bluuebunny/crossref_metadata_2025 huggingface dataset:
PERANAN KOMUNIKASI ANTAR PRIBADI ORANG TUA DENGAN ANAK DALAM MENINGKATKAN PRESTASI BELAJAR DI KELAS VI PADA SD NEGERI BTN PEMDA KOTA MAKASSAR
Authors: Kadariah Kadariah
Published: May 2019

This study aims to describe the role of communication between parents and children in improving student achievement in Class VI at SDN BTN Pemda of Makassar City. The approach used is collaboration between qualitative approaches and quantitative approaches. This type of research is classroom action research. To obtain data and information needed, tests, documentation and observations are used. For the purposes of managing data in this study, descriptive analysis is used. The results of the study showed that there was a significant relationship between interpersonal communication between parents and children with the learning achievements of class VI students. This is evidenced by the research data calculated using the product moment correlation formula with the help of SPSS 16. The results of the study show that: (1) there is a significant positive relationship between parent and child interpersonal communication with student achievement. (2) The magnitude of the communication relationship between parents and children towards student achievement is classified as very strong
Pemanfaatan Permainan Tradisional Dalam Pencapaian Indikator Pembelajaran
Authors: Ilham Ilham , Ali Muhammad , Syaputra Endarman , Munar Hendri
Published: May 2019

The objective to be achieved in this activity is to provide an understanding to the penjas teacher of the need to do learning penjas in the form of play for the achievement of learning indicators. Based on the above objective, the target and the expected outcomes are: 1) The penjas teacher can know the various forms of traditional games that can be used for the achievement of learning indicator penjas. 2) The penjas teacher can do the learning of penjas by using traditional games for the achievement of learning indicator penjas. Techniques used in this implementation is to counseling teachers in penjas located in the West Muara Sabak, East Sabak, Geragai and Dendang sub-districts, amounting to approximately 71 people, this activity in cooperation with SMA Negeri 5 and SMA Negeri 8 Tanjung Jabung Timur. The conclusion of the implementation of this devotion are: (1) In an effort to achieve indicators of athletic learning can be done by using traditional game methods. (2) The utilization of traditional games in the achievement of learning indicators has not been done by the teacher of Penjas Orkes in Tanjung Jabung Timur Regency. (3) The used of traditional games in achieving the indicators of learning should be designed accordance with the learning materials.
Analisis Kemampuan Berhitung Siswa Kelas III SD Negeri Kecamatan Ulaweng Kabupaten Bone
Authors: S Syamsuddin , Jafar Muhammad Idris , Patta Rahmawati
Published: May 2019

This research aims to acquaire the description of ability level elementary students third grade at district Ulaweng, regency of Bone. The population is the entire elementary students third grade at district Ulaweng, regency of Bone. Samples are drawn by random in every group supervision UPTD grade at district Ulaweng, regency of Bone.Since there are four group supervision, those four schools become samples in which elementary students third grade are the subject of research.Instrument of data collection uses test. Data of test result is then analysed by descriptive statistical technique in the form of distribution of frequency, aritmetic mean, standard deviation, and percentage.Based on analysis data, it is summarizedthat the levelofcalculatingabilityelementary students third grade at district Ulaweng, regency of Bone is considered low. It is then recommended to all stakeholders in academic field to make serious effort to enhance math learning process at elementary school.
Keterampilan Informasi Melalui Pembuatan Media Literasi
Authors: Gunansyah Ganes , Rachmadiyanti Putri , Subagiyo FX Mas
Published: May 2019

Implementation of the School Literacy Movement (GLS) is still faced with a number of obstacles including: (1) literacy program still has not been socialized properly, (2) understanding of the participants on the implementation strategy literacy movements are still limited, (3) based on the analysis of the needs of teachers want practical experience integrating literacy into in learning. The obstacles are experienced by elementary school teachers in Teachers Working Group (KKG) Tosari- Pasuruan District. The purpose of this activity to facilitate a focused target groups (1) create literacy media both theory and practice conceptually, (2) the implementation strategy of literacy programs in schools. Methods of implementation of activities include the flow of activities stages, ways of working and output / outcome of community service activities. The ways of workings include (1) the distribution of material according to field of expertise, (2) mentoring  participants through brainstorming, discussion and discussion, practice simulations and demonstrations, (3) sustainable mentoring; (4) documentation of training and mentoring. While the output of activities includes (1) training module, (2) product of literacy mentoring , (3) implementation strategy design of literacy media in learning. One of the the training and mentoring results is participants has good understanding of the essence of the program School Literacy Movement (GLS) and designing procedure and create resources and literacy media, practice in creating some media literacy media like big books, mini-books, pop-up books, picture story, content posters and word wall, as well as participant delivered a high level of satisfaction with the material about training an mentoring that have been implemented.
KEEFEKTIFAN MODEL PEMBELAJARAN STAD BERBANTUAN MEDIA PEMBELAJARAN TERHADAP SIKAP DAN KEMAMPUAN PEMECAHAN MASALAH MATEMATIKA
Authors: Dewi Arcy Suzana , Isnani Isnani , Ahmadi Ahmadi
Published: May 2019

Penelitian ini bertujuan untuk mendeskripsikan: 1) kemampuan pemecahan masalah matematika peserta didik yang diajar menggunakan model pembelajaran STAD berbantuan media pembelajaran mencapai target, 2) model pembelajaran STAD berbantuan media pembelajaran lebih baik daripada model pembelajaran konvensional terhadap sikap, 3)-model pembelajaran STAD berbantuan media pembelajaran lebih baik daripada model pembelajaran konvensional terhadap kemampuan pemecahan masalah matematika, 4) ada perbedaan model pembelajaran STAD berbantuan media pembelajaran dengan model pembelajaran konvensional terhadap sikap dan kemampuan pemecahan masalah matematika, 5) model pembelajaran STAD berbantuan media pembelajaran lebih baik daripada model pembelajaran konvensional terhadap sikap dan kemampuan pemecahan masalah matematika. Sampel yang digunakan sebanyak 3 kelas dengan teknik pengambilannya menggunakan Cluster Random Sampling. Teknik analisis data menggunakan uji proporsi satu pihak kanan, uji t satu pihak kanan, uji manova dan  Hotelling. Hasil penelitian ini menunjukkan bahwa: 1) kemampuan pemecahan masalah matematika peserta didik yang diajar menggunakan model pembelajaran STAD berbantuan media pembelajaran mencapai target, 2) model pembelajaran STAD berbantuan media pembelajaran lebih baik daripada model pembelajaran konvensional terhadap sikap, 3) model pembelajaran STAD berbantuan media pembelajaran lebih baik daripada model pembelajaran konvensional terhadap kemampuan pemecahan masalah matematika, 4) ada perbedaan model pembelajaran STAD berbantuan media pembelajaran dengan model pembelajaran konvensional terhadap sikap dan kemampuan pemecahan masalah matematika, 5) model pembelajaran STAD berbantuan media pembelajaran lebih baik daripada model pembelajaran konvensional terhadap sikap dan kemampuan pemecahan masalah matematika.
PENERAPAN PEMBELAJARAN ENTREPRENEUR BERBASIS MATEMATIKA
Authors: Masduki Lusi Rachmiazasi , Kurniasih Eem
Published: May 2019

Di Indonesia masih banyak pengangguran dan makin kecil peluang untuk mendapatkan pekerjaan bagi para lulusan sekolah. Diperlukan inovasi pengajar dalam pembelajaran untuk menumbuhkan karakter siswa seperti kerja keras, tanggung jawab, ulet, jujur, dan sebagainya, dalam karakter tersebut bisa dirangkum sebagai karakter kewirausahaan. Karakter kewirausahaan perlu ditumbuhkan pada setiap siswa untuk membentuk jiwa wirausaha, sehingga dapat mewujudkan pembangunan ekonomi dan membuka lapangan kerja sendiri. Untuk membangun karakter kewirausahaan melalui internalisasi dalam kehidupan, pembelajaran di sekolah dibutuhkan suatu kajian yang komprehensif mengenai potensi dari mata pelajaran matematika yang diajarkan kepada siswa. Pembelajaran Entrepreneur berbasis matematika dapat menjadi solusi dalam menanamkan karakter kewirausahaan kepada siswa melalui pembelajaran matematika. Pembelajaran matematika secara tidak langsung memiliki nilai-nilai kewirausahaan salah satu contohnya materi aritmatika yang dapat mengenalkan siswa mengenai prinsip jual-beli, untung dan rugi.
Heavy Metal and the Oratorio
Authors: Helyer Nigel , Drummond Jon
Published: May 2019

This paper explores different approaches to the sonification and visualisation of two environmental projects:-

”Heavy Metal” is focussed upon the real-time analysis and sonification of the chemical elements in a painting via a camera vision system, whilst “Oratorio for a Million Souls” concerns the behaviour and acoustic properties of live bee colonies manifest in the creation of real-time multi-channel sound compositions and associated sound architectures.

Whilst these two projects differ in terms of methodology, aesthetics and technical approach they both share a direct concern with a deep analysis of the underlying environmental structures and perceptual frameworks that emerge in direct ‘live’ encounters - one one hand the discover of what lies behind the surface of a painted image in terms of chemical and colour structures - and in the case of Oratorio, a compelling immersion into the acoustic environment of Bees.
e-Oral Health and Teledentistry in Finland - an Overview
Authors: Palander Anni Marjukka , Holopainen Arto , Rantamo Tiina Rantamo
Published: May 2019

Despite universal health coverage and a strong public health system, the oral health profile of Finland falls behind in an international age-matched prevalence of oral diseases. The oral healthcare system is organised and funded mainly by municipalities. Other stakeholders include the Finnish Student Health Service foundation (FSHS), government and private practices, where the Social Insurance Institution of Finland plays a major role in funding. Rise in the treatment need in recent years due to the increasing dentulous ageing population has challenged the healthcare system. Governmental response to the demand is an ongoing social and healthcare reform and increase of oral health professional education since 2004. However, the current and future treatment need is not met only by conventional prevention strategies and physical service provision. Finland has over the years supported a determined policy of building a digital healthcare architecture. This applies also to all fields of oral healthcare: virtual education, digital diagnostics, digital clinical workflow, national electronic patient records, patient-generated data registers, electronic prescriptions, remote consultation, digital service  management, as well as research and big data mining. These tools could play an important role in improving national oral health and increasing equity. This is an overview of the above-mentioned fields of e-Oral health and teledentistry in Finland based on current scientific literature, national reports, strategies and legislation.
Teledentistry Overview: United States of America
Authors: Nichols Katelyn
Published: May 2019

This paper describes current teledentistry practices in the United States of America.  The health landscape of the country is reviewed and the emerging need for remote health services discussed. The origins, current guidelines, legal issues, and financial arrangements for teledentistry are described.  Specific attention is paid to emerging teledentistry programmes throughout the country, including a case study of a successful and expanding teledentistry programme in the state of Oregon. Although the literature has long touted the health and economic benefits associated with teledentistry, it has become clear that this technology has generally outpaced policymaking and regulatory agencies. This paper attempts to contextualise and review leading developments in teledentistry to aid in the dissemination of otherwise fragmented efforts and experiences.
THE SOLIDARITY IN ADDRESSING TERMS OF RJ. PALACIO’S CHILDREN NOVEL ‘WONDER’: A SOCIOLINGUISTIC ANALYSIS
Authors: Jannah Nur , Ratnadewi Dwijani
Published: May 2019

Physical deficiencies sometimes cause bullying, but there are also many people who have senseof solidarity. “Wonder” (2012) by RJ. Palacio tells about a boy with this deficiency and thisstudy was meant to analyze the addressing terms used among the characters illustratingsolidarity. The aims of the research were to find kinds of solidarity addressing terms chosen bythe characters; the reason and the kind of situation of using the addressing terms. The dialogueswere framed and foregrounded to collect the data. Wardhaugh (2006) addressing terms andLindenberg et. al. (2006) solidarity behaviour indicators were used as the main theories toanalyze the data. The result revealed that there were four kinds of addressing terms foundmentioning first name, kinship term, nickname, and endearment name used in various butmostly friendly, quarreling and serious situation.
SUPERVISI SEBAGAI PENINGKAT MUTU PENDIDIKAN UNTUK MENCAPAI KUALITAS PENDIDIKAN INDONESIA
Authors: Kurniawati Sri
Published: May 2019

Supervisi pendidikan merupakan pembinaan yang berupa bimbingan kearah perbaikan dalam pendidikan pada umumnya dan peningkatan mutu mengajar dan belajar pada khususnya. Supervisi dilaksanakan oleh seorang supervisor. Supervisor bertanggung jawab dalam mengawasi jalannya pendidikan, membimbing dan membina guru untuk mengembangkan keterampilan dan kemampuan yang ada pada dirinya dalam mewujudkan pendidikan yang bermutu dan tercapainya tujuan pendidikan nasional. Dalam pelaksanaannya supervisi memiliki komponen-komponen antara lain, Pengumpulan data, penilaian, deteksi kelemahan, memperbaiki kelemahan, dan bimbingan dan pengembangan. Semua itu dilakukan agar pendidikan di Indonesia memiliki mutu yang tinggi sehingga mencapai kualitas pendidikan nasional.
Globalization and the Rise and Fall of Cognitive Control
Authors: Mosleh Mohsen , Kyker Katelynn , Cohen Jonathan D. , Rand David Gertler
Published: May 2019

The scale of human interaction patterns is larger now than ever before – people regularly interact with and learn from others around the world, and we each have the ability to impact the global environment that is shared by all. The consequences of local versus global interaction - particularly for the evolution of cooperation - have been studied extensively by evolutionary game theorists for decades. Here, we use this lens to explore a new question: How does the scale of interaction affect the evolution of cognition, and in particular the use of automatic (e.g., reflexive or habitual) versus controlled (e.g., deliberative) cognitive processing? We find robust evidence of cycles of automaticity versus control, and that these dynamics are influenced by the scale of interaction. Specifically, globalized environment disfavors cognitive control; globalized direct contact can either favor or disfavor control, depending on whether controlled agents are harmed or helped by contact with automatic agents; and globalized learning phase-locks the whole population and destroys meso-scale communities of more versus less controlled agents. These results emphasize the importance of the scale of interaction for the evolution of cognition, and help shed light on challenges currently facing our species.
Inclusive STEM Education: Theoretical Framework for Examining the Experienes of Women Students of Color in STEM Education
Authors: Kim Kelly
Published: May 2019

Women students of color (WSOC) continue to be excluded from science, technology, engineering and mathematics (STEM) fields, despite efforts to promote diversity. The existing research to develop inclusive STEM education adopts a deficit approach and fails to address the intersectionality of gender, race and class. By not addressing this intersectionality, research has failed to consider the effects of racial privilege for white women and the unique experiences of each woman of color. In contrast, my research will take an anti- deficit approach and value the intersectionality of each student. The objective of this study is to examine the experiences of WSOC in their secondary STEM education according to the intersection of race, gender and class. This research is also guided by the following questions: (1) What are WSOC’s social and academic experiences of STEM-related courses, and in-class and extracurricular activities? (2) What support systems and barriers do WSOC recognize in their schools pertaining to STEM, if any? (3) How are their experience, support systems and barriers unique yet similar according to their intersectionality? This paper develops the theoretical approach that guides my research. To better understand how WSOC are racialized and gendered in the settler state, I adopt Critical Race Theory (CRT) approach. In the education setting, it describes how schools, as a state funded institute, act as a site of reinforcement of this oppression. I also incorporate post- structualist work on identity and power to refine how WSOC are situated in the STEM education setting. The research will adopt the Counter-Storytelling as a methodology which emphasizes the importance of telling the stories of people, whose experiences are not often told to expose, analyze and challenge the majoritarian stories of racial privilege.
The Persistent Effect of U.S. Civil Rights Protests on Political Attitudes
Authors: Mazumder Soumyajit
Published: May 2019

Protests can engender significant institutional change. Can protests also continue to shape a nation’s contemporary politics outside of more formalized channels? I argue that social movements can not only beget institutional change, but also long-run, attitudinal change. Using the case of the U.S. civil rights movement, I develop a theory in which protests can shift attitudes and these attitudes can persist. Data from over 150,000 survey respondents provide evidence consistent with the theory. Whites from counties that experienced historical civil rights protests are more likely to identify as Democrats and support affirmative action, and less likely to harbor racial resentment against blacks. These individual-level results are politically meaningful—counties that experienced civil rights protests are associated with greater Democratic Party vote shares even today. This study highlights how social movements can have persistent impacts on a nation’s politics.
Association of Thrombocytopenia and Mortality in Critically ill Children Admitted to PICU in Tertiary Hospital In Biratnagar
Authors: Sah Vijay Kumar , Giri Arun , KC Milan , Niraula Niraj
Published: May 2019

Introduction: Thrombocytopenia is a clinical condition characterized by decrease in number of platelets below the normal range. It is associated with bleeding tendency, hemodynamic instability, impaired inflammatory process and thus affecting host defence mechanism. There has been only few studies published till date in pediatric intensive care units suggesting thrombocytopenia is associated with increased mortality.

Objectives: To determine the prevalence of thrombocytopenia in the critically ill children and its relationship with mortality in Pediatric intensive care unit (PICU) admitted children.

Methodology: A prospective observational study was performed over a period of 12 months on 102 critically ill children admitted in PICU who fulfilled the criteria. Two patients left the study due to financial problems and as outcome could not be assessed on them, they were excluded from the study. Platelet count was noted at the time of admission and consecutively for the initial four days at PICU. Thrombocytopenia was defined as platelet count less than 150/nL. Mortality in PICU was recorded as primary outcome.

Results: The prevalence of thrombocytopenia during consecutive 4 days was 34% (n=34) and at the time of admission in PICU was 16% (n=16) among 100 children analysed in the study. The mortality in the PICU was 27% (n=27). Mortality among thrombocytopenic children was 61.7% (n=21) as compared to 7.6% (n=5) in non-thrombocytopenic children (p=<0.001). Mortality was 18 times more for those who were thrombocytopenic at the time of admission as compared to those who subsequently developed thrombocytopenia during course of stay in PICU.

Conclusion: Thrombocytopenia has significant association with increased mortality. Thrombocytopenic children at the time of admission have more likelihood of mortality than nonthrombocytopenic children in intensive care units.
'Selfie Elbow'- A Public Health Problem among Mobile Users
Authors: Khanal Laxman , Khan Gulam Anwer , Pandeya Anup
Published: May 2019

Introduction: While taking a selfie picture, a person is in a position in which the arm is fully extended or sometimes a little bent and maintained until the picture of choice is adjusted in the camera frame. One Person must have a firm grip on phone to hold it and hit click. When the process is repeated for a few photos, it causes repetitive strain injury, resulting in various signs, including pain in the elbow joint, which has now been named 'selfie elbow.' Doctors assume that as many as 25% of cell phone users in Kolkata are suffering from this problem (selfie-elbow).

Although a selfie is generally seen as an expression of self to others, the American Psychiatric Association (APA) has officially confirmed that taking 'selfies' is seen as a mental disorder and has been given the term 'selfitis.' Selfie elbow is a condition due to overuse injury caused by extending and twisting one's arm for too many phone selfies. Like tennis elbow or golfer's elbow, an addiction to selfie-taking and clicking too many can cause pain in your primary picture-snapping elbow and may affect the upper limb, elbow, and shoulder muscles – which leads to degradation in function. Joints involved in the process of selfie-taking are the shoulder joint, the elbow joint, and the wrist joint, all of which help the hand attain a perfect frame for the picture. However, most of the strain is referred to the elbow, because the person extends (or sometimes bends) the elbow in an extremely strained position during the selfie. Selfie elbow is more of an abnormal and repetitive loading of muscles around the elbow, leading to microruptures, and resulting in inflammation and pain; this ultimately heals with scarring, but causes recurrent pain. As stated, it is a form of repetitive stress injury, similar to carpal tunnel syndrome (or the compression of the median nerve in the wrist, usually due to overuse of the hand) and tendonitis (which occurs when the tendon becomes inflamed).
Degradation of a Main Combustion Chamber Liner on a Space Shuttle Main Engine
Authors: Sanders J.H. , Chen P.S. , Parr R.A.
Published: May 2019

Pinhole defects were found in a main combustion chamber made from NARloy-Z after an unexpectedly short time in service. Analysis indicated that the throat section of the liner had been exposed to very severe environmental conditions of high temperature and high oxygen content, which caused ductility loss and grain-boundary separation. The excessive oxygen content in the liner was attributed to diffusion from an oxygen-rich environment that had resulted from nonuniform mixing of propellants. The internal oxygen embrittled the alloy and reduced its thermal conductivity, which resulted in a higher hot-gas wall temperature and associated degradation of mechanical properties.
Failure of a Stirling Engine Heat Pipe
Authors: Moore Thomas J. , Cairelli James E. , Khalili Kaveh
Published: May 2019

A Stirling engine heat pipe failed after only 2h of operation in a test situation. Cracking at the leading edge of an evaporator fin allowed air to enter the system and react with the sodium coolant. The fin was fabricated from 0.8 mm (0.03 in.) thick Inconel 600 sheet. The wick material was type 316 stainless steel. Macro- and microexaminations of specimens from the failed heat pipe were conducted. The fin cracking was caused by overheating that produced intergranular corrosion in both the fin and the wick. Recommendations for alleviating the corrosion problem included reducing the heat flux, redesigning the wick, and reducing the oxygen content of the sodium.
Failure of Wrist Pins in an Automotive Engine
Authors: Mackay W.B.F.
Published: May 2019

Six wrist pins in a high-performance six-cylinder automotive engine failed after 4800 km (3000 mi) of normal operation. The pins were made of low-carbon steel that had been carburized both inside and outside. Two failed pins were examined. One had fractured into three pieces. The other had not fractured, but exhibited circumferential cracks on the surface of the central zone. Visual surface examination and metallographic and chemical analyses were performed on the specimens. Cracking was attributed primarily to poor heat treatment, resulting in a brittle grain-boundary network of cementite, and to a design that had a raised central section of the inner diameter whose fillets were locations of high stress concentration. Rough machining of the inner diameter and an excessively deep case also contributed to failure. A double type of heat treatment after carburizing and change of the design to eliminate the raised central section were recommended.
Fatigue Failure of a 1000 mm (40 in.) Diam Trailer Wheel at the Bolt Holes
Authors: Jones W.F.
Published: May 2019

The rear outside wheel of an over-the-road 18-wheel tractor-trailer failed at its bolt holes, permitting the tire and wheel to separate from the hub. Failure analysis was conducted using photographic examination of actual fracture surfaces and SEM examination of fracture replicas. The examinations indicated that fatigue cracks had originated at the rim backside and propagated to the rim midsection. Catastrophic failure occurred at a final overland. Fatigue fracture of the wheel rim was attributed to cyclic loading created by improper wheel mounting of a spare tire.
Embrittlement of a 76 mm (3 in.) Stainless Steel Pipe and Liner From a Hydrogen Plant Quench Pot Vessel
Authors: Bowman Ralph D.
Published: May 2019

A 76 mm (3 in.) type 304 stainless steel tube that was used as a heat shield and water nozzle support in a hydrogen gas plant quench pot failed in a brittle manner. Visual examination of a sample from the failed tube showed that one lip of the section was eroded from service failure, whereas the opposite side exhibited a planar-type fracture. Sections were removed from the eroded area and from the opposite lip for microscopic studies and chemical analysis. The eroded edges exhibited river bed ditching, indicative of thermal fatigue. Microstructural analysis showed massive carbide formations in a martensite matrix and outlining of prior-austenite grains by a network of fine, white lines. These features indicated that the material had been transformed by carburization by the impinging gas. The outer surface exhibited a heavy scale deposit and numerous cracks that originated at the surface of the tube. The cracks were covered with scale, indicating that thermal fatigue (heat cracking) had occurred. Chemical analysis confirmed that the original material was type 304 stainless steel that had been through-carburized by the formation of an endothermic gas mixture. It was recommended that plant startup and shutdown procedures be modified to reduce or eliminate the presence of the carburizing gas mixture.
Intergranular Corrosion in an E-Brite-Clad Ferralium Tube Sheet in Nitric Acid Service
Authors: Colwell Richard L.
Published: May 2019

An E-Brite /Ferralium explosively bonded tube sheet in a nitric acid condenser was removed from service because of corrosion. Visual and metallographic examination of tube sheet samples revealed severe cracking in the heat-affected zone between the outer tubes and the weld joining the tube sheet to the floating skirt. Cracks penetrated deep into the tube sheet, and occasionally into the tube walls. The microstructures of both alloys and of the weld appeared normal. Intergranular corrosion characteristic of end-grain attack was apparent. A low dead spot at the skirt / tube sheet joint allowed the Nox to condense and subsequently reboil. This, coupled with repeated repair welding in the area, reduced resistance to acid attack. Intergranular corrosion continued until failure. Recommendations included changing operating parameter inlet to prevent HNO3 condensation outside the inlet and replacement of the floating skirt with virgin material (i.e., material unaffected by weld repairs).
Corrosion Fatigue Cracking of a Steam Generator Vessel From a Pressurized Water Reactor
Authors: Czajkowski Carl J.
Published: May 2019

A pair of steam generators operating at a pressurized water reactor site were found to be leaking near a closure weld. The generators were the vertical U-tube type, constructed from ASTM A302 grade B steel. The shell material exhibited high hardness values prior to confirmatory heat treatment, indicating high residual stresses in the area of the weld. All cracks were transgranular and were associated with pits on the inside surfaces of the vessels. It was concluded that the cracking was caused by a low-cycle corrosion fatigue phenomenon, with cracks initiating at areas of localized corrosion and propagating by fatigue. The cause of the pitting/cracking was related to the unit's copper species in solution.
Failure of a High-Pressure Water-Line Plug in a Fire Sprinkler System
Authors: Leeser David O.
Published: May 2019

A white cast iron water-line plug in a fire sprinkler systems split during leak repair. Examination revealed no material flaws, fatigue, or excessive corrosion. The plug head exhibited signs of excessive loads used in attempts to force the plug farther into the pipe. The evidence obtained indicated that the failure resulted from human error.
Intergranular Stress-Corrosion Cracking of Carbon Steel Pipe Welds in a Kamyr Continuous Digester Equalizer Line
Authors: Chakrapani Durgam G.
Published: May 2019

Schedule 80 low-carbon steel pipes used to transfer kraft liquor in a Kamyr continuous pulp digester failed within 18 months after installation. Visual and metallographic examinations established that the cracking initiated on the internal surfaces of the equalizer pipes in the welds and heat-affected zones (HAZs). Fracture/crack morphology was brittle and primarily intergranular and deposits at crack tips were primarily iron oxides with significant amounts of sodium compounds. On these bases, the cracking was characterized as intergranular stress-corrosion cracking (IGSCC). Corrosion-related deterioration was not found, indicating that the material was generally suitable for the intended service. High residual tensile stresses in the welds and HAZS, resulting from field welding under highly constrained conditions using inadequate weld procedures, were the most probable cause of the failures. Minimizing residual stresses through use of welding procedures that include appropriate preweld and interpass temperatures and postweld stress relief heat treatment at 650 deg C (1200 deg F) was recommended to prevent further failures.
Pitting Corrosion of Stainless Steel by Potable Municipal Water in an Organic Chemical Plant
Authors: Perumal K.E.
Published: May 2019

Several tubes in a 35 m2 (115 ft2) type 316 stainless steel shell-and-tube condenser leaked unexpectedly in an organic chemical plant that produces vinyl acetate monomer. Leaks were discovered after 5 years of operation and relocation of the condenser to another unit in the same plant. Examination of tubes and tube sheets revealed pitting damage on the OD surface. Some of the pits had penetrated fully, resulting in holes. Inside diameter surfaces were free of corrosion. Macro- and microexaminations indicated that the tubes had been properly manufactured. Pitting was attributed to stagnant water on the shell side. It was recommended that the surfaces not be kept in contacts with closed stagnant water for appreciable lengths of time.
Stress-Corrosion Cracking of C-Mn Steel in a CO2 Absorber in a Chemical Plant
Authors: Chauhan Sushil K.
Published: May 2019

The source of cracking in the circumferential weld seam in a JIS-SM50B carbon-manganese steel pipe used in a CO2 absorber was investigated, the absorber had been in service for 18 years. The seam had been weld-repaired twice, and the repair welds had been locally stress relieved. Longitudinal seams in the same vessel, which had been stress relieved in a furnace, showed no tendency toward cracking. The solution passing through the vessel contained CO2-CO-H20, KHCO, and Cl− ions. Nondestructive testing revealed that the cracks originated in the heat-affected zone and propagated into the base metal and weld. Severe branching of the cracks characteristic of stress-corrosion cracking was observed. Microexamination revealed that crack propagation was transgranular further supporting the possibility of stress-corrosion cracking. Simulation tests carried out in the vessel confirmed this mode of cracking. It was recommended that weld seams be furnace heat treated at a temperature of 600 to 640 deg C (1110 to 1180 deg F) for a minimum of 1 h per inch of section thickness.
Unexpected Corrosion of Type 316L Stainless Steel Neutralization Tanks
Authors: Degnan Thomas F.
Published: May 2019

Although field corrosion tests had indicated that type 316L stainless steel would be a suitable material for neutralization tanks, the vessels suffered severe corrosion when placed in service. Welded coupons of type 316L had been tested along with similar Alloy 20Cb® (UNS NO8020) specimens in a lead-lined tank equipped with copper coils that had served in this function prior to construction of the new tanks. Both materials exhibited virtually no corrosion and no preferential weld attack. Type 316L was selected for the project. The subsequent corrosion was the result of the borderline passivity of type 316L in hot dilute sulfuric acid (about 0.1%). Inaccuracy of the testing was attributed to the presence of cupric ions in the lead-lined vessel fluids, which had been released by corrosion of the copper coils. Careful control of both temperature and pH was recommended to reduce the corrosion to an acceptable limit.
Environmental Cracking of a Low-Alloy Steel Welded Impeller Cover From a Centrifugal Unit
Authors: Ebert Harry E.
Published: May 2019

Radial cracking occurred adjacent to 11 vanes in a 19-vane impeller operating in a chemical plant environment. The impeller vanes were fillet welded to both the disk and the cover Cracks were next to the fillet welds and near the cover outer diameter They generally did not extend to the outer diameter. The entire impeller surface was tested by the dry magnetic particle method. Visual and microstructural examinations revealed intergranular cracking. Energy-dispersive spectroscopy of corrosion products contained in the cracks disclosed the presence of chlorine and sulfur The failure was attributed to stress-corrosion cracking caused by a corrosive atmosphere.
Excessive Wear of Plain Carbon Steel Sprockets in a Chemical Plant Producing Fibers
Authors: Mackay W.B.F.
Published: May 2019

Replacement sprockets installed on chain drive shafts for winding fibers exhibited excessive wear. Metallographic and chemical analyses conducted on the original and replacement sprockets showed that the material of the replacement sprocket was 1020 low-carbon steel, whereas the original (and specified) material was medium-carbon 1045 steel. The low-carbon steel also had lower hardness because of a lower pearlite fraction in the microstructure. It was recommended that replacement sprockets be made of normalized 1045 steel. It was further suggested that wear resistance could be improved by through hardening or induction surface hardening of the teeth.
Fatigue Fracture of Stainless Steel Wires in an Electrostatic Precipitator at a Paper Plant
Authors: Brooks Charlie R.
Published: May 2019

Several type 316L stainless steel wires in an electrostatic precipitator at a paper plant fractured in an unexpectedly short time. Failed wires were examined using optical and scanning electron microscope, and hardness tests were conducted. Fractography clearly established that fracture was caused by fatigue originating at corrosion pits on the surface of the wire. It was recommended that higher-molybdenum steel in the annealed condition be used to combat pitting corrosion.
Fatigue Fracture of Aircraft Engine Compressor Disks
Authors: Koul Ashok K. , Dainty Raymond V.
Published: May 2019

Several compressor disks in military fighter and trainer aircraft gas turbine engines cracked prematurely in the bolt hole regions. The disks were made of precipitation-hardened AM355 martensitic stainless steel. Experimental and analytical work was performed on specimens from the fifth-stage compressor disk (judged to be the most crack-prone disk in the compressor) to determine the cause of the failures. Failure was attributed to high-strain low-cycle fatigue during service. It was also determined that the cyclic engine usage assumed in the original life calculations had been under estimated, which led to low-cycle fatigue cracking earlier than expected. Fracture mechanics analysis of the disks was carried out to assess their damage tolerance and to predict safe inspection intervals.
Repeated Failure of Rubber Slurry Pump Impellers and Liners in a Flue Gas Desulfurization Plant
Authors: Ellis Peter F.
Published: May 2019

The repeated failure of rubber-covered rotors and volute liners in a flue gas desulfurization system after conversion from lime slurry reagent to limestone slurry reagent was investigated. The pump was a horizontal 50 x 65 mm (2 x 2.5 in.) Galiger pump with a split cast iron case and open rotor (impeller). Both the case and the ductile iron rotor core were covered by natural rubber. Analyses conducted included surface examination of wear patterns, chemical analysis of materials, measurement of mechanical properties, and in-place flow tests. It was determined that the proximate cause of failure was cavitation and vortexing between the rotor and the lining. The root cause of the failure was the conversion from lime to limestone slurry without appropriate modification of the pump. Conversion to the limestone slurry resulted in fluid dynamics outside the operational limits of the pump. The recommended remedial action was replacement with a pump appropriately sized for the desired pressures and flow rates for limestone slurry.
Cracking of an Alloy Steel Bolt
Authors: Levy Eli
Published: May 2019

A heat-treated, cadmium-plated AISI 8740 steel bolt broke through the head-to-shank fillet while being handled during assembly. Fractographic and metallographic examination of the bolt traced the cause of failure to quench cracking, which occurred when the part was water cooled following hot heading and prior to the production run. The process chart for hot heading was changed from water quenching to air cooling following the forming operation.
Environmentally-Induced Fracture of Type 410 Martensitic Stainless Steel Self-Drilling Tapping Screws
Authors: Chakrapani Durgam G.
Published: May 2019

Cadmium-coated type 410 martensitic stainless steel 14-14 self-drilling tapping screws fractured during retorquing tests within a few weeks after installation. The screws were used to assemble structural steel frames for granite panels that formed the outer skin of a high-rise building. Fractographic and metallographic examination showed that the fractures occurred in a brittle manner from intergranular crack propagation. Laboratory and simulated environmental tests showed that an aqueous environment was necessary for the brittle fracture/cracking phenomenon. The cracks were singular and intergranular with little branching. Secondary subsurface cracks suggested possible hydrogen embrittlement. The 410 screws had been introduced to replace conventional case-hardened carbon steel screws that conform to SAE specification J78. Carbon steel screws had a proven record of acceptable performance for the intended application. It was recommended that use of the 410 screws be discontinued in preference to the case-hardened carbon steel screws.
Fatigue Fracture of 316L Stainless Steel Screws Employed for Surgical Implanting
Authors: Snyder Harold J. , Snyder Casey B.
Published: May 2019

Two type 316L stainless steel orthopedic screws broke approximately 6 weeks after surgical implant. The screws had been used to fasten a seven-hole narrow dynamic compression plate to a patient's spine. The broken screws and screws of the same vintage and source were examined using macrofractography, SEM fractography, and hardness testing. Fractography established that fracture was by fatigue and that the fatigue cracking originated at corrosion pits. Hardness while below specification, still indicated that the screws were in the cold-worked condition and notch sensitive during fatigue loading. Use of a steel with a higher molybdenum content (317L) in the annealed condition was recommended.
Fatigue Failure of Six Cap Screws From a Hydraulic Coupling
Authors: Tanner G. Mark
Published: May 2019

Six ASTM A-574 steel cap screws from a hydraulic coupling failed after 3 months in service. The screws were replacements for smaller-diameter cap screws that had been installed during an outage. Six new cap screws were examined along with the failed screws. Eight fracture locations were identified—three at the head-to-shank fillet, four at the eighth thread root from the cap, and one at the sixth thread root from the cap. Fracture surfaces were examined using a stereomicroscope and SEM, and the fracture mode was shown to be transgranular. EDS on the fracture surfaces showed sulfur and chlorine in the surface deposits. The observations indicated that the screws had failed by fatigue. Insufficient preloading was considered to be the most likely cause of the fatigue cracking. It was recommended that the proper preload on the screws be verified and maintained.
Fracture of Alloy Steel Cap Screws in a Refrigeration Compressor
Authors: Witherell Charles E.
Published: May 2019

Uncoated high-strength alloy steel cap screws retaining a cast aluminum (356.0) diffuser assembly in a centrifugal refrigerant compressor failed in a brittle manner a short time after the system was placed in operation. Evidence obtained during the failure analysis indicated that the failures were the result of hydrogen embrittlement produced by galvanic corrosion and attendant evolution of hydrogen at the dissimilar junction, which was also the site of the highest tensile stress. Suggested measures for minimizing recurrences included use of lower-strength, galvanically-compatible fasteners and appropriately-applied and treated compatible coatings.
Furnace Element Tube Failures
Authors: Wellington K.G.
Published: May 2019

Three radiant heating element tubes from an aluminum holding furnace failed after a few months of service. One side of each of the tubes had disintegrated, leaving large holes and thinned cross sections. Microstructural analysis showed that the surface of the tube had been oxidized along the grain boundaries and had extensive precipitation inside the grains. Chemical analysis indicated that the steel used for the tubes was AISI type 316 stainless steel Specifications for the tubes had called for AISI type 310S to be used. It was recommended that other tubes made from the same batch of steel sheet be checked.
Hydrogen-Induced Cracking of Welded Truss Gusset Plates
Authors: Jones William F.
Published: May 2019

Six cracked A36 steel gusset plates that formed part of the roof trusses of a large manufacturing facility were discovered during a routine final inspection of a new building construction. Two different-size plates from different locations in the building were removed and tested. It was determined that the gusset plates failed in the heat-affected zone via an intergranular microcracking mode due to hydrogen-assisted underbead and toe-weld cracking. Proper nondestructive testing techniques for magnetic particle and radiographic inspection of the plate-weld gusset areas were recommended.
Failure of Two Plastic Toilet-Tank Floats
Authors: Leeser David O.
Published: May 2019

Two plastic tank floats in separate toilets in one dwelling failed within a relatively brief period of time. Examination of the floats and of a brass connecting rod revealed that the fracture occurred at the base of the threaded hole in the nipple and was brittle in nature. The fracture surfaces were coated with zinc oxide. It was concluded that the failure resulted from improper repairs and/or adjustments, including the use of a cosmetic zinc oxide cream as a lubricant. The cream initiated deterioration of the originally ductile plastic, causing it to become brittle and fragile.
Failure of Pendent Sprinkler Heads
Authors: Chaudhari Mohan D.
Published: May 2019

A sprinkler head unit that was installed in a smoking lounge of a multi story office building in 1975 failed, causing substantial water damage. There was no fire in the building. A set of four sprinkler heads -- three that had been installed in 1975 (the failed unit, an unfailed unit from the same room, and an unfailed unit from another room) and an unused 1991 unit -- were examined. casting revealed no material defects or mechanical damage. Because of several environmental factors, it was suspected that the failed unit was exposed to temperatures much above the normal office environment. On this basis, it was concluded that creep of the solder alloy was the most probable cause of failure.
Fatigue Failure of Steering Arms Due to Forging Defects
Authors: Baggerly Roy G.
Published: May 2019

Several heavy truck Cr-Mo steel steering arms in service less than three years fractured during stationary or low-speed turning maneuvers that required power-assisted steering. Metallographic examination of the cracked AISI 4135 arms, heat treated to a hardness of 285 to 341 HB, revealed that fatigue crack initiation occurred from the tip of oxide scale inclusions forged into the U-shaped arm at the inside radius. Corrective action involved redesigning the steering arm to increase the minimum forging radius and reduce the stress level at the inner-bend radius, and reducing the level of power assistance to the wheels to encourage the driver to put the vehicle in motion prior to turning.
Brittle Failure of a Titanium Nitride-Coated High Speed Steel Hob
Authors: Stone Alan
Published: May 2019

Recurring, premature failures occurred in TiN-coated M2 gear hobs used to produce carbon steel ring gears. Fractographic and metallographic examination, microhardness testing, and chemical analysis by means of EDS revealed that the primary cause of failure was a coarse cellular carbide network, which created a brittle path for fracture to occur longitudinally. As the cellular carbide network must be dispersed and refined during hot working of the original bar of material, the hobs were not salvageable. Minor factors contributing to the hob failures were premature wear resulting from lower matrix hardness and high sulfur content of the material, which contributed to lower ductility through increased nucleation sites. It was recommended that the hob manufacturer specify a minimum amount of required reduction for the original bar of tool steel material, to provide for sufficient homogenization of the carbides in the resultant hob, and lower sulfur content.