured graded composite transition joint (AM-GCTJ) (300), the method comprising preparing a grid or mesh pattern (101) from a first alloy A (100); the grid or mesh pattern (101) comprising pores (110) in the grid or mesh pattern (101). The grid pattern is constructed from a first end to a second end, having a greater density at the first end than at the second end, and gradually decreasing in density by increasing the pore size and / or decreasing the density of the grid or mesh pattern; adding a second alloy B (200) powder to the second end of the grid or mesh pattern. The first end is filled with the second alloy B (200) powder. A composite material is formed from the first alloy A (100) and the second alloy B (200) powder in the AM-GCTJ (300). The composite material is subjected to hot isostatic pressing (HIP) to densify the composite material. The second alloy B (200) gradually changes from the first end to the second end of the AM-GCTJ (300).

Description

[0001] Statement Regarding Federally Funded Research

[0002] This invention was made with Government support under Grant No. DE-FE0031819 awarded by the Department of Energy. The Government has certain rights in this invention.

[0003] This application claims priority to U.S. Provisional Application No. 62 / 704,965, filed on June 4, 2020. The entire contents of U.S. Provisional Patent Application No. 62 / 704,965 are incorporated by reference into this application, non-provisional patent application. Technical Field

[0004] The present disclosure relates to additively manufactured graded composite transition joints. Specifically, the present disclosure relates to additively manufactured graded composite transition joints for dissimilar metal weldments. In another aspect, the present disclosure relates to additively manufactured graded composite transition joints for dissimilar metal weldments in advanced ultra-supercritical (A-USC) power plants. Additionally, the present disclosure relates to a method of producing an additively manufactured graded composite transition joint ("AM-GCTJ"). Background Art

[0005] Since 2001, as part of the U.S. Department of Energy (DOE) Coal Power Program, the National Energy Technology Laboratory (NETL) has launched a research program called "Advanced Materials Development for Ultra-Supercritical Boiler Systems" to identify and develop next-generation materials for advanced ultra-supercritical (A-USC) boiler and turbine systems. In these boiler and turbine systems, the target steam temperature and pressure are approximately 760°C (1400°F) and approximately 35 MPa (5000 psi), respectively, which can reduce all emissions, including carbon dioxide (CO2), by approximately 20% or more compared to some boiler and turbine systems.

[0006] One challenge for coal-fired A-USC systems lies in the area of ​​materials and manufacturing technology. As a critical material component in the boiler, superheater tubes face harsh operating conditions and must meet stringent requirements for furnace-side ash corrosion / erosion, steam-side oxidation and spalling, creep strength, thermal fatigue strength, and weldability. During the DOE A-USC program, alloys 740H and 282 were identified as candidates for components in A-USC systems. Therefore, the application and success of these systems require acceptable manufacturing and welding processes, especially for the materials used in dissimilar metal welds (DMWs). Summary of the Invention

[0007] All aspects, examples and features mentioned below can be combined in any technically possible way.

[0008] One aspect of the present disclosure provides a method for producing an additively manufactured graded composite transition joint (AM-GCTJ), the method comprising preparing a grid or mesh pattern from a first alloy A, wherein the grid or mesh pattern includes pores in the grid or mesh pattern; building the grid or mesh pattern from a first end to a second end of the grid or mesh pattern, the grid or mesh pattern having a higher density at the first end than at the second end, and wherein the grid or mesh pattern gradually decreases in density by at least one of increasing the size of the pores from the first end to the second end and decreasing the density of the grid or mesh pattern as the grid or mesh pattern is additively manufactured; adding a second alloy B powder to the first end of the grid or mesh pattern; filling the second end of the grid or mesh pattern with the second alloy B powder; forming a composite of the first alloy A and the second alloy B powder in the AM-GCTJ; and subjecting the composite to hot isostatic pressing to densify the composite, wherein the second alloy B powder has a graded concentration from the first end to the second end of the AM-GCTJ.

[0009] Another aspect of the present disclosure includes any of the preceding aspects, and wherein preparing includes preparing the grid or mesh pattern by at least one of selective laser melting (SLM) or selective laser sintering (SLS).

[0010] Another aspect of the present disclosure includes any of the aforementioned aspects, and wherein filling includes vibrating the second alloy B so that the second alloy B falls from a first end toward a second end of the grid or mesh pattern.

[0011] Another aspect of the present disclosure includes any of the preceding aspects, and wherein preparing includes preparing the grid or mesh pattern by additively building the grid or mesh pattern from the first end to the second end.

[0012] Another aspect of the present disclosure includes any of the aforementioned aspects, and wherein the pores have a pore size ranging from about tens of microns to sub-millimeter diameters.

[0013] Another aspect of the present disclosure includes any of the foregoing aspects, and wherein vibrating the second alloy B powder toward the second end of the grid or mesh pattern includes ultrasonically vibrating the second alloy B powder.

[0014] Another aspect of the present disclosure includes any of the foregoing aspects, and wherein the second alloy B powder is graded from about 0% at the second end of the grid or mesh pattern to about 100% at the first end of the grid or mesh pattern.

[0015] Another aspect of the present disclosure includes any of the preceding aspects, and wherein the first alloy A comprises austenitic stainless steel, and the second alloy B comprises creep-strength-enhanced ferritic steel.

[0016] Another aspect of the present disclosure includes any of the foregoing aspects, and wherein the first alloy A comprises a creep strength enhanced ferritic steel and austenitic stainless steel, and the second alloy B comprises austenitic stainless steel.

[0017] Another aspect of the present disclosure includes any of the preceding aspects and wherein the first alloy A comprises a creep strength enhanced ferritic steel and an austenitic stainless steel and the second alloy B comprises a superalloy.

[0018] One aspect of the present disclosure provides an additively manufactured graded transition joint (AM-GCTJ) comprising a first alloy A; a second alloy B; a transition joint, wherein a greater concentration of the first alloy A is disposed at a first end of the transition joint and a greater concentration of the second alloy B is disposed at a second end of the transition joint; and a gradient composite transition piece disposed between the first end of the transition joint and the second end of the transition joint, wherein the gradient composite transition of the first alloy A and the second alloy B comprises a graded transition of the first alloy A and the second alloy B from the first end of the transition joint to the second end of the transition joint.

[0019] Another aspect of the present disclosure includes any of the preceding aspects, and wherein the first alloy A is configured to be welded at a first end of the transition joint, and the second alloy B is configured to be welded at a second end of the transition joint.

[0020] Another aspect of the present disclosure includes any of the foregoing aspects, and wherein the graded transition from the end of the transition joint to the second end of the transition joint is a transition from approximately 0% second alloy B at the second end to approximately 100% second alloy B at the first end.

[0021] Another aspect of the present disclosure includes any of the preceding aspects and wherein the first alloy comprises a creep strength enhanced ferritic steel and an austenitic stainless steel and the second alloy comprises an austenitic stainless steel.

[0022] Another aspect of the present disclosure includes any of the preceding aspects and wherein the first alloy comprises a creep strength enhanced ferritic steel and an austenitic stainless steel and the second alloy comprises a superalloy.

[0023] Aspects of the present disclosure provide an additively manufactured graded transition joint (AM-GCTJ) comprising a mixture of a first alloy A and a second alloy B, the first alloy A comprising a grid or mesh pattern having a graded density, the grid or mesh pattern having a first end and a second end, and the grid or mesh pattern comprising at least one pore, the at least one pore having a pore size diameter in a range from about tens of microns to about sub-millimeter, and the density of the grid or mesh pattern at the second end being greater than the density of the grid or mesh pattern at the first end, and the density being graded from 0% to 100% by volume by at least one of increasing the void size from the second end to the first end and decreasing the density of the grid or mesh pattern as layers are additively built from the first end to the second end, and wherein a second alloy B is added to the second end of the grid or mesh pattern to form a composite material having the grid or mesh pattern, wherein the composite material has a smooth graded transition from 0% alloy B to 100% alloy B from the second end of the AM-GCTJ to the first end of the AM-GCTJ.

[0024] Another aspect of the present disclosure includes any of the foregoing aspects, and wherein the first alloy A comprises a creep strength enhanced ferritic steel and austenitic stainless steel, and the second alloy B comprises austenitic stainless steel.

[0025] Another aspect of the present disclosure includes any of the preceding aspects and wherein the first alloy A comprises a creep strength enhanced ferritic steel and an austenitic stainless steel and the second alloy B comprises a superalloy.

[0026] Another aspect of the present disclosure includes any of the preceding aspects, and wherein the first alloy A is configured to be welded at a first end of the transition joint, and the second alloy B is configured to be welded at a second end of the transition joint.

[0027] Two or more aspects described in this disclosure, including those described in this Summary, can be combined to form embodiments not specifically described herein.

[0028] The details of one or more implementations are set forth in the drawings and the description below. Other features, objects, and advantages will be apparent from the description and drawings, and from the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] These and other features of the present disclosure will be more readily understood from the following detailed description of various aspects of the disclosure taken in conjunction with the accompanying drawings which depict various embodiments of the disclosure, in which:

[0030] Figure 1 shows a schematic diagram of components of an A-USC power plant as embodied by the present disclosure;

[0031] Figure 2 shows a perspective view of an A-USC header as embodied by the present disclosure;

[0032] FIG3( a ) shows a schematic diagram of a fusion line crack or a bond line crack and heat affected zone (HAZ) damage of a dissimilar metal weld (DMW) as embodied by the present disclosure;

[0033] FIG3( b ) shows a microscopic view of localized creep damage near a fusion line or bond line associated with decarburization in a DMW as embodied by the present disclosure;

[0034] Figure 4 A schematic flow chart of a method, as embodied by the present disclosure, for additively manufacturing a graded composite transition joint, as embodied by the present disclosure, is shown.

[0035] Figure 5 A graph illustrating a thermal load cycle employed in an Integrated Computational Welding Engineering (ICWE) model for transition joint design as embodied in the present disclosure;

[0036] Figure 6 Graph showing ICWE simulation results for two AM-GCTJ designs between Grade 91 steel and SS 316H DMW as embodied in the present disclosure;

[0037] Figure 7 shows a perspective view of using an AM-GCTJ in a header of an A-USC power plant as embodied by the present disclosure; and

[0038] Figure 8 Schematic diagrams showing various exemplary and non-limiting configurations of grid or mesh patterns as embodied by the present disclosure. DETAILED DESCRIPTION

[0039] First, in order to clearly describe the subject matter of the present disclosure, it is necessary to select certain terms when referring to and describing the relevant features, properties and components within the additively manufactured graded composite transition joint. To the extent possible, common industry terms will be used and adopted in a manner consistent with the accepted meaning of the terms. 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 understand that several different or overlapping terms may often be used to refer to a particular component. An object that may be described herein as a single part may include multiple components and be referenced in another context as consisting of multiple components. Alternatively, an object that may be described herein as comprising multiple components may be referred to elsewhere as a single part.

[0040] The terms used herein are only used to describe the purpose of specific embodiments and are not intended to limit the present disclosure. As used herein, the singular forms "a", "an" and "the" are intended to also include plural forms, unless the context clearly indicates otherwise. It will be further understood that when used in the specification, the terms "comprise" and / or "comprising" specify the presence of stated features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or their groups. "Optional" or "optionally" means that the event or situation described subsequently may or may not occur, or the parts or features described subsequently may or may not exist, and the description includes instances in which the event occurs or the parts exist and instances in which the event does not occur or the parts do not exist.

[0041] When an element or layer is referred to as being “on,” “engaged to,” “connected to,” or “coupled to” another element or layer, it may be directly on, engaged to, connected to, or coupled to the other element or layer, or there may be intervening elements or layers. In contrast, when an element is referred to as being “directly on,” “directly engaged to,” “directly connected to,” or “directly coupled to” another element or layer, there may be no intervening elements or layers. 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.

[0042] Robust dissimilar metal welds (DMWs) can enable advanced ultra-supercritical (A-USC) systems. Robust DMWs can also be used to retrofit and retrofit existing A-USC power plants, enabling enhancements through retrofits and retrofits. As renewable energy becomes affordable and integrated into the power grid, the electric utility industry may need to retrofit and retrofit fossil coal-fired and natural gas-fired power plants to operate in flexible modes utilizing renewable energy. Flexible operating modes allow for the use of intermittent and variable power generation, which may be inherent to renewable energy. DMWs may fail under the increased cyclic operating conditions in existing fossil fuel power plants. Cycling places the DMWs under stressful conditions. In certain cyclic operations, stress conditions may shift from creep-dominated to thermal creep-fatigue-dominated. The weakened microstructure at the DMW fusion or bond line interface may be subjected to high cyclic stresses caused by the mismatch in the coefficients of thermal expansion (CTE) of the two dissimilar materials being fused together at the fusion or bond line. As a result, the service life and performance of the DMWs may be reduced.

[0043] Thus, as embodied in the present disclosure, a functionally gradient composite transition joint is formed by an additive manufacturing process. As embodied in the present disclosure, an additively manufactured dissimilar metal weldment (DMW) can provide a gradient composite transition joint. As embodied in the present disclosure, the gradient composite transition joint can meet the compositional physical property requirements of the DMW. As embodied in the present disclosure, the compositional physical property requirements include, but are not limited to, room temperature and high temperature strength, creep resistance, and corrosion resistance. In addition, as embodied in the present disclosure, the gradient composite transition joint can reduce stress concentration caused by the transition of CTE between the two sides of the additively manufactured dissimilar metal weld. Thus, as embodied in aspects of the present disclosure, the additively manufactured dissimilar metal weldment will improve the crack resistance and thermal creep fatigue (TCF) resistance of the DMW.

[0044] The A-USC system can use superalloys to manufacture parts with favorable compositional physical property requirements. As embodied in the present disclosure, superalloys can include but are not limited to nickel (Ni)-based superalloys, or iron (Fe)-based superalloys, or cobalt (Co)-based superalloys, or combinations thereof. In addition, A-USC materials may include austenitic stainless steel (ASS), creep strength enhanced ferritic steel (CSEFS), which can be used alone or in combination or in combination with other materials. Depending on the temperature and corrosion resistance requirements of the DMW in the A-USC structure, these materials can be provided in different DMW areas. Therefore, the differences in CTE side effects between the DMW materials can mitigate and can facilitate the design, development and manufacture of enhanced A-USCs.

[0045] For example, and not intended to limit the embodiments of the present disclosure in any way, the average linear CTE of alloy steels is approximately 16.2 μ / °C (9 μ / °F) over the temperature range of approximately 70°F to approximately 1100°F, while that of austenitic stainless steel is approximately 34.2 μ / °C (19 μ / °F). A temperature change from room temperature to approximately 595°C (1100°F) will produce a thermal strain of approximately 0.1%, resulting in thermal stresses in the range of approximately 150 megapascals (MPa), which is far higher than the normal operating stress allowance. Thermal stresses are expected to decrease over time (months or years) and therefore play only a minor role in DMW performance compared to the stresses imposed under steady-state operating conditions of approximately 595°C (1100°F) (creep-dominated), which has been the standard for fossil fuel power plants for the past few decades. On the other hand, under thermal cycling operating conditions, such thermal strains will continue to generate and accumulate until they are released. Under cyclic operation associated with thermal creep fatigue (TCF), the considerable thermal strain accumulation and damage may have a greater effect, potentially leading to premature failure of the DMW. Therefore, thermal stress in DMW joints poses new challenges to the safe operation of fossil fuel power plants under increased cyclic operating modes. Understanding and managing thermal stress in DMW in future operations can improve new DMW installations and extend their lifespan.

[0046] Eliminating composition variations across DMW fusion or bond lines can prevent DMW failure.

[0047] In DMWs containing nickel-based fillers, failure by creep and / or creep fatigue cracking has been attributed to carbide morphology. DMWs containing stainless steel fillers have exhibited failure by creep and / or creep fatigue cracking, which may form along austenite grain boundaries near fusion or bond line boundaries.

[0048] Embodiments of the present disclosure provide a method for producing gradient (or graded) composite transition joint (GCTJ) parts. In one aspect of the embodiment, the GCTJ can be used to join and bond dissimilar metals, where the gradient characteristics accommodate the different properties of the metals of the components to be joined by the GCTJ, such as different physical and thermal properties. In another aspect of the embodiment, the GCTJ can cost-effectively remedy the premature failure of conventional dissimilar metal welds (DMWs) under the increased cycle operating conditions of fossil fuel power plants.

[0049] As embodied in the present disclosure, additively manufactured GCTJs (AM-GCTJs) may be suitable for use in next-generation advanced ultra-supercritical (A-USC) power plants. In certain aspects of the present disclosure, AM-GCTJs may be provided for augmentation by retrofitting or replacing conventional DMWs in existing fossil fuel power plants. Such retrofits or replacements may enable safe and economical operation in cycle modes beyond their original intended design life.

[0050] For example, welding dissimilar metals including creep strength enhanced ferritic steels (CSEFS) or austenitic stainless steels (ASS) to superalloys are two important DMWs that may be applied in the next generation A-USC systems.

[0051] In one non-limiting exemplary aspect of the embodiment, austenitic stainless steel (ASS) is based on 18% Cr-8% Ni. As embodied in the present disclosure, ASS may include, but is not limited to, Super 304H or Sanicro 25 and their equivalents.

[0052] In another non-limiting aspect of the embodiment, CSEFS (also known as martensitic or superferritic steel) may include, but is not limited to, Grade 91 and Grade 92. Additionally, superalloys may include, but are not limited to, nickel-based, iron-based, and / or cobalt-based superalloys.

[0053] Additively manufactured graded composite transition joint (AM-GCTJ)

[0054] In an A-USC system, DMWs may be disposed between features in the system that are formed of different materials, such as, but not limited to, CSEFS (in one aspect of the embodiment, Grade 91 / 92) and ASS (in one aspect of the embodiment, Super 304H). Figure 1 and Figure 2 In the embodiment, the tubes 10 are connected to the header 20 at a joint weld 30, which can be located at the inlet of the final superheater / reheater. In a non-limiting embodiment of the present disclosure, the superheater design conditions can be approximately 387 bar / 640°C. In a non-limiting embodiment of the present disclosure, the DMW size has an outer diameter (OD) of approximately 40 mm and a thickness of approximately 8 mm. DMWs ranging from ASS (Sanicro 25 in one aspect of the embodiment) to Ni-based superalloys (740H or H0282 in one aspect of the embodiment) can extend from the tubes 10 to the header 20 at the joint weld 30 at the outlet of the final superheater / reheater. The superheater design conditions can be approximately 387 bar / 670°C. The DMW size can have an outer diameter of approximately 44 millimeters (mm) and a thickness of approximately 10 mm.

[0055] As embodied in the present disclosure, potentially undesirable DMW properties may be mitigated by an additively manufactured graded composite transition joint (AM-GCTJ) 300 . Figure 4 One aspect of an AM-GCTJ 300 embodying the present disclosure is shown in FIG.

[0056] The microstructural changes across the fusion line or bond line of as-welded DMW may be due to the steep chemical concentration gradient. Figure 3A Shown is the heat affected zone (HAZ) between Grade 91 steel and a nickel-based filler metal. Figure 3B Creep and / or creep fatigue crack failures in the DMW fusion line or bond line are shown. Creep and / or creep fatigue cracks can occur along the fusion line or bond line boundary and HAZ between different alloys of the DMW. Creep and / or creep fatigue cracks can be attributed to at least one of residual stress, external stress, and thermal stress caused by CTE mismatch. The thermal stress caused by CTE mismatch can be significant. Failure may be accompanied by damage to the HAZ.

[0057] Figure 4 An additive manufacturing process for forming an additively manufactured graded composite transition piece (AM-GCTJ) 300 is shown. First, an additively manufactured graded composite transition piece (AM-GCTP) is formed. AM-GCTP 300 includes a first alloy or alloy A 100 and a second alloy or alloy B 200. The GCTP is formed by a mixture of alloy A 100 and alloy B 200 that gradually gradients along its structure. The composition of the mixture of alloy A 100 and alloy B 200 ranges from 100% alloy A 100 at a first (first) end to 100% alloy B 200 at a second (second) end, such that the region between the ends transitions from substantially all alloy B 200 at the first end to all alloy A 100 at the second end in a controlled concentration. Thus, alloy A 100 and alloy B 200 constitute a specially formulated composite material comprising a mixture of alloy A 100 and alloy B 200. However, the mixture may optionally include other additives between the ends.

[0058] The transition of Alloy A 100 and Alloy B 200 in the composite material, or more specifically, the ratio or concentration of Alloy A 100 and Alloy B 200, gradually changes from the first end of the AM-GCTP to the second end of the AM-GCTP. This gradual concentration change is provided to mitigate and reduce abrupt changes in chemical and thermal stresses in the DMW, such as, but not limited to, changes caused by CTE differences.

[0059] After the AM-GCTP is formed, the AM-GCTP can be placed between two structural members and welded to the two structural members, as shown in FIG. Figure 1 and Figure 2As shown, to form AM-GCTJ 300. In certain aspects of the embodiment, AM-GCTJ 300 can be formed between nickel-based superalloy and CSEFS in DMW. Similarly, AM-GCTJ 300 can be formed between ASS and CSEFS in DMW.

[0060] Because the ends of the AM-GCTJ 300 have substantially similar chemistry to the material of the structural member to which the AM-GCTJ is to be welded, the weld connecting the AM-GCTJ 300 to the two structural members is essentially disposed between two materials having matching or compatible chemistries (including, but not limited to, matching CTEs). This same-material welding can eliminate factors that lead to premature failure of DMWs, such as, but not limited to, thermal stresses induced at the DMW fusion line or bond line by chemical transitions and CTE mismatches.

[0061] Another aspect of the embodiment includes producing AM-GCTP by an additive manufacturing (AM) process to produce AM-GCTJ300. Figure 4 As shown in A, the first process step consists in producing a grid or mesh pattern 101 from alloy A 100. (See also Figure 8 , which shows an exemplary and non-limiting grid or mesh pattern 101 as embodied in the present disclosure. In exemplary aspects of the embodiment, alloy A 100 may include, but is not limited to, ASS. The grid or mesh pattern 101 of alloy A 100 may be produced using an additive manufacturing process. Such additive manufacturing processes include, but are not limited to, at least one of selective laser melting (SLM) and selective laser sintering (SLS).

[0062] A grid or mesh pattern 101 formed from alloy A 100 includes pores 110. The size of the pores 110 in the grid or mesh pattern 101 can vary. The cross-sectional size of the pores 110 can range from approximately tens of microns to approximately sub-millimeter. The grid or mesh pattern 101 can be formed denser at a first end of the grid or mesh pattern and less densely at a second end of the grid or mesh pattern 101. Density or concentration can be expressed as a volume ratio. In the grid or mesh pattern 101, the density / volume ratio gradually decreases from approximately 0% to approximately 100%. This gradual decrease in the volume ratio of the grid or mesh pattern 101 can be achieved by at least one of increasing the size of the pores 110 and decreasing the density of the grid or mesh 101 as layers are additively manufactured and built toward the top of the grid or mesh pattern 101.

[0063] After the grid or mesh pattern 101 is formed by the additive manufacturing process, Alloy B 200 powder may be supplied to the grid or mesh pattern 101. The Alloy B 200 powder includes, but is not limited to, Grade 91 steel powder. The Alloy B 200 powder is supplied at the first end of the grid or mesh pattern 101, i.e., the end where the Alloy A 100 density is less ( Figure 4 B). Alloy B 200 powder includes, but is not limited to, steel powder (e.g., Grade 91 steel powder). After the Alloy B 200 powder is added, ultrasonic energy can be applied to the grid or mesh pattern 100 to fill the grid or mesh pattern 100 and the Alloy B 200 powder therein, wherein the filling includes vibrating the Alloy B 200 powder. The ultrasonic energy ultrasonically vibrates and causes the Alloy B 200 powder to fill by falling (shaking) through the pores 110 in the grid or mesh pattern 101 toward the end of the grid or mesh pattern 101 where the density of Alloy A 100 is highest.

[0064] Next, the grid or mesh pattern having Alloy A 100 and Alloy B 200 may be subjected to hot isostatic pressing (HIP). Figure 4 C) is used to densify Alloy A 100 and Alloy B 200 within a grid or mesh pattern 101. Hot isostatic pressing (HIP) can utilize the grid or mesh pattern to densify Alloy A 100 and Alloy B 200 to approximately 100% density and form a composite material. After HIP, a graded composite transition of Alloy A 100 and Alloy B 200 within the grid or mesh pattern 101 is achieved from a first end to a second end of the grid or mesh pattern 101. As embodied in the present disclosure, the graded composite transition transitions from approximately 0-100% Alloy A 100 to Alloy B 200 from one end to the second end of the grid or mesh pattern 101.

[0065] The Integrated Computational Welding Engineering (ICWE) modeling tool from Oak Ridge National Laboratory (ORNL) can be used to design AM-GCTJ 300. ICWE can help evaluate the thermal stresses caused by thermal cycling loads in dissimilar metal welds (DMWs) under service conditions. Some of the advantages of AM-GCTJ 300 are summarized below using an example. An exemplary, non-limiting application is the welding and preparation of a piping system having a DMW formed from 91 grade steel against stainless steel 316 (see Figure 5 The two pipes were connected using a straight section of piping with a DMW system, with an outer diameter (OD) of approximately 5.1 mm (2 inches) and a thickness of approximately 0.95 mm (3 / 8 inches) (common dimensions in fossil fuel power plants). The thermal cycle load curve used in the simulation is as follows Figure 6As shown in Figure 1, the temperature was increased from ambient to the operating temperature of approximately 650°C in approximately two hours. The modeled system was then maintained at the operating temperature for seven days before cooling to ambient temperature in two hours. This type of thermal load cycling modeling was repeated to simulate operation and calculate the cumulative effects of the thermal cycling loads.

[0066] Figure 8 An exemplary and non-limiting grid or mesh pattern 101 is shown. The grid and pores 101 of alloy A 100 can be provided in any configuration, size, cross-section, and dimensions, with density and pore size provided as embodied in the present disclosure. Thus, the configuration, size, cross-section, and dimensions of the grid or mesh and pores 101 of alloy A 100 can vary, as long as the density at a first end of the grid or mesh pattern (101) is greater than the density at a second end, and the density gradually decreases by at least one of increasing the pore size from the first end to the second end and decreasing the density of the grid or mesh pattern (101) as the grid or mesh pattern (101) is additively manufactured.

[0067] Note that the step transition joint (GTJ) can be produced using a variety of manufacturing technologies that are easily scalable to large-scale manufacturing. Compared to traditional GTJ technology, the AM-GCTJ 300 method embodied in the present disclosure has several technical effects:

[0068] As embodied in the present disclosure, AM-GCTJ 300 produces a composite material that maintains the characteristics of Alloy A 100 and Alloy B 200, such as thermal and physical properties. Conventional GTJ technology, whether using wire or powder, melts Alloy A 100 and Alloy B 200 together to build the transition joint layer by layer. Melting and mixing two different alloys in different proportions requires significant time and resources and can produce a complex and irregular microstructure, which can have unpredictable microstructures and, therefore, unknown or unpredictable properties, such as thermal and physical properties. As an example of such an unpredictable microstructure, melting 91 grade steel and 304H steel in a 50 / 50 ratio will produce a "new" material with unproven microstructural stability and high temperature performance, as well as potential solidification defect issues.

[0069] Furthermore, as embodied in the present disclosure, Alloy A 100 and Alloy B 200 are not melted together, as compared to conventional welding operations. According to the present disclosure, Alloy A 100 and Alloy B 200 are bonded together through a solid-state hot isostatic pressing process. The solid-state hot isostatic pressing process (hiping) forms a "composite" material of Alloy A 100 and Alloy B 200. Therefore, the hot isostatically pressed composite material of Alloy A 100 and Alloy B 200 does not introduce the metallurgical complexity of a melted "new" A+B alloy.

[0070] After appropriate heat treatment, AM-GCTJ 300 can be used as an intermediate connector between two structural components that exhibit properties similar to those of Alloy A 100 and Alloy B 200. Fusion welding can be provided at both ends of the DMW, if desired. Thus, fusion welding can be applied to the interface or fusion line or joint line between two structural components that exhibit properties similar to those of Alloy A 100 and Alloy B 200, eliminating issues previously encountered with DMW at the fusion line or joint line, such as different CTEs.

[0071] As embodied in the present disclosure, a further technical effect is the provision of a smooth transition between Alloy A 100 and Alloy B 200. The smooth transition is graded and should reduce and mitigate issues associated with CTE mismatch. Reduced CTE mismatch can improve turbine component life, including during cyclic operation.

[0072] Another technical effect of this embodiment is that the process and weld can provide enhanced control over the composition of the DMW. Furthermore, as embodied in the present disclosure, processes including additively manufactured grids and mesh patterns 101 can achieve diverse DMW geometries that may not be feasible with other welding processes. Thus, as embodied in the present disclosure, scaling issues can be reduced in the manufacture of large numbers of GTJs required for A-USC systems. Furthermore, the lifespan of existing equipment fleets can be extended through the AM-GCTJ 300 embodiments herein.

[0073] The present embodiment provides an additively manufactured graded composite transition joint for dissimilar metal weldments in advanced ultra-supercritical power plants. In another embodiment of the present disclosure, a method for producing an additively manufactured graded composite transition joint ("AM-GCTJ 300") is provided.

[0074] It should be understood that the above invention is described with respect to advanced ultra-supercritical (A-USC) power plants and related alloys. However, one aspect of the present disclosure is that these concepts and embodiments can be applied to other dissimilar metal welds (DMWs). Furthermore, another aspect of the present disclosure is that these concepts and embodiments can be applied to other applications or industries besides power plants.

[0075] It will be apparent to those skilled in the art that many modifications and variations of the described examples and embodiments set forth herein are possible in light of the foregoing teachings of the present disclosure. The disclosed examples and embodiments are presented for illustrative purposes only. Other alternative embodiments may include some or all of the features disclosed herein. Therefore, it is intended to cover all such modifications and alternative embodiments that may fall within the scope of the present invention.

[0076] Additionally, the disclosure of a numerical range is a disclosure of every number within that range, inclusive of the endpoints.

[0077] Those skilled in the art will appreciate that changes may be made to the embodiments of the invention described herein without departing from the broad inventive concept thereof. Therefore, it should be understood that the present invention is not limited to any particular embodiment disclosed, but is intended to cover modifications within the spirit and scope of the invention as defined by the appended claims.

Claims

1. A method for producing an additively manufactured graded composite transition joint (AM-GCTJ) (300), the method comprising: preparing a grid or mesh pattern (101) from a first alloy A (100), wherein the grid or mesh pattern (101) comprises pores (110) therein; constructing the grid or mesh pattern (101) from a first end to a second end of the grid or mesh pattern, the grid or mesh pattern (101) having a higher density at the first end than at the second end, and wherein the grid or mesh pattern (101) gradually decreases in density by at least one of increasing the pore size from the first end to the second end and decreasing the density of the grid or mesh pattern (101) as the grid or mesh pattern (101) is additively manufactured; adding a second alloy B (200) powder to the second end of the grid or mesh pattern (101); Filling the second alloy B (200) powder from the second end of the grid or mesh pattern (101) toward the first end; forming a composite material of the first alloy A (100) and the second alloy B (200) powders in the AM-GCTJ (300); as well as The composite material is subjected to hot isostatic pressing (HIP) to densify the composite material, wherein the second alloy B (200) powder has a graded concentration from the first end to the second end of the AM-GCTJ (300).

2. The method according to claim 1, wherein the preparing comprises preparing the grid or mesh pattern (101) by at least one of selective laser melting (SLM) or selective laser sintering (SLS).

3. The method according to any one of the preceding claims, wherein the filling comprises vibrating the second alloy B so that the second alloy B falls from the second end towards the first end of the grid or mesh pattern (101).

4. The method of claim 1, wherein the preparing comprises preparing the grid or mesh pattern (101) by additively building the grid or mesh pattern (101) from the first end to the second end.

5. The method according to claim 1 or 2, wherein the pores (110) have a pore size of the order of tens of micrometers to sub-millimeter diameter.

6. The method of claim 3, wherein the vibrating comprises ultrasonically vibrating the second alloy B (200) powder.

7. The method of claim 1 or 2, wherein the concentration of the second alloy B (200) powder is graded from 0% at the first end of the grid or mesh pattern (101) to 100% at the second end of the grid or mesh pattern (101).

8. The method of claim 1 or 2, wherein the first alloy A (100) comprises austenitic stainless steel and the second alloy B (200) comprises creep-strength-enhanced ferritic steel.

9. The method of claim 1 or 2, wherein the first alloy A (100) comprises a creep-strength-enhanced ferritic steel and the second alloy B (200) comprises an austenitic stainless steel.

10. The method of claim 1 or 2, wherein the first alloy A (100) comprises a creep-strength-enhanced ferritic steel and the second alloy B (200) comprises a superalloy.

11. An additively manufactured graded transition joint (AM-GCTJ) (300), comprising: First alloy A (100); Second alloy B (200); A transition joint (300), wherein a greater concentration of the first alloy A (100) is disposed at a first end of the transition joint (300), and a greater concentration of the second alloy B (200) is disposed at a second end of the transition joint (300); and A gradient composite transition of the first alloy A (100) and the second alloy B (200) is disposed between a first end of the transition joint and a second end of the transition joint, wherein the gradient composite transition of the first alloy A (100) and the second alloy B (200) comprises a graded transition of the first alloy A (100) and the second alloy B (200) from the first end of the transition joint to the second end of the transition joint (300), and the gradient composite transition comprises a grid or mesh pattern (101) of the first alloy A (100), the grid or mesh pattern (101) having pores (110) that increase in size from the first end of the transition joint (300) to the second end of the transition joint (300).

12. The additively manufactured graded transition joint (AM-GCTJ) (300) of claim 11, wherein the first alloy A (100) is configured to be welded at the first end of the transition joint, and the second alloy B (200) is configured to be welded at the second end of the transition joint.

13. The additively manufactured graded transition joint (AM-GCTJ) (300) according to claim 11 or 12, wherein the graded transition from the first end of the transition joint to the second end of the transition joint is a transition from 0% of the second alloy B (200) at the first end to 100% of the second alloy B (200) at the second end.

14. The additively manufactured stepped transition joint (AM-GCTJ) (300) according to claim 11 or 12, wherein the first alloy A (100) comprises a creep-strength-enhanced ferritic steel and the second alloy B (200) comprises an austenitic stainless steel.

15. The additively manufactured graded transition joint (AM-GCTJ) (300) according to claim 11 or 12, wherein the first alloy A (100) comprises a creep-strength enhanced ferritic steel and the second alloy B (200) comprises a superalloy.

16. An additively manufactured graded transition joint (AM-GCTJ) (300), comprising: A mixture of a first alloy A (100) and a second alloy B (200); The first alloy A (100) comprises a grid or mesh pattern (101) having a graded density of the first alloy A (100), the grid or mesh pattern (101) having a first end and a second end, and the grid or mesh pattern (101) comprises at least one pore (110), the at least one pore (110) having a pore size diameter on the order of tens of micrometers to sub-millimeter; and The grid or mesh pattern (101) has a greater density at the second end than at the first end, and the density has a graduated volume ratio from 0% to 100% by at least one of increasing the pore size from the second end to the first end and decreasing the density of the grid or mesh pattern (101) as layers are additively built from the second end to the first end, and wherein the second alloy B (200) is added to a first end of the grid or mesh pattern (101) to form a composite material having the grid or mesh pattern (101), wherein the composite material has a second alloy B concentration ranging from 0% of the second alloy B (200) at the second end to 100% of the second alloy B (200) at the first end of the AM-GCTJ (300).

17. The additively manufactured stepped transition joint (AM-GCTJ) (300) of claim 16, wherein the first alloy A (100) comprises a creep-strength-enhanced ferritic steel and the second alloy B (200) comprises an austenitic stainless steel.

18. The additively manufactured graded transition joint (AM-GCTJ) (300) according to claim 16 or 17, wherein the first alloy A (100) comprises a creep-strength enhanced ferritic steel and the second alloy B (200) comprises a superalloy.

19. The additively manufactured graded transition joint (AM-GCTJ) (300) of claim 16 or 17, wherein the first alloy A (100) is configured to be welded at the second end, and the second alloy B (200) is configured to be welded at the first end.

Images