Search Results for design process

The advancement of additive manufacturing (AM) technology has heightened interest in producing components from nickel-based superalloys for high-temperature applications; however, developing high gamma prime (γ’) strengthened alloys suitable for AM at temperatures of 1000°C or higher poses significant challenges due to their “non-weldable” nature. Traditional compositions intended for casting or wrought processes are often unsuitable for AM due to their rapid heating and cooling cycles, leading to performance compromises. This study introduces ABD-1000AM, a novel high gamma prime Ni-based superalloy designed using the Alloys-by-Design computational approach to excel in AM applications at elevated temperatures. Tailored for AM, particularly powder bed fusion, ABD-1000AM demonstrates exceptional processing capability and high-temperature mechanical and environmental performance at 1000°C. The study discusses the alloy design approach, highlighting the optimization of key performance parameters, composition, and process-microstructure-performance relationships to achieve ABD-1000AM’s unique combination of processability and creep resistance. Insights from ABD-1000AM’s development inform future directions for superalloy development in complex AM components.

This paper addresses thermal shock cracking, a critical damage mechanism for pressurized components, currently absent from design and fitness-for-purpose codes. It analyzes the crack growth mechanisms and proposes guidelines for designing vessels to resist thermal shock crack initiation and for assessing the significance of existing cracks discovered during service. Thermal shock crack growth is influenced by factors like shock severity, applied mechanical stress, and the corrosive environment. In service, cracks often arrest and pose minimal risk. This work explores a broader range of conditions, offering a less conservative approach compared to existing EPRI guidelines.

The aspiration to deploy Nb-based alloys as viable upgrade for Ni-based superalloys is rooted in their potential for superior performance in high-temperature applications, such as rocket nozzles and next-generation turbines. However, realizing this goal requires overcoming formidable design hurdles, including achieving high specific strength, creep resistance, fatigue, and oxidation resistance at elevated temperatures, while preserving ductility at lower temperatures. Additionally, the requisite for alloy bond-coatings, to ensure compatibility with coating materials, further complicates the design process. QuesTek Innovations has its Integrated Computational Materials Engineering (ICME) technologies to design a superior performance high-temperature Nb-based superalloy based on solid solution and precipitation strengthening. Additionally, utilizing a statistical learning method from very limited available data, QuesTek engineers were able to establish physics-based material property models, enabling accurate predictions of equilibrium phase fraction, DBTT, and creep properties for multicomponent Nb alloys. With the proven Materials by Design methodology under the ICME framework, QuesTek successfully designed a novel Nb superalloy that met the stringent design requirements using its advanced ICMD materials modeling and design platform.

This paper discusses the design of a prototype for accurately inspecting the degree of wall thinning in boiler tubes, which plays a critical role in power plants. The environment in power plants is characterized by extreme conditions such as high temperatures, high pressure, and ultrafine dust (carbides), making the maintenance and inspection of boiler tubes highly complex. As boiler tubes are key components that deliver high-temperature steam, their condition critically affects the efficiency and safety of the power plant. Therefore, it is essential to accurately measure and manage the wall thinning of boiler tubes.

The pursuit of reduced emissions and increased efficiency in ultra-critical steam plants has led to the investigation of systems operating at temperatures up to 720°C and pressures up to 300 bars, necessitating the use of nickel-based alloys. This study focuses on control valves manufactured from Alloy 617, designed for steam temperatures of 725°C, examining specific challenges in their design and manufacture, including machining and welding processes. Initial operational experiences with the valve at 725°C are presented, along with ongoing tribological investigations of nickel-based alloys at 725°C, as standard material pairings with optimized wear behavior are unsuitable at such elevated temperatures. These investigations aim to develop material pairings that can maintain good wear behavior under these extreme conditions.

The Alloys-by-Design approach, involving large-scale CALPHAD calculations to search a compositional range, has been used to isolate a suitable nickel-based superalloy for additive manufacturing (AM) by optimizing the trade-off between processability and increasing strength. This has been done in response to the limited focus on development of new superalloys designed to overcome the limitations of the AM process, specifically the high defect density of parts made from high-performance alloys. Selected compositions have been made using gas atomization, and laser powder-bed fusion AM trials were performed. The resulting properties were evaluated in the as-processed, heat treated and thermally exposed conditions. The assessment, combined with characterization techniques including scanning electron microscopy and atom probe tomography, rationalizes a temperature capability up to and above 850 °C, and demonstrate the opportunity to develop alloys with properties beyond the current state of the art.

Recently, single-phase flow accelerated corrosion (FAC) has been found extensively in Thailand, especially in single shaft combined cycle power plant heat recovery steam generators, the design of which are compact and cannot be easily accessed for service. This takes at least one week for repairing and costs at least half a million dollar per shutdown. In this paper, the investigation of the single-phase FAC in a high-pressure economizer of a combined cycle power plant is demonstrated. Water chemical parameters such as pH and dissolved oxygen are reviewed, the process simulation of the power plant is performed to capture risk areas for the FAC. A computational fluid dynamics study of the flow is done to understand the flow behavior in the damaged tubes next to an inlet header. Some modifications such as flow distributor installation and tube sleeve installation were performed for short-term solutions. Moreover, new economizer headers are designed with low alloy material to mitigate the problem. The installation process of the newly fabricated headers is finally described. The findings in this paper serve as a guideline for FAC risk assessment, FAC investigation and mitigation, and service in compact heat recovery steam generators.

Advanced 700°C-class steam turbines demand austenitic alloys for superior creep strength and oxidation resistance beyond 650°C, exceeding the capabilities of conventional ferritic 12Cr steels. However, austenitic alloys come with a higher coefficient of thermal expansion (CTE) compared to 12Cr steels. To ensure reliability, operability, and performance, these advanced turbine alloys require low CTE properties. Additionally, for welded components, minimizing CTE mismatch between the new material and the welded 12Cr steel is crucial to manage residual stress. This research investigates the impact of alloying elements on CTE, high-temperature strength, phase stability, and manufacturability. As a result, a new material, “LTES700R,” was developed specifically for steam turbine rotors. LTES700R boasts a lower CTE than both 2.25Cr steel and conventional superalloys. Additionally, its room-temperature proof strength approaches that of advanced 12Cr steel rotor materials, while its creep rupture strength around 700°C significantly surpasses that of 12Cr steel due to the strengthening effect of gamma-prime phase precipitates. To assess the manufacturability and properties of LTES700R, a medium-sized forging was produced as a trial run for a turbine rotor. The vacuum arc remelting process was employed to minimize segregation risk, and a forging procedure was meticulously designed using finite element method simulations. This trial production resulted in a successfully manufactured rotor with satisfactory quality confirmed through destructive evaluation.

As the demand for worldwide electricity generation grows, pulverized coal steam generator technology is expected to be a key element in meeting the needs of the utility power generation market. The reduction of greenhouse gas emissions, especially CO 2 emissions, is vital to the continued success of coal-fired power generation in a marketplace that is expected to demand near-zero emissions in the near future. Oxycombustion is a technology option that uses pure oxygen, and recycled flue gas, to fire the coal. As a result, this system eliminates the introduction of nitrogen, which enters the combustion process in the air, and produces a highly-concentrated stream of CO 2 that can readily be captured and sequestered at a lower cost than competing post-combustion capture technologies. Oxycombustion can be applied to a variety of coal-fired technologies, including supercritical and ultra-supercritical pulverized coal boilers. The incorporation of oxycombustion technology in these systems raises some new technical challenges, especially in the area of advanced boiler materials. Local microclimates generated near and at the metal interface will influence and ultimately govern corrosion. In addition, the fireside corrosion rates of the boiler tube materials may be increased under high concentration oxygen firing, due to hotter burning coal particles and higher concentrations of SO 2 , H 2 S, HCl and ash alkali, etc. There is also potential to experience new fouling characteristics in the superheater and heat recovery sections of the steam generator. The continuous recirculation of the flue gases in the boiler, may lead to increasing concentrations of deleterious elements such as sulfur, chlorine, and moisture. This paper identifies the materials considerations of oxycombustion supercritical and ultrasupercritical pulverized coal plants that must be addressed for an oxycombustion power plant design.

A modified version of Alloy 706, designated FENIX-700, was developed using the CALPHAD method to improve high-temperature stability above 700°C. The new alloy features reduced Nb and increased Al content, relying on γ' (Ni 3 Al) strengthening while eliminating γ'' (Ni 3 Nb), δ, and η phases. This modification improved both creep temperature capability (from 650°C to 700°C) and segregation properties. Successful manufacturing trials included a 760 mm² forging shaft using triple melt processing and a 1050 mm ESR ingot, demonstrating industrial viability. The study also explores compatible Ni-base welding materials for joining FENIX-700 to 12% Cr ferritic steel in 700°C class steam turbine applications.

The use of high-nickel superalloys has greatly increased among many industries. This is especially the case for advanced coal-fired boilers, where the latest high temperature designs will require materials capable of withstanding much higher operating temperatures and pressures than current designs. Inconel alloy 740H (UNS N07740) is a new nickel- based alloy that serves as a candidate for steam header pipe and super-heater tubing in coal-fired boilers. Alloy 740H has been shown to be capable of withstanding the extreme operating conditions of an advanced ultra-super-critical (AUSC) boiler, which is the latest boiler design, currently under development. As with all high nickel alloys, welding of alloy 740H can be very challenging, even to an experienced welder. Weldability challenges are compounded when considering that the alloy may be used in steam headers, where critical, thick-section and stub-to-header weld joints are present. This paper is intended to describe the proper procedures developed over years of study that will allow for ASME code quality welds in alloy 740H with matching composition filler metals.

India's current installed power generating capacity is about 225,000 MW, of which about 59% is coal based. It is projected that India would require an installed capacity of over 800,000 MW by 2032. Coal is likely to remain the predominant source of energy in India till the middle of the century. India is also committed to reducing the CO 2 emission intensity of its economy and has drawn up a National Action Plan for Climate Change, which, inter alia, lays emphasis on the deployment of clean coal technologies. With this backdrop, a National Mission for the Development of Advanced Ultra Supercritical Technology has been initiated. The Mission objectives include development of advanced high temperature materials, manufacturing technologies and design of equipment. A corrosion test loop in an existing plant is also proposed. Based on the technology developed, an 800 MW Demonstration A-USC plant will be established. Steam parameters of 310 kg/cm 2 , 710 °C / 720 °C have been selected. Work on selection of materials, manufacture of tubes, welding trials and design of components has been initiated. The paper gives details of India's A-USC program and the progress achieved.

To improve the economics of critical components, such as receivers and heat exchangers, for Generation 3 (Gen 3) concentrating solar power (CSP) plants, research was conducted to understand how manufacturing impacts the high-temperature performance of various tube production routes. Gen 3 CSP components are expected to require the use of heat-resistant nickel- based alloys due to the elevated operating temperatures in designs carrying molten salt or supercritical CO 2 . INCONEL alloy 740H (alloy 740H) was investigated as an alternative to UNS N06230 (alloy 230) as it possesses superior high-temperature creep strength which can lead to overall reductions in material cost. A key challenge is understanding how autogenous seam welding with and without re-drawing can be used to manufacture thin-wall tubing for CSP receivers and heat-exchangers to further reduce costs over traditional seamless production routes. Alloy 740H welded tube was successfully fabricated and re-drawn to several relevant tube sizes. Since traditional mechanical testing samples could not be removed from the thin-wall tubing, full-sized tubes were used for tensile, fatigue, and vessel testing (internally pressurized creep- rupture) which was critical to understanding the weld performance of the manufactured product forms. The generated vessel test data exhibited a creep strength reduction when compared to wrought product with no clear trend with temperature or test duration. It was found that redrawing the welded tubes improved the creep strength to approximately 82% of the wrought material performance and elevated temperature tensile and fatigue behavior exceeded 85% of the design minimums. Detailed, post-test characterization found that nano-sized carbides formed during the laser seam-welding process remained stable after multiple solution-annealing steps, which restricted grain growth, and impacted the time-dependent performance. This paper will focus on the time-dependent behavior of the examined welded and redrawn tubes, supporting metallographic evidence, and give perspective on future considerations for using alloy 740H in CSP components.

INCONEL 740H has been developed by Special Metals for use in Advanced Ultra Super Critical (A-USC) coal fired boilers. Its creep strength performance is currently amongst the ‘best in class’ of nickel based alloys, to meet the challenge of operating in typical A-USC steam temperatures of 700°C at 35 MPa pressure. Whilst the prime physical property of interest for INCONEL 740H has been creep strength, it exhibits other physical properties worthy of consideration in other applications. It has a thermal expansion co-efficient that lies between typical values for Creep Strength Enhanced Ferritic (CSEF) steels and austenitic stainless steels. This paper describes the validation work in support of the fabrication of a pipe transition joint that uses INCONEL 740H pipe, produced in accordance with ASME Boiler Code Case 2702, as a transition material to join P92 pipe to a 316H stainless steel header. The paper gives details of the material selection process, joint design and the verification process used for the joint.

The manufacture of large, complex components for ultra-supercritical and oxy-combustion applications will be extremely costly for industry over the next few decades as many of these components will be manufactured from expensive, high strength, nickel-based alloys casting and forgings. The current feasibility study investigates the use of an alternative manufacturing method, powder metallurgy and hot isostatic processing (PM/HIP), to produce high quality, and potentially less expensive components for power generation applications. Benefits of the process include manufacture of components to near-net shapes, precise chemistry control, a homogeneous microstructure, increased material utilization, good weldability, and improved inspectability.

The voestalpine foundry group, operating at locations in Linz and Traisen, Austria, specializes in heavy steel casting components ranging from 1 to 200 tons for power generation, oil and gas, chemical processing, and offshore applications. Their manufacturing expertise encompasses high-alloyed martensitic 9-12% Cr-steels and nickel-based Alloy 625, particularly for ultra-supercritical (USC) and advanced USC power generation systems operating at temperatures from 600°C to over 700°C. The production of these complex, thick-walled components relies on advanced thermodynamic calculation and simulation for all thermal processes, from material development through final casting. The foundries’ comprehensive capabilities include specialized melting, molding, heat treatment, non-destructive testing, and fabrication welding, with particular emphasis on joining dissimilar cast, forged, and rolled materials. Looking toward future innovations, the group is exploring additive manufacturing for mold production and robotic welding systems to enhance shaping and surface finishing capabilities.

This study explores the expanded applications of Alloy J513, a high-performance material traditionally used in cast engine valvetrain components, for powder metallurgy and surface cladding applications. While already recognized for its superior heat and wear resistance at a lower cost compared to cobalt-based hardfacing materials, J513 demonstrates additional advantages in powder metallurgy applications due to its ability to achieve desired powder characteristics through atomization without requiring post-atomization annealing. Through experimental investigation based on fundamental metallurgical principles and cladding engineering processes, the presented research demonstrates J513’s exceptional weldability and favorable weldment structure compared to conventional cobalt-based alloys. The study establishes crucial relationships between weldment behavior and unit energy input, providing valuable insights for advanced cladding techniques while highlighting J513’s potential as a sustainable alternative to traditional nickel- and cobalt-based alloys in various manufacturing processes, including surface overlay and additive manufacturing.

A failure of the upper casing of the circulation pump led to a big damage in the PP Staudinger unit 5 on 12th of May 2014. According to the §18(2) BetrSichV an extensive root cause analysis (RCA) was started. From the beginning on different lines of activities were initiated to handle the situation with the required diligence. Decisions were made, taking into account safety regulations, possibility of repair and best practice engineering. Following the board decision to repair the unit 5, a lot of detailed work was done. All of the performed work packages were linked in different timelines and needed to meet in the key points. Consequently it was a challenge to achieve the agreed date of unit 5 restart on 15th of January 2015. The unit restart on the targeted date was a proof of the excellent collaboration between all involved parties. The presentation gives a summarizing overview about the damage, the main results of the RCA and the repair activities.

A United States-based consortium has successfully completed the Advanced Ultra-Supercritical Component Test (A-USC ComTest) project, building upon a 15-year materials development effort for coal-fired power plants operating at steam temperatures up to 760°C. The $27 million project, primarily funded by the U.S. Department of Energy and Ohio Coal Development Office between 2015 and 2023, focused on validating the manufacture of commercial-scale components for an 800 megawatt power plant operating at 760°C and 238 bar steam conditions. The project scope encompassed fabrication of full-scale components including superheater/reheater assemblies, furnace membrane walls, steam turbine components, and high-temperature transfer piping, utilizing nickel-based alloys such as Inconel 740H and Haynes 282 for high-temperature sections. Additionally, the team conducted testing to secure ASME Code Stamp approval for nickel-based alloy pressure relief valves. This comprehensive effort successfully established technical readiness for commercial-scale A-USC demonstration plants while developing a U.S.-based supply chain and providing more accurate cost estimates for future installations.

ENCIO (European Network for Component Integration and Optimization) is a European project aiming at qualifying materials, components, manufacturing processes, as well as erection and repair concepts, as follow-up of COMTES700 activities and by means of erecting and operating a new Test Facility. The 700°C technology is a key factor for the increasing efficiency of coal fired power plants, improving environmental and economic sustainability of coal fired power plants and achieving successful deployment of carbon capture and storage technologies. The ENCIO-project is financed by industrial and public funds. The project receives funding from the European Community's Research Fund for Coal and Steel (RFCS) under grant agreement n° RFCPCT-2011-00003. The ENCIO started on 1 July 2011. The overall project duration is six years (72 months), to allow enough operating hours, as well as related data collection, investigations and evaluation of results. The ENCIO Test Facility will be installed in the “Andrea Palladio” Power Station which is owned and operated by ENEL, located in Fusina, very close to Venice (Italy). The Unit 4 was selected for the installation of the Test Facility and the loops are planned for 20.000 hours of operation at 700°C. The present paper summarizes the current status of the overall process design of the thick-walled components, the test loops and the scheduled operating conditions, the characterizations program for the base materials and the welded joints, like creep and microstructural analysis also after service exposure.