The hydrogen trapping ability of TiC and V4C3 by thermal desorption spectroscopy and permeation experiments

Available online at www.sciencedirect.com Available online at www.sciencedirect.com

ScienceDirect ScienceDirect

Structural Integrity Procedia 00 (2018) 000–000 Available online www.sciencedirect.com Available online at at www.sciencedirect.com Structural Integrity Procedia 00 (2018) 000–000

ScienceDirect ScienceDirect

Procedia Structural Integrity 13 00 (2018) 1414–1420 Structural Integrity Procedia (2016) 000–000

www.elsevier.com/locate/procedia www.elsevier.com/locate/procedia

www.elsevier.com/locate/procedia

ECF22 - Loading and Environmental effects on Structural Integrity ECF22 - Loading and Environmental effects on Structural Integrity

The hydrogen trapping ability of TiC and V4C3 by thermal The hydrogen trapping ability of TiC and V4C3 by thermal desorption spectroscopy XV Portuguese Conference on Fracture, PCFand 2016,permeation 10-12 Februaryexperiments 2016, Paço de Arcos, Portugal desorption spectroscopy and permeation experiments T. Depover*, E . Van Eeckhout, K. Verbeken Thermo-mechanical modeling of den a high pressure turbine blade of an T. Depover*, E . Van den Eeckhout, K. Verbeken Department of Materials, Textiles and Chemical Engineering, Ghent University (UGent), Gent, Belgium airplane gas turbine engine Department of Materials, Textiles and Chemical Engineering, Ghent University (UGent), Gent, Belgium Abstract P. Brandãoa, V. Infanteb, A.M. Deusc* Abstract Hydrogen (H) presence in metals is detrimental as unpredictable failure might occur. Recent developments in material’s design a of Mechanical Engineering, Superior Técnico, Universidade Lisboa, Av. increasing Rovisco Pais, 1049-001 Lisboa, Hydrogen (H)microstructural presence in metals is detrimental as unpredictable might Recent developments in material’s design indicatedDepartment that features such asInstituto precipitates play anfailure essential role occur. indepotentially the1,resistance against H indicated that microstructural features the suchHastrapping precipitates playPortugal an essential role inVpotentially increasing the resistance againstand H desorption spectroscopy induced failure. This work evaluates characteristics for TiC and 4C3 by thermal b IDMEC, Department of Mechanical Engineering, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1, 1049-001 Lisboa, induced failure. This work evaluates the H trapping characteristics for TiC and V by thermal desorption spectroscopy and 4C3vs. permeation experiments. Two microstructural conditions are compared: as quenched quenched and tempered, in which the Portugal c permeation Two microstructural are as quenched vs.Lisboa, quenched and in which the carbides are experiments. introduced. The tempered induced conditions precipitates arecompared: able to deeply trap a significant amount oftempered, H, which decreases CeFEMA, Department of Mechanical Engineering, Instituto Superior Técnico, Universidade de Av. Rovisco Pais, 1, 1049-001 Lisboa, carbides are introduced. The and tempered induced are Portugal able deeply trap a significant of H, which decreases the H diffusivity in the materials removes some precipitates of the detrimental H to from the microstructure. Foramount microstructural design purposes, H is diffusivity materials and removes some of detrimental Htofrom the microstructure. For microstructural design purposes, it importantintothe know the position of H. Here, H the is demonstrated be trapped at the carbide/matrix interface by modifying the it is important to know the position of H. Here, H is demonstrated to be trapped at the carbide/matrix interface by modifying the tempering treatment. tempering Abstracttreatment. © 2018 The Authors. Published by Elsevier B.V. © 2018 Authors. Published by Elsevier B.V. B.V. © During 2018The The Authors. Published by their operation, modern aircraft engine components are subjected to increasingly demanding operating conditions, Peer-review under responsibility of Elsevier the ECF22 organizers. Peer-review under responsibility of the ECF22 organizers. Peer-review under responsibility of the(HPT) ECF22 organizers. especially the high pressure turbine blades. Such conditions cause these parts to undergo different types of time-dependent degradation, one of whichspectroscopy, is creep. A permeation model using the finite hydrogen element trapping, method (FEM) was developed, in order to be able to predict Keywords: thermal desorption experiments, hydrogen diffusivity, carbides Keywords: thermal desorption spectroscopy, experiments, hydrogenfor trapping, hydrogen diffusivity, carbides the creep behaviour of HPT blades.permeation Flight data records (FDR) 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 for the FEM analysis, a HPT blade scrap was scanned, and its chemical composition and material properties were 1.needed Introduction The data that was gathered was fed into the FEM model and different simulations were run, first with a simplified 3D 1.obtained. Introduction rectangular block shape,carrier, in orderhydrogen to better establish model, and withrevolution. the real 3D mesh obtained the economy blade scrap. The As a clean energy (H) canthecatalyze an then energy Lately, the Hfrom based has overall expected behaviour in terms of displacement was observed, in particular at the trailing edge of the blade. Therefore such As a clean energy carrier, hydrogen can catalyze an energy revolution. Lately,the theclimate H based economy has a production aiddata. to address change. Though, regained attention (Brandon et of al. (2017)).(H) An increased H2 given model can be useful in the goal predicting turbine blade life, a set ofcan FDR

can aid to address the climate change. Though, regained attentionof (Brandon et al. (2017)). Anrecognized increased Hto2 production the development a H economy has been be challenging. Also the offshore industry encounters H the© development of a H economy has been recognized to be challenging. Also the offshore industry encounters H related concerns since corrosion is there tackled by cathodic protection, forming H as a byproduct (Olden et al. (2009)). 2016 The Authors. Published by Elsevier B.V. related concerns since corrosion is there tackled by cathodic protection, forming H as a byproduct (Olden et al. (2009)). Moreover, high strength steels are gradually more used in the automotive industry, as they guarantee an improved safety Peer-review under responsibility of the Scientific Committee of PCF 2016. Moreover, high strength steels are gradually more usedare, in the automotivereported industry,toasbethey guarantee safety together with weight reduction. However, these steels unfortunately, more prone toan Himproved induced failure. together with weight reduction. However, steels are, unfortunately, reported to be more prone to H induced failure. Keywords: High Pressure Turbine Blade; Creep; these Finite Element Method; 3D Model; Simulation.

* Corresponding author. Tel.: +32-9-331-0453; * Corresponding author. Tel.: +32-9-331-0453; E-mail address: [email protected] E-mail address: [email protected] 2452-3216 © 2018 The Authors. Published by Elsevier B.V. 2452-3216 © 2018 Authors. Published Elsevier B.V. Peer-review underThe responsibility of theby ECF22 organizers. Peer-review underauthor. responsibility the ECF22 organizers. * Corresponding Tel.: +351of 218419991. E-mail address: [email protected]

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.2018.12.294

2

T. Depover et al. / Procedia Structural Integrity 13 (2018) 1414–1420 Author name / Structural Integrity Procedia 00 (2018) 000–000

1415

The role of carbides has been a relevant subject in recent steel alloy development. Precipitates may induce material strenghtening due to precipitation hardening and are also often cited to be beneficial as potential H traps. As such highly diffusible H, which is supposed to be the most harmful one, is removed from the microstructure. Nevertheless, steels with increased strength appear to be more prone to H assisted failure (Hilditch et al. (2003) and Koyama et al. (2017)). The interaction of high strength steels with H has been considered thoroughly in the last decade (Ronevich et al. (2010), Venezuela et al. (2015) and Yu et al. (2016)). Recently, we also thoroughly studied these high strength steels, e.g. Pérez Escobar et al. (2012), Depover et al. (2014, 2016 (a)) and Laureys et al. (2015, 2016). The detrimental H effect was less outspoken for steels containing Ti- and Nb- carbo-nitrides, indicating their potential in this context. Hence, trapping diffusible H using nano-sized particles is generally assumed to be one of the main strategies to decrease the sensitivity to H related failure (Wei et al. (2006), Frappart et al. (2010) and Nagao et al. (2014)). However, multiphase steels contain a complex microstructure, complicating the interpretation of the H related data. Consequently, the study of H in simplified microstructures allows an improved understanding of the mechanisms (Barnoush et al. (2015), Di Stefano et al. (2016) and Hajilou et al. (2017)). In this perspective, Fe-C-X alloys were recently thoroughly examined by our group. Carbide forming elements, i.e. Ti, Cr, Mo, W and V, were added as ternary alloying element X. The findings for each carbide forming element were published separately by Depover et al. (2016 (b), 2016 (c), 2016 (d), 2016 (e), 2018 (a), 2018 (b), 2018 (c)). The present study, however, aims at comparing the carbides, which showed the most outspoken H trapping capacity, i.e. TiC and V4C3. 2. Experimental procedure 2.1. Materials Fe-C-Ti and Fe-C-V were chosen as materials of study, containing 0.313 wt% C - 1.34 wt% Ti and 0.286 wt% C 1.670 wt% V, respectively. The Fe-C-X materials were cast, hot rolled and subsequently austenitized at 1250°C for 10 minutes followed by a brine water quench. This first condition will be referred to as “as-Q”. Next, a tempering treatment of 1h at 600°C was done to induce carbides. This condition will be referred to as “Q&T”. 2.2. Thermal desorption spectroscopy TDS measurements were done on samples which were H saturated by pre-charging the materials for 1 h in a 1g/L thiourea, 0.5 M H2SO4 solution at 0.8 mA/cm2. TDS allowed identifying both the H traps and their corresponding activation energy (Ea). Hence, 3 different heating rates (𝜙𝜙) were used (200, 600 and 1200°C/h). The applied procedure required 1 h between the end of H charging and the start of the TDS measurement as sufficient vacuum needs to be created in the analysis chamber. To determine the Ea of H traps from the peaks in the TDS spectra, the Kissinger (1957) method was used, with Tmax (K) the TDS peak temperature and R (J∙K-1∙mol-1) the universal gas constant: 𝜙𝜙 � � 𝐸𝐸� 𝑇𝑇��� �� 1 𝑅𝑅 � �𝑇𝑇 � ���

� ���

2.3. Permeation experiments

Permeation experiments were done based on the Devanathan and Stachurski technique (1962) to determine the H diffusion coefficient. The electrolyte (0.1 M NaOH) was stirred in both cell compartments using a nitrogen flow to minimize the amount of dissolved oxygen, while the ambient temperature was kept constant at 25°C. The sample was polarized cathodically by applying a constant cathodic current density of 3 mA/cm². The absorbed H diffused through the sample to the anodic cell. There, H was oxidized, producing an external current recorded by a potentiostat. For this purpose, the sample was anodically polarized at a constant potential of -500 mV with respect to the reference electrode (Hg/Hg2SO4,+650mV vs. SHE). Dapp was then calculated using the H oxidation current with following formula: 𝐷𝐷��� � 𝐷𝐷�.� �

𝐿𝐿𝐿 7.7𝑡𝑡

where 𝑡𝑡 is the time (s) when the normalized steady-state value has reached 0.1, 𝐿𝐿 is the specimen thickness, equal 1 mm.

T. Depover et al. / Procedia Structural Integrity 13 (2018) 1414–1420 Author name / Structural Integrity Procedia 00 (2018) 000–000

1416

3

3. Results and discussion 3.1. Materials Characterization Optical microscopy images revealed a martensitic (as-Q) and Q&T microstructure (cf. related publications). However, the Fe-C-Ti as-Q material still contained large incoherent TiC since austenitizing at 1250°C was not sufficient to dissolve all the carbides present from processing. Their presence is illustrated by TEM in Fig. 1(a). For Fe-C-V, all particles were dissolved during the austenitizing step and the as-Q condition did not contain any V based precipitates. Next, carbides were introduced for both materials during tempering, i.e. the Q&T condition. TEM bright field images for the Q&T samples were also taken to confirm their presence, as shown in Fig. 1 (b) and (c). For the Q&T condition, small nano-sized carbides of less than 10 nm were identified in both Fe-C-Ti and Fe-C-V. Additional microstructural details and a comprehensive TEM analysis comprising the study of diffraction patterns for the identification of the different carbide morphologies (TiC and V4C3) can be found in the related publications.

2.0m

(a) (b) (c) Figure 1: TEM bright field images for Fe-C-Ti as-Q (a) and for Fe-C-Ti Q&T (b) and Fe-C-V Q&T (c).

3.2. Hydrogen trapping ability deliberated by thermal desorption spectroscopy The available traps were evaluated by performing TDS for both the as-Q and Q&T condition. The TDS spectra together with their deconvoluted peaks are presented in Fig. 2. For the as-Q conditions, only one peak was present for both materials with Ea’s of about 27 – 30 kJ/mol. This first peak was therefore associated to H trapped by the martensitic lath boundaries (Thomas et al. (2002)). As-Q

0.005

0.003 0.002

0.003 0.002 0.001

0.001 0.000

Experimental Fit Peak 1 Fit Peak 2 Fit Peak 3 Fit Peak 4 Cumulative Fit Peak

0.004

H2 (wppm/s)

H2 (wppm/s)

Fe-C-Ti

0.004

Q&T

0.005

Experimental Fit Peak 1 Cumulative Fit Peak 2 Fit Peak

0

200

400

600

0.000

800

0

200

Temperature (°C) 0.004

0.002

0.001

0.000

600

800

Experimental Fit Peak 1 Fit Peak 2 Fit Peak 3 Fit Peak 4 Cumulative Fit Peak

0.004

H2 (wppm/s)

H2 (wppm/s)

Fe-C-V

0.005

Experimental Fit Peak 1 Cumulative Fit Peak 2 Fit Peak

0.003

400

Temperature (°C)

0.003 0.002 0.001

0

200

400

Temperature (°C)

600

800

0.000

0

200

400

600

800

Temperature (°C)

Figure 2: TDS curves of Fe-C-Ti and Fe-C-V in the as-Q and Q&T condition, at a heating rate of 600°C/h.

4

Author name / Structural Integrity Procedia 00 (2018) 000–000 T. Depover et al. / Procedia Structural Integrity 13 (2018) 1414–1420

1417

Although H trapped at dislocations shows Ea’s in the same range (Pressouyre (1979)), this trapping site is confirmed to be undetectable due to the specific experimental requirements to perform the TDS analysis with the equipment used in this work. Moreover, the H which has been released from the sample before the TDS measurement started, has been confirmed to be linked to H trapped by dislocations (Depover et al. (2018 (c)) and Pérez Escobar et al. (2012)). Furthermore, a single peak was also exposed for the as-Q condition of Fe-C-Ti, indicating that the incoherent large TiC particles, shown in Fig. 1(a) were not able to trap H from electrochemical cathodic charging. This confirmed previous results where gaseous H charging at elevated temperature was required to charge these large particles (Wei et al. (2006)) and H from the gaseous charging being presumably trapped inside the carbide rather than at its interface. Considering the Q&T condition, a significantly different trapping behavior was observed due to the tempered induced carbides. The additional peaks in the TDS spectra were therefore attributed to the presence of these precipitates. The small TiC and V4C3 precipitates were capable of trapping a lot of H, resulting in three peaks with activation energies in the range of 44-71 kJ/mol. The H trapping characteristics of the carbides will be further considered by increasing the tempering time. 3.3. Effect of carbide addition on H diffusivity evaluated by permeation transients H diffusion plays an important role to understand the interaction between H and a material. Therefore, H permeation tests were performed. The permeation curves for both materials are shown in Fig. 3. A remarkably slower hydrogen permeation was obtained after tempering which was due to the presence of abundant nano-sized TiC or V4C3 particles. The resulting H diffusion coefficients for Fe-C-Ti were 1.14 x 10-10 and 3.02 x 10-12 m2/s for the as-Q and Q&T condition, respectively. This is consistent with previous reported results on the effect of nano-scale precipitates on the H diffusivity (Brass et al. (2006) and Liu et al. (2017)). For Fe-C-V, the corresponding diffusion coefficients were 8.53 x 10-11 and 1.16 x 10-12 m2/s for the as-Q and Q&T material, respectively. The slower H diffusivity properties for the as-Q condition of Fe-C-V compared Fe-C-Ti can be understood by the density of the martensitic matrix. Since a considerable amount of large TiC was not dissolved during austenitizing (cf. Fig. 1 (a)), less carbon was present in the lath martensitic matrix of Fe-C-Ti after quenching. Consequently, a harder and stronger material was obtained for Fe-C-V as-Q, as confirmed in our previous publications, as such slowing down the H diffusion in Fe-C-V as-Q. 1.0

0.8 0.6 0.4 0.2 0.0 0.1

a)

As-Q Q&T

Normalized current

Normalized current

1.0

1

10

100

As-Q Q&T

0.8 0.6 0.4 0.2 0.0 0.1

1

10

100

Time (h) Time (h) b) Figure 3: Hydrogen permeation curves of Fe-C-Ti (a) and Fe-C-V (b) in the as-Q and Q&T condition.

3.4. Effect of carbide characteristics on TDS and permeation results in Fe-C-Ti Fe-C-Ti tempering was also done for 2 h to increase the carbide size and evaluate the H trapping ability. The corresponding TDS spectra and carbide size distributions are included in Fig. 4. The larger incoherent TiC were unable to trap electrochemically charged H. When the material got tempered for 2 h (Q&T 2h), peak 4 disappeared, whereas peak 2 and 3 diminished compared to Q&T 1h. Since the total interfacial area between carbides and matrix decreases with carbide growth during tempering, H was confirmed to be present at the interface of the carbides. Drexler et al. (2018) recently made a model based interpretation of these TDS data and revealed that peak 4 was linked to carbon vacancies inside TiC, whereas indeed the other carbide related peaks were linked to the carbide/matrix interface. An alternative estimation of the available trapping sites can be made by performing permeation tests, shown in Fig. 5.

1418

T. Depover et al. / Procedia Structural Integrity 13 (2018) 1414–1420 Author name / Structural Integrity Procedia 00 (2018) 000–000

5

The H diffusivity increased from Q&T 1 h < Q&T 2h < as-Q, which was in the opposite order than the amount of available traps (cf. TDS results in Fig. 4). Generally, the H diffusion coefficient decreased with increasing number of available trapping sites indicating the potential of carbides, not only as a way to trap diffusible hydrogen, but also to reduce its mobility in the steel microstructure. An extensive analysis can be found elsewhere (Depover et al. (2016)).

Figure 4: Representative TEM bright field images with corresponding carbides size distribution maps and related TDS spectrum for Fe-C-Ti in the as-Q, Q&T 1h and Q&T 2h condition (heating rate: 600 °C/h).

Normalized current

1.0

As-Q Q&T 2h Q&T 1h

0.8 0.6 0.4 0.2 0.0 0.1

1

10

100

Time (h) Figure 5: Permeation curves for Fe-C-Ti in the as-Q, Q&T 1h and Q&T 2h condition.

6

T. Depover et al. / Procedia Structural Integrity 13 (2018) 1414–1420 Author name / Structural Integrity Procedia 00 (2018) 000–000

1419

4. Conclusions The H trapping ability of TiC and V4C3 precipitates was evaluated in this work. Two conditions, as-Q and Q&T i.e with temper induced carbides, were compared. The tempered induced particles trapped a significant amount of H, as observed by TDS. Due to their efficient trapping, carbides slowed down H diffusion and effectively contributed to an enhanced resistance to H induced failure. Modified thermal treatments allow to steer the microstructure and its interaction with H as demonstrated by longer tempering times and subsequent analysis. Therefore, detailed investigation of the hydrogen/microstructure interaction allow to improve the material’s HE resistance. Acknowledgements The authors wish to thank the postdoctoral fellowship via grant nr BOF01P03516 and the Special Research Fund (BOF), UGent (BOF15/BAS/06). References Barnoush, A., Kheradmand, N., Hajilou, T., 2015. Correlation between the hydrogen chemical potential and pop-in load during in situ electrochemical nanoindentation, Scripta Mat 108, 76-79. Brandon, N.P., and Kurban, Z., 2017. Clean energy and the hydrogen economy, Phil Trans R Soc A, 375: 20160400. Brass, A., Chêne, J., 2006. Influence of tensile straining on the permeation of hydrogen in low alloy Cr-Mo steels, Corrosion Science, 481-497. Depover, T., Pérez Escobar, D., Wallaert, E., Zermout, Z., Verbeken, K., 2014. Effect of in-situ hydrogen charging on the mechanical properties of advanced high strength steels, Int Journal of Hydrogen Energy 39, 4647-4656. Depover, T., Wallaert, E., Verbeken, K., 2016. Fractographic analysis of the role of hydrogen diffusion on the hydrogen embrittlement susceptibilty of DP steel, Mat Sci and Eng A 649, 201-208. Depover, T., Verbeken, K., 2016. The effect of TiC on the hydrogen induced ductility loss and trapping behavior of Fe-C-Ti alloys, Corrosion Science 112, 308-326. Depover, T., Verbeken, K., 2016. Evaluation of the effect of V4C3 precipitates on the hydrogen induced mechanical degradation in Fe-C-V alloys, Materials Science and Engineering 675, 299-313. Depover, T. Verbeken, K., 2016. Hydrogen trapping and hydrogen induced mechanical degradation in lab cast Fe-C-Cr alloys, Mat Sci and Eng A 669, 134-149. Depover, T., Verbeken, K., 2016. Evaluation of the role of Mo2C in hydrogen induced ductility loss in Q&T Fe-C-Mo alloys, Int Journal of Hydrogen Energy 41, 14310-14329. Depover, T., Van den Eeckhout, E., Verbeken, K., 2018. Hydrogen induced mechacnial degradation in tungsten alloyed steels, Materials Characterization 136, 84-93. Depover, T., Verbeken, K., 2018. Thermal desorption spectroscopy study of the hydrogen trapping ability of W based precipitates in a Q&T matrix, Int Journal of Hydrogen Energy 43, 5760-5769. Depover, T., Verbeken, K., 2018. The detrimental effect of hydrogen at dislocations on the hydrogen embrittlement susceptibility of Fe-C-X alloys: An experimental proof of the HELP mechanism, International Journal of Hydrogen Energy 43, 3050-3061. Devanathan, M., Stachurski, Z., 1962. The adsorption and diffusion of electrolytic hydrogen in palladium, Proc Roy Soc A 270, 90-101 Di Stefano, D., Nazarov, R., Hickel, T., Neugebauer, J., Mrovec, M., Elsässer, 2016. First principles investigation of hydrogen interaction with TiC precipitates in alpha-Fe, Physical Review 93, 184108-1-14. Drexler, A., Depover, T., Verbeken, K., Ecker, W., 2018. Model-based interpretation of TDS of Fe-C-Ti alloys, Acta Mat, submitted. Hajilou, T., Deng, Y., Rogne, B.R., Kheradmand, N., Barnoush, A., 2017. In situ electrochemical microcantilever bending test: A new insight into hydrogen enhanced cracking, Scripta Mat 132, 17-21. Hilditch, T.B., Lee, S.B., Speer, J.G., Matlock, D.K., 2003. Response to Hydrogen Charging in High Strength Automotive Sheet Steel Products, SAE Technical Paper, http://dx.doi.org/10.4271/2003-01-0525. Frappart, S., Feaugas, X., Creus, J., Thebault, F., Delattre, L., Marchebois, H., 2010. Study of the hydrogen diffusion and segregation into Fe-CMo martensitic HSLA steel using electrochemical premeation test, Journal of Physics and Chemistry of Solids 71, 1467-1479. Kissinger, H.E., 1957. Reaction kinetics in differential thermal analysis, Analytical Chemistry 29, 1702-1706. Koyama, M., Akiyama, E., Lee, Y.K., Raabe, D., and Tsuzaki, K., 2017. Overview of hydrogen embrittlement in high-Mn steels, Int Journal of Hydrogen Energy 42, 12706-12723. Laureys, A., Depover, T., Petrov, R., Verbeken, K., 2015. Characterization of hydrogen induced cracking in TRIP-assisted steel, International Journal of Hydrogen Energy 40, 16977-16984. Laureys, A., Depover, T., Petrov, R., Verbeken, K., 2016. Microstructural characterization of hydrogen induced cracking in TRIP-assisted steel by EBSD, Materials Characterization 112, 169-179. Liu, Q., Venezuela, J., Zhang, M., Zhou, Q., Atrens, A. 2017. Hydrogen trapping in some advanced high strength steels,” Corrosion Science 125, 114-138. Nagao, A., Martin, M.L., Dadfarnia, M., Sofronis, P., Robertson, M., 2014. The effect of nanosized (Ti,Mo)C precipitates on hydrogen embrittlement of tempered lath martensitic steel, Acta Mat 74, 244-254. Olden, V., Thaulow, C., Johnsen, R., Ostby, E., Berstad, T., 2009. Influence of hydrogen from cathodic protection on the fracture susceptibility of 25%Cr duplex stainless steel - Constant load SENT testing and FE-modelling using hydorgen influenced cohersive zone elements, Engineering Fracture Mechanics 76, 827-844.

1420

T. Depover et al. / Procedia Structural Integrity 13 (2018) 1414–1420 Author name / Structural Integrity Procedia 00 (2018) 000–000

7

Pérez Escobar, D., Depover, T., Wallaert, E., Duprez, L., Verbeken, K., Verhaege, M., 2012. Combined thermal desorption spectroscopy, differential scanning calorimetry, scanning electron microscopy and X-ray diffraction study of hydrogen trapping in cold deformed TRIP steel, Acta Mat 60, 2593-2605. Pressouyre, G.M., 1979, Classification of hydrogen traps in steel, Met Trans A 10A, 1571-1573. Ronevich, J.A., Speer, J.G., Matlock, D.K., 2010. Hydrogen embrittlement of commercially produced advanced high strength steels, SAE Int Journal Mater Manuf 3, 255-267. Thomas, L.S.R., Li, D., Gangloff, R.P., Scully, J.R., 2002. Trap-governed hydrogen diffusivity and uptake capacity in ultrahigh strength aermet 100 steel, Met Mat Trans A 33A, 1991-2004. Venezuela, J., Liu, Q., Zhang, M., Zhou, Q., Atrens, A., 2015. The influence of hydrogen on the mechanical and fracture properties of some martensitic advanced high strength steels studied using the linearly increasing stress test, Corrosion Science 99, 98-117. Yu, H., Olsen, J.S., Alvaro, A., Olden, V., He, J., Zhang, Z., 2016. A uniform hydrogen degradation law for high strength steels, Engineering Fracture Mechanics 157, 56-71. Wei, F.G., Tsuzaki, K., 2006. Quantitative Analysis on hydrogen trapping of TiC particles in steel, Met Mat Trans A 37A, 331-353.