Thermal diffusivity measurements of metastable austenite during continuous cooling

The thermal diffusivity of the metastable undercooled austenite is relevant for the quantitative analysis of the carbon and low-alloy steel quench. The standard laser-flash method requires prior thermal equilibrium between the sample and the furnace, which may not be possible to achieve without allowing the metastable phase to transform. Nevertheless, depending upon the steel's hardenability, the thermal transient due to a laser pulse may be much shorter than a cooling transient sufficiently steep to prevent the transformation of the austenite. In one such case, flash measurements were performed during continuous sample cooling and the thermal diffusivity of the metastable austenite was determined by using an extension of the standard analytical model. The adopted analytical model and data reduction procedure are described and the limitations and uncertainties of this method are discussed, also with the aid of a non-linear numerical simulation. The measured thermal diffusivity of the under cooled low-alloy austenite decreases linearly from 5.4•10−6 m2 s−1 at 1133 K to 4.3•10−6 m2 s−1 at 755 K; this trend is in broad agreement with one previous set of measurements upon a low-alloy undercooled austenite and with a large number of previous standard measurements upon stable (high-alloy) austenitic stainless steels

Methodology for the Evaluation of Production Systems During Early Development Phase

Digitalisierung und Globalisierung führen für produzierende Unternehmen zu einer stetigen Verkürzung der Produktlebenszyklen und zunehmend intensiven Wettbewerb. Um diesen Herausforderungen gerecht werden zu können, müssen Produkt und zugehöriges Produktionssystem bereits in der Konzipierungsphase aufeinander abgestimmt werden. Obwohl in der Konzipierung die entscheidende Weichenstellung für die weitere Ausarbeitung erfolgt, unterstützen bestehende Bewertungsmethoden für Produktionssysteme die integrative Entwicklung nicht adäquat. Gegenstand der Arbeit ist daher eine Methodik zur Bewertung von Produktionssystemkonzepten in der frühen Entwicklungsphase. Die Methodik umfasst dazu ein Vorgehensmodell, das die Anwender durch den Bewertungsprozess führt, sowie ein Analysemodell, das die notwendigen Methoden und Berechnungsvorschriften enthält. Ergänzt wird die Methodik durch eine Erweiterung der Spezifikationstechnik zur Beschreibung und rechnerinternen Repräsentation von Produkt- und Produktionssystemkonzepten in Hinblick auf die Behandlung der relevanten Bewertungsparameter. Die Validierung der praktischen Einsatzfähigkeit erfolgt anhand eines durchgängigen Anwendungsbeispiels zur Produktion eines tretkraftunterstützenden Elektrofahrrades.Digitalization as well as globalization lead to a tremendous reduction of product life cycle times and an increasingly intensive competition among producing companies. To cope with these challenges product and according production system have to be aligned with each other already in the conceptual design phase. Although many crucial constraints for the subsequent system elaboration are already determined during conceptual design, current methods for the evaluation of production systems cannot adequately support the necessary integrative development. This contribution comprises a methodology for an early evaluation of production system concepts within the product engineering process. The methodology consists of a process model, that leads the user through the evaluation procedure as well as an analysis model, which comprises all necessary methods and calculation rules. An extension to the specification technique for the description and computer-internal representation of product and production system concepts complements the methodology with respect to the application of relevant evaluation parameters. A validation of the practical usability is conducted by means of a continuous application example for the production of a pedal electric cycle.von Dipl.-Ing. oec. Vinzent Rudtsch. Referent: Prof. Dr.-Ing. Jürgen Gausemeier, 1. Korreferent: Prof. Dr.-Ing. habil. Ansgar Trächtler, 2. Korreferent: Prof. Dr. Leena SuhlTag der Verteidigung: 01.06.2016Universität Paderborn, Fakultät Maschinenbau, Univ., Dissertation, 201

Photonic contact thermometry using silicon ring resonators and tuneable laser-based spectroscopy

Photonic sensors offer the possibility of purely optical measurement in contact thermometry. In this work, silicon-based ring resonators were used for this purpose. These can be manufactured with a high degree of reproducibility and uniformity due to the established semiconductor manufacturing process. For the precise characterisation of these photonic sensors, a measurement setup was developed which allows laser-based spectroscopy around 1550 nm and stable temperature control from 5 °C to 95 °C. This was characterised in detail and the resulting uncertainty influences of both the measuring set-up and the data processing were quantified. The determined temperature stability at 20 °C is better than 0.51 mK for the typical acquisition time of 10 s for a 100 nm spectrum. For a measurement of >24 h at 30 °C a standard deviation of 2.6 mK could be achieved. A hydrogen cyanide reference gas cell was used for traceable in-situ correction of the wavelength. The determined correction function has a typical uncertainty of 0.6 pm. The resonance peaks of the ring resonators showed a high optical quality of 157 000 in the average with a filter depth of up to 20 dB in the wavelength range from 1525 nm to 1565 nm. When comparing different methods for the determination of the central wavelength of the resonance peaks, an uncertainty of 0.3 pm could be identified. A temperature-dependent shift of the resonance peaks of approx. 72 pm/K was determined. This temperature sensitivity leads together with the analysed uncertainty contributions to a repeatability of better than 10 mK in the analysed temperature range from 10 °C to 90 °C.Photonische Sensoren bieten die Möglichkeiten einer rein optischen Messung in der Berührungsthermometrie. In dieser Arbeit wurden hierfür siliziumbasierte Ringresonatoren verwendet. Diese lassen sich aufgrund der etablierten Halbleiterfertigung mit hoher Reproduzierbarkeit und Uniformität herstellen. Zur genauen Charakterisierung dieser photonischen Sensoren wurde ein Messplatz entwickelt, welcher eine laser-basierte Spektroskopie um 1550 nm und Thermostatisierung von 5 °C bis 95 °C ermöglicht. Dieser wurde ausführlich charakterisiert und resultierende Unsicherheitseinflüsse sowohl des Messplatzes als auch der Datenverarbeitung quantifiziert. Die ermittelte Temperatur-stabilitäten bei 20 °C ist besser als 0,51 mK für die typische Aufnahmezeit von 10 s eines 100 nm Spektrums. Für eine Messung von >24 h konnte bei 30 °C ein Standardabweichung von 2,6 mK erreicht werden. Eine Cyanwasserstoff-Referenzgaszelle diente zur rückführbaren in-situ Korrektur der Wellenlänge. Die ermittelte Korrekturfunktion hat hierbei typischerweise eine Unsicherheit von 0,6 pm. Die Resonanzpeaks der Ringresonatoren zeigten im Durschitt eine hohe optische Güte von 157 000 mit einer Filtertiefe von bis zu 20 dB im Wellenlängenbereich von 1525 nm bis 1565 nm. Beim Vergleich verschiedener Methoden zur Bestimmung der zentralen Wellenlänge der Resonanzpeaks konnte eine Unsicherheit von 0,3 pm ermittelt werden. Es wurde eine temperaturabhängige Verschiebung der Resonanzpeaks von ca. 72 pm/K bestimmt. Diese Temperatursensitivität führt mit den analysierten Unsicherheitsbeiträgen zu einer Wiederholbarkeit von besser als 10 mK im untersuchten Temperaturbereich von 10 °C bis 90 °C

Intercomparación bilateral entre LATU y PTB de calibración en puntos fijos (ITS-90) del Zn al Hg de un SPRT con PTB como laboratorio piloto

El Laboratorio Tecnológico del Uruguay, LATU, es el Instituto Metrológico Nacional del Uruguay, miembro fi rmante del Acuerdo de Reconocimiento Mutuo (MRA) entre Laboratorios Nacionales de Metrología del Comité Internacional de Pesas y Medidas (CIPM). Las capacidades de medida y calibración (CMCs) del LATU fueron reconocidas en junio de 2004 y se encuentran publicadas en la BIPM- Key Comparison Data Base (BIPM, 2009). El LATU estuvo acreditado desde 2001 hasta junio de 2007 por el Deutscher Kalibrier Dienst (Servicio de Acreditación Alemán) en las magnitudes Masa, Balanzas y Temperatura (Laboratorio DKD, DKD-K-25601). Se decidió a partir de ese momento probar el cumplimiento con los criterios establecidos por el CIPM MRA y los requisitos de la Norma ISO/IEC 17025 en el marco de una auditoría in situ llevada a cabo en el LATU en enero de 2008. Como parte de ese proceso de revisión de pares, se realizó una Intercomparación Bilateral entre el PTB y el LATU en los puntos fi jos de la Escala Internacional de Temperatura (ITS-90), desde el punto triple de Hg hasta el punto de congelación del Zn, con el PTB como laboratorio piloto. En este artículo los resultados son presentados y discutidos de manera de sostener la declaración de mejores capacidades de medida y calibración (CMCs) en sustitución de las ya declaradas. Abstract Laboratorio Tecnológico del Uruguay, LATU, is the National Metrology Institute of Uruguay, signatory of the CIPM Mutual Recognition Arrangement (CIPM MRA), has Calibration and Measurement Capabilities (CMCs) in temperature that were fi rst published in the BIPM Key Comparison Data Base (BIPM, 2009) in June 2004. LATU was a DKD Laboratory accredited in Mass, Balances and Temperature from 2001 until June 2007 when it was decided to adopt the CIPM criteria for proving compliance with ISO/IEC 17025 through a Peer Review process. The LATU on site Peer Review was carried out in January 2008, as part of the process. During the evaluation, a bilateral intercomparison was performed between PTB and LATU at the ITS- 90 fi xed points covering the range from Hg TP to Zn FP with PTB acting as the Pilot Laboratory. In this paper the results are presented and discussed in order to support the declaration of better Calibration and Measurement Capabilities (CMCs) and substitute the declared ones

Designing ad hoc temperature fixed point cells

The design of the ad hoc (made of hand-on materials) temperature fixed-point cell (TFPC) is considered in this paper. There was developed a TFPC filled with lead and an apparatus for its investigation. The feature of the considered TFPC is minimization of the stray thermal fluxes distorting the temperature plateau during a phase change. Conclusions about the influence of the design of a TFPC on the temperature plateau of phase change are described

ITS-90 SPRT calibration from the Ar TP to the Zn FP

International audienceThis is a report to the Consultative Committee for Thermometry (CCT) on the key comparison 9 of Standard Platinum Resistance Thermometer (SPRT) calibration on the International Temperature Scale of 1990 (ITS-90) [1] from 83.8058 K (the Ar triple point) to 692.677 K (the Zn freezing point). The comparison followed a collapsed star protocol, with each of the fourteen participating laboratories shipping two standard platinum resistance thermometers (SPRTs) as transfer standards to the pilot laboratory (National Institute of Standards and Technology, NIST) for a direct comparison of SPRT calibration at the National Metrology Institute (NMI) of origin to calibration at NIST. Measurements were taken at the participating laboratories before and after measurement at NIST to assess the effect of transportation on the transfer standards. The pooled results from all laboratories were combined to calculate a key comparison reference value (KCRV). This report includes the calculation of, and comparisons to, the KCRV as well as bilateral comparisons between labs. In addition, there is space devoted to analysis of the shifts in SPRT values following travel. To reach the main text of this paper, click on Final Report . Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/ . The final report has been peer-reviewed and approved for publication by the CCT, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA)

Radiation-induced melting in coherent X-ray diffractive imaging at the nanoscale

Coherent X-ray diffraction techniques play an increasingly significant role in imaging nanoscale structures which range from metallic and semiconductor samples to biological objects. The conventional knowledge about radiation damage effects caused by ever higher brilliance X-ray sources has to be critically revised while studying nanostructured materials