TY - JOUR A1 - Olbricht, Jürgen A1 - Bismarck, Marc A1 - Skrotzki, Birgit T1 - Characterization of the creep properties of heat resistant 9-12% chromium steels by miniature specimen testing N2 - A miniature specimen geometry is presented that allows to extract small samples for tensile creep tests directly from critical components of steam generators in power plants like e.g. superheater tubes. In this way, material can be tested which has been subjected to the full processing chain of the component. The specimens then exhibit all microstructural modifications that are present in the component after the shaping process and heat treatment, and representative mechanical properties are determined. Similarly, specimens can be extracted from pre-corroded test pieces or used components after service to determine the impact of complex aging/loading/oxidation conditions during service on the mechanical properties of the material. The applicability of the miniature specimen test method is demonstrated in a comparative creep study involving standard and miniature specimens of P91 tempered martensite ferritic steel. Test results indicate satisfactory accuracy/repeatability of the method. Comparison with large scale specimen data reveals an influence of specimen size on the obtained creep behavior. These size effects need to be considered for a correct interpretation of results from miniature specimen creep tests. KW - Fossil fuel power plants KW - Creep testing KW - Miniature specimen KW - Size effects KW - Tempered martensite ferritic steels KW - P91 PY - 2013 DO - https://doi.org/10.1016/j.msea.2013.07.067 SN - 0921-5093 SN - 1873-4936 VL - 585 SP - 335 EP - 342 PB - Elsevier B.V. CY - Amsterdam AN - OPUS4-29080 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Jürgens, Maria A1 - Olbricht, Jürgen A1 - Fedelich, Bernard A1 - Skrotzki, Birgit T1 - FLEXIKON - Teil 2: Ermüdungsverhalten, Schädigungsentwicklung und Lebensdauer von 9-12% Cr-Stählen im zyklischen Kraftwerksbetrieb N2 - Schnelle Lastwechsel führen v.a. in dickwandigen Kraftwerksbauteilen zu starken thermischen und mechanischen Beanspruchungen, da sich hohe Temperaturgradienten über der Wand des Bauteils einstellen. Es ergeben sich komplexe Lastkollektive aus zeitlich veränderlichen Spannungen/Dehnungen und Temperaturen, die formal einer Kombination aus Kriechbeanspruchung, Kriechermüdung und thermomechanischer Ermüdung (TMF) entsprechen. T2 - 47. Kraftwerkstechnisches Kolloquium CY - Dresden DA - 13.10.2015 KW - TMF KW - LCF KW - P91 KW - P92 PY - 2015 AN - OPUS4-35613 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Jürgens, Maria A1 - Fedelich, Bernard A1 - Olbricht, Jürgen A1 - Skrotzki, Birgit T1 - Thermo-mechanical fatigue behavior of P91/P92 N2 - 9-12% Cr ferritic-martensitic stainless steels are widely used as high temperature construction materials in power plants due to their excellent creep resistance and good oxidation resistance. Creep resistance is considered as the primary parameter in material selection for base-load power plants, but the growing share of renewable energy sources in power generation forces many installations into more "flexible" operation with frequent load reductions and shutdowns. Under cyclic operation of power plants, temperature gradients occur especially in thick-walled components. Locally, these gradients lead to complex time- and temperature-dependent loading scenarios which may result in superimposed creep deformation/damage, creep-fatigue and thermo-mechanical fatigue. The combination of different damage processes may seriously reduce the lifetimes of respective components. A fundamental understanding of the damage evolution in ferritic-martensitic steels under combined static and cyclic loading is therefore required. In the present contribution, the thermo-mechanical fatigue and creep-fatigue behavior of two different 9% Cr steel grades (P91 and P92) was investigated. Standard LCF/TMF-tests as well as near-service loading tests with different hold times have been carried out to study the material behavior of the new loading scenarios. Microstructural investigations help to identify the observed deformation characteristics (like e.g. pronounced softening) and the dominating damage mechanisms under different loads. The test programme is complemented by selected tests on service-aged material which demonstrate possible reactions of older components in existing plants to changes in operation profiles. In a next step, the experimental results will be used for parameter identification of a deformation and lifetime model to predict the material behavior. T2 - LCF08 CY - Dresden, Germany DA - 27.06.2017 KW - Near-service testing KW - Power plant KW - Ferritic-martensitic steels KW - P91 KW - P92 KW - Thermo-Mechanical Fatigue PY - 2017 SN - 978-3-9814516-5-8 VL - 2017 SP - 101 EP - 105 PB - DVM CY - Berlin AN - OPUS4-42268 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -