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 U6 - 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 - Olbricht, Jürgen A1 - Bismarck, Marc A1 - Skrotzki, Birgit T1 - Size effects in miniature specimen creep testing of heat resistant ferritic-martensitic steels N2 - The use of miniaturized specimen geometries in mechanical testing allows extracting the sample material directly from the sidewall of critical components of power plants, like e.g. headers and steam pipes. In this way, both the impacts of the processing of the component (including all shaping and tempering influences) and of the exposure to the complex aging/loading/oxidation conditions in the plant (in case of post-Service tests) can be analyzed and representative mechanical properties are obtained. T2 - CREEP 2015 - 13th International conference on creep and fracture of engineering materials and structures CY - Toulouse, France DA - 31.05.2015 PY - 2015 SP - 163 EP - 164 AN - OPUS4-33528 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Olbricht, Jürgen A1 - Bismarck, Marc A1 - Skrotzki, Birgit T1 - Size effects in miniature specimen creep testing of P91 N2 - The use of miniaturized specimen geometries in mechanical testing allows extracting the sample material directly from critical components of power plants like e.g. headers and pipes. In this way, both the impacts of the manufacture of the component (including all shaping and tempering influences) and of the complex aging/loading/oxidation conditions during Service can be analyzed and representative mechanical properties are obtained. In the present study, example results of a comparative creep and creep rupture study on P91 tempered martensite ferritic Steel, involving Standard and miniature specimens that were all taken from one batch of material, are presented. Cylindrical creep specimens with a minimum gauge length diameter of 3 mm were used, representing the smallest recommended test geometry of ISO 204. The test results of miniature specimens exhibit all characteristic creep features of tempered martensite ferritic steels, and analysis of the stress and temperature dependence of creep results in values that correspond well to literature data for P91. However, direct comparison with large scale specimen data reveals small but systematic variations in minimum creep rates, elongations at fracture and times to rupture. In our contribution, these differences are discussed in the light of literature findings on specimen size influences in other heat resistant alloys. Size effects need to be considered for a correct interpretation of results from miniature specimen creep tests. T2 - 3rd International ECCC Creep & Fracture Conference 2014 CY - Rome, Italy DA - 05.05.2014 PY - 2014 SN - 978-88-7484-380-0 SP - Paper 43, 1 EP - 9 AN - OPUS4-30726 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -