TY - JOUR A1 - Loveday, M.S. A1 - Bicego, V. A1 - Hähner, P. A1 - Klingelhöffer, Hellmuth A1 - Kühn, Hans-Joachim A1 - Roebuck, B. T1 - Analysis of a European TMF inter-comparison exercise JF - International Journal of Fatigue N2 - A major international inter-comparison exercise on strain-controlled thermo-mechanical fatigue (TMF) has been undertaken to validate a new European Code of Practice for TMF Testing and to provide underpinning information for an ISO Standard. This paper focuses on (a) distribution of samples of Nimonic 90, (b) the establishment of a protocol for testing and reporting results, and (c) the analysis of the results. Participants in the inter-comparison exercise comprised eight inner-circle partners who primarily used test pieces which were all manufactured at the same workshop, albeit of three different test piece geometries, and ten outer-circle participants who manufactured their own test pieces, of their own in-house geometry. Each participant undertook three repeat in-phase (IP) tests and three repeat out-of-phase (OP) tests. The tests were conducted at temperatures cycling between 400 °C and 850 °C, with a strain range selected to give a failure life of approximately 1000 cycles, resulting in a stress range of up to ~1000 MPa. The testing conditions were chosen following a preliminary evaluation of critical testing parameters. Results from solid circular and solid flat test piece geometries, together with hollow tubular test pieces have been compared. The influence of temperature measurement using different types of temperature sensors has also been investigated. In-house repeatability has been assessed, together with inter-laboratory reproducibility. The results have been correlated with modulus and thermal expansion data for individual tests. Initially, the largest contribution to scatter in the results was attributed to human errors in reporting the results, compounded by computer assisted ‘cut-and-paste’ errors. Once these obvious discrepancies had been corrected, it was possible to use the data sets to point to some recommendations regarding testing procedures that can be incorporated into the Code of Testing Practice [Hähner P et al. Code of practice for thermo-mechanical fatigue testing – TMF-Standard-Work Package 6 Report, September 2005] and provide technical underpinning for the ISO Standard. The results and the procedures used for analysis are presented. KW - Thermomechanical KW - Fatigue KW - Test methods KW - Analysis KW - Nickel-base superalloys PY - 2008 DO - https://doi.org/10.1016/j.ijfatigue.2007.01.059 SN - 0142-1123 VL - 30 IS - 2 SP - 382 EP - 390 PB - Elsevier CY - Oxford AN - OPUS4-17535 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hähner, P. A1 - Rinaldi, C. A1 - Bicego, V. A1 - Affeldt, E. E. A1 - Brendel, T. A1 - Andersson, H. A1 - Beck, T. A1 - Klingelhöffer, Hellmuth A1 - Kühn, Hans-Joachim A1 - Köster, A. A1 - Loveday, M. A1 - Marchionni, M. A1 - Rae, C. T1 - Research and development into a European code-of-practice for strain-controlled thermo-mechanical fatigue testing JF - International Journal of Fatigue N2 - Thermo-mechanical fatigue (TMF) testing plays an increasingly important role in the design, the reliability assessment and the lifecycle management of safety critical components used, for instance, for power generation, in the process industry and in aeronautical and automotive applications, with a view to increasing the fuel efficiency, safety and service intervals, while reducing production (and material) costs. In a European Commission funded research project (acronym: TMF-Standard) of the 5th Framework Programme, 20 European laboratories have undertaken a joint research effort to establish a validated code-of-practice (CoP) for strain-controlled TMF testing. Starting from a survey of the testing protocols and procedures previously used by the partners, a comprehensive pre-normative research activity into various issues has been completed, addressing the dynamic temperature control, the effects of deviations in nominal temperatures and phase angles, the influences of temperature gradients, as well as the practicalities of test interruption and restart procedures. Meaningful allowable tolerances for the various test parameters were identified and practical recommendations as to the test techniques were formulated. From this a preliminary CoP was compiled and used to guide an extensive round robin exercise among the project partners. From the statistical analysis of that exercise, a validated CoP was derived dealing with strain-controlled constant amplitude TMF of nominally homogeneous metallic materials subjected to spatially uniform temperature fields and uniaxial mechanical loading. It is intended to give advice and guidance on the appropriate test setup, testing procedures and the analysis of results, in particular for newcomers in the field of strain-controlled TMF. This paper highlights some of the results of the TMF-Standard project. Moreover, commonalities and differences of the present CoP with respect to the standard documents for strain-controlled TMF, which have been developed at ISO and ASTM levels, are presented in this paper. KW - Thermo-mechanical fatigue KW - Ni-base superalloy KW - Standardisation KW - Test methods PY - 2008 DO - https://doi.org/10.1016/j.ijfatigue.2007.01.052 SN - 0142-1123 VL - 30 IS - 2 SP - 372 EP - 381 PB - Elsevier CY - Oxford AN - OPUS4-17536 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Brookes, Stephen-Peter A1 - Kühn, Hans-Joachim A1 - Skrotzki, Birgit A1 - Klingelhöffer, Hellmuth A1 - Sievert, Rainer A1 - Pfetzing, J. A1 - Peter, D. A1 - Eggeler, G. ED - Kim, Young-Won ED - David Morris, ED - Rui Yang, ED - Christoph Leyens, T1 - Axial-torsional thermo-mechanical fatigue of Ti-45 Al-5Nb-0.2B-0.2C T2 - Structural aluminides for elevated temperatures T2 - TMS 2008 Annual Meeting & Exhibition, "Structural Aluminides for Elevated Temperatures - Gamma Titanium and Other Metallic Aluminides" CY - New Orleans, Louisiana, USA DA - 2008-03-09 KW - Titanium Aluminide KW - Thermo-mechanical Fatigue KW - Axial-torsional Loading PY - 2008 SN - 978-0-87339-7209 SP - 103 EP - 109 PB - TMS CY - Warrendale, Pa AN - OPUS4-17904 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Klingelhöffer, Hellmuth A1 - Epishin, A. A1 - Link, T. A1 - Portella, Pedro Dolabella ED - Portella, Pedro Dolabella ED - T. Beck, ED - M. Okazaki, T1 - Low cycle fatigue of the single crystal nickel-base superalloy CMSX-4: anisotropy and effect of creep damage T2 - 6th International Conference on Low Cycle Fatigue (LCF 6), September 8-12, 2008, Berlin (Proceedings) T2 - 6th International Conference on Low Cycle Fatigue (LCF 6) CY - Berlin, Germany DA - 2008-09-08 KW - Anisotropy of mechanical properties KW - Effect of creep damage on LCF KW - Single-crystal nickel-base superalloys PY - 2008 SP - 403 EP - 408 AN - OPUS4-17914 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bonnand, V. A1 - Klingelhöffer, Hellmuth ED - Portella, Pedro Dolabella ED - T. Beck, ED - M. Okazaki, T1 - SC16 at 950°C under LCF loading on smooth cylindrical specimen: influence of secondary orientation T2 - 6th International Conference on Low Cycle Fatigue (LCF 6), September 8-12, 2008, Berlin (Proceedings) T2 - 6th International Conference on Low Cycle Fatigue (LCF 6) CY - Berlin, Germany DA - 2008-09-08 KW - Ni-base superalloy KW - Single crystal KW - Fractography KW - LCF KW - Secondary direction KW - Precipitates KW - Damage PY - 2008 SP - 397 EP - 402 AN - OPUS4-17913 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -