bluuebunny/crossref_metadata_2025_split huggingface dataset:
Geological study of the Khutti Khola Watershed, Siraha District, eastern Nepal
Authors: Acharya Manjari , Dhungana Sumitra , Khadka Goma , Sah Ram Bahadur , Paudayal Khum Narayan , Paudyal Kabi Raj 
Published: February 2025

This study presents a detailed geological mapping at a 1:25,000 scale, aiming to establish the stratigraphy and geological structures of Khutti Khola Watershed, Lahan and Dhangadhi Municipalities, Siraha district. The Sub-Himalayan rock sequence of the study area is divided into the Lower Siwalik, Middle Siwalik, and Upper Siwalik units. The Middle Siwalik is further subdivided into the Middle Siwalik 1 and the Middle Siwalik 2. Structurally, the Main Frontal Thrust (MFT) divides the Terai Plain to the southern section and the Siwalik Group to the northern section. The Terai plain is subdivided into the Bhabar Zone and the Middle Terai in the studied section.Lithologically, the study area is characterized by sedimentary rocks, including siltstone, variegated mudstone, and fine-to coarse-grained sandstone. Features like the slickensides on sandstone, shear zones with many landslides, fault breccias, and sudden topographic breakages are field evidence to locate the MFT in the field. The sandstone in the Lower and the Middle Siwalik are classified as Feldspathic Wacke while those in the Upper Siwalik are as Lithic Arenite.
Spatial analysis of causative factors for landslide susceptibility mapping in parts of Makwanpur District, central Nepal
Authors: Silwal Champak Babu , Sigdel Ashok , Subedi Pratima , Acharya Subash , Chamlagain Deepak 
Published: February 2025

Landslides pose a persistent and severe risk, frequently resulting in substantial harm to both people and infrastructures in Nepal. Understanding the underlying cause-and-effect dynamics of these events is crucial for effective mitigation measures to minimize their impacts. This research delves into assessing the susceptibility to landslides in the Thaha, Bhimphedi, Kailash, and Indrasarobar Rural Municipalities of the Makawanpur district. Considering the area's predisposition to landslides and soil erosion, exacerbated by the highly dissected topography and monsoon rainfall, this region is critically important for landslide susceptibility mapping. Using the satellite and aerial images, an inventory of 230 landslides was prepared. A total of nine landslide influencing factors including slope, aspect, curvature, distance to road, distance to stream, landuse/landcover, topographic position index, lithology, and lineament density were integrated to produce the landslide susceptibility index using the Analytic Hierarchy Process (AHP). Landslide susceptibility map thus generated was divided into five classes ranging from very low to very high susceptible zones. Validation of the susceptibility map was done using the landslide inventory, where the area under the Receiver Operating Characteristic (ROC) curve indicated a success rate of 0.727, demonstrating a commendable accuracy in predicting landslide occurrences. Similarly, the landslide density along with different susceptibility classes also indicate better performance to predict the susceptible zone. This susceptibility map can be very useful for planning the effective landslide disaster response and mitigation in the study area.
Creep Properties of Carbon and Nitrogen Free Austenitic Alloys for USC Power Plants
Authors: Muneki S. , Okubo H. , Abe F. 
Published: February 2025

Abstract
Various carbon and nitrogen free martensitic alloys were produced for the application which required long time creep properties at high temperatures. But they were easy transformed to austenite phase before the creep tests because of low Ac1 temperature. In this paper, a new attempt has been demonstrated using carbon and nitrogen free austenitic alloys strengthened by intermetallic compounds. We choose Fe-12Ni-9Co-10W-9Cr-0.005B based alloy. Furthermore, we discussed about creep characteristics among the wide range of the testing conditions more over 700°C and steam oxidation resistance to confirm the possibility of the alloys for the future USC power plants under the severe environments.
Development of High Strength HCMA (1.25Cr-0.4Mo-Nb-V) Steel Tube
Authors: Nakashima T. , Miyata K. , Hirata H. , Igarashi M. , Iseda A. 
Published: February 2025

Abstract
Improvement of thermal efficiency of new power plants by increasing temperature and pressure of boilers has led us to the development of high creep strength steels in the last 10 years. HCMA is the new steel with base composition of 1.25Cr-0.4Mo-Nb-V-Nd, which has been developed by examining the effects of alloying elements on microstructures, creep strength, weldability, and ductility. The microstructure of the HCMA is controlled to tempered bainite with low carbon content and the Vickers hardness value in HAZ is less than 350Hv to allow the application without preheating and post weld heat treatment. The HCMA tube materials were prepared in commercial tube mills. It has been demonstrated that the allowable stress of the HCMA steel tube is 1.3 times higher than those of conventional 1%Cr boiler tubing steels in the temperatures range of 430 to 530°C. It is noted that creep ductility has been drastically improved by the suitable amount of Nd (Neodymium)-bearing. The steam oxidation resistance and hot corrosion resistance of the HCMA have been proved to be the same level of the conventional 1%Cr and 2%Cr steels. It is concluded that the HCMA has a practical capability to be used for steam generator tubing from the aspect of good fabricability and very high strength. This paper deals with the concept of material design and results on industrial products.
Investigating the Strain Limits of Cold Formed, High Temperature Austenitic Materials for Fabricating USC Boiler Components
Authors: Mohn Walt , Stanko Greg 
Published: February 2025

Abstract
The construction of highly efficient Ultra Supercritical (USC) boiler systems to operate with steam temperatures up to 760°C (1400°F) and with steam pressures up to 34.5 MPa (5000 psi) will require the use of advanced high temperature, high strength materials. As part of a 5-year project to qualify advanced boiler materials for USC power plants, a number of austenitic materials have been selected for further development and use in USC boiler systems, including alloys 230, 740, CCA 617, HR6W, and Super 304H. In one task of this project, boiler fabrication guidelines appropriate for the use of these alloys were investigated. Because it is recognized that cold formed and mechanically strained austenitic materials can degrade in material creep strength, a study to investigate the limits of strain and temperature exposure for the USC alloys was undertaken. An objective of this work was to determine for each USC alloy a relationship between the level of cold strain and the conditions of time and temperature that will cause recrystallization and significant microstructural change. The ultimate goal of this work was to determine limits of strain, due to cold forming, that can be tolerated before heat treatment is required, similar to those limits provided for the austenitic materials (e.g., 300-series stainless steels, alloy 800H) in Table PG-19 in Section I of the ASME Boiler and Pressure Vessel Code. This paper will describe the technical approach for 1) preparing specimens having discrete cold strains ranging from about 1 to 40 percent, 2) exposing these strained specimens for selected times at various elevated temperatures, 3) identifying the onset of recrystallization in the microstructures of the exposed specimens, and 4) establishing a useful engineering method to predict conditions for the onset of recrystallization in the USC alloys using the experimental results.
Creep Properties and Strengthening Mechanisms In 23Cr-45Ni-7W (HR6W) Alloy and Ni-Base Superalloys For 700°C A-USC Boilers
Authors: Semba H. , Okada H. , Igarashi M. 
Published: February 2025

Abstract
The development of materials technologies for piping and tubing in advanced ultrasupercritical (A-USC) power plants operating at steam temperatures above 700°C represents a critical engineering challenge. The 23Cr-45Ni-7W alloy (HR6W), originally developed in Japan as a high-strength tubing material for 650°C ultra-supercritical (USC) boilers, was systematically investigated to evaluate its potential for A-USC plant applications. Comparative research with γ-strengthened Alloy 617 revealed that the tungsten content is intimately correlated with Laves phase precipitation and plays a crucial role in controlling creep strength. Extensive creep rupture tests conducted at temperatures between 650-800°C for up to 60,000 hours demonstrated the alloy's long-term stability, with 105-hour extrapolated creep rupture strengths estimated at 88 MPa at 700°C and 64 MPa at 750°C. Microstructural observations after creep tests and aging confirmed the material's microstructural stability, which is closely linked to long-term creep strength and toughness. While Alloy 617 exhibited higher creep rupture strength at 700 and 750°C, the materials showed comparable performance at 800°C. Thermodynamic calculations and microstructural analysis revealed that the Laves phase in HR6W gradually decreases with increasing temperature, whereas the γ' phase in Alloy 617 rapidly diminishes and almost completely dissolves at 800°C, potentially causing an abrupt drop in creep strength above 750°C. After comprehensive evaluation of creep properties, microstructural stability, and other reported mechanical characteristics, including creep-fatigue resistance, HR6W emerges as a promising candidate for piping and tubing in A-USC power plants.
VM12, a New 12%Cr Steel for Application at High Temperature in Advanced Power Plants: Status of Development
Authors: Gabrel J. , Zakine C. , Lefebvre Bo. , Vandenberghe B. 
Published: February 2025

Abstract
The T/P91 and T/P92 steel grades were developed as a result of a demand of high creep strength for advanced power plants. Nevertheless, their operating temperature range is limited by their oxidation performance which is lower compared with usual 12%Cr steels or austenitic steels. Moreover, the new designed power plants require higher pressure and temperature in order to improve efficiency and reduce harmful emissions. For these reasons, Vallourec and Mannesmann have recently developed a new 12%Cr steel which combines good creep resistance and high steam-side oxidation resistance. This new steel, with a chromium content of 12% and with other additional elements such as cobalt, tungsten and boron, is named VM12. Manufacturing of this grade has been successfully demonstrated by production of several laboratory and industrial heats and rolling of tubes and pipes in several sizes using different rolling processes. This paper summarizes the results of the investigations on base material, including creep tests and high temperature oxidation behavior, but also presents mechanical properties after welding, cold bending and hot induction bending.
A New Improvement of Inconel Alloy 740 for USC Power Plants
Authors: Xie Xishan , Zhao Shuangqun , Dong Jianxin , Smith G. D. , Baker B. A. , Patel S. L. 
Published: February 2025

Abstract
A new nickel-base superalloy, Inconel alloy 740, is being developed for ultra-supercritical (USC) boiler applications operating above 750°C, designed to meet critical requirements for long-term high-temperature stress rupture strength (100 MPa for 105 hours) and corrosion resistance (2 mm/2 × 105 hours). Experimental investigations revealed key structural changes at elevated temperatures, including γ coarsening, γ' to η transformation, and G phase formation. To enhance strengthening effects and structural stability, researchers conducted a systematic optimization process based on thermodynamic calculations, implementing small adjustments to several alloying elements and designing modified alloy compositions. Comprehensive testing examined the long-term structural stability of these modifications, with investigations conducted up to 5,000 hours at 750 and 800°C, and 1,000 hours at 850°C. Mechanical property and oxidation resistance tests compared the modified alloys with the original Inconel alloy 740, yielding preliminary results that demonstrate minimal modifications can improve stress rupture strength while maintaining corrosion resistance. Microstructural examinations further confirmed the enhanced thermal stability of the modified alloy, positioning Inconel alloy 740 as a promising candidate for USC boiler applications at 750°C or higher temperatures.
Materials Qualification for 700 °C Power Plants
Authors: Chen Qiurong , Stamatelopolous Georg-Nikolaus , Helmrich Andreas , Heinemann Josef , Maile K. , Klenk A. 
Published: February 2025

Abstract
Components exposed to the highest temperatures and mechanical loading in 700°C power plants are predominantly manufactured from nickel-based alloys, with ongoing material development for boiler and turbine components in this challenging temperature regime. This paper presents comprehensive investigations of various components, including tubing, membrane walls, and thick-walled structures constructed from nickel-based alloys. Qualification programs for boiler components have demonstrated the applicability of Alloy 617, with similar extensive programs and investigations currently underway for Alloy 263 and Alloy 740. Researchers have conducted detailed experiments and investigations to optimize and qualify welding consumables, aiming to transfer critical knowledge directly to component manufacturing processes. Recognizing the complexity of material performance, the study emphasizes the necessity of long-term material qualification, which extends beyond traditional creep behavior assessments to include detailed investigations of deformation capabilities following extended aging periods. These comprehensive evaluations are crucial for ensuring the reliability and performance of advanced high-temperature power plant components under extreme operational conditions.
Nickel Alloys for High Efficiency Fossil Power Plants
Authors: Agarwal D.C. , Gehrmann B. 
Published: February 2025

Abstract
To address the escalating energy demands of the 21st century and meet environmental protection objectives, new fossil-fueled power plant concepts must be developed with enhanced efficiency and advanced technologies for CO2, sulfur oxide, and nitrogen reduction. As plant temperatures and pressures increase to improve overall efficiency, the property requirements for alloys used in critical components become increasingly demanding, particularly regarding creep rupture strength, high-temperature corrosion resistance, and other essential characteristics. Newer and existing nickel alloys emerge as promising candidates for these challenging applications, necessitating comprehensive development through detailed property investigations across multiple categories. These investigations encompass a holistic approach, including chemical composition analysis, physical and chemical properties, mechanical and technological properties (addressing short-term and long-term behaviors, aging effects, and thermal stability), creep and fatigue characteristics, fracture mechanics, fabrication process optimization, welding performance, and component property evaluations. The research spans critical areas such as materials development for membrane walls, headers, piping, reheater and superheater components, and various other high-temperature power plant elements. This paper provides a comprehensive overview of existing and newly developed nickel alloys employed in components of fossil-fueled, high-efficiency 700°C steam power plants, highlighting the intricate materials science challenges and innovative solutions driving next-generation power generation technologies.
Material Development and Mechanical Integrity Analysis for Advanced Steam Turbines
Authors: Pirscher Andreas , Scarlin Brendon , Vanstone Rod 
Published: February 2025

Abstract
Development activities initiated over a decade ago within the COST 522 program and continuing through the COST 536 Action have yielded significant progress in constructing a new generation of steam power plants capable of operating under advanced steam conditions. These innovative plants promise substantially improved thermal efficiency, with steam temperatures reaching up to 620°C (1150°F). Recent successful power plant orders in Europe and the United States stem from critical advancements, including the development, testing, and qualification of 10% Cr steels with enhanced long-term creep properties for high-temperature components such as turbine rotors and valve casings. Extensive in-house development efforts have focused on fabrication, weldability, mechanical integrity, and fracture mechanics evaluations of full-sized forged and cast components. These materials will be implemented in several new coal-fired power plants, notably the Hempstead plant in the USA, which will operate with live steam temperatures of 599°C (1111°F) and reheat steam temperatures of 607°C (1125°F). The improved creep properties enable the construction of casings with reduced wall thicknesses, offering greater thermal flexibility at lower component costs and facilitating welded turbine rotors for high-temperature applications without requiring cooling in the steam inlet region. Looking forward, further efficiency improvements are anticipated through the introduction of nickel alloys in steam turbine and boiler components, with the European AD700 project targeting reheat steam temperatures of 720°C (1328°F) and the US Department of Energy project aiming even higher at 760°C (1400°F). The AD700 project has already demonstrated the technical feasibility of such advanced steam power plants, with engineering tasks progressing toward the construction of a 550 MW demonstration plant, while DOE activities continue to address boiler concerns and focus on rotor welding, mechanical integrity, and steam oxidation resistance.
Effects of Fuel Composition and Temperature on Fireside Corrosion Resistance of Advanced Materials in Ultra-Supercritical Coal-Fired Power Plants
Authors: Hack Horst , Stanko Greg 
Published: February 2025

Abstract
The U.S. Department of Energy (DOE) and the Ohio Coal Development Office (OCDO) are co-sponsoring a multi-year project managed by Energy Industries of Ohio (EIO) to evaluate materials for ultra-supercritical (USC) coal-fired boilers. USC technology improves cycle efficiency and reduces CO2 and pollutant emissions. With turbine throttle steam conditions reaching 732°C (1350°F) at 35 MPa (5000 psi), current boiler materials, which operate below 600°C (1112°F), lack the necessary high-temperature strength and corrosion resistance. This study focuses on the fireside corrosion resistance of candidate materials through field testing. Evaluated materials include ferritic steels (SAVE12, P92, HCM12A), austenitic stainless steels (Super304H, 347HFG, HR3C), and high-nickel alloys (Haynes 230, CCA617, Inconel 740, HR6W), along with protective coatings (weld overlays, diffusion coatings, laser claddings). Prior laboratory tests assessed corrosion under synthesized coal-ash and flue gas conditions for three North American coal types (Eastern bituminous, Midwestern high-sulfur bituminous, and Western sub-bituminous), with temperatures ranging from 455°C (850°F) to 870°C (1600°F). Promising materials were installed on retractable corrosion probes in three utility boilers burning different coal types. The probes maintained metal temperatures between 650°C (1200°F) and 870°C (1600°F). This paper presents new fireside corrosion probe results after approximately one year of exposure for Midwestern and Western coal types.
Impact of Steam-Side Oxidation on Boiler Heat Exchanger Tubes Design
Authors: Billard P. , Fillon R. , Gabrel J. , Vandenberghe B. 
Published: February 2025

Abstract
In fossil-fired boilers, combustion-generated thermal energy transfers to the working fluid via exchanger tubes, where an internal oxide layer forms over time, reducing thermal conductivity and raising metal temperatures. This self-activating process accelerates creep damage, significantly shortening component lifespan. Boiler design codes set Maximum Allowable Stresses based on mechanical properties, primarily creep resistance, but oxidation effects are only indirectly considered through “design temperature” selection—an approach inadequate for next-generation high-performance boilers with increasingly severe steam conditions. This paper highlights the need to integrate oxidation behavior into the design of advanced heat-exchanging components by examining the impact of steam oxidation on tube lifespan, including oxide layer growth, metal loss, temperature rise, and reduced creep rupture time, with thermal flux effects illustrated through examples. It also compares the behavior of two 9-12Cr% steels: Grade 92, known for strong creep resistance, and VM12, which offers superior oxidation resistance. Additionally, it proposes a revised “design temperature” expression incorporating oxidation resistance performance indices and exchanger thermal characteristics. The study concludes by emphasizing the need for further research into oxidation kinetics, thermal properties, and oxide layer exfoliation mechanisms.
Steamside Oxidation Behavior of Experimental 9%Cr Steels
Authors: Doğan Ö. N. , Holcomb G. R. , Alman D.E. , Jablonski P. D. 
Published: February 2025

Abstract
Reducing emissions and increasing economic competitiveness require more efficient steam power plants that utilize fossil fuels. One of the major challenges in designing these plants is the availability of materials that can stand the supercritical and ultra-supercritical steam conditions at a competitive cost. There are several programs around the world developing new ferritic and austenitic steels for superheater and reheater tubes exposed to the advanced steam conditions. The new steels must possess properties better than current steels in terms of creep strength, steamside oxidation resistance, fireside corrosion resistance, and thermal fatigue resistance. This paper introduces a series of experimental 9%Cr steels containing Cu, Co, and Ti. Stability of the phases in the new steels is discussed and compared to the phases in the commercially available materials. The steels were tested under both the dry and moist conditions at 650°C for their cyclical oxidation resistance. Results of oxidation tests are presented. Under the moist conditions, the experimental steels exhibited significantly less mass gain compared to the commercial P91 steel. Microstructural characterization of the scale revealed different oxide compositions.