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Structural Integrity Procedia 00 (2017) 000–000 Structural Integrity Procedia 00(2016) (2017) 000–000 Procedia Structural Integrity 800 (2018) 501–508 Structural Integrity Procedia 000–000
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AIAS 2017 International Conference on Stress Analysis, AIAS 2017, 6–9 September 2017, Pisa, AIAS 2017 International Conference on StressItaly Analysis, AIAS 2017, 6–9 September 2017, Pisa, Italy
Experimental study of hydrogen embrittlement in Maraging steels Experimental study on ofFracture, hydrogen embrittlement Maraging steels XV Portuguese Conference PCF 2016, 10-12 Februaryin 2016, Paço de Arcos, Portugal a,b a b a a a,b,∗ M. M. Barsanti Barsantia,b,, M. M. Beghini Beghinia,, F. F. Frasconi Frasconib,, R. R. Ishak Ishaka,, B. B. D. D. Monelli Monellia,, R. R. Valentini Valentinia,b,∗
Universit`a di Pisa, Dipartimento di Ingegneria e Industriale, 56122 Pisa, Italy Thermo-mechanical modeling of a Civile high pressure turbine blade of an Universit`a di Pisa, Dipartimento di Ingegneria Civile e Industriale, 56122 Pisa, Italy INFN Sezione di Pisa, Largo Pontecorvo 2, 56125 Pisa, Italy INFN Sezione di Pisa, Largo Pontecorvo 2, 56125 Pisa, Italy airplane gas turbine engine a a
b b
P. Brandãoa, V. Infanteb, A.M. Deusc* Abstract Abstract a This research activity at investigating theInstituto hydrogen embrittlement of Maraging steels in to1,real suddenLisboa, failures Department of aims Mechanical Engineering, Superior Técnico, Universidade de Lisboa, Av.connection Rovisco Pais, 1049-001 This research aimsblades at investigating the Project hydrogen embrittlement of Maraging in failed connection sudden failures Portugal of some of theactivity suspension of the Virgo experimental apparatus. Some steels of them after to 15 real years of service in b of some of the suspension blades of the Virgo Project experimental apparatus. Some of them failed after 15 years of service in IDMEC, Department of Mechanical Engineering, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1, 1049-001 Lisboa, working conditions. Typically, in the Virgo detector, blades are loaded up to 50-60% of the material yield strength. For a deeper working conditions. Typically, in the Virgo detector, blades are loaded up to 50-60% of the material yield strength. For a deeper Portugal understanding of the failure, the relationship between hydrogen concentration and mechanical properties of the material,have been c CeFEMA, Department of Mechanical Engineering, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1, 1049-001 Lisboa, understanding of specimens the failure, the relationship hydrogen concentration and mechanical properties of the material,have been investigated with prepared in orderbetween to simulate blade Portugal working conditions. A mechanical characterization of the material investigated with specimens prepared in order to simulate blade working conditions. A mechanical characterization of the material has been carried out by standard tensile testing in order to establish the effect of hydrogen content on the material strength. Further has been carried out by standard tensile testing in order to establish the surface effect ofand hydrogen content on the material strength. experimental activity was executed in order to characterize the fracture to measure the hydrogen content. Finally,Further some experimental activityhave wasbeen executed in order to characterize the fracture surface and to measure the hydrogen content. Finally,can some of the failed blades analyzed in DICI-UNIPI laboratory. The experimental results show that the blades failure be Abstract of the failed blades have been analyzed in DICI-UNIPI laboratory. The experimental results show that the blades failure can be related with the hydrogen embrittlement phenomenon. related with the hydrogen embrittlement phenomenon. During their operation, modern aircraft engine components are subjected to increasingly demanding operating conditions, cCopyright 2017 The Authors. Published by Elsevier B.V. especially the high pressure turbine (HPT) blades. © 2018 The Authors. Published by Elsevier B.V.Such conditions cause these parts to undergo different types of time-dependent c 2017 The Authors. Published by Elsevier B.V. degradation, one of which isofcreep. AScientific model using the method (FEM) was developed, orderAnalysis. to be able to predict Peer-review under responsibility of the Committee of element AIAS 2017 International Conference on in Stress Peer-review under responsibility the Scientific Committee of finite AIAS 2017 International Conference on Stress Analysis Peer-review responsibility the Scientific Committee AIAS 2017 Conference on Stress the creep under behaviour of HPT of blades. Flight data recordsof(FDR) for aInternational specific aircraft, provided by a Analysis. commercial aviation Keywords: embrittlement; fracture analysis. data for three different flight cycles. In order to create the 3D model company,Hydrogen were used to obtain Maraging; thermal mechanical Hydrogen embrittlement; Maraging;and fracture analysis. Keywords: 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. 1. Introduction 2016 The Authors. Published by Elsevier B.V. 1. ©Introduction
Peer-review under responsibility of the Scientific Committee of PCF 2016.
Purpose of this work is the study of Hydrogen embrittlement of Maraging steel. Maraging is a class of Ultra High Purpose of this work is the study of Hydrogen embrittlement of Maraging steel. Maraging is a class of Ultra High Strength Steels (UHSS)Turbine with a yield strength that canMethod; reach 2400 MPa, hardened by precipitation of intermetallic Keywords: High Pressure Creep; Finite Element Model; Simulation. Strength Steels (UHSS) with Blade; a yield strength that can reach3D2400 MPa, hardened by precipitation of intermetallic compounds during an aging process [Sha and Guo (2009)]. These steels are highly susceptible to hydrogen damage, compounds during an aging process [Sha and Guo (2009)]. These steels are highly susceptible to hydrogen damage, as is common for high-strength alloys. as is common for high-strength alloys. Maraging steel is the material used for the construction of some crucial components of the Virgo experiment Maraging steel is the material used for the construction of some crucial components of the Virgo experiment [Beccaria et al. (1998)], like the blades of the suspension system of the interferometer mirrors (super-attenuators) [Beccaria et al. (1998)], like the blades of the suspension system of the interferometer mirrors (super-attenuators) shown in Fig. 1. The loads acting on the blades are very strong, because each filter must carry the weight of the shown in Fig. 1. The loads acting on the blades are very strong, because each filter must carry the weight of the underlying ones. Therefore these high loads can cause microcreep [Gurewitz et al. (1977)], that is present also in the underlying ones. Therefore these high loads can cause microcreep [Gurewitz et al. (1977)], that is present also in the Corresponding author. Tel.: +351 218419991. ∗ *R. Valentini Tel.: +39-50-221-7859 ; fax: +39-50-221-8065. ∗ R. E-mail address:
[email protected] Valentini Tel.: +39-50-221-7859 ; fax: +39-50-221-8065.
E-mail address:
[email protected] E-mail address:
[email protected] 2452-3216 © 2016 Authors. Published Elsevier B.V. c 2017 2210-7843 TheThe Authors. Published by by Elsevier B.V. cunder 2210-7843 2017 The responsibility Authors.ofPublished by Elsevier B.V. Peer-review under of the Scientific Committee of PCF 2016. Conference on Stress Analysis. Peer-review responsibility the Scientific Committee of AIAS 2017 International Peer-review under responsibility of the Scientific Committee of AIAS 2017 International Conference on Stress Analysis. 2452-3216 Copyright 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of AIAS 2017 International Conference on Stress Analysis 10.1016/j.prostr.2017.12.049
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M. Barsanti et al. / Procedia Structural Integrity 8 (2018) 501–508 M. Barsanti et al. / Structural Integrity Procedia 00 (2017) 000–000
Fig. 1. The seismic super attenuator chain of Virgo (from Braccini et al. (2000)). The blades (b, c on the right) are clamped on the outer circumference of the filter bottom part (a on the right).
elastic regime. As the creep permanently modifies the position of the mirror and influences the measurement, a very high yielding strength was imposed. Since nickel plating by surface deposition can produce hydrogen absorption, the possibility that this phenomenon could affect the mechanical properties of the Maraging steel used in the Virgo project has been investigated.
2. Material and methods 2.1. Material This study examined a commercially available Maraging steel (Marval 18 produced by Aubert & Duvall) whose chemical composition is reported in table 1. The material was supplied as plates 3.4 mm thick. To improve its mechanical properties, the material has undergone an aging treatment (100 hours @435 ◦ C). The values of the most important mechanical properties are shown in table 2. Four groups of samples were prepared and studied as follows: 1. Failed blades: hydrogen content was measured. 2. Specimens with nickel electroless plating to simulate the plating procedure adopted for blade surface finishing, without de–hydrogenation treatment. Hydrogen content and mechanical properties were measured. This group helps to check the effect of missed steps in the adopted plating procedure for the blades.
M. Barsanti et al. / Procedia Structural Integrity 8 (2018) 501–508 M. Barsanti et al. / Structural Integrity Procedia 00 (2017) 000–000
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Table 1. Chemical composition of the Maraging steel Marval 18. Elements % in the alloy C
Ni
Co
Mo
Ti
Al
Si
Mn
P
Zr
B
S
