PSI - Issue 2_A

ScienceDirect Available online at www.sciencedirect.com Av ilable o line at ww.sciencedire t.com ScienceDirect Structural Integrity Procedia 00 (2016) 000 – 000 Procedia Struc ural Integrity 2 (2016) 3399–34 6 Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2016) 000–000 Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2016) 000–000

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XV Portuguese Conference on Fracture, PCF 2016, 10-12 February 2016, Paço de Arcos, Portugal Thermo-mechanical modeling of a high pressure turbine blade of an airplane gas turbine engine P. Brandão a , V. Infante b , A.M. Deus c * a Department of Mechanical Engineering, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1, 1049-001 Lisboa, Portugal b IDMEC, Department of Mechanical Engineering, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1, 1049-001 Lisboa, Portugal c CeFEMA, Department of Mechanical Engineering, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1, 1049-001 Lisboa, Portugal Abstract During their operation, modern aircraft engine components are subjected to increasingly demanding operating conditions, especially the high pressure turbine (HPT) blades. Such conditions cause these parts to undergo different types of time-dependent degradation, one of which is creep. A model using the finite element method (FEM) was developed, in order to be able to predict the creep behaviour of HPT blades. Flight data records (FDR) for a specific aircraft, provided by a commercial aviation company, were used to obtain thermal and mechanical data for three different flight cycles. In order to create the 3D model needed for the FEM analysis, a HPT blade scrap was scanned, and its chemical composition and material properties were obtained. The data that was gathered was fed into the FEM model and different simulations were run, first with a simplified 3D rectangular block shape, in order to better establish the model, and then with the real 3D mesh obtained from the blade scrap. The overall expected behaviour in terms of displacement was observed, in particular at the trailing edge of the blade. Therefore such a model can be useful in the goal of predicting turbine blade life, given a set of FDR data. 21st European Conference on Fracture, ECF21, 20-24 June 2016, Catania, Italy Effect of hydrogen on tensile behavior of low alloy steel in the regime of dynamic strain ageing G Sudhakar Rao*, Hans-Peter Seifert, Stefan Ritter, Philippe Spätig, Zaiqing Que Laboratory for Nuclear Materials, Nuclear Energy and Safety Division, Paul Scherrer Institut, 5232 Villigen-PSI, Switzerland Abstract Low alloy steels typically used for reactor pressure vessel (RPV) in light water reactors may undergo different degradations and ageing mechanisms during service like fatigue, strain-induced corrosion cracking and corrosion fatigue or irradiation embrittlement, the latter being recognized as life limiting factor. There is growing concern that hydrogen, absorbed from the high temperature water environment and corrosion reactions, may potentially reduce toughness of RPV steels in synergy (or com tition) wit ot er embrittlement mechanisms like irradiation embrittlem nt, thermal ageing or dynamic strain aging (DSA). Strain rate, temperature and oc urrence of DSA these ste ls may affec the severity of the ffect of hy rogen on toughness. The pres nt investigation was envis g d to characteriz the effect of hydrogen on tensile and fracture behavior f low alloy RPV steels at different train rates and temperatur s with a special emphasis o the synergy between DSA and hydrogen embrittlement. For this reason, tensile tests were arried out with as-received and hydrogen pre-charge specimens betwe n 25 and 400 °C and at strain rates between 10 -1 and 10 -6 s -1 . The fracture mode was evaluated by detailed post-test fractography in the scanning electron microscope. DSA in these steels was established by the occurrence of serrations, negative strain-rate sensitivity and a maximum/minimum in strength/ductility at intermediate temperatures and strain rates. The DSA peak and range were found to be shifted to lower temperatures with decreasing strain rates and vice-versa. The hydrogen pre-charging resulted in marginal softening and strain-rate dependent reduction in ductility at 250/288 °C. The hydrogen embrittlement and reduction in ductility were more pronounced and the strain rate range for hydrogen embrittlement significantly extended in the RPV steel with higher DSA susceptibility demonstrating some synergy between DSA and hydrogen effects, probably due to the localization of plastic deformation. In presence of hydrogen, shear dominated ductile fracture (microvoid coalescence) with varying amounts of quasi-cleavage regions and secondary cracking along the prior austenite grain boundaries were observed. A detailed investigation on these aspects and a tentative mechanistic explanation is presented in this paper. 21st European Conference on Fracture, ECF21, 20-24 June 2016, Catania, Italy Effect of hydrogen on tensile behavior of low alloy steel in the regime of dynamic strain ageing G Sudhakar Rao*, Hans-Peter Seifert, Stefan Ritter, Philippe Spätig, Zaiqing Que Laboratory for Nuclear Materials, Nuclear Energy and Safety Division, Paul Scherrer Institut, 5232 Villigen-PSI, Switzerland Abstract Low alloy steels typically used for reactor pressure vessel (RPV) in light water reactors may undergo different degradations and ageing mechanisms during service like fatigue, strain-induced corrosion cracking and corrosion fatigue or irradiation embrittlement, the latter being recognized as life limiting factor. There is growing concern that hydrogen, absorbed from the high temperature water environment and corrosion r actions, may potentially reduce toughness of RPV st els in synergy (or competition) with other embrittlement mechanisms like irradiation embrittlement, thermal geing or dynamic strain aging (DSA). Strain rate, temp rature and occurre ce of DSA in these steels may affect the severity of the effect of hydr gen on toughness. The p esen investigation was envisaged to charact rize the effect of hydrogen on tensile nd fracture behavior of low alloy RPV ste ls at different strain rates and temperatur wit a special emphasis on he sy ergy betw en DSA and hydrogen embrittlement. For this reason, tensile tests were carried out with as-received and hydrogen pre-charged specimens betwee 25 and 400 °C a d at strain rates between 10 -1 and 10 -6 s -1 . The fracture mo e was evaluated by detailed post-test fractography in the scanning electron microscope. DSA in these steels was established by the occurre ce of serrations, egative strain-rate sensitivity and a maximum/minimum in strength/ductility at int rmediate temperatur s strain rates. The DSA ak and rang were found to be shifted to low r temperatures with decreasing strain rates and vice-versa. The hydrogen pr -chargin resulted in m rginal softeni g and strain-rate dependent reduction in ductility at 250/288 °C. The hydroge embrittlement and reduction in ductility were more pronounced and the strain rate range for hydrogen embrittlement significantly extended in the RPV steel with higher DSA susc ptibility demonstrating some synergy between DSA and hydrogen effects, probably due to the localization of pl stic def rmation. In presence of hydrogen, shear dominated ductile fracture (microvoid coalescence) with varying amounts of quasi-cleavage regions and secondary cracki g long the prior austenite grain boundaries were observed. A detailed investigation on these aspects and a tentative mechanistic explanation is prese ted in this paper. © 2016 The Authors. Published by Elsevier B.V. Copyright © 2016 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of the Scientific Committee of ECF21. © 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of PCF 2016. Keywords: High Pressure Turbine Blade; Creep; Finite Element Method; 3D Model; Simulation.

© 2016 The Authors. Published by Elsevier B.V.

* Corresponding author. Tel.: +41563102793; fax: +41 56 310 44 60. E-mail address: sudhakar-rao.gorja@psi.ch

* Corresponding author. Tel.: +351 218419991. E-mail address: amd@tecnico.ulisboa.pt * Corresponding author. Tel.: +41563102793; fax: +41 56 310 44 60. E-mail address: s dhakar-rao.gorja@psi.ch 2452-3216 © 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of ECF21.

2452-3216 © 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of PCF 2016. Copyright © 2016 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/ ). Peer review under responsibility of the Scientific Committee of ECF21. 10.1016/j.prostr.2016.06.424 2452-3216 © 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of ECF21.