Method for manufacturing additively manufactured inclined composite material transition joints

Abstract

A method for manufacturing a graded composite transition joint. [Solution] A method for manufacturing an additively manufactured graded composite transition joint (AM-GCTJ) (300) includes preparing a lattice or lattice pattern (101) from a first alloy A (100), the lattice or lattice pattern (101) including pores (110) within the lattice or lattice pattern (101). The lattice pattern is constructed from a first end to a second end, with a higher density at the first end than at the second end, and tapered by increasing the pore size and / or decreasing the density of the lattice or lattice pattern. A second alloy B (200) powder is added to the second end of the lattice or lattice pattern. The second alloy B (200) powder is packed toward the first end. A composite of the first alloy A (100) and second alloy B (200) powders is formed in the AM-GCTJ (300). The composite is subjected to hot isostatic pressing (HIP) to densify the composite. The second alloy B (200) is graded in concentration from the first end to the second end of the AM-GCTJ (300).

Description

Technical Field

[0001] Statement on research supported by the U.S. federal government This invention was made under government support awarded by the United States Department of Energy under Contract No. DE-FE0031819. The United States government has certain rights in this invention.

[0002] This application claims priority based on U.S. Provisional Patent Application No. 62 / 704,965, filed on June 4, 2020. The disclosure of U.S. Provisional Patent Application No. 62 / 704,965 is incorporated herein by reference and made a part of the content of this patent application.

[0003] This disclosure relates to additively manufactured graded composite transition joints. In particular, this disclosure relates to additively manufactured graded composite transition joints for dissimilar metal welding. In a further aspect, this disclosure relates to additively manufactured graded composite transition joints for dissimilar metal welding in advanced ultra-supercritical (A-USC) power plants. Additionally, this disclosure relates to a method for manufacturing additively manufactured graded composite transition joints (AM-GCTJ).

Background Art

[0004] Since 2001, as part of the U.S. Department of Energy's (DOE) coal-fired power program, the National Energy Technology Laboratory (NETL) has launched a research program titled "Development of Advanced Materials for Ultra-supercritical Boiler Systems" to identify and develop next-generation materials for advanced ultra-supercritical (A-USC) boiler and turbine systems. These boiler and turbine systems can reduce all emissions, including carbon dioxide (CO2), by approximately 20% compared to some other boiler and turbine systems, at target steam temperatures and pressures of approximately 760°C (1400°F) and 35 MPa (5000 psi), respectively.

[0005] The challenges for coal-fired A-USC systems lie in the areas of materials and manufacturing technology. As critical material components of the boiler, superheater tubes are exposed to harsh operating conditions and must meet stringent requirements regarding corrosion / erosion by coal ash on the combustion side, oxidation and delamination on the steam side, creep strength, thermal fatigue strength, and weldability. The DOE's A-USC program has identified alloys 740H and 282 as candidate alloys for components of A-USC systems. Therefore, for the application and success of these systems, acceptable manufacturing and welding processes are desired, particularly for materials in dissimilar metal welding (DMW). [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] U.S. Patent Application Publication No. 2009 / 0308773 Specification [Overview of the Initiative]

[0007] All of the embodiments, specific examples, and features listed below can be combined in any way that is technically possible.

[0008] One aspect of the present disclosure is a method for manufacturing an additively manufactured gradient composite transition joint (AM-GCTJ), the method comprising the steps of: preparing a grid or grid pattern from a first alloy A, wherein the grid or grid pattern includes pores within the grid or grid pattern; and constructing the grid or grid pattern from a first end to a second end, wherein the grid or grid pattern has a denser density at the first end than at the second end, and the pore size increases from the first end to the second end, and while additively manufacturing the grid or grid pattern The present invention provides a method comprising the steps of: gradually decreasing the density of a grid or grid pattern by at least one of the following: adding a second alloy B powder to a first end of the grid or grid pattern; filling the second alloy B powder toward the second end of the grid or grid pattern; forming a composite material of a first alloy A and a second alloy B powder in an AM-GCTJ; and densifying the composite material by subjecting it to a high-temperature hydrostatic press (HIP), wherein the second alloy B powder has a concentration that gradually changes from the first end to the second end of the AM-GCTJ.

[0009] Another aspect of the present disclosure encompasses the aforementioned aspect, wherein the preparation step includes preparing a grating or grating pattern by at least one of selective laser melting (SLM) or selective laser sintering (SLS).

[0010] Another aspect of the present disclosure encompasses any of the above aspects, wherein the filling step includes vibrating the second alloy B to cause it to fall from the first end to the second end of the grid or grid pattern.

[0011] Another aspect of the present disclosure encompasses any of the above aspects, wherein the preparation step includes preparing the grid or grid pattern by additively manufacturing the grid or grid pattern from a first end to a second end.

[0012] Another aspect of the present disclosure encompasses any of the above aspects, wherein the pores have pore dimensions in the range of approximately several tens of micrometers to sub-millimeters in diameter.

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

[0014] Another aspect of the present disclosure encompasses any of the above aspects, wherein the second alloy B powder is gradually varied from about 0% at the second end of the grid or grid pattern to about 100% at the first end of the grid or grid pattern.

[0015] Another aspect of the present disclosure encompasses any of the above aspects, wherein the first alloy A comprises an austenitic stainless steel and the second alloy B comprises a creep-strengthened ferritic steel.

[0016] Another aspect of the present disclosure encompasses any of the above aspects, wherein the first alloy A comprises creep-strengthened ferritic steel and austenitic stainless steel, and the second alloy B comprises austenitic stainless steel.

[0017] Another aspect of the present disclosure encompasses any of the above aspects, wherein the first alloy A includes creep-strengthened ferritic steel and austenitic stainless steel, and the second alloy B includes a superalloy.

[0018] One aspect of the present disclosure provides an additively manufactured inclined transition joint (AM-GCTJ) comprising: a first alloy A; a second alloy B; a transition joint wherein a higher concentration of the first alloy A is disposed at a first end of the transition joint and a higher concentration of the second alloy B is disposed at a second end of the transition joint; and an inclined composite material transition member disposed between the first end and the second end of the transition joint, wherein the inclined composite material transition portion between the first alloy A and the second alloy B includes an inclined transition between the first alloy A and the second alloy B from the first end to the second end of the transition joint.

[0019] Another aspect of the present disclosure encompasses the above aspect, wherein the first alloy A is configured to be welded at the first end of the transition joint, and the second alloy B is configured to be welded at the second end of the transition joint.

[0020] Another aspect of the present disclosure encompasses any of the above aspects, wherein the gradient transition of the first alloy A to the second alloy B from the first end of the transition joint to the second end of the transition joint is from approximately 0% of the second alloy B at the second end to approximately 100% of the second alloy B at the first end.

[0021] Another aspect of the present disclosure encompasses any of the above aspects, wherein the first alloy includes creep-strengthened ferritic steel and austenitic stainless steel, and the second alloy includes austenitic stainless steel.

[0022] Another aspect of the present disclosure encompasses any of the above aspects, wherein the first alloy includes creep-strengthened ferritic steel and austenitic stainless steel, and the second alloy includes superalloys.

[0023] One aspect of the present disclosure provides an additive manufacturing gradient transition joint (AM-GCTJ) comprising a mixture of a first alloy A and a second alloy B, wherein the first alloy A comprises a grid or grid pattern with gradually changing density, the grid or grid pattern having a first end and a second end, the grid or grid pattern comprising one or more pores, the one or more pores having a pore diameter in the range of about several tens of micrometers to about sub-millimeters, and the grid or grid pattern having a denser density at the second end than at the first end of the grid or grid pattern. The density of the grid or grid pattern is gradually changed by volume ratio from 0% to 100% by increasing the pore size up to the first end and decreasing the density of the grid or grid pattern as layers are laminated from the second end to the first end, and the second alloy B is added to the second end of the grid or grid pattern to form a composite material having a grid or grid pattern, and the composite material undergoes a smooth gradual 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 the above aspect, where the first alloy A includes creep strength enhanced ferritic steel and austenitic stainless steel, and the second alloy B includes austenitic stainless steel.

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

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

[0027] Combinations of two or more aspects described in this disclosure, including the aspects described in the Summary section of this invention, may also be used as embodiments not specifically described herein.

[0028] The details of one or more embodiments are described in the accompanying drawings and the following description. Other features, objects, and advantages will become apparent from the detailed description of the invention, the drawings, and the claims.

[0029] Regarding the other features of the present disclosure, a better understanding can be obtained by referring to the following detailed description in conjunction with the accompanying drawings that describe various embodiments of the present disclosure.

Brief Description of the Drawings

[0030] [Figure 1] It is a schematic diagram of an A-USC power generation plant component according to an embodiment of the present disclosure. [Figure 2] It is a perspective view of an A-USC header according to an embodiment of the present disclosure. [Figure 3]Figure 3A shows a schematic diagram of molten boundary or bond cracking and heat-affected zone (HAZ) damage in a dissimilar metal weld (DMW) according to one embodiment of the present disclosure, and Figure 3B shows a microscopic view of localized creep damage near the molten boundary or bond in a DMW according to one embodiment of the present disclosure, related to carbon deficiency. [Figure 4] A schematic flowchart of a method according to one embodiment of the present disclosure for additive manufacturing of an inclined composite material transfer joint according to one embodiment of the present disclosure is shown. [Figure 5] The graph shows the thermal load cycle employed in an Integrated Computational Weld Engineering (ICWE) model for transition joint design according to one embodiment of this disclosure. [Figure 6] The graphs show the ICWE simulation results for two AM-GCTJ designs in HDMW for Grade 91 steel and SS316 according to one embodiment of the present disclosure. [Figure 7] A perspective view is shown of an example in which an AM-GCTJ is used in the header of an A-USC power plant according to one embodiment of the present disclosure. [Figure 8] The following are schematic diagrams of various exemplary and non-limiting configurations of a grid or grid pattern according to one embodiment of the present disclosure. [Modes for carrying out the invention]

[0031] First, in order to clearly explain the subject matter of this disclosure, it is necessary to select certain terms when referring to and describing the characteristics, properties, and components related to additively manufactured gradient composite transition joints. Whenever possible, terms common in the art will be used, in accordance with their ordinary meanings. Unless otherwise stated, such terms should be interpreted broadly in accordance with the context of this application and the appended claims. It will be obvious to those skilled in the art that a component is often referred to using several different or overlapping terms. What is described as a single component in this specification may be described as consisting of multiple components in another context. Conversely, what is described as comprising multiple components in one part of this specification may be described as a single component in another part.

[0032] The terms used herein are for the purpose of describing specific embodiments and do not limit the scope of the disclosure. In this specification, even if a term is described in the singular form, it means the plural unless the context makes otherwise clear. In this specification, the terms “includes” and / or “compose” indicate the existence of a described feature, integer, step, operation, component, and / or part, and do not exclude the existence or addition of one or more other features, integers, steps, operations, components, parts, and / or groups thereof. The terms “optional” and “as appropriate” mean that the event or situation described following the term may or may not occur, or that the part or component described following the term may or may not exist, and such description includes the cases in which the event or situation may or may not occur, and the cases in which the part or component may or may not exist.

[0033] When one component or layer is said to be “located,” “engaged,” “connected,” or “joined” with another component or layer, it may be directly located, engaged, connected, or joined to that other component or layer, or there may be an intervening component or layer. In contrast, when one component is said to be “directly located,” “directly engaged,” “directly connected,” or “directly joined” with another component or layer, there is no intervening element or layer. Other terms used to describe relationships between components (e.g., “between” and “directly between,” “adjacent” and “directly adjacent,” etc.) are interpreted similarly. The term “and / or” as used herein encompasses any and all combinations of one or more of those described.

[0034] Robust dissimilar metal welds (DMWs) enable the realization of advanced ultra-supercritical (A-USC) systems. Robust DMWs can also be used to modify and refurbish existing A-USC power plants, contributing to their strengthening. As renewable energy becomes more affordable and integrated into the power grid, the power industry may need to modify and refurbish fossil coal and natural gas power plants to operate in flexible operating modes alongside renewable energy. Flexible operating modes allow for the use of the intermittent and unstable power generation inherent in renewable energy sources. Increased cyclical operating conditions in existing fossil fuel power plants can lead to failure in DMWs. Cyclical operation places DMWs under stress conditions. In certain cyclical operating conditions, the stress conditions may shift from creep-dominant stress to thermal creep fatigue-dominant stress. The weakened microstructure at the molten boundary or bond of the DMW may be exposed to high cyclical stresses due to the mismatch in the thermal expansion coefficients (CTEs) of the two different materials fused at the molten boundary or bond. As a result, the lifespan and performance of DMW may be reduced.

[0035] Therefore, in one embodiment of the present disclosure, the gradient functional composite transition joint is formed by an additive manufacturing process. In one embodiment of the present disclosure, an additively manufactured dissimilar metal weld (DMW) can provide a gradient composite transition joint. The gradient composite transition joint according to one embodiment of the present disclosure can satisfy the compositional property requirements of the DMW. The compositional property requirements according to one embodiment of the present disclosure include, but are not limited to, room temperature and high temperature strength, creep resistance, and corrosion resistance. Furthermore, in one embodiment of the present disclosure, the gradient composite transition joint can reduce stress concentration due to CTE migration between both sides of the additively manufactured dissimilar metal weld. Therefore, in one embodiment of the present disclosure, the additively manufactured dissimilar metal weld improves the crack resistance and thermal creep fatigue (TCF) resistance of the DMW.

[0036] In the A-USC system, superalloys can be used for components in light of beneficial compositional property requirements. In one embodiment of this disclosure, superalloys may include, but are not limited to, nickel (Ni)-based superalloys, iron (Fe)-based superalloys, cobalt (Co)-based superalloys, or combinations thereof. Furthermore, the A-USC material may include austenitic stainless steel (ASS), creep-strengthened ferritic steel (CSEFS), either alone or in combination with other materials. These materials can be placed in various DMW regions depending on the temperature and corrosion resistance requirements of the DMW of the A-USC structure. As a result, the DMWs between materials may mitigate the adverse effects of differences in CTE and contribute to the design, development, and manufacture of reinforced A-USC.

[0037] For example, without limiting the embodiments of this disclosure, the average wire CTE of alloy steel is on the order of approximately 16.2 μF / °C (9 μF / °F) in the temperature range of approximately 70°F to approximately 1100°F, and that of austenitic stainless steel is approximately 34.2 μF / °C (19 μF / °F). When the temperature changes from room temperature to approximately 595°C (1100°F), a thermal strain of approximately 0.1% occurs, generating thermal stress in the range of approximately 150 MPa, which is significantly higher than the amount of typical allowable operating stress. Since thermal stress is expected to relax over time (in months or years), it plays only a secondary role (creep dominant) compared to the applied stress in DMW performance under steady-state operating conditions of approximately 595°C (1100°F), which has been the practice in fossil fuel power plants for the past several decades. On the other hand, under thermal cycle operating conditions, such thermal strain continues to be generated and accumulated before it can be relaxed. Significant thermal strain accumulation and damage play a greater role under cyclic operation associated with thermal creep fatigue (TCF), potentially leading to premature failure of DMWs. Therefore, thermal stress in DMW joints presents new challenges for the safe operation of fossil energy plants under increased cyclic operation modes. Understanding and managing thermal stress in DMWs for future operations can facilitate new DMW installations and extend their service life.

[0038] DMW failure can be prevented by eliminating compositional changes across the melting boundary or bond area of ​​the DMW.

[0039] In DMW containing nickel-based filler materials, failure due to creep and / or creep fatigue cracking is caused by the morphology of carbides. DMW containing stainless steel filler materials exhibit failure due to creep and / or creep fatigue cracking that may form along austenite grain boundaries near the molten boundary or bond area.

[0040] Embodiments of this disclosure provide a method for manufacturing a gradient (or gradually changing) composite transition joint (GCTJ) member. In one embodiment, the GCTJ can be used for joining and connecting dissimilar metals when the gradient characteristics are suited to the different properties (such as different physical and thermal properties) of the metals of the parts to be joined by the GCTJ. In another embodiment, the GCTJ can cost-effectively solve the problem of premature failure of conventional dissimilar metal welds (DMWs) under increasing cycle operating conditions in fossil fuel power plants.

[0041] Additive-type gas-cooled turbine joints (AM-GCTJs) may be suitable for next-generation advanced ultra-supercritical (A-USC) power plants in one embodiment of this disclosure. In one embodiment, AM-GCTJs can be installed to enhance existing fossil fuel power plants by modifying or replacing conventional DMWs. This modification or replacement may enable safe and economical operation beyond the original design life in cycling mode.

[0042] For example, welding of dissimilar metals, including superalloys and creep-strengthened ferritic steel (CSEFS) or austenitic stainless steel (ASS), are two important types of DMWs that can find applications in next-generation A-USC systems.

[0043] In some non-limiting and exemplary embodiments, the austenitic stainless steel (ASS) is based on 18%Cr-8%Ni. In one embodiment of the present disclosure, the ASS may include, but is not limited to, Super304H or Sanicro25, and their equivalents.

[0044] In another non-limiting embodiment, CSEFS, also known as martensitic steel or superferritic steel, includes, but is not limited to, grade 91 and grade 92 steels. Furthermore, superalloys include, but is not limited to, Ni-based, Fe-based, and / or Co-based superalloys.

[0045] Additive-type gradient composite material transition joint (AM-GCTJ) In the A-USC system, the DMW can be provided between the features of a system formed from dissimilar materials, such as CSEFS (grade 91 / 92 in one embodiment) and ASS (Super304H in one embodiment), although this is not limited to the DMW. In Figures 1 and 2, the tube 10 is connected to the header 20 by a nipple weld 30 which may be located at the inlet of the final stage superheater / reheater. The design conditions for the superheater are approximately 387 bar / 640°C in the non-limiting embodiments of this disclosure. The DMW dimensions are approximately 40 mm outer diameter (OD) and approximately 8 mm thickness in the non-limiting embodiments of this disclosure. The DMW of Ni-based superalloy (740H or H0282 in one embodiment) and ASS (Sanicro25 in one embodiment) may be between the header 20 and the tube 10 at the nipple weld 30 at the outlet of the final stage superheater / reheater. The design conditions for the superheater are approximately 387 bar / 670°C. The DMW dimensions can be approximately 44 mm in outer diameter (OD) and 10 mm in thickness.

[0046] Potentially undesirable DMW characteristics can be mitigated in one embodiment of this disclosure by an additive manufacturing gradient composite transfer joint (AM-GCTJ) 300. One embodiment of the AM-GCTJ 300 according to one embodiment of this disclosure is shown in Figure 4.

[0047] Microstructural changes across the molten boundary or bond area of ​​DMW in the as-welded state can be due to abrupt chemical concentration gradients. Figure 3A shows the heat-affected zone (HAZ) between Grade 91 steel and Ni-based filler material. Figure 3B shows creep and / or creep fatigue cracking failure at the DMW molten boundary or bond area. Creep and / or creep fatigue cracking can occur along the molten boundary or bond area and HAZ between dissimilar alloys in DMW. Creep and / or creep fatigue cracking can be caused by at least one of residual stress due to CTE mismatch, external stress, and thermal stress. Thermal stress due to CTE mismatch can be significant. Failure may be accompanied by HAZ damage.

[0048] Figure 4 shows the additive manufacturing process for forming an additively manufactured gradient composite transfer member (AM-GCTJ) 300. First, an additively manufactured gradient composite transfer member (AM-GCTP) is formed. The AM-GCTP 300 contains a first alloy (alloy A) 100 and a second alloy (alloy B) 200. The GCTP is formed by a gradual gradient change in the mixture of alloy A100 and alloy B200 along its structure. The composition of the mixture of alloy A100 and alloy B200 is 100% alloy A100 at the first end to 100% alloy B200 at the second end, and in the region between those ends, it migrates at a controlled concentration from substantially all alloy B200 at the first end to all alloy A100 at the second end. Thus, alloy A100 and alloy B200 form a deliberately constructed composite material containing a mixture of alloy A100 and alloy B200. However, the mixture may contain other additives between these ends as appropriate.

[0049] The transition between alloy A100 and alloy B200 in the composite material, specifically the ratio or concentration of alloy A100 to alloy B200, gradually changes from the first end of AM-GCTP to the second end of AM-GCTP. This gradual change in concentration is intended to mitigate and reduce abrupt changes in the chemical properties and thermal stress of the DMW, such as those caused by differences in CTE.

[0050] After forming the AM-GCTP, the AM-GCTP may be placed between two structural members, as shown in Figures 1 and 2, and welded to them to form the AM-GCTJ300. In one embodiment, the AM-GCTJ300 can be formed between the Ni-based superalloy and the CSEFS in the DMW. Similarly, the AM-GCTJ300 can also be formed between the ASS and the CSEFS in the DMW.

[0051] Since the ends of AM-GCTJ300 have substantially the same chemical properties as the material of the structural member to which AM-GCTJ is to be welded, welding connecting the two structural members to AM-GCTJ300 is essentially performed between two materials with matching or compatible chemical properties, including matching CTEs. This homogeneous welding eliminates factors that cause premature failure of the DMW, such as changes in chemical composition at the molten boundary or bond area of ​​the DMW and thermal stress caused by mismatched CTEs.

[0052] Another embodiment involves manufacturing AM-GCTP by an additive manufacturing (AM) process to manufacture AM-GCTJ300. Referring to Figure 4A, the first process step includes forming a grid or grid pattern 101 from alloy A100. (See also Figure 8, which shows an exemplary and non-limiting grid or grid pattern 101 according to one embodiment of the present disclosure). In the exemplary embodiment, alloy A100 includes, but is not limited to, ASS. The grid or grid pattern 101 can be manufactured from alloy A100 by an additive manufacturing process. Such an additive manufacturing process includes, but is not limited to, at least one of selective laser melting (SLM) and selective laser sintering (SLS).

[0053] A grid or grid pattern 101 formed from alloy A100 contains pores 110. The dimensions of the pores 110 in the grid or grid pattern 101 can be changed. The cross-sectional dimensions of the pores 110 can be in the range of about several tens of micrometers to about sub-millimeters. The grid or grid pattern 101 may be densely formed at a first end and less densely formed at a second end. Density or concentration can be expressed as a volume ratio. The density / volume ratio gradually decreases the volume ratio of the grid or grid pattern 101 from about 0% to about 100%. This decrease in the volume ratio of the grid or grid pattern 101 can be achieved by increasing the dimensions of the pores 110 and decreasing the density of the grid or grid pattern 101 when additively manufacturing toward the upper end of the grid or grid pattern 101.

[0054] After forming a grid or grid pattern 101 by an additive manufacturing process, alloy B200 powder can be supplied to the grid or grid pattern 101. The alloy B200 powder includes, but is not limited to, grade 91 steel powder. The supply of alloy B200 powder is to the first end of the grid or grid pattern 101, i.e., the less dense end of alloy A100 (Figure 4B). The alloy B200 powder includes, but is not limited to, steel powder (e.g., grade 91 steel powder). After adding the alloy B200 powder, ultrasonic energy may be applied to the grid or grid pattern 100 to fill the inside of the grid or grid pattern 100 with alloy B200 powder, and the filling includes vibrating the alloy B200 powder. The ultrasonic energy can be used to ultrasonically vibrate the alloy B200 powder, causing it to fall (shake) through the pores 110 of the lattice or lattice pattern 101 towards the densest end of the alloy A100 in the lattice or lattice pattern 101, thereby filling the lattice with alloy B200 powder.

[0055] Next, the grid or grid pattern having alloy A100 and alloy B200 can be subjected to hot isostatic pressing (HIP). The HIP treatment (Figure 4C) is performed to densify the alloy A100 and alloy B200 within the grid or grid pattern 101. The HIP treatment can achieve a density of approximately 100% of alloy A100 and alloy B200 in the grid or grid pattern, thereby forming a composite material. After the HIP treatment, the gradient composite material transition of alloy A100 and alloy B200 in the grid or grid pattern is achieved from the first end of the grid or grid pattern 101 to the second end of the grid or grid pattern 101. In one embodiment of the present disclosure, the gradient composite material transition area is approximately 0-100% alloy A100 to alloy B200 from the first end to the second end of the grid or grid pattern 101.

[0056] The Integrated Computational Welding Engineering (ICWE) modeling tool from Oak Ridge National Laboratory (ORNL) can be used in the design of AM-GCTJ300. ICWE can be used to evaluate the thermal stress caused by thermal cycling loads under operating conditions for dissimilar metal welds (DMWs). Several advantages of AM-GCTJ300 are summarized below, along with an example. An exemplary and non-limiting application was to weld and prepare a piping system with DMWs formed from Grade 91 steel to stainless steel 316 (see Figure 5). A straight section of the piping system with DMWs was used to join two pipes, with an outer diameter (OD) of approximately 5.1 mm (2 inches) and a wall thickness of approximately 0.95 mm (3 / 8 inch) (dimensions commonly found in fossil fuel plants). The thermal cycling load profile used in the simulation is shown in Figure 6. The temperature was raised from ambient temperature to the operating temperature of approximately 650°C in about 2 hours. The modeling system was then held at the operating temperature for 7 days and then cooled to ambient temperature in 2 hours. By repeatedly performing this thermal load cycle modeling, we simulated operation and calculated the cumulative effect of the thermal cycle load.

[0057] Figure 8 shows an exemplary and non-limiting grid or grid pattern 101. The grid 100 and pores 101 of alloy A can be supplied in any configuration, dimensions, cross-section and dimensions, and the density and pore dimensions are supplied as described herein. Thus, the configuration, dimensions, cross-section and dimensions of the grid or grid 100 and pores 101 of alloy A can be varied in any way, as long as the density decreases gradually by increasing the pore dimensions from the first end to the second end and decreasing the density of the grid or grid pattern 101 while additively manufacturing the grid or grid pattern 101, insofar as the first end is denser than the second end of the grid or grid pattern 101 and at least one of these is done.

[0058] Furthermore, graded transition joints (GTJs) can be manufactured using various manufacturing technologies that can be easily scaled to mass production. Compared with conventional GTJ technologies, the AM-GCTJ300 approach according to one embodiment of this disclosure has several technical advantages.

[0059] AM-GCTJ300, according to one embodiment of this disclosure, produces a composite material that retains the characteristics (thermal properties and physical properties, etc.) of alloy A100 and alloy B200. In conventional GTJ technology, alloy A100 and alloy B200 are melted together using either wire or powder to construct a transition joint layer by layer. Melting and mixing two different alloys in varying ratios is time- and resource-intensive, and can result in complex and irregular microstructures, potentially leading to unpredictable microstructures and unknown or unpredictable properties (such as thermal properties and physical properties). As an example of such an unpredictable microstructure, melting Grade 91 and 304H in a 50 / 50 ratio produces a "new" material with uncertain microstructural stability and high-temperature performance, and potential solidification defect problems.

[0060] Furthermore, in one embodiment of this disclosure, alloys A and B200 are not melted together, in contrast to conventional welding methods. According to this disclosure, alloys A100 and B200 are bonded together by a solid-phase HIP process. The solid-phase HIP process (HIP treatment) forms a "composite" material of alloys A100 and B200. Therefore, the HIP-treated composite material of alloys A100 and B200 does not introduce the metallurgical complexity of a molten "new" A+B alloy.

[0061] After appropriate heat treatment, AM-GCTJ300 can be used as an intermediate connection between two structural members having properties similar to alloys A100 and B200. Fusion welding may be performed at both ends of the DMW as needed. For example, fusion welding may be performed at the boundary, molten boundary, or bond between two structural members having properties similar to alloys A100 and B200, resolving previous problems that occurred at the molten boundary or bond of the DMW, such as CTE mismatch.

[0062] An additional technical benefit obtained in one embodiment of this disclosure is a smooth transition between alloy A100 and alloy B200. The smooth transition is gradual, reducing and mitigating problems associated with CTE mismatch. Reduced CTE mismatch can potentially improve the service life of turbomachinery components, including during cyclic operation.

[0063] Another technical effect of this embodiment is that the process and welding can enhance control over the DMW composition. Furthermore, in one embodiment of this disclosure, a process including the additive manufacturing of the grid and grid pattern 101 can achieve a variety of DMW shapes that cannot be achieved with other welding processes. Thus, in one embodiment of this disclosure, the scale-up problem is mitigated when producing the large quantities of GTJs required for the A-USC system. Furthermore, the service life of existing fleets can be extended by the AM-GCTJ300 according to one embodiment of this disclosure.

[0064] This embodiment provides an additively manufactured gradient composite transition joint for dissimilar metal welding in advanced ultra-supercritical power plants. Another embodiment of this disclosure provides a method for manufacturing an additively manufactured gradient composite transition joint ("AM-GCTJ300").

[0065] The present invention has been described above with reference to advanced ultra-supercritical (A-USC) power plants and related alloys. However, in one aspect of this disclosure, the technical idea and embodiments can also be used for other dissimilar metal welding (DMW). Furthermore, in a further aspect of the present invention, the technical idea and embodiments can be used for other applications or industries other than power plants.

[0066] In light of the above teachings of this disclosure, it will be apparent to those skilled in the art that numerous modifications and variations are possible to the examples and embodiments described herein. The disclosed examples and embodiments are presented solely for illustrative purposes. Other alternative embodiments may include some or all of the features disclosed herein. Accordingly, all such modifications and alternative embodiments are within the technical scope of the present invention.

[0067] Furthermore, disclosure regarding the range of the numerical values ​​includes all numerical values ​​within that range, including upper and lower limits.

[0068] It will be apparent to those skilled in the art that modifications can be made to the embodiments described herein without departing from the technical spirit of the present invention. Accordingly, the present invention is not limited to the specific embodiments disclosed, but encompasses modifications that fall within the technical spirit and scope of the present invention as defined by the claims. [Explanation of Symbols]

[0069] 100 First alloy 101 Grid or grid pattern 110 pores 200 Second alloy 300 Additive Manufacturing Inclined Composite Material Transition Joint

Claims

1. A method for manufacturing an additively manufactured inclined composite material transition joint (300), wherein the method is A step of preparing a lattice or lattice pattern (101) from a first alloy A (100), wherein the lattice or lattice pattern (101) includes pores (110) within the lattice or lattice pattern, A step of constructing a grid or grid pattern (101) from a first end to a second end, wherein the grid or grid pattern (101) has a denser density at the first end than at the second end, and the density of the grid or grid pattern (101) is gradually reduced 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 grid pattern (101) while additively manufacturing the grid or grid pattern (101). The steps include adding the second alloy B (200) powder to the first end of the lattice or lattice pattern (101), A step of filling a lattice or lattice pattern (101) with a second alloy B (200) powder from the first end toward the second end, In an additive manufacturing gradient composite material transfer joint (300), the step of forming a composite material of a first alloy A (100) and a second alloy B (200) powder, The steps include: densifying the composite material by subjecting it to a hot hydrostatic press (HIP); A method comprising a second alloy B (200) powder having a concentration that gradually changes from the first end to the second end of the additively manufactured inclined composite material transition joint (300).

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

3. The method according to claim 1 or 2, wherein the filling step includes vibrating the second alloy B to cause it to fall from the first end to the second end of the grid or grid pattern (101).

4. The method according to any one of claims 1 to 3, wherein the preparation step includes preparing the grid or grid pattern (101) by additionally constructing the grid or grid pattern (101) from a first end to a second end.

5. The method according to any one of claims 1 to 4, wherein the pore (110) has a pore size in the range of several tens of micrometers to sub-millimeters in diameter.

6. The method according to any one of claims 1 to 5, wherein the step of vibrating the second alloy B(200) powder toward the second end of the lattice or lattice pattern (101) includes the step of ultrasonically vibrating the second alloy B(200) powder.

7. The method according to any one of claims 1 to 6, wherein the second alloy B (200) powder is gradually varied from a concentration of 0% at the second end of the grid or grid pattern (101) to a concentration of 100% at the first end of the grid or grid pattern (101).

8. The method according to any one of claims 1 to 7, wherein the first alloy A (100) comprises austenitic stainless steel and the second alloy B (200) comprises creep-strengthened ferritic steel.

9. The method according to any one of claims 1 to 7, wherein the first alloy A (100) comprises creep-strengthened ferritic steel and the second alloy B (200) comprises austenitic stainless steel.

10. The method according to any one of claims 1 to 7, wherein the first alloy A (100) comprises creep-strengthened ferritic steel and the second alloy B (200) comprises a superalloy.

11. A laminated gradient composite transition joint (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 grid pattern (101) in which the density of the first alloy A (100) gradually changes, the grid or grid pattern (101) has a first end and a second end, the grid or grid pattern (101) contains one or more pores, and the one or more pores have a pore diameter in the range of several tens of microns to sub-millimeters. The grid or grid pattern (101) has a denser density at the second end than at the first end of the grid or grid pattern (101), and the density of the grid or grid pattern (101) is gradually changed from 0% to 100% by volume ratio by increasing the pore size from the second end to the first end and decreasing the density of the grid or grid pattern (101) as layers are additionally constructed from the second end to the first end. A second alloy B (200) is added to the second end of a grid or grid pattern (101) to form a composite material having a grid or grid pattern (101), wherein the composite material has an alloy B concentration ranging from 0% alloy B at the second end of the additively manufactured gradient composite material transition joint to 100% alloy B at the first end of the additively manufactured gradient composite material transition joint (300).

12. The additively manufactured gradient composite transition joint (300) according to claim 11, wherein the first alloy A (100) comprises creep-strengthened ferritic steel and the second alloy B (200) comprises austenitic stainless steel.

13. The additively manufactured gradient composite transition joint (300) according to claim 11, wherein the first alloy A (100) comprises creep-strengthened ferrite steel and the second alloy B (200) comprises a superalloy.

14. A laminated gradient composite transition joint (300) according to any one of claims 11 to 13, wherein a first alloy A (100) is configured to be welded at a first end of the transition joint, and a second alloy B (200) is configured to be welded at a second end of the transition joint.

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