Search results for: Jilt Sietsma

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Sietsma</title> <meta name="description" content="Search results for: Jilt Sietsma"> <meta name="keywords" content="Jilt Sietsma"> <meta name="viewport" content="width=device-width, initial-scale=1, minimum-scale=1, maximum-scale=1, user-scalable=no"> <meta charset="utf-8"> <link href="https://cdn.waset.org/favicon.ico" type="image/x-icon" rel="shortcut icon"> <link href="https://cdn.waset.org/static/plugins/bootstrap-4.2.1/css/bootstrap.min.css" rel="stylesheet"> <link href="https://cdn.waset.org/static/plugins/fontawesome/css/all.min.css" rel="stylesheet"> <link href="https://cdn.waset.org/static/css/site.css?v=150220211555" rel="stylesheet"> </head> <body> <header> <div class="container"> <nav class="navbar navbar-expand-lg navbar-light"> <a class="navbar-brand" href="https://waset.org"> <img src="https://cdn.waset.org/static/images/wasetc.png" alt="Open Science Research Excellence" title="Open Science Research Excellence" /> </a> <button class="d-block d-lg-none navbar-toggler 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id="custom-search-input"> <div class="input-group"> <i class="fas fa-search"></i> <input type="text" class="search-query" name="q" placeholder="Author, Title, Abstract, Keywords" value="Jilt Sietsma"> <input type="submit" class="btn_search" value="Search"> </div> </div> </form> </div> </div> <div class="row mt-3"> <div class="col-sm-3"> <div class="card"> <div class="card-body"><strong>Commenced</strong> in January 2007</div> </div> </div> <div class="col-sm-3"> <div class="card"> <div class="card-body"><strong>Frequency:</strong> Monthly</div> </div> </div> <div class="col-sm-3"> <div class="card"> <div class="card-body"><strong>Edition:</strong> International</div> </div> </div> <div class="col-sm-3"> <div class="card"> <div class="card-body"><strong>Paper Count:</strong> 3</div> </div> </div> </div> <h1 class="mt-3 mb-3 text-center" style="font-size:1.6rem;">Search results for: Jilt Sietsma</h1> <div class="card paper-listing mb-3 mt-3"> <h5 class="card-header" style="font-size:.9rem"><span class="badge badge-info">3</span> Substantial Fatigue Similarity of a New Small-Scale Test Rig to Actual Wheel-Rail System</h5> <div class="card-body"> <p class="card-text"><strong>Authors:</strong> <a href="https://publications.waset.org/abstracts/search?q=Meysam%20Naeimi">Meysam Naeimi</a>, <a href="https://publications.waset.org/abstracts/search?q=Zili%20Li"> Zili Li</a>, <a href="https://publications.waset.org/abstracts/search?q=Roumen%20Petrov"> Roumen Petrov</a>, <a href="https://publications.waset.org/abstracts/search?q=Rolf%20Dollevoet"> Rolf Dollevoet</a>, <a href="https://publications.waset.org/abstracts/search?q=Jilt%20Sietsma"> Jilt Sietsma</a>, <a href="https://publications.waset.org/abstracts/search?q=Jun%20Wu"> Jun Wu</a> </p> <p class="card-text"><strong>Abstract:</strong></p> The substantial similarity of fatigue mechanism in a new test rig for rolling contact fatigue (RCF) has been investigated. A new reduced-scale test rig is designed to perform controlled RCF tests in wheel-rail materials. The fatigue mechanism of the rig is evaluated in this study using a combined finite element-fatigue prediction approach. The influences of loading conditions on fatigue crack initiation have been studied. Furthermore, the effects of some artificial defects (squat-shape) on fatigue lives are examined. To simulate the vehicle-track interaction by means of the test rig, a three-dimensional finite element (FE) model is built up. The nonlinear material behaviour of the rail steel is modelled in the contact interface. The results of FE simulations are combined with the critical plane concept to determine the material points with the greatest possibility of fatigue failure. Based on the stress-strain responses, by employing of previously postulated criteria for fatigue crack initiation (plastic shakedown and ratchetting), fatigue life analysis is carried out. The results are reported for various loading conditions and different defect sizes. Afterward, the cyclic mechanism of the test rig is evaluated from the operational viewpoint. The results of fatigue life predictions are compared with the expected number of cycles of the test rig by its cyclic nature. Finally, the estimative duration of the experiments until fatigue crack initiation is roughly determined. <p class="card-text"><strong>Keywords:</strong> <a href="https://publications.waset.org/abstracts/search?q=fatigue" title="fatigue">fatigue</a>, <a href="https://publications.waset.org/abstracts/search?q=test%20rig" title=" test rig"> test rig</a>, <a href="https://publications.waset.org/abstracts/search?q=crack%20initiation" title=" crack initiation"> crack initiation</a>, <a href="https://publications.waset.org/abstracts/search?q=life" title=" life"> life</a>, <a href="https://publications.waset.org/abstracts/search?q=rail" title=" rail"> rail</a>, <a href="https://publications.waset.org/abstracts/search?q=squats" title=" squats"> squats</a> </p> <a href="https://publications.waset.org/abstracts/18986/substantial-fatigue-similarity-of-a-new-small-scale-test-rig-to-actual-wheel-rail-system" class="btn btn-primary btn-sm">Procedia</a> <a href="https://publications.waset.org/abstracts/18986.pdf" target="_blank" class="btn btn-primary btn-sm">PDF</a> <span class="bg-info text-light px-1 py-1 float-right rounded"> Downloads <span class="badge badge-light">515</span> </span> </div> </div> <div class="card paper-listing mb-3 mt-3"> <h5 class="card-header" style="font-size:.9rem"><span class="badge badge-info">2</span> Influence of Thermal Ageing on Microstructural Features and Mechanical Properties of Reduced Activation Ferritic/Martensitic Grades </h5> <div class="card-body"> <p class="card-text"><strong>Authors:</strong> <a href="https://publications.waset.org/abstracts/search?q=Athina%20Puype">Athina Puype</a>, <a href="https://publications.waset.org/abstracts/search?q=Lorenzo%20Malerba"> Lorenzo Malerba</a>, <a href="https://publications.waset.org/abstracts/search?q=Nico%20De%20Wispelaere"> Nico De Wispelaere</a>, <a href="https://publications.waset.org/abstracts/search?q=Roumen%20Petrov"> Roumen Petrov</a>, <a href="https://publications.waset.org/abstracts/search?q=Jilt%20Sietsma"> Jilt Sietsma</a> </p> <p class="card-text"><strong>Abstract:</strong></p> Reduced Activation Ferritic/Martensitic (FM) steels like EUROFER are of interest for first wall application in the future demonstration (DEMO) fusion reactor. Depending on the final design codes for the DEMO reactor, the first wall material will have to function in low-temperature mode or high-temperature mode, i.e. around 250-300掳C of above 550掳C respectively. However, the use of RAFM steels is limited up to a temperature of about 550掳C. For the low-temperature application, the material suffers from irradiation embrittlement, due to a shift of ductile-to-brittle transition temperature (DBTT) towards higher temperatures upon irradiation. The high-temperature response of the material is equally insufficient for long-term use in fusion reactors, due to the instability of the matrix phase and coarsening of the precipitates at prolonged high-temperature exposure. The objective of this study is to investigate the influence of thermal ageing for 1000 hrs and 4000 hrs on microstructural features and mechanical properties of lab-cast EUROFER. Additionally, the ageing behavior of the lab-cast EUROFER is compared with the ageing behavior of standard EUROFER97-2 and T91. The microstructural features were investigated with light optical microscopy (LOM), electron back-scattered diffraction (EBSD) and transmission electron microscopy (TEM). Additionally, hardness measurements, tensile tests at elevated temperatures and Charpy V-notch impact testing of KLST-type MCVN specimens were performed to study the microstructural features and mechanical properties of four different F/M grades, i.e. T91, EUROFER97-2 and two lab-casted EUROFER grades. After ageing for 1000 hrs, the microstructures exhibit similar martensitic block sizes independent on the grain size before ageing. With respect to the initial coarser microstructures, the aged microstructures displayed a dislocation structure which is partially fragmented by polygonization. On the other hand, the initial finer microstructures tend to be more stable up to 1000hrs resulting in similar grain sizes for the four different steels. Increasing the ageing time to 4000 hrs, resulted in an increase of lath thickness and coarsening of M23C6 precipitates leading to a deterioration of tensile properties. <p class="card-text"><strong>Keywords:</strong> <a href="https://publications.waset.org/abstracts/search?q=ageing%20experiments" title="ageing experiments">ageing experiments</a>, <a href="https://publications.waset.org/abstracts/search?q=EUROFER" title=" EUROFER"> EUROFER</a>, <a href="https://publications.waset.org/abstracts/search?q=ferritic%2Fmartensitic%20steels" title=" ferritic/martensitic steels"> ferritic/martensitic steels</a>, <a href="https://publications.waset.org/abstracts/search?q=mechanical%20properties" title=" mechanical properties"> mechanical properties</a>, <a href="https://publications.waset.org/abstracts/search?q=microstructure" title=" microstructure"> microstructure</a>, <a href="https://publications.waset.org/abstracts/search?q=T91" title=" T91"> T91</a> </p> <a href="https://publications.waset.org/abstracts/65950/influence-of-thermal-ageing-on-microstructural-features-and-mechanical-properties-of-reduced-activation-ferriticmartensitic-grades" class="btn btn-primary btn-sm">Procedia</a> <a href="https://publications.waset.org/abstracts/65950.pdf" target="_blank" class="btn btn-primary btn-sm">PDF</a> <span class="bg-info text-light px-1 py-1 float-right rounded"> Downloads <span class="badge badge-light">261</span> </span> </div> </div> <div class="card paper-listing mb-3 mt-3"> <h5 class="card-header" style="font-size:.9rem"><span class="badge badge-info">1</span> Effect of Thermal Treatment on Mechanical Properties of Reduced Activation Ferritic/Martensitic Eurofer Steel Grade</h5> <div class="card-body"> <p class="card-text"><strong>Authors:</strong> <a href="https://publications.waset.org/abstracts/search?q=Athina%20Puype">Athina Puype</a>, <a href="https://publications.waset.org/abstracts/search?q=Lorenzo%20Malerba"> Lorenzo Malerba</a>, <a href="https://publications.waset.org/abstracts/search?q=Nico%20De%20Wispelaere"> Nico De Wispelaere</a>, <a href="https://publications.waset.org/abstracts/search?q=Roumen%20Petrov"> Roumen Petrov</a>, <a href="https://publications.waset.org/abstracts/search?q=Jilt%20Sietsma"> Jilt Sietsma</a> </p> <p class="card-text"><strong>Abstract:</strong></p> Reduced activation ferritic/martensitic (RAFM) steels like EUROFER97 are primary candidate structural materials for first wall application in the future demonstration (DEMO) fusion reactor. Existing steels of this type obtain their functional properties by a two-stage heat treatment, which consists of an annealing stage at 980掳C for thirty minutes followed by quenching and an additional tempering stage at 750掳C for two hours. This thermal quench and temper (Q&T) treatment creates a microstructure of tempered martensite with, as main precipitates, M23C6 carbides, with M = Fe, Cr and carbonitrides of MX type, e.g. TaC and VN. The resulting microstructure determines the mechanical properties of the steel. The ductility is largely determined by the tempered martensite matrix, while the resistance to mechanical degradation, determined by the spatial and size distribution of precipitates and the martensite crystals, plays a key role in the high temperature properties of the steel. Unfortunately, the high temperature response of EUROFER97 is currently insufficient for long term use in fusion reactors, due to instability of the matrix phase and coarsening of the precipitates at prolonged high temperature exposure. The objective of this study is to induce grain refinement by appropriate modifications of the processing route in order to increase the high temperature strength of a lab-cast EUROFER RAFM steel grade. The goal of the work is to obtain improved mechanical behavior at elevated temperatures with respect to conventionally heat treated EUROFER97. A dilatometric study was conducted to study the effect of the annealing temperature on the mechanical properties after a Q&T treatment. The microstructural features were investigated with scanning electron microscopy (SEM), electron back-scattered diffraction (EBSD) and transmission electron microscopy (TEM). Additionally, hardness measurements, tensile tests at elevated temperatures and Charpy V-notch impact testing of KLST-type MCVN specimens were performed to study the mechanical properties of the furnace-heated lab-cast EUROFER RAFM steel grade. A significant prior austenite grain (PAG) refinement was obtained by lowering the annealing temperature of the conventionally used Q&T treatment for EUROFER97. The reduction of the PAG results in finer martensitic constituents upon quenching, which offers more nucleation sites for carbide and carbonitride formation upon tempering. The ductile-to-brittle transition temperature (DBTT) was found to decrease with decreasing martensitic block size. Additionally, an increased resistance against high temperature degradation was accomplished in the fine grained martensitic materials with smallest precipitates obtained by tailoring the annealing temperature of the Q&T treatment. It is concluded that the microstructural refinement has a pronounced effect on the DBTT without significant loss of strength and ductility. Further investigation into the optimization of the processing route is recommended to improve the mechanical behavior of RAFM steels at elevated temperatures. <p class="card-text"><strong>Keywords:</strong> <a href="https://publications.waset.org/abstracts/search?q=ductile-to-brittle%20transition%20temperature%20%28DBTT%29" title="ductile-to-brittle transition temperature (DBTT)">ductile-to-brittle transition temperature (DBTT)</a>, <a href="https://publications.waset.org/abstracts/search?q=EUROFER" title=" EUROFER"> EUROFER</a>, <a href="https://publications.waset.org/abstracts/search?q=reduced%20activation%20ferritic%2Fmartensitic%20%28RAFM%29%20steels" title=" reduced activation ferritic/martensitic (RAFM) steels"> reduced activation ferritic/martensitic (RAFM) steels</a>, <a href="https://publications.waset.org/abstracts/search?q=thermal%20treatments" title=" thermal treatments"> thermal treatments</a> </p> <a href="https://publications.waset.org/abstracts/59346/effect-of-thermal-treatment-on-mechanical-properties-of-reduced-activation-ferriticmartensitic-eurofer-steel-grade" class="btn btn-primary btn-sm">Procedia</a> <a href="https://publications.waset.org/abstracts/59346.pdf" target="_blank" class="btn btn-primary btn-sm">PDF</a> <span class="bg-info text-light px-1 py-1 float-right rounded"> Downloads <span class="badge badge-light">300</span> </span> </div> </div> </div> </main> <footer> <div id="infolinks" class="pt-3 pb-2"> <div class="container"> <div style="background-color:#f5f5f5;" class="p-3"> <div class="row"> <div class="col-md-2"> <ul class="list-unstyled"> About <li><a href="https://waset.org/page/support">About Us</a></li> <li><a href="https://waset.org/page/support#legal-information">Legal</a></li> <li><a target="_blank" rel="nofollow" href="https://publications.waset.org/static/files/WASET-16th-foundational-anniversary.pdf">WASET celebrates its 16th foundational 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Search results for: Jilt Sietsma