bluuebunny/crossref_metadata_2025 huggingface dataset:
Artificial intelligence, machine learning, and mental healthcare: An introduction for mental health services and clinicians
Authors: Mazzer Kelly , Curll Sonia , Hopkins Danielle , Rickwood Debra
Published: July 2024

The increasing rates, severity, and complexity of mental health problems are putting immense strain on Australia’s mental healthcare system. The rapidly advancing field of Machine Learning (ML) offers a promising pathway to more efficient and effective mental healthcare. Currently, however, there are multiple ethical and practical barriers to real-world implementation of ML-based tools. This document aims to introduce mental health clinicians to the opportunities and challenges involved with bringing ML into practice. We provide an overview of the ML process and how ML methods can overcome some of the limitations of traditional statistical methods. We then describe how ML-driven tools have the potential to improve detection, diagnosis, prognosis, and treatment of mental health problems, as well as automate clinical administration and enhance clinicians’ professional development. We include applied examples from the literature that, while not a comprehensive review, offer a glimpse into the diversity of ML-driven innovations in the mental health field. Finally, we outline the key challenges and risks involved with translating ML research into clinical practice, and the key next steps toward overcoming them.
Sample size estimation for task-related functional MRI studies using Bayesian updating
Authors: Klapwijk Eduard T. , Jongerling Joran , Hoijtink Herbert , Crone Eveline
Published: July 2024

Task-related functional MRI (fMRI) studies need to be properly powered with an adequate sample size to reliably detect effects of interest. But for most fMRI studies, it is not straightforward to determine a proper sample size using power calculations based on published effect sizes. Here, we present an alternative approach of sample size estimation with empirical Bayesian updating. First, this method provides an estimate of the required sample size using existing data from a similar task and similar region of interest. Using this estimate researchers can plan their research project, and report empirically determined sample size estimations in their research proposal or pre-registration. Second, researchers can expand the sample size estimations with new data. We illustrate this approach using four existing fMRI data sets where Cohen’s d is the effect size of interest for the hemodynamic response in the task condition of interest versus a control condition, and where a Pearson correlation between task effect and age is the covariate of interest. We show that sample sizes to reliably detect effects differ between various tasks and regions of interest. We provide an R package to allow researchers to use Bayesian updating with other task-related fMRI studies.A reproducible version of this manuscript including associated code notebooks is available here: https://eduardklap.github.io/sample-size-fmri/
Audiomotor temporal recalibration modulates feeling of control: Exploration through an online experiment and Bayesian modeling
Authors: Sugano Yoshimori
Published: July 2024

This online experiment aimed to replicate Sugano's (2021) findings on how exposure to delayed auditory feedback affects feeling of control (agency). Participants first adapted by repeatedly reproducing a short sequence of tones while receiving either immediate (10 ms) or delayed (110 ms) auditory feedback on their keypresses. This exposure aimed to recalibrate their timing perception. Following adaptation, they reproduced the sequence again. However, the computer would assume control of the tone pips from the participants with 50% probability. Participants judged whether their keypresses caused the tones (agency judgment: AJ) or if the tones felt synchronized with their keypresses (simultaneity judgment: SJ). Analyses revealed similar shifts in both judgments after exposure to delay, however, the AJ exhibited a greater shift compared to the SJ. In addition, the shift reflects a change in bias, not in sensitivity. The result aligns with previous in-person study, suggesting online experiments can effectively explore agency.
The effect of anxiety on gait: a threat-of-scream study
Authors: Mennella Rocco , Bazin Sabine , Ferrel Carole , Vernazza-Martin Sylvie , Beaurenaut Morgan
Published: July 2024

It is known that fear responses to clearly identified threats can inhibit motion, slowing down gait and inducing postural freezing. Nonetheless, it is less clear how anxiety, which emerges during threat anticipation, affects gait parameters. In the present work, we used a threat-of-scream paradigm to study the effects of anxiety on gait. Twenty-five participants (15 female, aged 23.4 ± 1.8) were instructed to walk on a 5-meter walking track, while motion was recorded in 3D, via a VICON system. Four alternating blocks, two “threat” and two “safe” blocks of 10 trials each, were signaled by colored stripes on a screen in front of the walking path. Participants were informed that they could hear a human scream in their headphones at any time during threat blocks, which were in fact always delivered during walking. On the contrary, no screams were delivered in the safe blocks. Results indicated that participants reported higher subjective anxiety during threat vs. safe blocks. Furthermore, increases in self-reported anxiety from safe to threat showed significant moderate correlations with increased stride speed and length, decreased stride time and decreased stance phase duration. Increases in anxiety were also moderately correlated with increased arm/leg swing amplitude, an effect that was fully mediated by increased stride speed. Overall, these results indicate that anxiety invigorates motion in healthy subjects, by increasing speed. These results are discussed in terms of the recent advancements in the understanding of defensive behavior, its neural correlates and on clinical implications relative to pathological anxiety.
Language-Specific or Universal? The Nature and Roles of Consistency and Gradiency in Speech Perception
Authors: Wong Brian , Samuel Arthur G. , Kapnoula Efthymia C
Published: July 2024

Speech perception gradiency allows listeners to detect and maintain subphonemic information, thereby enhancing speech perception flexibility. However, its nature is not fully understood; it is unclear whether gradiency is a generic trait, or if it depends on language status (L1 vs. L2) and/or language-specific properties (e.g., voice onset time). To address these questions, we investigated the functions of gradiency in spoken word recognition by Spanish (L1)-English (L2) bilinguals. In addition, we examined the role of perceptual consistency, a measure reflecting the stability of auditory cue encoding. Gradiency and perceptual consistency were assessed using the Visual Analogue Scale (VAS). Spoken word recognition was evaluated through initial lexical activation and speech perception flexibility, quantified by the likelihood and speed of recovery from misleading information, using an eye-tracking Visual World Paradigm (VWP) task. Seventy Spanish-English bilinguals performed these tasks in both Spanish and English. Results revealed that listeners with higher gradiency recovered faster from misleading information in L1 Spanish and those with higher perceptual consistency relied more on early information to activate lexical candidates in both languages. This study highlights the language-specific benefit of gradiency in speech perception flexibility and provides general evidence that speech processing stability facilitates initial lexical activation.
Producción de lípidos a partir de microalgas psicrofílicas, presentes en los glaciares antárticos para la síntesis de biodiesel
Authors: Huilca Geovanny , Licto Lissete , Flores Ronny , Proaño Freddy
Published: July 2024

Las microalgas han tenido un impacto negativo en la calidad sensorial en general. Las microalgas psicrofílicas viven en ambientes de frío extremo. Además, su crecimiento aumenta porque tienen en su estructura enzimas que solo se adaptan a temperaturas por debajo de 0 °C. Por este motivo, el Laboratorio de Química Sostenible de la Universidad Central del Ecuador, junto con el Instituto Antártico del Ecuador (INAE), realizó una expedición en Greenwich, Roberts, Dee, Barrientos y Antarctic Towers donde se recolectaron varias colecciones de microalgas, donde se analizaron 15 muestras de Greenwich Island y Roberts durante 21 días en diferentes niveles de temperatura, de los géneros Chlorella sp, Chlorococcum sp y Stichococcus sp. Posteriormente, se realizó el  aislamiento en placas Petri para obtener cultivos de monoalgal. Cada uno de los géneros aislados se masificó en un volumen de 5 ml hasta alcanzar un volumen de 250 ml en medio M1 modificado a una temperatura de 4 °C y 24 °C, 5000 lux y un fotoperíodo de 12:12 horas. El método de Bligh & Dyer se  utilizó para la extracción de lípidos. Los valores de la concentración de lípidos mostraron que el género Chlorella sp tiene la concentración más alta con un valor de 0,2802 mg/ml a 4 °C y un valor de 2.6704 mg/ml a 24 °C, el día 22 de su fase exponencial en comparación con los géneros Chlorococcum y Stichococcus sp
Lepidópteros comestibles: pasado, presente y futuro
Authors: Hernández-Ramírez Angélica María
Published: July 2024

Muchas especies de insectos han sido utilizados como comida tradicional por los pueblos locales, principalmente en la región tropical. En este estudio, los lepidópteros comestibles en México se utilizaron como estudio de caso que ejemplifica el progreso y los desafíos para incorporar a los insectos comestibles a la nutrición humana a gran escala. Si bien los insectos comestibles han ganado un interés creciente como fuente alternativa de alimento para el futuro, se debe prestar atención a algunos aspectos relacionados con el manejo y la conservación de los mismos. La falta de un Reglamento específico para insectos comestibles surge como un elemento clave necesario para garantizar el consumo seguro y la conservación de las poblaciones de insectos silvestres.
Evidence-Based Ruminal Microbiota
Authors: Haro Haro Andrés , Andrade Rojas María José , Suarez Andrés
Published: July 2024

Ruminants break down the fiber of the feed intake in the rumen through a microbial symbiosis, which performs its enzymatic hydrolysis and subsequent fermentation. The objective was demonstrating the activity of rumen microorganisms consisting of bacteria, protozoa, fungi and methanogenic archaea. Bacterial populations are located at three different levels in the rumen: attached to the solid. The concentration of bacteria in the rumen is higher than that of protozoa. Protozoa support a fundamental role in fiber degradation, store large amounts of starch and slow down the production of acids that reduce rumen pH. Fungi have an important function in the digestion of the cell walls of plants, especially those of low quality. Archaea in the rumen are strictly anaerobic microorganisms and produce methane from CO2 and hydrogen. Conclusion: Rumen microorganisms establish complex relationships among themselves, which allow the degradation of the feed that reaches the rumen and consequently the use of the nutrients it contains.
“भिखारी” कवितामा मानवतावाद{ Humanism in "The Beggar" Poem}
Authors: तुल्सीराम Tulshiram पोख्रेल Pokharel
Published: July 2024

प्रस्तुत लेखमा लक्ष्मीप्रसाद देवकोटाद्वारा लिखित भिखारी कविताभित्र प्रयुक्त मानवतावादी दृष्टिको स्थितिपहिचान र खोजअन्वेषण गरिएको छ । कविद्वारा अभिव्यक्त मानवीय संवेदनाहरूलाई नौ श्लोकमा संरचितभिखारी कविताका पृष्ठभूमिमा केन्द्रित रही मानवतावादी सिद्घान्तका आधारमा केलाउनु नै यस अध्ययनकोमूल उद्देश्य रहेको छ । कविताको अर्थापनका लागि पूर्वीय र पाश्चात्य साहित्य सिद्घान्तका सन्दर्भहरूमाआधारित भएर पाठ विश्लेषण विधिका जगमा सूक्ष्म पठन गरी गुणात्मक प्रकृतिको अध्ययन गरिएको छ ।कवितामा प्रस्तुत मानवतावादी चिन्तनसम्बन्धी समस्यालाई मूल प्राज्ञिक समस्या बनाएर त्यसको समाधानखोज्न कवितामा प्रयुक्त भनाइको गाम्भीर्यता र मानव मनको संवेदनालाई मानवतावादी काव्य सौन्दर्यका आधारमा विश्लेषण गर्नु नै अध्ययनको केन्द्रबिन्दु हो । आजको युगमा मानव जातिमा बढ्दै गएको स्वार्थ र लोभानिपापानिबाट मुक्त हुन नसकेको यथार्थता, समाजमा मानवभित्रको दानवीय प्रवृत्ति र गर्विलो स्वाभिमानबाट स्खलित हुँदै घृणित बन्नुपरेको अवस्थालाई मानवतावादी दृष्टिकोणका आधारमा केलाइएको छ । यसमा मानव–मानव बिचमा हुनुपर्ने समानता र मानवतावादी दृष्टिकोणलाई मानवजीवन, दर्शन र सभ्य समाज निर्माणमा मानवको भूमिका के कस्तो रेहेको छ भन्ने कुरालाई विश्लेषण गरिएको छ । पुस्तकालयीय सन्दर्भ सामग्रीको उपयोग गरिएको यस लेखमा विशेष गरेर मानवतावादी काव्य सौन्दर्य पहिचान गर्नुलाई मुल उद्देश्य बनाइएको छ । समसामयिक मानवीय जीवनका जटिलताहरूले मानवमनमा पार्ने आघातबाट उत्पन्न संवेदनागत विषयवस्तुलाई प्रतीकात्मक अभिव्यक्ति दिँदै ‘भिखारी’ कवितामा व्यञ्जित बिम्बात्मक भावका आधारमा मानवतावादी काव्य सौन्दर्यचेत मुखरित भएको निष्कर्ष निकालिएको छ ।
{In the presented article, the position of the humanist vision used in the beggar poem written by Lakshmi Prasad Devkota has been identified and researched. The main purpose of this study is to analyze the human feelings expressed by the poet on the basis of humanistic principles while focusing on the background of the beggar poem structured in nine stanzas. Based on the references of Eastern and Western literary theory for the meaning of the poem, qualitative nature has been studied by careful reading on the basis of text analysis method. The focus of the study is to analyze the seriousness of the words used in the poem and the sentiments of the human mind on the basis of the humanist poetic beauty by making the problem related to humanist thinking presented in the poem an original academic problem. In today's age, the reality that human beings cannot be freed from selfishness and greed, the demonic tendencies in the society and the situation where they have to become hateful from proud self-respect, has been explained on the basis of humanistic point of view. It has analyzed the equality between humans and the humanistic approach to human life, philosophy and the role of humans in building a civilized society. In this article, which uses library reference material, the main objective is to identify the humanistic poetic beauty. By giving a symbolic expression to the emotional content arising from the trauma of the contemporary human life, it is concluded that the humanist poetic aesthetic is expressed based on the figurative expression expressed in the poem 'Bhikhari'.}
Anthropogenic effects on physical landscape: A case study of Purmandal and Uttar Behni in Samba district of Jammu and Kashmir UT
Authors: Raja Ramaiz , Arif Sahifa
Published: July 2024

The study “ Anthropogenic effects on physical landscape”  has been carried out in Purmandal and Uttar Behni area of Samba district in Jammu and Kashmir. The study area Purmandal is a tehsil in Samba district of the state Jammu and Kashmir and lies between 32.370N-32.440N latitude and 74.940E-750.00Elongitude. This area is about 37km away from Jammu in south eastern side and connected with NH 44A from Bari Brahamna. It is an empirical deductive study in which field tour of three days was conducted in order to assess the area i.e role of humans in shaping the physical landscape. Detailed study was done and photographs were taken as an evidence of Anthropogenic effects. This study has revealed   that Purmandal and Uttar Behni have witnessed many types of anthropogenic activities. Anthropogenic influences in the area are clearly perceptible in agriculture, mining, transportation, construction, and deforestation activities. The study has revealed the   relationship between level of modernization and contrasting influence of   agricultural practices on natural landscape. The study focuses on various anthropogenic dimensions in the context of the study area which includes Purmandal and Uttar Behni. The Purmandal area is suffering from various effects which are caused or played by human. These effects are in term of agricultural practices, infrastructural development, cutting of forests for domestic fuel as well as for timber and also for clearing of land to make it good for agricultural practices. To prove the anthropogenic effects on the landscape, field observations have been the main source of information. Besides few prominent local persons as well revenue officer were interviewed to make assessment of the changes taken place in the area.
Politeness Strategy in the Usage of Language Among Young People
Authors: Sianturi Indah Karina
Published: July 2024

The purpose of this research is to study the Politeness Strategy by Penelope Brown and Stephen Levinson that is used by young people to communicate with community members and other peers. This is a fact that can be claimed that young people are easily provoked because of a lack of politeness when solving or facing problems that often might be considered foul and taboo like death, illness, different bodily functions and gender problems. Although such complaints are unprecedented in the way young people use their language, this research began to examine older people by obtaining various Politeness Strategies that allow young children to communicate with various groups of people. The study notes that the language used by young people who have politeness in speaking depends on the level during communication.
Alloy Development and Material Issues with Increasing Steam Temperature
Authors: Masuyama Fujimitsu
Published: July 2024

In the later half of the last century great progress in alloy development for power applications was seen to improve thermal efficiency with increasing steam temperature. Meanwhile, many material-related troubles have been experienced due to rising temperature and uncertainty in the properties of fabricated metal. For further improvement in the thermal efficiency of fossil-fired power plants with ultra supercritical steam parameter conditions aiming at temperatures above 700°C, alloy development concepts and material issues with increasing steam temperature must be reviewed and discussed. In this paper new findings in the areas of alloy developments, creep failure in base metal and weldments, thermal fatigue failure and steam oxidation/hot corrosion are presented and discussed, as well as the economical aspect of material development, which is essential to realize unprecedented ultra supercritical steam conditions.
Construction Planning for 600/620 °C USC Boilers in Japan
Authors: Iwasaki Tetsuya , Kajigaya Ichiro , Nakagawa Hirokatsu
Published: July 2024

Japanese USC-PC units successfully operate with steam temperatures of 610°C (1130°F). IHI is developing the next generation of USC-PC boilers, targeting 620°C (1150°F) for improved efficiency. Investigations are underway for even higher 700°C (1290°F) steam temperatures. IHI collaborates with turbine manufacturers to create reliable and efficient boiler-turbine packages for both new and existing power plants.
Supercritical Fossil Steam Plants: Operational Issues and Design Needs for Advanced Plants
Authors: Armor A.F. , Viswanathan R.
Published: July 2024

As electricity markets become increasingly competitive, ultrasupercritical power plants must operate efficiently and flexibly. This necessitates attention to equipment design features and optimal material selection. Early studies by EPRI highlighted the need for boiler and steam turbine design improvements, as well as material advances, to enable the flexible operation of advanced supercritical units. Improvements such as turbine rotor cooling, cycling capability through improved control systems, enhanced blade tip sealing designs, turbine vibration control approaches, and erosion-resistant control stage designs were required. With ultrasupercritical plants moving towards even higher steam temperatures exceeding 700°C, these concerns need to be revisited from both metallurgical and design perspectives. Furthermore, features for efficiency improvements beyond advanced steam conditions should be considered, while minimizing environmental emissions like CO2. This paper reviews the needs for future ultrasupercritical plants with steam temperatures approaching or exceeding 700°C.
Considerations in Fabricating USC Boiler Components from Advanced High Temperature Materials
Authors: Mohn Walter R. , Tanzosh James M.
Published: July 2024

The construction of highly efficient, coal-burning Ultra Supercritical (USC) boiler systems to operate with steam temperatures up to 760°C (1400°F) and with steam pressures up to 35 MPa (5000 psi) will require the use of advanced high temperature, high strength materials. As part of a 5-year project to develop boiler materials for advanced USC power plants, principally funded by the Department of Energy (U.S. DOE No. DE-FG26-01NT41175) and the Ohio Coal Development Office (OCDO No. D-00-20), six alloys have been selected for development and implementation in USC boiler systems. The selected alloys are Haynes 230 (produced by Haynes International), Inconel 740 (produced by Special Metals Corp.), CCA 617 (produced by Krupp VDM GMBH), HR6W, Super 304H, and SAVE 12 (all three produced by Sumitomo Metal Industries). In this project, one of the goals has been to establish boiler fabrication guidelines for the use of these alloys. The principal objectives have been 1) to understand the behavior of these materials when subjected to conventional boiler fabrication processes, 2) to determine the thermomechanical treatments or other actions necessary to restore material properties which might degrade due to fabrication operations, and 3) to investigate prototypical manufacturing operations for producing both thick wall components (such as headers) and thin wall components (such as superheaters) from the USC alloys. This paper discusses some of the characteristics of these alloys, describes the technical approach used to assess their fabricability, and presents some of the results that have thus far been generated in this task effort.
Practical Experience with Advanced Steels
Authors: Parker Jonathan
Published: July 2024

With the desire for higher operating temperatures and pressures to improve the thermal efficiency of new power generating plant there have been significant changes in the materials used. For operation up to 620°C, a new range of ferritic steels with 9-13%Cr has been developed. With proper control of composition and heat treatment these materials, including Grades 91 and 92,exhibit predominantly martensitic microstructures and a good balance between strength and ductility. However, fabrication processes such as welding and bending, normally combined with extreme operating conditions have resulted in in-service damage. Examples of factors leading to accelerated creep, creep fatigue and oxidation damage are described.
Sandvik Sanicro 25, A New Material for Ultrasupercritical Coal Fired Boilers
Authors: Rautio R. , Bruce S.
Published: July 2024

The power generation industry worldwide aims to develop coal-fired boilers operating at much higher efficiencies than current supercritical plants. This increased efficiency is expected through ultrasupercritical steam conditions, requiring new materials for critical components. To limit the use of expensive alloying materials, it is necessary to maximize the strength and corrosion capabilities across the material spectrum from ferritic to austenitic and nickel-based alloys. Sandvik Materials Technology has developed an austenitic alloy, Sanicro 25, with excellent high-temperature strength and corrosion resistance using an economical alloy composition. The alloy is designed for use within 700°C (1300°F)/300 bar (4500 psi) steam conditions and is a leading candidate material for such high-temperature applications. This paper introduces Sanicro 25, its development status, and properties.
Properties of a Newly Developed 18Cr-9NI-Nb-V-W-N-Low C Austenitic Boiler Tube
Authors: Tetsuo Ishitsuka , Hiroyuki Mimura , Hiroshi Morimoto , Mitsuhiro Matsumoto , Manabu Mizumoto , Junich Okamoto
Published: July 2024

A new 18Cr-9Ni-Nb-V-W-N-low C austenitic boiler tube (XA704) has been developed. Conventional high-strength austenitic stainless steel boiler tubes usually have high susceptibility to intergranular corrosion because of their high carbon content, and require special care for heated sections such as weld joints. Generally, when the carbon content decreases, the intergranular corrosion resistance improves, while the creep strength reduces. However, the creep strength of the developed steel is very high despite lower carbon content in comparison to conventional austenitic boiler tubes. The high temperature strength and the intergranular corrosion resistance of the steel are superior to those of conventional 18Cr steels such as TP347H. This excellent creep strength of XA704 is mainly due to precipitation strengthening by CrVN, and solid solution strengthening by tungsten and nitrogen. Matching welding consumables for the developed steel have also been developed. Thus, newly developed XA704 is a promising material for superheater and reheater tubes for the “600°C generation” of USC boilers. XA704 has already been used in six power plants in Japan. Currently, the steel is being standardized in the ASME Code.
Coal Ash Corrosion Resistant Materials Testing Program: Evaluation of the Second Section Removed in August 2003
Authors: McDonald Dennis K. , Robitz Edward S.
Published: July 2024

The “Coal Ash Corrosion Resistant Materials Testing Program” by The Babcock & Wilcox Company (B&W), the U.S. Department of Energy (DOE), and the Ohio Coal Development Office (OCDO) at Reliant Energy's Niles plant provides full-scale in-situ testing of advanced boiler superheater materials to address fireside corrosion, a key issue for improving efficiency in new coal-fired plants and service life in existing ones. In 1998, B&W developed a system with three identical sections containing multiple segments of twelve different materials from contributors like Oak Ridge National Laboratory (ORNL), cooled by reheat steam and installed in 1999 above the furnace entrance in the Niles Plant 110 MWe Unit #1 firing high-sulfur Ohio coal to test materials at advanced supercritical steam temperatures (1100°F+) in corrosive conditions. The first section was evaluated after 29 months in 2001, the second in 2003, and the final section is expected for removal in 2005. This paper outlines the program, test system, and materials, and it presents the evaluation results for the first two sections.
Corrosion Behavior of an HVOF-Sprayed Fe3Al Coating in a High-Temperature Oxidizing/Sulfidizing Environment
Authors: Covino B. S. , Bullard S. J. , Cramer S. D. , Holcomb G. R. , Ziomek-Moroz M. , Shrestha S. , Harvey D.
Published: July 2024

An iron aluminide (Fe3Al) intermetallic coating was deposited onto F22 (2.25Cr-1Mo) steel substrate using a JP-5000 high velocity oxy-fuel (HVOF) thermal spray system. The as-sprayed coating was characterized by electron microscopy, X-ray diffraction, oxidation, and adhesion. Fe3Al coated steel specimens were exposed to a mixed oxidizing/sulfidizing environment of N2-10%CO-5%CO2-2%H2O-0.12%H2S (by volume) at 500, 600, 700, and 800°C for approximately seven days. All specimens gained mass after exposure, inversely proportional to temperature increases. Representative cross-sectioned specimens from each temperature underwent scanning electron microscopy (SEM) and X-ray mapping examination. Results are presented in terms of corrosion weight gain and product formation. The research evaluated the effectiveness of an HVOF-sprayed Fe3Al coating in protecting a steel substrate exposed to a fossil energy environment.
Steam Oxidation Property of Fine-Grain Steels
Authors: Matsuo H. , Nishiyama Y. , Yamadera Y.
Published: July 2024

This paper describes the steam oxidation behavior of two 18Cr-8Ni austenitic fine-grained stainless steels, TP347HFG and SUPER304H, which have been developed for ultra-supercritical (USC) boilers. A field exposure test was conducted by installing these tubes, along with comparative materials, in the tertiary superheater of a utility power boiler. After periodic service, the fine-grained tubes were removed to examine their steam oxidation behavior. Examination of the steam oxidation scale on the inner surface of the tubes indicated an extremely low scale growth rate for the fine-grained steels, even after 10 years of service. The oxidation structure is discussed and compared with conventional materials, TP321H and TP347H. Accelerated steam oxidation tests were conducted using an oxidation test with saturated dissolved oxygen concentration. The combination of fine-grained steel and a shot-peening layer exhibits high steam oxidation resistance at 700°C or higher temperatures.
Effect of Argon Gas Pre-Oxidation Treatment on the Oxidation Behavior of NIMS High-Strength Steels
Authors: Kutsumi H. , Haruyama H. , Abe F.
Published: July 2024

For high-strength steels developed at the National Institute for Materials Science (NIMS) in Japan, a dispersion of nano-sized MX nitride particles along boundaries and in the matrix is achieved by reducing carbon concentration below 0.02%. This structure results in excellent creep strength at 923K, approximately two orders of magnitude longer rupture time than P92. Additionally, adding a large amount of boron exceeding 0.01% combined with minimized nitrogen effectively improves creep rupture strength by stabilizing the martensitic microstructure during creep. Efforts have been made to enhance the steam oxidation resistance of these 9Cr steels strengthened by boron and fine MX nitrides. A combination of 0.7% Si, 40-60 ppm S, and pre-oxidation treatment was applied. Steam oxidation tests were conducted at 923K for up to 4000h. Pre-oxidation treatment in argon gas at 973K for 50h significantly improved oxidation resistance in steam at 923K by forming a protective Cr-rich oxide layer. The pre-oxidized steels exhibited much lower mass gain in steam at 923K than Mod.9Cr-1Mo steel at 873K, and lower than T91 at 873K after 1000h. After 4000h, their mass gain was about zero, much lower than P91 at 873K and 923K. SEM/EDS analysis and low mass gain suggest a protective Cr-rich oxide scale formed on the pre-oxidized steel surface, exhibiting excellent oxidation resistance in steam at 923K.
Oxide Scaling and Oxidation-Assisted Microstructural Degradation in Weldments Steam Generator Steels
Authors: Raman R.K. Singh
Published: July 2024

‘Chromium-Molybdenum’ ferritic steels are the most popular materials for construction of steam generators. Microstructure of ‘Cr-Mo’ steels is highly susceptible to changes due to heat- treatments. This susceptibility is often exploited for improving creep strength of these alloys, via suitable heat treatments, that are employed in order to incorporate changes in grain size and secondary precipitates. This paper presents a general overview of the role of microstructure in various aspects of gaseous oxidation, and the synergistic role of the alloy microstructure and oxidation in deterioration of mechanical properties. In the light of this overview, the paper also presents oxidation kinetics and oxidation-assisted microstructural degradation in the microstructurally different regions of weldments of a common variety of ‘Cr-Mo’ steel, viz., 2.25Cr-1Mo steel.
Materials and Design for Advanced High Temperature Steam Turbines
Authors: Fukuda Masafumi , Tsuda Yoichi , Yamashita Katsuya , Shinozaki Yukio , Takahashi Takeo
Published: July 2024

Natural gas has long been regarded as the primary energy source for advanced power systems because of its cleanliness and highly efficient nature. Nevertheless, coal is gaining attention again as a stable energy source for power generation. In this paper, high efficiency pulverized coal power plant technology, especially materials and the design for high temperature turbine systems, is discussed. The development of materials has contributed to the high efficiency plant development, so far. The development of 12% Cr steel was key in building the state-of-the-art 600-deg C class steam turbine system. It is believed that a 700-deg C class steam turbine system will be realized with Ni-based super alloys and austenitic steels. In the near future, the system with a 700-deg C reheat temperature and 630-deg C main steam temperature is promising for the pulverized coal power plant because of the need for only moderate development work, low capital expenditure, and its high efficiency.
Superalloy Forgings for Advanced High Temperature Power Plants
Authors: Schönfeld K.H. , Blaes N. , Bokelmann D.
Published: July 2024

Improving power plant efficiency through supercritical steam pressures and very high steam temperatures up to 700°C and beyond is an effective approach to reducing fuel consumption and CO2 emissions. However, these extreme steam temperatures necessitate the use of nickel-base alloys in the high-pressure/intermediate-pressure turbine sections requiring very large component sections that cannot be met by steels. Saarschmiede, involved in manufacturing large components for the power generation industry and research programs on advanced 9-12% chromium steels, has extensive experience producing nickel and cobalt-base alloy forgings for applications like aircraft engines, aerospace, land-based gas turbines, and offshore. This paper reports on the manufacturing and testing of large-section forgings made from candidate nickel-base alloys like 617 and 625 for high-pressure/intermediate-pressure turbine components in power stations operating at 700°C and higher steam temperatures.
High Temperature Steel Forgings for Power Generation
Authors: Blaes N. , Donth B. , Schönfeld K.H. , Bokelmann D.
Published: July 2024

Steels with 9-12% chromium content are widely used in steam turbines operating above 550°C due to their improved creep properties. Saarschmiede has extensive experience manufacturing high chromium steels, such as the X12CrMoWVNbN10-11-1 steel designed through the European COST program for application up to 610°C (COST Rotor E). From this steel, Saarschmiede produces high-pressure rotor shafts and gas turbine discs. To meet ever-increasing steam temperatures, a modified steel type with elevated boron content was developed, and pilot rotors have been manufactured. For ingot manufacturing of high chromium steels, Saarschmiede utilizes the Electro-Slag-Remelting process, allowing ingots up to 165 tons. Optimized forging and heat treatment procedures ensure reproducible forging properties. All products undergo rigorous destructive and non-destructive testing.
Wrought Nl-Base Alloys for Rotor Shafts in Advanced USC Power Plants
Authors: Schubert F. , Penkalla H.J. , Rösler J.
Published: July 2024

Three Ni-base wrought alloys with different hardening mechanisms (INCONEL 706, Waspaloy and INCONEL 617) were investigated as candidates for steam turbine rotor applications at temperatures up to 700 °C in respect to their microstructure and microstructural stability. The Nb containing alloy Inconel 706 had a complex microstructure with γ', γ" and η phases which are stable in long term service up to 620 °C. At higher temperatures significant particle coarsening and phase transformation were observed. Waspaloy is hardened by γ' particles and after ageing at 700 °C and higher, it tended to a stable microstructure. Inconel 617 is a solid solution hardened material additionally hardened by homogeneously distributed fine M23C6 carbides. After long term ageing at temperatures of 650 °C to 750 °C the carbides tended to form carbide films along the grain boundaries and at 700 °C to 750 °C γ' precipitated as homogeneously distributed particles with low coarsening during long term service. In order to optimize the candidate alloys Inconel 706 and Waspaloy were modified to the new alloys DT 706 and DT 750. The aspects of modification and first experimental results are reported.
Development of Wrought Ni-Based Superalloy with Low Thermal Expansion for 700C Steam Turbines
Authors: Yamamoto Ryuichi , Kadoya Yoshikuni , Ueta Shigeki , Noda Toshiharu , Magoshi Ryotaro , Nishimoto Shin , Nakano Takashi
Published: July 2024

Advanced 700C class steam turbines require austenitic alloys instead of conventional ferritic heat-resistant steels which have poor creep strength and oxidation resistance above 650C. Austenitic alloys, however, possess a higher thermal expansion coefficient than ferritic 12Cr steels. Therefore, Ni-based superalloys were tailored to reduce their coefficients to the level of 12Cr steels. Regression analysis of commercial superalloys proves that Ti, Mo and Al decrease the coefficient quantitatively in this order, while Cr, used to secure oxidation resistance, increases it so significantly that Cr should be limited to 12wt%. The newly designed Ni-18Mo-12Cr-l.lTi-0.9Al alloy is strengthened by gamma-prime [Ni3(Al,Ti)] and also Laves [Ni2(Mo,Cr)] phase precipitates. It bears an RT/700C mean thermal expansion coefficient equivalent to that of 12Cr steels and far lower than that of low-alloyed heat resistant steels. Its creep rupture life at 700C and steam oxidation resistance are equivalent to those of a current turbine alloy, Refractaloy 26, and its tensile strength at RT to 700C surpasses that of Refractaloy 26. The new alloy was trial produced using the VIM-ESR melting process and one ton ingots were successfully forged into round bars for bolts without any defects. The bolts were tested in an actual steam turbine for one year. Dye penetrant tests detected no damage. The developed alloy will be suitable for 700C class USC power plants.
Perspectives on Improved Life Assessment Methods for New Plants
Authors: Berger Christina , Scholz Alfred
Published: July 2024

New martensitic steels (9-10 CrMoNi(W)VNbN) are being developed for ultrasupercritical power plants to achieve higher efficiency and reduced environmental impact. Improved life assessment methods are crucial for the safe and economical long-term operation of these high-temperature components. This includes gathering creep, creep-fatigue, and crack data to establish design curves, as well as advanced modeling to predict deformation and lifetime. Complex experiments under various loading conditions and multiaxial behavior are necessary for verification. Furthermore, understanding how creep processes affect pre-existing defects is essential for ensuring long-term component integrity.
Evaluation of the Failure in the Texas Genco W. A. Parish Unit #8 Cold Reheat Line
Authors: Alexander Chris , Frey, P.E. Joe , Shin Steve
Published: July 2024

Texas Genco requested Stress Engineering Services to assist in reviewing and assessing a failure that occurred in the cold reheat (CRH) steam line at the W.A. Parish Unit around 12:10 PM on July 15, 2003, resulting in a catastrophic failure scattering components within a 1,200-foot radius. Reliant Resources and Texas Genco conducted their own investigation involving metallographic examinations, fracture surface inspection, review of operating conditions at failure time, and studies related to the CRH line weld profile. Stress Engineering Services' efforts included computational fluid dynamics studies to address how attemperator droplet sizes might impact downstream piping system behavior, followed by mock-up testing and field monitoring using high-temperature strain gauges, accelerometers, and thermocouples. The field monitoring data, along with process data from Texas Genco, were used for finite element analyses calculating static stresses and transient stresses from attemperator cycling (thermal stresses) and line vibration (mechanical stresses). A consulting firm contracted by the Electric Power Research Institute (EPRI) performed a fracture mechanics evaluation of the line, though detailed results are not included. The work by Texas Genco, Stress Engineering Services, and EPRI points to the stress concentration factor associated with the internal weld profile near the failure as the primary cause, with the cyclic thermal shocks from frequent intermittent attemperator use being sufficient to initiate the crack.
Life Management of High Energy Piping Systems - An Integrated Maintenance and Operations Approach
Authors: Tilley R.
Published: July 2024

To obtain the maximum life for fossil power plant high energy piping systems requires a management process that goes beyond a maintenance response to discovered damage or problems. The catastrophic failure of a cold reheat piping system in 2003 and the ongoing damage reported for feedwater and steam piping systems in other power plants suggest a need for a comprehensive process of life management This paper proposes a process based upon the successful EPRI program for boiler tube failure reduction. Key to this process is a structure that fully confirms the damage or failure mechanism, that identifies the root cause for the mechanism, and that establishes short and long-term corrective actions for the damage. Finally, the process must be implemented through a cross-functional team of plant staff covering maintenance, operations, and engineering disciplines to assure the most complete and cost effective actions to prevent future damage.
Stability of Similar and Dissimilar Welded Joints, High-Temperature Creep Resistant Martensitic Steels Containing 9% Cr
Authors: Pasternak Jerzy , Kielbus Andrzej
Published: July 2024

This paper presents RAFAKO S.A. experience within the field of research and implementation of new group of creep-resistant steel grades with addition of tungsten, including the selection of filler metal, welding procedures and selected results of mechanical properties testing carried out during the implementation of welding process for elements of steam superheaters of the boilers with supercritical parameters. It summarizes the experience and results of research works carried out in RAFAKO, Silesian Technical University in Katowice and Welding Institute in Gliwice within the framework of COST 522 program concerning the influence of simulation of element temperature operating conditions on Chaгpy V notch toughness, HV10 hardness, microstructure of simulated HAZ's, assessment of steel weldability, strength properties. The welded joints structure stability and HAZ after stress relief annealing and after ageing - simulation of element operating conditions are presented in the form of graphs and prints of microstructures.
VM12 - A New 12%Cr Steel for Boiler Tubes, Headers and Steam Pipes in Ultra Supercritical Power Plants
Authors: Gabrel J. , Bendick W. , Vaillant J.C. , Vandenberghe B. , Lefebvre Bo.
Published: July 2024

A new 12%Cr steel, VM12, has been developed with the combined strength and oxidation resistance characteristics desired for high-temperature applications. The steel increases chromium content by around 0.2% to improve oxidation properties while alloying with other elements such as cobalt, tungsten, and boron to meet a range of requirements, including extending fatigue life. The steel is designed to have the same creep strength as T/P92 but with better oxidation resistance due to the higher chromium content. It has about a 0.2% increase in mechanical properties compared to T/P92 steel. Results are presented for tubes and pipes cast with a variety of surface conditions. In addition, detailed results are provided on the effects of alloying elements on creep and oxidation resistance.
Z-Phase in 9-12%Cr Steels
Authors: Danielsen H. , Hald J.
Published: July 2024

The complex nitride Z-phase, Cr(V,Nb)N, has recently been identified as a major cause for premature breakdown in creep strength of a number of new 9-12%Cr martensitic steels, especially the high Cr variants. A thermodynamic model of the Z-phase has been created based on the Thermo-Calc software. The model predicts the Z-phase to be stable in all of the new 9- 12%Cr martensitic steels, and this has generally been confirmed by experimental observations. Z-phase precipitation seems then to be a kinetic problem, and driving force calculations, using Thermo-Calc with the developed model, have been used to predict steel compositions, which could delay Z-phase precipitation. The model also predicted the existence of a new niobium free Z-phase variant, which has since been discovered in a niobium free 12CrMoV steel.
Long Term Creep Behavior and Microstructural Evolution of ASTM Grade 91 Steel
Authors: Caminada S. , Cumino G. , Cipolla L. , Di Gianfrancesco A.
Published: July 2024

TenarisDalmine, in collaboration with CSM, developed and characterized ASTM Grade 91 steel tubes and pipes for high-temperature boilers in ultrasupercritical power plants. This paper details the mechanical properties of both untreated and long-term exposed tubes. Extensive creep testing allowed extrapolation of stress values for rupture in 100,000 hours (93 MPa at 600°C) and 1% elongation in 250,000 hours (83 MPa at 600°C), satisfying ECCC and TÜV requirements. Additionally, STEM analysis investigated microstructure and precipitate evolution after long-term exposure, revealing changes in precipitate chemistry, size, and distribution.
Degradation Processes in Creep of 9-12%Cr Ferritic Steels
Authors: Sklenicka V. , Kucharova K. , Kloc L. , Svoboda M. , Kudrman J.
Published: July 2024

Creep behavior and degradation of creep properties of advanced 9-12%Cr ferritic steels are phenomena of major practical relevance, often limiting the lives of power plant components and structures designed to operate for long periods under stress at elevated temperatures. Because life expectancy is, in reality, based on the ability of the material to retain its high-temperature creep strength for a period of at least twice the projected design life, methods of creep property assessment based on physical changes in the material that are likely to occur during service exposure rather than simple parametric extrapolation of the short-term data are necessary. This work attempts to highlight the problem areas just in this respect. The proposed approaches are illustrated by recent experimental results on advanced high creep strength 9-12%Cr ferritic- martensitic steels (P91 and P92).
Long-Term Creep Deformation Characteristics of Advanced Ferritic Steels for USC Power Plants
Authors: Igarashi M. , Yoshizawa M.
Published: July 2024

Creep deformation behavior of the T122 type steels with different matrix phases such as α’ (martensite) and α’+δ (martensite and delta-ferrite) at different stress levels has been studied comparing with those of the model steels with the initial microstructures consisting of the various combination of matrices such as ferrite (α), martensite (α’) and austenite (γ), and precipitates such as MX and M23C6. The heterogeneous creep deformation is found to be pronounced at lower stress level in the steel with a dual phase matrix of α’+δ, resulting in a complex sigmoidal nature in the creep rupture life. The creep deformation process of the steel with the dual phase matrix is similar to that of the model steel with the α phase matrix which exhibits a typical heterogeneous creep deformation and the early transition to the acceleration creep at a very small creep strain. Such a heterogeneous creep deformation is much pronounced along the interfaces between the soft δ ferrite and the hard martensite (α’) phases, and has a viscous nature in creep deformation which was first identified in P91 steel. It is concluded that the homogeneous microstructure is a key for achieving the long-term creep strength in the advanced ferritic steels at elevated temperatures over 600°C.