bluuebunny/crossref_metadata_2025 huggingface dataset:
Long‐term cottonwood establishment along the Green River, Utah, USA
Authors: Scott M. L. , Miller M. E.
Published: December 2016

Cottonwood (Populus spp.) riparian forest and woodlands provide valuable ecological goods and services, especially in arid and semiarid regions of North America. Successful establishment and survival for cottonwoods requires bare, moist alluvium that is relatively safe from fluvial disturbance. These are restrictive requirements in dry regions. Cottonwoods can survive for three to four centuries and thus may provide a long‐term record of specific fluvial and geomorphic events. We used C14 analysis and ring counts of cottonwood stems to document a long‐term record of cottonwood establishment. We related this record to the century‐long gage record at Green River, Utah along with historical photos and paleoflood records. Radiometric carbon dating and ring counts suggest some cottonwood stems established on high alluvial deposits following large floods as early as the late 1600s through the late 1800s. Cottonwoods also established on inset floodplain surfaces following sustained decreases in peak flows resulting from climatic drought and the closing of Flaming Gorge Dam. Finally, establishment occurred on both higher post‐dam flood deposits as well as low, active channel surfaces following floods and during a series of low flow years. With continued peak‐flow reduction, cottonwood recruitment will likely be restricted to spatially limited, lower elevation surfaces and subjected to competition from an array of herbaceous and woody riparian species.
Transition‐Metal Nitrosyls for Photocontrolled Nitric Oxide Delivery
Authors: Xiang Hui‐Jing , Guo Min , Liu Jin‐Gang
Published: December 2016

Nitric oxide (NO) is an endogenously produced biological signaling compound, involved not only in various physiological processes but also in cancer biology. The potential therapeutic applications of NO in regulation of vascular tone, anticancer, antibacterial, anti‐inflammatory, and wound healing processes has resulted in an explosion of research interest in NO donor compounds and in related materials capable of delivering NO to desired sites. Transition‐metal nitrosyls such as those of ruthenium (Ru‐NOs) are photolabile NO donors from which NO release can be manipulated on demand by application of light. This enables control of spatiotemporal delivery and of optimal NO dosage at a desired site and time. In this microreview we highlight advances of the past few years in rational ligand design, the sensitization of metal nitrosyls (especially Ru‐NOs) by use of light from ultraviolet (UV) to near‐infrared (NIR) wavelengths for efficient NO release, and integration of metal nitrosyls with various nanoplatforms for photocontrolled targeted NO delivery.
On the “Where” of Social Experiments: Selecting More Representative Samples to Inform Policy
Authors: Olsen Robert B. , Orr Larry L.
Published: December 2016

Most social experiments are conducted in samples of sites that are not formally representative of the population of policy interest. These studies may produce impact estimates that are unbiased for the sample but biased for the population from which the sample was selected. Recent research has estimated the bias associated with nonrandom inclusion. Although some research has focused on solutions to the problem at the design stage or the analysis stage, research on ways to address this problem is still sparse. This paper provides four recommendations to help researchers obtain more representative samples in impact studies. The fundamental challenge is that, in most impact studies, sites are not required to participate if selected. Therefore, obtaining a sample that adequately represents the population of policy interest can be difficult, and the resulting impact estimates may suffer from external validity bias. The recommendations in this chapter address this challenge to help researchers obtain more representative samples when obtaining a perfectly representative sample is not possible. The recommendations, which are based on standard survey sampling methods, demonstrate that researchers can take practical steps to obtain impact estimates that are more generalizable from the study sample to the broader population of policy interest—and therefore more relevant for informing policy decisions.
Building work engagement: A systematic review and meta‐analysis investigating the effectiveness of work engagement interventions
Authors: Knight Caroline , Patterson Malcolm , Dawson Jeremy
Published: December 2016

Low work engagement may contribute towards decreased well‐being and work performance. Evaluating, boosting and sustaining work engagement are therefore of interest to many organisations. However, the evidence on which to base interventions has not yet been synthesised. A systematic review with meta‐analysis was conducted to assess the evidence for the effectiveness of work engagement interventions. A systematic literature search identified controlled workplace interventions employing a validated measure of work engagement. Most used the Utrecht Work Engagement Scale (UWES). Studies containing the relevant quantitative data underwent random‐effects meta‐analyses. Results were assessed for homogeneity, systematic sampling error, publication bias and quality. Twenty studies met the inclusion criteria and were categorised into four types of interventions: (i) personal resource building; (ii) job resource building; (iii) leadership training; and (iv) health promotion. The overall effect on work engagement was small, but positive, k = 14, Hedges g = 0.29, 95%‐CI = 0.12–0.46. Moderator analyses revealed a significant result for intervention style, with a medium to large effect for group interventions. Heterogeneity between the studies was high, and the success of implementation varied. More studies are needed, and researchers are encouraged to collaborate closely with organisations to design interventions appropriate to individual contexts and settings, and include evaluations of intervention implementation. © 2016 The Authors. Journal of Organizational Behavior published by John Wiley & Sons, Ltd.
The Interplay of Self–Certainty and Prosocial Development in the Transition from Late Adolescence to Emerging Adulthood
Authors: Crocetti Elisabetta , Moscatelli Silvia , Van der Graaff Jolien , Rubini Monica , Meeus Wim , Branje Susan
Published: December 2016

The transition from late adolescence to emerging adulthood is a period of the life span that offers young people the possibility to consolidate their self–certainty and prosociality. Both aspects are of core importance for increasing personal and societal well–being. The purpose of this longitudinal study was twofold: (i) to examine patterns of change and stability in self–concept clarity and prosociality; and (ii) to unravel over time associations between these constructs in the transition from late adolescence to emerging adulthood. In addressing both aims, we explored the moderating effects of gender. Participants were 244 Dutch emerging adults (46% male; mean age at T1 = 16.73 years) who completed six waves of data collection (mean age at T6 = 22.7 years). Findings highlighted that (i) self–concept clarity developed nonlinearly, with an initial decline from T1 to T2 followed by an increase thereafter, while prosociality increased linearly over time and both self–concept clarity and prosociality were characterized by high rank–order consistency; (ii) self–concept clarity and prosociality were positively related over time, with the effect of prosociality on self–concept clarity being stronger than the reciprocal effect of self–concept clarity on prosociality. Gender differences were detected in mean levels of self–concept clarity and prosociality (male participants reported higher self–concept clarity and lower prosociality than female participants) but not in their developmental pathways nor in their reciprocal associations. Copyright © 2016 European Association of Personality Psychology
TREATMENT OF PEDIATRIC OBSESSIVE COMPULSIVE DISORDER UTILIZING PARENT‐FACILITATED ACCEPTANCE AND COMMITMENT THERAPY
Authors: Barney Jennifer Y. , Field Clint E. , Morrison Kate L. , Twohig Michael P.
Published: December 2016

Acceptance and commitment therapy (ACT) is a modern form of cognitive behavior therapy that uses acceptance and mindfulness‐based procedures to address clinical issues. A brief protocol of ACT was used with 3 children ages 10 and 11 years who were diagnosed with obsessive compulsive disorder (OCD). Results showed notable and clinically significant reductions of OCD across participants. These findings are noteworthy because the treatment was provided by a school psychologist, it is the first application of ACT for pediatric OCD, and it is one of a few studies using ACT with children. Limitations and future directions are discussed.
The cosmological constant as an eigenvalue of the Hamiltonian constraint in a varying speed of light theory
Authors: Garattini Remo , De Laurentis Mariafelicia
Published: December 2016

In the framework of a Varying Speed of Light theory, we study the eigenvalues associated with the Wheeler‐DeWitt equation representing the vacuum expectation values associated with the cosmological constant. We find that the Wheeler‐DeWitt equation for the Friedmann‐Lemaître‐Robertson‐Walker metric is completely equivalent to a Sturm‐Liouville problem provided that the related eigenvalue and the cosmological constant be identified. The explicit calculation is performed with the help of a variational procedure with trial wave functionals related to the Bessel function of the second kind . After having verified that in ordinary General Relativity no eigenvalue appears, we find that in a Varying Speed of Light theory this is not the case. Nevertheless, instead of a single eigenvalue, we discover the existence of a family of eigenvalues associated to a negative power of the scale. A brief comment on what happens at the inflationary scale is also included.
Misspecification of at‐risk periods and distributional assumptions in estimating COPD exacerbation rates: The resultant bias in treatment effect estimation
Authors: Law M. , Sweeting M.J. , Donaldson G.C. , Wedzicha J.A.
Published: December 2016

In trials comparing the rate of chronic obstructive pulmonary disease exacerbation between treatment arms, the rate is typically calculated on the basis of the whole of each patient's follow‐up period. However, the true time a patient is at risk should exclude periods in which an exacerbation episode is occurring, because a patient cannot be at risk of another exacerbation episode until recovered. We used data from two chronic obstructive pulmonary disease randomized controlled trials and compared treatment effect estimates and confidence intervals when using two different definitions of the at‐risk period. Using a simulation study we examined the bias in the estimated treatment effect and the coverage of the confidence interval, using these two definitions of the at‐risk period. We investigated how the sample size required for a given power changes on the basis of the definition of at‐risk period used. Our results showed that treatment efficacy is underestimated when the at‐risk period does not take account of exacerbation duration, and the power to detect a statistically significant result is slightly diminished. Correspondingly, using the correct at‐risk period, some modest savings in required sample size can be achieved. Using the proposed at‐risk period that excludes recovery times requires formal definitions of the beginning and end of an exacerbation episode, and we recommend these be always predefined in a trial protocol.
Practical Perspectives of 1,4‐Dioxane Investigation and Remediation
Authors: Chiang Sheau‐Yun (Dora) , Anderson Richard (Hunter) , Wilken Michael , Walecka‐Hutchison Claudia
Published: December 2016

1,4‐Dioxane (dioxane) is a contaminant of emerging concern that is classified by the U.S. Environmental Protection Agency as a likely human carcinogen. Dioxane has been used as a minor or major ingredient in many applications, and is also generated as an unwanted by‐product of industrial processes associated with the manufacturing of polyethylene, nonionic surfactants, and many consumer products (cosmetics, laundry detergents, shampoos, etc.). Dioxane is also a known stabilizer of chlorinated solvents, particularly 1,1,1‐trichloroethane, and has been commonly found comingled with chlorinated solvent plumes. Dioxane plumes at chlorinated solvent sites can complicate site closure strategies, which to date have not typically focused on dioxane. Aggressive treatment technologies have greatly advanced and are clearly capable of achieving lower parts per billion cleanup criteria using ex situ advanced oxidation processes and sorption media. In situ chemical oxidation has also been demonstrated to effectively remediate dioxane and chlorinated solvents. Other in situ remedies, such as enhanced bioremediation, phytoremediation, and monitored natural attenuation, have been studied; however, their ability to achieve cleanup levels is still somewhat questionable and is limited by co‐occurring contaminants. This article summarizes and provides practical perspectives on dioxane analysis, plume stability relative to other contaminants, and the development of investigation tools and treatment technologies.
Schlußfolgerungen aus den Ergebnissen von Gemeinschaftsversuchen über das Zähigkeitsverhalten von Stahl
Authors: Dahl Winfried
Published: December 2016

Kritische Betrachtung des Bruchmechanikkonzepts. Mögliche Kriterien im Bereich der Fließbruchmechanik. Vergleich mit Rechnungen nach der Finite‐Element‐Methode. Kennzeichnende Einflußgrößen bei verschiedenen Prüfverfahren: Temperatur, Beanspruchungsgeschwindigkeit, Spannungszustand. Probleme bei der Anwendung, vor allem bei Schweißverbindungen.
Untersuchungen über die Naßabsiebung von Feinerzen im Feinkornbereich
Authors: Burghardt Otmar , Kortmann Heinrich , Bock Wolfgang
Published: December 2016

Einführung einer maschinellen Naßsieb‐Analysenmethode anstelle der bisher üblichen manuellen Naßsiebanalyse im Fein‐ und Feinstkornbereich von Eisenerzen. Verbesserung der Maschinensiebung durch Belüftung der Einzelsiebe sowie durch kontinuierliche Messung des Siebdurchganges mit Endpunktbestimmung der Siebung. Entwicklung eines Verfahrensganges zur praktikablen Ausführung einer Prüfsiebanalyse auch bei relativ großen Siebgutmengen. Erfolgreicher Abschluß der Versuche zur Reproduzierbarkeit innerhalb des eigenen Labors sowie durch Ringuntersuchungen in verschiedenen Laboratorien.
Zur Definition eines Vergleichsumformgrades bei inhomogener plastischer Umformung
Authors: Herbertz Rainer , Wiegels Herbert
Published: December 2016

Aufzeigen der Problematik bei inhomogener Umformung. Bestimmung der mittleren Fließspannung mittels eines dem Schrifttum entnommenen „mittleren Umformgrades“. Quantitative Berechnung des auftretenden Fehlers mittels Geschwindigkeitsfeldansätzen. Herleitung eines anderen Vergleichsumformgrades.
Kinetik der Wassergasreaktion an Eisen
Authors: Münster Petra , Grabke Hans Jürgen
Published: December 2016

Messungen der Reaktion CO2 + H2 = CO + H2O in beiden Richtungen an Eisenfolien im Temperaturbereich 750 bis 1000°C. Ableitung und Bestätigung der Geschwindigkeitsgleichung. Änderungen der katalytischen Aktivität durch Facettierung der Oberfläche und Wachstum von Oxidkristalliten.
Microstructure‐mechanical property correlation in a forged 0.03C‐4 Mn‐Si‐Mo‐Nb high strength low alloy „mar“ steel
Authors: Patwardhan Arun Kumar , Mehta M.L.
Published: December 2016

Determination of the characteristic values in the tensile test, and of the notched‐bar impact strength at ambient temperature, as well as light‐optical, transmission and scanning electron microscopic structural investigation of a steel with approx. 0.03% C, 0.4% Si, 4.1% Mn, 0.4% Mo, and 0.07% Nb after a) controlled forging, b) forging with intermediate reheating, and schedule b) and subsequent normalizing. Conclusions, particularly in regard to the influence of grain size on overall toughness.
Einfluß der wichtigsten Parameter auf das Zeitstandbruchverhalten warmfester Stähle unter rechteckzyklisch veränderter Beanspruchung
Authors: Kloos Karl Heinz , Granacher Joachim , Barth Hubert
Published: December 2016

Zeitstandversuche bis 20000 h Beanspruchungsdauer unter rechteckzyklisch veränderter Spannung oder Temperatur an sechs warmfesten Stählen. Auswertung der Beanspruchungsdauer bis zum Bruch nach der modifizierten Lebensdaueranteilregel mit einer mittleren relativen Lebensdauer als Festwert. Abhängigkeit dieses Festwertes von der Stahlart und den hauptsächlichen Versuchsparametern. Gültigkeit der Regel bei der Beschreibung der Versuchsergebnisse und Gesichtspunkte zu ihrer Anwendung.
Das Verschleißverhalten von alitiertem Stahl bei Trockenreibung
Authors: Yoshida Kaoru , Takeuchi Eiichi
Published: December 2016

Untersuchung einer alitierten Stiftprobe und einer Scheibe aus dem Stahl Ck 45 mit mittlerem Kohlenstoffgehalt als Verschleißprobenpaar bei Trockenreibung. Einfluß von Normalspannung, Gleitgeschwindigkeit und Verschleißweg auf den Verschleiß. Analyse der Verschleißflächen mit der Mikrosonde und dem Raster‐Elektronenmikroskop (SEM) zur Klärung der Verschleißmechanismen. Maximaler Verschleißabrieb bei einer Verschleißgeschwindigkeit von 0,7 m/s aufgrund von Adhäsion und Furchenbildung. Verschleißversuch nach der Mikrosondenanalyse innerhalb der Legierungsschicht.
Stand der instrumentellen Analytik zur schnellen Bestimmung von Sauerstoff, Stickstoff und Wasserstoff in Stählen
Authors: Koch Karl‐Heinz
Published: December 2016

Metallurgische Erfordernisse und metallkundliche Zusammenhänge. Minutenschnelle Analytik zur Erzeugungsüberwachung. Kalibrationstechnik und Standardreferenzverfahren.
Einfluß des Molybdäns auf die Zähigkeit von Schnellarbeitsstählen
Authors: Pacyna Jerzy , Mazur Adam
Published: December 2016

Unterschiede im Gefüge von Schnellarbeitsstählen der Grundzusammensetzungen (%) 18W‐0Mo‐1V und 6W‐5Mo‐2V. Härten von Proben aus je einer Schmelze dieser Stähle und anschließendes Anlassen bei Temperaturen von 250 bis 650°C. Bruchmechanische Biegeprüfungen, quantitative Messung des Carbidteilchendurchmessers, rasterelektronenmikroskopische Untersuchungen und Messung der Oberflächenrauheit. Folgerungen, besonders über kritische Carbidteilchengrößen in Hinsicht auf das Rißwachstum.
Zur Frage der Kohlenstoffbestimmung bei emissionsspektrometrischen Verwechslungsprüfungen an Stählen
Authors: Koch Karl‐Heinz , Loose Wilfried , Aukskel Hans
Published: December 2016

Notwendigkeit der Kohlenstoffbestimmung bei Verwechslungsprüfungen. Spektralanalytische Möglichkeiten bei Funken‐und Bogenanregung in Luft. Einflüsse einiger Legierungselemente. Wiederholbarkeit und Bestimmungsgrenzen. Bestehende Forderungen.
Elektrofunkenerosive Bearbeitbarkeit von vergütbaren Warmarbeitsstählen und ledeburitischen Chromstählen
Authors: Hribernik Bruno , Russ Franz
Published: December 2016

Entwicklung des Elektrofunkenerodierens. Abtragmechanismus und Kenngrößen beim Senkerodieren. Strukturparameter und Abtragvorgang. Oberflächenbeeinflussung durch den Funkenübergang. Bearbeitung von weichgeglühten und gehärteten Werkzeugstählen. Einflüsse der Oberflächenveränderungen auf die Werkzeugstandzeiten.
Die Grundlagen eines mathematischen Modells zur Ermittlung der Temperaturverteilung im Winderhitzermantel als Beitrag zur Aufklärung der Spannungsrißkorrosion an Hochtemperaturwinderhitzern
Authors: Imer Sencer
Published: December 2016

Grundlagen eines mathematischen Modells zur Ermittlung der Temperaturverteilung im Winderhitzermantel. Annahmen. Lösung der Temperaturverteilungsaufgabe in den Isolationsschichten und im Winderhitzermantel nach dem Differenzenverfahren.
Grundlagen für das Richten von Flachmaterial, Profilen, Rundstäben und Rohren
Authors: Fangmeier Ralf
Published: December 2016

Zustandekommen der Richtwirkung bei den verschiedenen Richtverfahren. Für ein gutes Richtergebnis erforderliche Krümmungen, Durchbiegungen, Biegemomente und Richtkräfte.
Ergebnisse eines Ringversuchs zur Bestimmung magnetischer Streufelder in Elektronenstrahlmikroanalysatoren
Authors: Pries Helge
Published: December 2016

Die Elektronenstrahlmikroanalyse ferromagnetischer Werkstoffe kann durch magnetische Streufelder, die infolge einer ungenügenden Abschirmung der elektromagnetischen Linsen auftreten, stark verfälscht werden. Es kommt zu Strahlauswanderungen, die, in Abhängigkeit vom Meßort auf der Probe, im Bereich von 100 μm liegen können. In einem Ringversuch des Arbeitskreises Elektronenstrahl‐Mikroanalyse des VDEh wurden mit einer definierten Stahlprobe die Geräte der 13 beteiligten Labore auf magnetische Streufelder hin untersucht.
Corrosion fatigue of some carbon steels in main aqueous environments in Kuwait
Authors: Al‐Marafie Abbas M. R. , Malik Hussein Ibrahim , Abdo Mohammed Saffat El‐Mahedi , Awwal Mohammed Abdul
Published: December 2016

Corrosion fatigue of carbon steel 1018 and 4140 was studied in three types of water in Kuwait, potable, brackish and sea water using a rotary fatigue bending machine with a corrosion chamber attached. Results have shown that fatigue strength of both steels is reduced much more in potable water than in brackish water, with maximum reduction occurring in seawater. The low alkalinity and chemical instability of the potable water in Kuwait is a factor that influences the corrosion fatigue of such carbon steels.
Determination of CCT diagrams by thermal analysis after simulated hot deformation processes
Authors: Kaspar Radko , Kapellner Werner , Pawelski Oskar
Published: December 2016

By use of the hot deformation simulator (Wumsi) the plane strain hot compression test permits the simulation of hot forming processes up to a logarithmic strain of 2.5, whereby the cooling rate of the specimen after the deformation can be varied within a wide range. By employing a recently developed method the (residual) strengthening S of austenite is determined during any anisothermal deformation sequence by evaluating the flow curves. In this way the effective S‐value, corresponding to the transformation start, can be established. In order to determine the transformation temperatures, the stored cooling curves are differentiated numerically, whereafter the transformation temperatures are marked on each cooling curve. Such marked cooling curves are plotted on a graph with zero time taken as the moment of crossing the A3 temperature. The transformation lines can be traced through the markings, so that a complete continuous cooling transformation (CCT) diagram of a steel after a simulated hot deformation schedule can be obtained directly on the screen of a graphic terminal.
Oxygen and carbon sensing in Fe—O—C and Fe—O—C—Xn melts at elevated carbon contents
Authors: Romero Alberto Rafael , Härkki Jouko , Janke Dieter
Published: December 2016

In the present study on solid electrolyte probes, the attempt was made to measure accurate and reproducible EMF values representing the extremely low oxygen activities in Fe—O—C melts at varying C contents. Various types of sensors were designed and successfully tested in laboratory experiments. Reliable oxygen activities were measured in Fe—O—C melts up to 4 wt. % C under pure CO gas, and fo and fc values were derived as a function of C content at 1 400 to 1 600°C. Further measurements were made in Fe—O—4 wt. % C—Xn melts at various contents of Xn (Sn = Si, Mn, Cr). Moreover, a solid oxide electrolyte probe with a CO gas channel to measure oxygen and carbon activities was developed and successfully tested in high‐carbon iron melts.
Austenite grain development during reheating of microalloyed plate steels
Authors: Klaar Hans‐Joachim , Braag Klaus , Kaspar Radko , Siegfried Distl Josef , Zeislmair Ulrike
Published: December 2016

The influence of various reheating temperatures and times on austenite grain growth and dissolution behaviour of precipitates was investigated in three different microalloyed steels. The characteristics of these steels were compared with those of a non‐microalloyed steel of similar basic composition. Then, the interrelationships between precipitate distribution, precipitate dissolution and austenite grain growth were discussed.
Grundlagen des Thermocoil‐Verfahrens zur Herstellung höherfester Betonstähle auf Drahtwalzanlagen
Authors: Brennecke Norbert , Günther Ernst
Published: December 2016

Die anlagentechnischen und technologischen Bedingungen von modernen Drahtwalzanlagen bieten besondere Möglichkeiten zur Herstellung von höherfesten Betonstählen durch thermomechanische Behandlung. Vorverformungen in der Vor‐ und Mittelstaffel und die hohe und schnelle Endumformung im Drahtblock führen zu einem sehr feinkörnigem Austenitgefüge am Ende des Umformprozesses, das durch eine auf die chemische Zusammensetzung des Stahles abgestimmte Druckwasserkühlung im Anschluß an den Walzprozeß in ein entsprechend feinkörniges Sekundärgefüge, gegebenenfalls kombiniert mit einer partiellen Vergütung (Vergütung der Randzone), umgewandelt werden kann.

Die zeitliche Veränderung der Temperaturverteilung über den Querschnitt im Verlauf der Druckwasserkühlung und des nachfolgenden Temperaturausgleichs an Luft läßt sich mit geeigneten mathematischen Modellen berechnen, so daß aus den bekannten Zusammenhängen zwischen Eigenschaften, Struktur und Abkühlbedingungen die anlagentechnischen Parameter für die thermomechanische Behandlung von Betonstählen auf Drahtwalzanlagen rechnerisch ermittelt werden können. Die Beherrschung der beim Durchlauf durch die Wasserkühlstrecke auf den Walzdraht wirkenden Bremskräfte erfordert eine spezielle Technologie für den Betrieb der Drahttreiber.
Effect of carbon on the solidification morphology of Fe—Mn—Al steels
Authors: Aidun Daryush K. , Suh Jay
Published: December 2016

An investigation into the effect of carbon content on the weld solidification morphologies for two heats of Fe—Mn—Al steels was conducted. Preliminary results set the stage for extended research into weldability properties of a potentially invaluable steel.
Thermomechanische Behandlung von Manganhartstählen
Authors: Berns Hans , Franke Hans‐Georg
Published: December 2016

Die durch Walzen oder Schmieden im Bereich von 700 bis 1050°C thermomechanisch behandelten Manganhartstähle X 120 Mn 12 und X 120 MnCrSiV 12 werden unter Einbeziehung einer anschließenden Haltedauer bei Umformtemperatur bzw. bei 440°C bezüglich ihres Gefüges und ihrer Eigenschaften vergleichend untersucht. Es zeigt sich, daß die Legierungszusätze an Chrom, Silicium und Vanadin eine höhere Umformtemperatur zur Erzielung einer gewünschten Verfestigung zulassen und damit die thermomechanische Behandlung erleichtern. Der Verschleißwiderstand wird nicht beeinträchtigt.
Investigation of the conditions for weld metal hydrogen cracking of low carbon offshore steels by the IRC weldability test
Authors: Hoffmeister Hans , Harneshaug Idar S. , Roaas Stig
Published: December 2016

Three low carbon structural steels of different plate thickness have been investigated for hydrogen assisted cold cracking by the IRC weldability test at different restraint intensities. At diffusible hydrogen levels of 10–15 N ml/100 g Fe (ISO 3690), cracking decreases at increasing heat inputs due to a drop in restraint stress and hardness as well as an increase in hydrogen diffusion times. Critical heat inputs for crack prevention range from 0.95 to 1.4 kJmm−1. Higher restraints enforce higher cracking stresses as well as final stresses of uncracked test welds. Higher restraints and lower heat inputs also induce faster stress increase during cooling which, for the steels containing Ni and Cu, shift the location of cracking from the HAZ to the weld metal. The steel without Ni and lower maximum HAZ hardness reveals weld metal cracking only, regardless of welding conditions. It can be concluded that for weld metal cracking, the relation between stress increase‐ and hydrogen effusion rates but also the relation between weld metal and HAZ microstructure and mechanical properties are responsible.
Effect of hydrogen, restraint and welding conditions on weld metal cold cracking of HSLA steels in the IRC test
Authors: Bretz Wolfgang , Hoffmeister Hans
Published: December 2016

The effect of heat input and hydrogen partial pressure of the TIG process without filler wire and of restraining conditions in the IRC test on hydrogen induced cracking have been investigated for weld metals of StE 380, 15 NiCrMo 10 6 (HY 80) and 12 Ni 19. The weld metals are fused from the roots of the plate materials exclusively. The continuously measured combined nominal stresses transverse to the welds are strongly dependent on transformation stress release prior to cold cracking of the respective weld metals. Higher restraints are increasing nominal stresses. Critical heat inputs for prevention of hydrogen weld metal cracking are increased with restraint, hydrogen potentials and carbon contents of the weld metal, 12 Ni 19 revealing no fracture.
Anomalien in der Wärmeausdehnung austenitischer Cr—Ni‐Stähle
Authors: Richter Friedhelm
Published: December 2016

An folgenden sieben austenitischen Cr—Ni‐Stählen wurden zwischen 20 und rd. 900°C der differentielle und der mittlere lineare Wärmeausdehnungskoeffizient bestimmt: X 5 NiCrMoCuTi 20 18, X 10 NiCrMoTiB 15 15, X 2 CrNiMo 25 22 2, X 3 CrNiMoN 17 13, X 2 CrNiMo 18 12, X 6 CrNi 18 11 und X 5 CrNi 18 9. Im Verlauf des differentiellen linearen Ausdehnungskoeffizienten ergeben sich im Temperaturbereich um 200°C sowie um 600 bis 700°C ausgeprägte Maxima. Diese erweisen sich als streng reversibel und können weder Ausscheidungen noch Nahordnungsvorgängen oder magnetischen Ordnungseinstellungen zugeordnet werden. Durch Anpassung der Grundkurve an einen nach der Grüneisen‐Theorie berechneten Verlauf verbleibt ein zusätzlicher Beitrag, ein sogenannter Ausdehnungsexzeß. Dieser läßt sich wie bei einer früheren Untersuchung zur spezifischen Wärmekapazität auf thermisch induzierte Elektronenübergänge, basierend auf der γ1 – γ2‐Hypothese von R. J. Weiss, zurückführen.
Smelting reduction of iron ore
Authors: Barin Ihsan , Lemperle Michael , Modigell Michael
Published: December 2016

On the basis of MIP development several process concepts for primary ironmaking technology were investigated. In the smelting reduction process described the reduction of iron ore occurs in three stages: in the first step the ore is preheated and prereduced in a cyclon‐heat exchanger system. In the second step it is melted. The final reduction of the partially reduced and melted ore to metallic iron takes place in the MIP reactor.
The AISI steel initiative
Authors: W. Kor G. Jan
Published: December 2016

This paper briefly describes the history, the purpose and the present status of the “AISI Steel Initiative”. The American Iron and Steel Institute (AISI) started a cooperation between universities and steel industry to investigate new steelmaking processes. A concept for in‐bath smelting reduction has been developed.
Modelling of submerged gas injecting lance design parameters
Authors: Koria Satish C.
Published: December 2016

Submerged gas injecting bottom lance design parameters are modelled by applying the theory of compressible flow of gas under irreversible‐adiabatic conditions. Using the criterion of onsetting the jetting mode of injection of gas into liquid the lance design paramters such as upstream stagnation pressure and Mach number, length of the lance for a given diameter and material, gas injection rate etc. are determined. Nomograms are presented to determine the above mentioned lance design parameters. The derived parameters are discussed in relation to submerged gas injection practice.
Application of numerical techniques to the analysis of strains in the drawing process
Authors: Sadok Lucjan , Paćko Marek
Published: December 2016

For two variants of the drawing process of solid round profiles (α = 6°C, RO/Rk = 1.136, m = 0.15 and α = 4°C, RO/Rk = 1.192, m = 0.15) the effective strain distribution εj and the coordinate grid distortion are presented and compared. The results presented have been obtained theoretically using FEM and experimentally by means of the coordinate grid method. Based on the programme which simulates the drawing process of solid round profiles the distribution of the ε̇rz strain‐rate tensor component, the effective strainrate εj and the die pressure distributions on the metal‐die contact surface were presented. Exact description of the experiments carried out has also been presented. Investigations of strain distribution were done on copper specimens. Results were presented as three dimensional graphs. This helps to make a detailed analysis of changes occurring in the deformation zone for some of the quantities considered. Comparing effective strain distribution εj and grid distortions it follows that experimental data agree with theoretical calculations. Differences occur after the metal exits from the die.

The presented results of theoretical considerations and experimental investigations help to state that the programme constructed, while based on the FEM, simulated the drawing process of solid round profiles accurately.
Fracture mechanics safety assessment based on mechanics of materials
Authors: Roos Eberhard , Demler Thomas , Eisele Ulrich , Gillot Rainer
Published: December 2016

In order to determine the influence of the test temperature on the fracture mechanics characteristics for static and dynamic initiation, crack growth, and arrest, investigations were carried out on pressure vessel and piping steels of different toughness and strength. The selected temperature range allowed both linear‐elastic and elastic‐plastic material behaviour to be examined. In the regime of linear‐elastic fracture mechanics (LEFM) the conservatism of the reference curves of American and German guidelines could be demonstrated. In the upper shelf, where elastic‐plastic fracture mechanics (EPFM) parameters have to be applied, toughness‐dependent overestimations of the real material properties result from the application of the reference curves.
Modellmäßige Beschreibung des Temperaturfeldes eines Sinterprozesses
Authors: Streich Eckart , Hesse Bodo , Gudenau Heinrich‐Wilhelm
Published: December 2016

Im Rahmen einer Dissertation stellte sich die Aufgabe, die Partikelfiltration in einem Sinterprozeß modellmäßig zu beschreiben, der von Sinterabgas durchströmt wird. Dazu wurde ein Modell des Temperaturfeldes im Sinterprozeß entwickelt. Die Beschreibung dieses Temperaturmodells wird in dieser Arbeit ausführlicher als in der Dissertation dargestellt.

Ausgehend von der Differentialgleichung für den Wärmetransport wird mit vorgegebenen, idealisierenden Modellannahmen eine analytische Lösung gefunden, mit der der örtliche und zeitliche Temperaturverlauf des Sinterprozesses berechnet werden kann. Beim Vergleich von gemessenen Temperaturdaten und berechneten Modellwerten wird eine gute Übereinstimmung festgestellt. Neben der Überprüfung von Parametereinflüssen ist das Modell auch zur Überprüfung von numerischen Modellansätzen geeignet.
Evolution of the distribution function of the composition of oxide inclusions for the growth model of a disperse system formed during deoxidation
Authors: Kalicka Zofia
Published: December 2016

The growth model for nuclei of oxide inclusions growing during the process of steel deoxidation is proposed. The evolution of the inclusion composition has been analysed by solving the continuity equation for the probability‐density function f(x,t) (where x is the oxide mole fraction). The calculations were carried out for model parameters and for steel deoxidation by aluminium or silicon‐manganese. The result obtained cannot be verified due to the lack of any functional dependence relating chemical composition to inclusion radius.
Carbon utilization in direct smelting systems
Authors: Ganguly Amit , Reid Ken J.
Published: December 2016

Carbon is used in smelting systems for the two primary functions of reduction and heat generation. Depending on the nature of the smelting device, a variety of methods of introducing the carbon result. There is also a wide choice of carbon‐bearing raw materials with current emphasis on the utilization of coal. This paper analysis the underlying mechanisms for coal pyrolysis and char dissolution as they relate to the emerging in‐bath smelting systems. The influence of coal quality on process performance is discussed based on reported work in both the bench scale and pilot‐scale levels.
Hot‐rolling simulation and modelling using Gleeble 1500
Authors: Morgridge Reuben Austin , Karjalainen Pentti
Published: December 2016

Using the Gleeble 1500, incremental and continuous hot compression tests, simulating hot rolling, were performed on C‐Mn, Nb‐T, and Nb steels with test temperatures varying between 875 and 1100°C and strain rates between 0.5 and 20 s−1. Four models are proposed. The stress peak model allows the prediction of continuous stress‐strain curves from incremental curves and vice versa through the use of stress restoration index K. Variation in K for Nb‐T1, C‐Mn and Nb steels at strain rates of 3, 12 and 20 s−1 was found to be negligible. The predicted stress strain curve corresponds to experimental stress strain curve at same temperature and strain rate. The strain history model predicts continuous strain‐time curves from incremental stress‐strain curves using ‘constant’ ‘negative strain’ restoration index. At 950°C, with holding time 2 s and strain rate 12 s−1, strain time decay curves obtained for C‐Mn, Nb and Nb‐T, steels were ε = 1.5e−05t, ε = 1.2e−0.36t and ε = e−0.3t, respectively. The creep model analysis relates creep strain rate to the testing strain rate. For Nb steel at 875°C, and test strain rate of 12 s−1, ∊creep was found to be 9.5 s−1. The stress history model predicts continuous stress‐time curves from incremental stress‐time curves. Stress decay curve for C‐Mn steel at 1100°C and ∊ = 3s−1 was found to be σ = 181e−0.04t. Hot rolling characteristics of steels can be accurately predicted using hot compression tests and proposed models.
Anwendung eines Simulationsmodells zur Berechnung der Blechprofile beim Kaltwalzen breiter Bleche auf einem Sendzimir‐Sexto‐Walzgerüst
Authors: Funke Paul , Eckhardt Michael
Published: December 2016

Zur Überprüfung und Ergänzung eines Modells zur Simulation von Walzungen auf einem Sendzimir‐Sexto‐Walzwerk wurden Rechnungen durchgeführt. Deren Ergebnisse wurden mit Daten aus Betriebsmessungen verglichen. Die gute Übereinstimmung zwischen berechneten und gemessenen Werten bestätigt die Anwendbarkeit des Modells. In weiteren Rechnungen wird deutlich, daß mit diesem Gerüst eine Walzwerkskonzeption zur Verfügung steht, die insbesondere bei großen Blechbreiten die Erzeugung planen Walzgutes ermöglicht. Mit abnehmender Blechbreite wird jedoch auch hier die Beherrschung der Planlage schwieriger; die in den einzelnen Stichen erzielbaren Dickenabnahmen werden durch die Anforderungen an die Blechplanheit begrenzt. Eine höhere Ausnutzung der zulässigen Walzkräfte kann durch eine Vergrößerung des Stellbereiches der Stützwalzenbombierung und/oder durch eine Änderung des Arbeitswalzenschliffes erreicht werden.
High‐temperature, high‐pressure nitrogen concentration in Fe‐Cr‐Mn‐Ni alloys
Authors: Rawers James C. , Gokcen Nev A.
Published: December 2016

The thermodynamic expressions used to express the nitrogen concentration in iron based alloys prepared under high pressure requires the explicit use of pressure terms. The nitrogen concentration follows Sievert's law for low alloy additions, but significant deviations are observed at higher alloy additions. This Bureau of Mines study extends these new thermodynamic results to higher pressures (200 MPa) and to a greater range of iron alloys: Fe‐(0‐30)Cr‐(0‐30)Mn‐(0‐30)Ni. The experimental results also show that pressure‐alloy concentration effects exist.
Modelling water cooling of steel strip during hot rolling
Authors: Packo Marek , Kusiak Halina , Pietrzyk Maciej
Published: December 2016

Several tests of water cooling of steel samples are presented in the paper. The water spray and quenching conditions are considered. The temperature variations during the tests are monitored using the thermocouples embedded in the side of the samples. The experimental time – temperature profiles are compared with the results of calculations based on the finite element model. Comparison of the theoretical and experimental results allowed to suggest heat transfer coefficients of 10000 W/m2K for water in quenching, 6000 W/m2K for the top surface during water spray cooling and 4000 W/m2K for the bottom surface during water spray cooling.
Dynamic recovery in Nb‐Ti IF steels during hot and warm working
Authors: Pan Yeong‐Tsuen , Lenard John G.
Published: December 2016

Three ultra low carbon interstitial free steels, containing niobium and titanium, and a plain carbon steel were prepared to investigate their flow behaviour during hot and warm working. When the steels were subjected to compression at constant strain rates in the austenite region they exhibited typical work hardening and dynamic restoration behaviour. When they were worked in the ferrite region, they showed unusual and unexpected behaviour, featuring a rapid and quasi‐linear increase in flow stress at a low strain value, followed by a decrease with further increasing strain. Such abnormal flow behaviour was attributed to the presence of dissolved Nb atoms. When the niobium precipitated or when the steel was free from Nb, the typical work hardening and dynamic restoration curves were obtained during deformation in the ferrite region as well.
Calcium desulfurization equilibrium in liquid iron
Authors: Inoue Ryo , Suito Hideaki
Published: December 2016

Sulfur distribution ratios between CaO‐Al2O3 slags and liquid iron were measured at 1873 K as a function of aluminum content using an alumina or a lime crucible. Activity coefficients of CaS relative to a solid standard state were obtained as 52&2.6 and 23&1.7 for the CaO‐Al2O3 slags saturated with an Al2O3 and a CaO crucible, respectively, in the concentration range up to the CaS solubility limit. From these results, logarithm of the equilibrium constant, log KCaS, for the calcium desulfurization reaction CaS(s) = Ca + S and the first‐order interaction parameter eSCa (eSCa) were estimated to be –8.72&0.27 and –269&28 (–336&35), respectively.
Fatigue behaviour of Ni3Al(B) alloys at room temperature
Authors: Li Gang , Guo Jian‐Ting , Wang Zhong‐Guang , Shi Chang‐Xu
Published: December 2016

The high cycle fatigue behaviour of high boron polycrystalline Ni3Al alloys is studied. A single phase Ni3Al alloy with a mole fraction of 0.6% B and a Ni3Al alloy containing a mole fraction of 1.0% B with a small amount of the boride eutectic at the grain boundaries are selected for investigation. High cycle fatigue tests at room temperature with R (minimum stress/maximum stress) 0.1 are conducted in air and at 30 Hz. The results show that the Ni3Al(0.6% B) alloy is better than the Ni3Al(1.0% B) alloy in the fatigue resistance, although, the latter is much higher than the former in static strengths. The fatigue fracture surfaces are observed by SEM.
Effect of thermomechanical treatment on structure and mechanical properties of Mo‐bearing dual phase steel
Authors: Panda Ashok Kumar , Ganguly Ratan Indu , Sarma Dharba Subramanya , Gupta Ramesh Chandra , Misra Somnath
Published: December 2016

The effects of hot rolling of a dual phase steel in the (α + γ) range on microstructure and mechanical properties was investigated by using two thermomechanical (TMT) routes. The first consisted of heating Ac3, soaking, cooling to deformation temperature in the (α + γ) range. The second comprises heating to deformation temperature in the (α + γ) range, followed by rolling and quenching. Parameters varied were temperature (with the first route) and extent of deformation (with the second). The microstructures were characterised by optical and transmission electron microscopy. The results indicate a distinct difference in the final structure and properties due to the two different TMT routes. The first TMT route resulted in a greater amount of ferrite, finer lath width of martensite, finer ferrite grain size and increased density of dislocations. The strength properties decreased, the YS/UTS ratio decreased and ductility increased with the increase in the extent and temperature of deformation. However, TMT route 2 resulted in an increase in the amount of martensite, finer ferrite grain size, decrease in the martensite lath width and increased dislocation density. The strength properties increased, YS/UTS ratio increased and ductility decreased with increase in the extent and temperature of deformation.
The effect of Nb, V, N and Al on the creep rupture strength of 9–12 % Cr steel
Authors: Kubon Zdenek , Foldyna Václav
Published: December 2016

The creep resistance of advanced chromium steels can be significantly increased due to precipitation of very small particles of vanadium nitride VN. The solubility and precipitation of VN, Nb(C,N) and AIN in austenite and ferrite was analysed using relevant solubility products. The calculated values of nitrogen in solid solution were used for assessment of creep rupture strength of chromium steel (mean considered chemical composition, mass contents in %: 0.18 C; 10.5 Cr; 1.0 Mo; 0.2 V; 0.07 Nb; 0.05 N; 0.01 Al). Increasing N mass contents from 0.03 to 0.07 % leads to increasing creep rupture strength in 100 000 h at 600°C of about 60 %. Lowering AI mass contents from 0.045 to 0.005 % produces higher creep rupture strength of about 30 %.
Microstructural evolution of the martensitic cast steel GX12CrMoVNbN9‐1 during long‐term annealing and creep
Authors: Straub Stefan , Polcik Peter , Besigk Wiebke , Blum Wolfgang , König Hermann , Mayer Karl Heinz
Published: December 2016

The microstructure of four specimens of the martensitic cast steel GX12CrMoVNbN9‐1 crept to fracture at 873 K for 220‐33027 h was quantified by electron microscopy with regard to large M23C6‐particles, small V‐ and Nb‐containing particles, dislocations, pores, and oxidation layers. The laws of time‐dependent coarsening of particles and strain‐controlled growth of subgrains are consistent with those previously established for X20(22)CrMoV12‐1. Using these data the microstructural model of deformation developed for X20(22)CrMoV12‐1 can explain the creep behaviour of GX12CrMoVNbN9‐1. The minimum in creep rate is related to the coarsening of particles and subgrains. At low stresses (< 140 MPa) the fraction of small slowly coarsening V‐ and Nb‐containing particles leads to improved creep resistance. The material resists against pore formation; fracture occurs by necking.
Influence of the lubricant on temperature distribution in the forging dies
Authors: Gierzynska‐Dolna M. , Pietrzyk Maciej , Kucharczyk Z. , Lacki P.
Published: December 2016

Experimental and theoretical analysis of the influence of the lubricant on the temperature distribution in the tool during forging is presented. Finite element solution of the general diffusion equation is used to calculate the heat transfer contact between the die and the hot workpiece and during the interpass times. The results of calculations are compared with the results of measurements carried out using thermocouples inserted in the die. Two ways of modelling heat transfer through the contact surface are considered. The first treats a lubricant as a separate layer with the relevant thermal properties. The second assumes a temperature discontinuity at the interface and introduces the heat transfer coefficient. Insulating properties of various lubricants are compared. White‐water lubricant shows the best insulating properties. The values of the heat transfer coefficient obtained from the inverse analysis vary from 2600 (without lubrication) to 1500 W/m2K (white lubricant).