PSI - Issue 13

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 Structu al Integrity 13 (2018) 716–721 Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2018) 000 – 000 Available online at www.sciencedirect.com ScienceDirect Structural Int grity Procedia 00 (2018) 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. © 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ECF22 organizers. ECF22 - Loading and Environmental effects on Structural Integrity Localized Plasticity and Associated Cracking in Stable and Metastable High-Entropy Alloys Pre-Charged with Hydrogen Kenshiro Ichii a , Motomichi Koyama a , Cemal Cem Tasan b , Kaneaki Tsuzaki a, c a Department of Mechanical Engineering, Kyushu University, Japan b Department of Materials Science and Engineering, Massachusetts Institute of Technology, USA c Hydrogenious, Kyushu University, Japan Abstract We investigated hydrogen embrittlement in Fe20Mn20Ni20Cr20Co and Fe30Mn10Cr10Co (at.%) alloys pre-charged with 100 MPa hydrogen gas by tensile testing at three initial strain rates of 10 − 4 , 10 − 3 , and 10 − 2 s − 1 at ambient temperature. The alloys are classified as stable and metastable austenite-based high-entropy alloys (HEAs), respectively. Both HEAs showed the characteristic hydrogen-induced degradation of tensile ductility. Electron backscatter diffraction analysis indicated that the reduction in ductility by hydrogen pre-charging was associated with localized plasticity-assisted intergranular crack initiation. It should be noted as an important finding that hydrogen-assisted cracking of the metastable HEA occurred not through a brittle mechanism but through localized plastic deformation in both the ust ite and ε -mart site phases. © 2018 The Authors. Published by Elsevier B.V. Peer-revi w under responsibility of th ECF22 organiz rs. Keywords: High-entropy alloy; Hydrogen embrittlement; Martensitic transformation; Austenitic steels; Hydroge desorption 1. Introduction High-entropy alloys (HEA) are now one of the most focused alloy groups in the field of materials science and engineering because of their marked property improvem nts, e.g., combined strength and ductility (Zhang et al., 2014) and cryogenic fracture resistance (Gludovatz et al., 2014). As has been reported in steels, the reduction in phase stability of austenite in HEAs was reported to i prov their tensile properties through the transformation-induced plasticity (TRIP) effect (Li et al., 2016). It is interesting to note that the TRIP effect in HEAs arises from the ε martensitic transformation from a face-centered cubic (FCC) to a hexagonal close-packed (HCP) phase, and not from the α′ -martensitic transformation from a FCC to a body-centered cubic (BCC) phase (Li et al., 2016, Li et al., 2017). In recent studies, a Fe20Mn20Ni20Cr20Co HEA with stable austenite was reported to show high hydrogen embrittlement resistance (Zhao et al., 2017); hydrogen introduction instead showed a positive effect on elongation and ECF22 - Loading and Environmental effects on Structural Integrity Localized Plasticity and Associated Cracking in Stable and Me astable High-Ent opy Alloys Pre-Cha ged with Hydrogen Kenshiro Ichii a , Motomichi Koyama a , Cemal Cem Tasan b , Kaneaki Tsuzaki a, c a Department of Mechanical Engineering, Kyushu University, Japan b Department of Materials Scienc and Engi eering, Massachusetts Institute of Technology, USA c Hydrogenious, Kyushu University, Japa Abstract We investigated hydrogen embrittlement in Fe20Mn20Ni20Cr20Co and Fe30Mn10Cr10Co (at.%) alloys pre-charged with 100 MPa hydrogen gas by tensile testing at three initial strain rates of 10 − 4 , 10 − 3 , and 10 − 2 s − 1 at ambient temperature. The alloys are classifie as stable and metastable austenite-based high-e tropy alloys (HEAs), respectively. Both HEAs showed the characteristic hydrog n-induced degradation of ten ile ductility. Electron backscatter diffraction analysis indicated that t e r uction in ductility b hydroge pre-charging was associat d with localized plasticity-assisted intergr ular crack initiation. It should be noted as an important finding that hydrogen-assisted cracking of the metastable HEA occurred not through a brittle mechanism but through localized plastic deformation in both the austenite and ε -martensite phases. © 2018 The Aut ors. Published by Elsevier B.V. Peer-review under responsibility of the ECF22 organizers. Keywords: High-entropy alloy; Hydrogen e brittlement; Martensitic transformation; Austenitic steels; Hydrogen desorption 1. Introduction High-entropy alloys (HEA) are now one of the most focused alloy groups in the field of materials science and engineering because of their marked property improvements, e.g., combined strength and ductility (Zhang et al., 2014) a d cryog nic fracture resistance (Gludovatz et al., 2014). As has been reported in steels, the reduction in phase stability of austenite in HEAs was reported to improve their tensile properties through the transformation-induced plasticity (TRIP) effect (Li et al., 2016). It is interesting to note that the TRIP effect in HEAs arises from the ε martensitic transformation from a face-centered cubic (FCC) to a hexagonal close-packed (HCP) phase, and not from the α′ -martensitic transformation from a FCC to a body-centered cubic (BCC) phase (Li et al., 2016, Li et al., 2017). In recent studies, a Fe20M 20Ni20Cr20Co HEA with stable austenite was reported to show high hydrogen embrittlement resistance (Zhao et al., 2017); hydrogen introduction instead sho ed a positive effect on elongation and © 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.

* Corresponding author. Tel.: +351 218419991. E-mail address: amd@tecnico.ulisboa.pt 2452-3216 © 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ECF22 organizers. 2452-3216 © 2018 The Authors. Published by Elsevier B.V. Peer review under r sponsibility of the ECF22 o ganizers.

2452-3216 © 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of PCF 2016.

2452-3216  2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ECF22 organizers. 10.1016/j.prostr.2018.12.119