PSI - Issue 13

ScienceDirect Available online at www.sciencedirect.com Av ilable o line at www.sciencedire t.com ScienceDirect Structural Integrity Procedia 00 (2016) 000 – 000 Procedia Structu al Integrity 13 (2018) 292–297 Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2018) 000 – 000 Available online at www.sciencedirect.com ScienceDirect Structural I tegrity 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. ECF22 - Loading and Environmental effects on Structural Integrity A new design concept for prevention of hydrogen-induced mechanical degradation: viewpoints of metastability and high entropy Moto ichi Koyama a *, Takeshi Eguchi a , Kenshiro Ichii a , Cemal Cem Tasan b Kaneaki Tsuzaki a,c a Department of Mechanical Engineering, Kyushu University, Motooka 744, Nishi-ku, Fukuoka, 819-0395 Japan b Department of Materials Science and Engineering, Massatusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA c HYDROGENIOUS, Kyushu University, Motooka 744, Nishi-ku, Fukuoka, 819-0395 Japan Abstract ‟ How crack growth is prevented” is key to improve both fatigue and monotonic f racture resistances under an influence of hydrogen. Specifically, the key points for the crack growth resistance are hydrogen diffusivity and local ductility. For instance, type 304 austenitic steels show high hydrogen embrittlement susceptibility because of the high hydrogen diffusivity of bcc (α´) martensite. In contrast, metastability in specific austenitic steels enables fcc (γ) to hcp (ε) martensitic transformation, which decreases hydrogen diffusivity nd increases strength simultaneously. As a result, even if hydr gen-as isted cracking occurs during monotonic ten il deformation, the ε -martensite acts to arrest micro-damage evolution when the amo nt of ε -martensite is limited. Thus, the formation of ε -martensite can de ase hydr g n embrittl ment susceptibility in austenitic steels. How ver, a considerable amount of ε -martensite is requ red when we attempt to have rastic improvements f work hardening capability an strength level with respect to transformation-induced plasticity effect. Since the hcp structure contains a less umber of slip ystems than f c nd bcc, the less stress accommodation capacity often causes brittle- like f ilure when the ε -martens te fraction is large. Therefore, ductility of ε martensit is another key hen w maximiz the positive effect of ε -martensitic transformation. In fact, ε -martensite in a high entropy alloy was recently foun to be ex raordinary ductile. Consequently, the m tastable high entropy alloys showed low fatigue crack growth rates in a hydrog n atmosphere compared with conventional me astable aust nitic steels with α´ -mart n itic transformation. We here present ef ects of metastability to ε -phase and configurational entropy on hydrogen-induced mechanical degradation including monotonic tension properties and fatigue crack growth resistance. ECF22 - Loading and Environmental effects on Structural Integrity A new design concept for prevention of hydrogen-induced mechanical degradation: viewpoints of metastability and high entropy Motomichi Koyama a *, Takeshi Eguchi a , Kenshiro Ichii a , Cemal Cem Tasan b Kaneaki Tsuzaki a,c a Department of Mechanical Engineering, Kyushu University, Motooka 744, Nishi-ku, Fukuoka, 819-0395 Japan b Department of Mat rials Science and Engineering, Massatusetts Inst tute of Techn logy, 77 Massachusetts Avenue, Cambridge, MA 02139, USA c HYDROGENIOUS, Kyushu University, Motook 744, Nishi-ku, Fukuoka, 819-0395 Japan Abstract ‟ How crack growth is prevented” is key to improve both fatigue and monotonic f racture resistances under an influence of hydrogen. Specifically, the k y points for the crack g wth resist nce are hydrogen diffusivity and local ductility. For instance, type 304 austenitic stee s show high hydr gen embrittlement su ceptibility because o the high hydrogen diffusivity of b c (α´) martensi . In contra t, metastability in specific austenitic steels enables fcc (γ) to hcp (ε) martensitic transformation, which de reases hydrogen diffusivity and increases strength simultaneously. A a result, even if hydrogen-assisted racking occurs during monotonic tensile deformati n, the ε -marten ite acts to arrest mi ro-damage evolutio when the amoun of ε -martensite i lim ed. Thus, the formation f ε -martensit can d c eas hydr gen embrittlement susceptibility in aus enitic steels. H wev , a con iderable amount of ε -mar ensi e is required whe we attempt to have drastic i prov ments of work hardening capability and strength l v l with respect to tr nsformation-ind ced plasticity ffect. Sinc the hcp st ucture contains less numbe of sli systems ha f c and b c, the less stress accomm dation capacity often causes brit le- like f il re when the ε -mart site f action i large. Therefor , uctility of ε mart nsite is another key when w m ximize the positive effect of ε -martensi ic transfor ation. In fact, ε -ma tensite in a high ent opy alloy was r cently fou d o b e traordinary ductil . Consequently, th me astable high e t opy alloy showed low fatigue crack growth r tes in a hydrogen atmosphere compared with conv tional met stable austeni ic steels with α´ -martensitic tr nsformation. We here present ffects of metastability to ε -phas a d config r tional entropy o hydrog n-in uced echanical degra ation i cluding monotonic tension prop rties and fa igue cr ck growth resist nce.

© 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of PCF 2016. © 2018 The Authors. Published b Elsevier B.V. Peer-review under responsibility of the ECF22 organizers. © 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ECF22 organizers. © 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ECF22 organizers. Keywords: hydrogen embrittlement; austenitic steel; martensitic transformation; high entropy ll y Keywords: High Pressure Turbine Blade; Creep; Finite Element Method; 3D Model; Simulation. Keywords: hydrogen embrittlement; austenitic steel; martensitic transformation; high entropy alloy

* Corresponding author. Tel.: +81-92-802-3224 . E-mail address: koyama@mech.kyushu-u.ac.jp * Corresponding author. Tel.: +81-92-802-3224 . E-mail address: koyama@mech.kyushu-u.ac.jp

* 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.2018.12.049