PSI - Issue 5

ScienceDirect Available online at www.sciencedirect.com Av ilable o line at www.sciencedire t.com cienceDirect Structural Integrity Procedia 00 (2016) 000 – 000 Procedia Struc ural Integrity 5 (2017) 1275–1282 Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2017) 000 – 000 Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2017) 000 – 000 Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2017) 000 – 000 Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2017) 000 – 000 il l li t . i i t.com ect tr t r l I t rit r i ( ) Avail l online at www.s i ir t. tructural Int grity rocedia 00 (2017) 000 – 000 Available online at www.sciencedirect.com Sci nceDir t Structural Int grity Procedia 00 (2017) 000 – 000 il l li t . i i t. tr t r l I t rit r i ( ) S

www.elsevier.com/locate/procedia www.elsevier.com/locate/procedia www.elsevier.com/locate/procedia www.elsevier.com/locate/procedia . l i r.c /l t / r i .elsevier.co /locate/procedia www.elsevier.com/locate/procedia . l i r. /l t / r i o

www.elsevier.com/locate/procedia 2nd International Conference on Structural Integrity, ICSI 2017, 4-7 September 2017, Funchal, Madeira, Portugal Evaluation of strength and fracture toughness of ferritic high strength steels under hydrogen environments 2nd International Conference on Structural Integrity, ICSI 2017, 4-7 September 2017, Funchal, Madeira, Portugal Evaluation of strength and fracture toughness of ferritic high strength steels under hydrogen envi onments 2nd International Conference on Structural Integrity, ICSI 2017, 4-7 September 2017, Funchal, Madeira, Portugal Evaluation of strength and fracture toughness of ferritic high strength steels under hydrogen environments 2nd International Conference on Structural Integrity, ICSI 2017, 4-7 September 2017, Funchal, Madeira, Portugal Eval ation of strength and fracture toughness of ferritic high strength steels under hyd og n enviro ments 2nd Internatio 201 , F f gt nd I t r ti l f r tr t r l I t rit , I I , - t r , l, ir , rtugal u n a 2nd International Conference on Structural Integrity, ICSI 2017, 4-7 September 2017, Funchal, Madeira, Portugal Evaluation of strength and fracture toughness of ferritic high strength steels under hydrogen environments ernational Conference on Structural Integrity, ICSI 2017, 4-7 September 2017, Funchal, ngth and fracture toughness of ferritic high strength steels un t g h and fracture toughness of ferritic high 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. L.B.Peral a , A. Zafra a , C. Rodríguez a , J. Belzunce a * a School of Engineering, University of Oviedo, campus universitario, 33203 Gijón, Spain Abstract The susceptibility of high strength ferritic steels to hydrogen-assisted fracture in hydrogen gas is usually evaluated by mechanical testing in high-pressure hydrogen gas or testing in air after pre-charging the specimens with hydrogen. We have used this second methodology, conventionally known as inter al hydrogen. Samples were pre-charged in an autoclave under 195 bar of pure hydrogen at 450ºC for 21 hours. Different chromium-molybdenum steels submitted to diverse quenching and tempering heat treatments were employed. Diverse specimens were also used: small cylindrical samples to measure hydrogen contents and the kinetics of hydrogen egression at room temperature, tensile specimens, notched tensile specimens with a sharp notch, and also compact fracture toughness specimens. Fractographic examination in SEM was finally performed in order to know the way hydrogen modify fracture micromechanisms. The presence of hydrogen barely affects the conventional tensile properties of the steels, but it clearly alters their notched tensile strength and fracture toughness. This is due to the strong effect that stress triaxiality (dependent also on the steel yield strength) has on the accumulation of hydrogen on the notch/cra k front region, being the isplacement rate us d in the test another important variable to be controlled, d e to its influence on hydrogen diffusion to the embrittled pr cess zone. Moreover, the modification of fracture micromechanisms was finally determined, being ductil (initiation, growth and coalescence of microvoids) in the absence of hydrog n and brittle and intergranular under the mat rial conditions f maximum embrittlement. Keywords: High strength steels; hydrogen embrittlement; fracture mecha isms 1. Introduction Fuel Cell systems are a potential n xt-generation energy system. In this context, the increased demand of hydrogen in the years to come means that traditional systems and materials previously used for hydrogen transport and storage should be adapted to allow delivering larger hydrogen quantities in an efficient way, using higher hydrogen pressures, up to 70 MPa [1]. The best economical solution would be the use of medium and high-strength s t eels in order to reduce the thickness of pipes and vessels and so the material cost. 42CrMo4 and 2.25Cr1Mo belong to the family of Cr-Mo steels and are frequently used in the quenched and tempered condition when a good combination of strength and toughness is required. Nevertheless, it is well known that these steels are more sensitive to hydrogen embrittlement (HE) than low-strength steels, and this susceptibility increases with the strength level of the steel [2, 3]. L.B.Peral a , A. Zafra a , C. Rodríguez a , J. Belzunce a * a School of Engineering, University of Oviedo, campus universitario, 33203 Gijón, Spain Abstract The susceptibility of high strength ferritic steels to hydrogen-assisted fracture in hydrogen gas is usually evaluated by mechanical testing in high-pressure hydrogen gas or testing in air after pre-charging the specimens with hydrogen. We have used this second methodology, conventionally known as internal hydrogen. Samples were pre-charged in an autoclave under 195 bar of pure hydrogen at 450ºC for 21 hours. Different chromium-molybdenum steels submitted to diverse quenching and tempering heat treatments were employed. Diverse specimens were also used: small cylindrical samples to measure hydrogen contents and the kinetics of hydrogen egression at room temperature, tensile specimens, notched tensile specimens with a sharp notch, and also compact fracture toughness specimens. Fractogr phic examination in SEM was finally performed in order to know the way hydrogen modify fracture micromechanisms. The presence of hydrogen barely affects the conventional tensile properties of the steels, but it clearly alters their notched tensile strength and fracture toughness. This is due to the strong effect that stress triaxiality (dependent also on the ste l yield strength) has on the accumulation of hydroge on the notch/crack front regi , being the displacement rate used in the test another important variable to be c trolled, due to its influence on hydrog n diffusion to the embrittled process zone. Moreover, the modification of fracture micromechanisms was finally determined, being ductile (initiation, growth and coalescence of microvoids) in the absence of hydrogen and brittle and intergranular under th material conditions of maximum embrittlement. Keywords: High strength steels; hydrogen embrittlement; fracture mechanisms 1. Introduction Fuel Cell systems are a potential next-generation energy system. In this context, the increased demand of hydrogen in the years to come means that traditional systems and materials previously used for hydrogen transport and storage should be adapted to allow delivering larger hydrogen quantities in an efficient way, using higher hydrogen pressures, up to 70 MPa [1]. The best economical solution would be the use of medium and high-strength s t eels in order to reduce the thickness of pipes and vessels and so the material cost. 42CrMo4 and 2.25Cr1Mo belong to the family of Cr-Mo steels and are frequently used in the quenched and tempered condition when a good combination of strength and toughness is required. Nevertheless, it is well known that these steels are more sensitive to hydrogen embrittlement (HE) than low-strength steels, and this susceptibility increases with the strength level of the steel [2, 3]. L.B.Peral a , A. Zafra a , C. Rodríguez a , J. Belzunce a * a School of Engineering, University of Oviedo, campus universitario, 33203 Gijón, Spain Abstra t The susceptibility of high strength ferritic st els to hydr gen-assisted fracture in hydrogen gas is sually evaluated by mechanical testing i high-pressu e hydrogen gas or testing in air after pre-charging the specimens with hydrogen. We have used this second methodology, conventi nally known as internal hydrog n. Samples were pr -cha ged in an autoclave under 195 bar of pur hydrog at 450ºC for 21 hours. Different chromium-molybdenum steels submitted to diverse quenc ing and tempering heat treatments were employed. Div rse spe imens wer also used: small cylindrical samples to measure hydrogen contents and the kinetics of hydrogen eg ession at room tempe ature, tensile specimens, notched tensile specimens with a sharp notch, and also compact f acture toughness specimens. Fractographic examination in SEM was finally performed in order to know the w y hy rog modify fracture micromechanisms. The pres nc of hydr ge barely affects the conventional tensile prop rties of the ste ls, but i clearly alters their notched tensile strength and fracture toughn ss. This is due to th strong ef ect that stre s triaxiality (dependent also on the ste l yield strength) h s on the accumulation of ydrogen on the notch/crack fro t region, being the displ cement rat used in the test another important variable to be controlled, due o its i fluence on ydrogen diffusion to the embrittled pro ess zone. Moreover, the modification of fracture micromechanisms was finally determined, bei g ductile (initiation, growth and coalesc nce of microvoids) in the absence of hyd ogen and brittle and intergr nular und r the material conditions of maximu embrittlement. Keywords: High strengt steels; hydrogen embrittl ment; fracture mechanisms 1. Introduction Fuel Cell systems are a potential next-generation energy system. In this context, the increased demand of hydrogen in the years to come means that t aditional systems and materials previously used for hydro en transport and storage should be adapted to allow delivering larger hydrogen quantities in an efficient way, using higher hydrogen pressures, up to 70 MPa [1]. The best economical solution would be the use of medium and high-strength s t eels in order to reduce the thickness of pipes and vessels and so the material c st. 42CrMo4 and 2.25Cr1M bel ng to the family of Cr-Mo steels and are frequently used in the quenched and tempered condition when a good combination of strength and toughness is required. Nevertheless, it is well known that these steels are mor sensitive to ydrogen embrittlement (HE) than low-strength steels, and this susceptibility increases with the strength level of the steel [2, 3]. L.B.Peral a , A. Zafra a , C. Rodríguez a , J. Belzunce a * a School of Engineering, University of Oviedo, campus universitario, 33203 Gijón, Spain Abstra t The susceptibility of high strength ferritic st els to hydrogen-assisted fracture in hydrogen gas is sually evaluated by mechanical testing i high-pressure hydrogen gas or testing in air after pre-charging the specimens with hydrogen. We have used this second methodology, conventionally known a internal hydrogen. Samples were pr -cha ged in an autoclave und r 195 bar of pure hydrog at 450ºC for 21 hours. Different chromium-molybdenum steels submitted to diverse quenc ing and tempering heat treatments were employed. Div rse specimens wer also used: small cylindrical samples to measure hydrogen contents and the kinetics of hydrogen egression at room tempe ature, tensile specimens, notched tensile specimens with a sharp notch, and also compact fracture toughness specimens. F actogr phic examination in SEM wa finally performed in order to know the way hydroge modify fracture micromechanisms. The presence of hydr gen barely affects the conventional tensile properties of the ste ls, but it clearly alters their notched tensile strength and fracture toughness. This is due to t e strong ef ect that stress triaxiality (dependent also o the steel yield strength) h s on the accumulation of hydrogen on the notch/crack front region, being the displacement rate used in the test another important variable to be controlled, due to its influence on hydrogen diffusion to the embrittled process zone. Moreover, the modification of fracture micromechanisms was finally determined, being ductile (initiation, growth and coalescence of microvoids) in the absenc of hyd ogen and brittle nd intergranular und r the material conditions of maximum embrittlement. Keywords: High strength steels; hydrogen embrittlement; fracture mechanisms 1. Introduction Fuel Cell systems are a potential next-generation energy system. In this context, the increased demand of hydrogen in the years to come means that traditional systems and materials previously used for hydrogen transport and storage should be adapted to allow delivering larger hydrogen quantities in an efficient way, using higher hydrogen pressures, up to 70 MPa [1]. The best economical solution would be the use of medium and high-strength s t eels in order to reduce the thickness of pipes and vessels and so the material cost. 42CrMo4 and 2.25Cr1Mo belong to the family of Cr-Mo steels and are frequently used in the quenched and tempered condition when a good combination of strength and toughness is required. Nevertheless, it is well known that these steels are more sensitive to hydrogen embrittlement (HE) than low-strength steels, and this susceptibility increases with the strength level of the steel [2, 3]. st s l a a l f i i , i ity f i , u i it i , ij , i t The s scepti ilit f hi st engt e ritic s l to yd og - s i t tur in d i ll l t i l t ti i i g s o t ti i i t i t i it . t i t l , ti ll i t l . l i t l e t º 21 hours. i t i l t l mitt d t i chi g and t i h t t ment ere lo . i e im l : ll li i l l t nt t t i ti i t t t , t il i , t t il i it t , l t t t ughness specimens. t i i ti i i ll i t i i i . resence o h r l ct t onv nti nal t il o e ti t t l , t it l ly lte t i tc e t n il t en th a d f t t . i i t t t t t t t i i lit t l t t el i l t t th a lation t e t h/ a t i , t di lac m nt rat use in the t t t i t t i l to be cont ll d, ue o it i luence on ydrogen diffusion to th embrittled process zone. M eover, th modification of t i i i ll t i , i til i iti ti , t l i i i t f hydr d rittl i t l t t i l conditi i i tl t. : i tr t t l ; r rittl t; fr t r i 1. Introduc ion Fuel Cell syste s are a potential next-generation energy syste . t i t t, t i rog in the years to come means that traditional systems and materials previously use t t t l t to allow delivering larger hydrogen quantities in an efficient way, using higher hydroge pressu , t . t i l l ti l t o i i t t l i t t t i i l t t i l t. 2 . o l t t il Cr-Mo t el tl i t n t iti i ti t t t i i . t l , it i ll t t these st l iti t ittl t t l t th t l , t i sus ti ilit l t t l , . . . l a , . a , . í a , . l a School of Engineering, University of Oviedo, campus universitario, 33203 Gijón, Spain str ct The s sce ti ilit f high stre t ferritic steels to rogen-assisted fracture i r e as is s all e al ated ec a ical testing in high-pressure hydrogen gas or testin i air after pre-c ar i t e s eci e s it r e . We have used this sec methodology, conventionally known as internal hydrogen. Samples were pre-char e i a a t cla e er ar f re hydr e at º f r rs. Different chromium-molybdenum steels submitted to diverse quenching and temperi eat treat e ts ere e l e . i ers s eci e s ere als sed: small cylindrical samples to measure hydrogen contents and the inetics f dr e e ressi at r te erat re, te sile s eci e s, tc e te sile s eci e s it a s arp notc , a als c act fract re tou ess s eci e s. Fractographic exami ati i as fi all erf r e i r er t t e a r e if fract re icr ec a is s. The presence of hydrogen barely affects the conventional tensile r erties f t e steels, t it clearl alters their notched tensile stre t a fract re t ess. is is e t t e str effect t at stress tria ialit ( e e e t als t e steel iel stre t ) as n th acc lati f ro en the tch/crac fro t re i , i t e is lace e t rate se i t e test a t er i rta t variable t be c tr lle , e t its i fl e ce r e iff si t t e e rittle r cess z e. re er, t ificati f fract re micr ec a is s as fi all et r i e , ei ctile (i itiati , r t c alesc nc of micr i s) i t e a se ce of r en and rittle an intergra lar under t e material conditions of maximum embrittlement. Keywords: High strength steels; hydrogen e brittlement; fracture echanisms 1. Int d ti Fuel Cell s stems are a potential next-generation energy system. In this context, the increased demand of hydrogen in the ye rs t s t t tra iti l s st s t ri ls r vio sl s f r h r tra s rt st rage should pt to ll w d liv ri l r r dr gen quantities in a efficient w , si i r r r ss r s, up to 70 MPa [1]. Th be economical solution would be the use of medi m and high-strength s t eels in order t r t thi ss f i s ss ls s t t ri l st. 42CrMo4 and 2.25Cr1Mo bel to the f mily of Cr- st ls r fr tl s i t t r iti i ti n f str th and t ughness is required. Nevertheless, it is well known that t se st els re more sensiti t r n rittl t ( ) t an l w-str t st ls, t is s s ti ilit in r s s it t str t l l f t steel [2, ]. L.B.Peral a , A. Zafra a , C. Rodríguez a , J. Belzunce a * a School of Engineering, University of Oviedo, campus universitario, 33203 Gijón, Spain Abstract The susceptibility of high strength ferritic steels to hydrogen-assisted fracture in hydrogen gas is usually evaluated by mechanical testing in high- ressure hydroge gas or testing in air after pre-charging the specimens with hydrogen. We have used this second methodology, conventionally known as internal hydrogen. Samples were pre-charged in an autoclave under 195 bar of pure hydrogen at 450ºC for 21 hours. Different chromium-molybdenum steels submitted to diverse quenching and tempering heat treatments were employed. Diverse specimens were also used: small cylindrical samples to measure hydrogen contents and the kinetics of hydrogen egression at room temperature, tensile specimens, notched tensile specimens with a sharp notch, and also compact fracture toughness specimens. Fractographic examination in SEM was finally performed in order to know the way hydrogen modify fracture micromechanisms. The presence of hydrogen barely affects the conventional tensile properties of the steels, but it clearly alters their notched tensile strength and fracture toughness. This is due to the strong effect that stress triaxiality (dependent also on the steel yield strength) has on the accumulation of hydrogen on the notch/crack front region, being the displacement rate used in the test another important variable to be controlled, due to its influence on hydrogen diffusion to the embrittled process zone. Moreover, the modification of fracture micromechanisms was finally determined, being ductile (initiation, growth and coalescence of microvoids) in the absence of hydrogen and brittle and intergranular under the material conditions of maximum embrittlement. Keywords: High strength steels; hydrogen embrittlement; fracture mechanisms 1. Introduction Fuel Cell systems are a potential next-generation energy system. In this context, the increased demand of hydrogen in the years to co e means that t aditional systems a d ma erials previously used for hydrogen transport and storage should be adapted to allow delivering l rger hydrogen quantities in an efficient w y, us ng higher ydrogen pressures, up to 70 MPa [1]. The best economical solution would be the use of medium and high-strength s t eels in order to reduce the thickness of pipes and vessels and so the material cost. 42CrMo4 and 2.25Cr1M bel ng to he family of Cr-Mo steels and are frequ ntly us d in the quenched and tempered condition when a g od combination of strength and toughness is required. Nevertheless, it is well known that thes teels are mo sensitive to ydrogen embrittlement (HE) than low-strength steels, and this susceptibility increases with the strength level of the steel [2, 3]. L.B.Peral a , A. Zafr a , C. Rodríg ez elzunce * a l f i i , i it f i , i it i , ij , i tract ti ilit i t t iti t ls to h r n sisted fracture in hydrogen ga i ll l t i l t ti i i p r o t ti i i t a i t i it . t i c et l , tio ll nown as t nal hydrogen. Samples were pr -ch rg i t l t º . i t i l t l itt t i i t i t t t t l . i i l : ll li i l l t t t t i ti gre i t t rature, tensil i , t t il i it t , l t r t t i . t i i ti i i ll i t t en i t micromechanisms. l t t ti l t il ti t t l , t it l l lt t i t t il t t t t . i i t t t t t t t t i i lit t l o t te l yi l t t t l ti t t / t i , i t i l t t i t t t t i t t v i l t t ll , t it in l i i t t rittl . , t i ti f f t i i ll t i , i til i iti i , l i i i t r ittl i t l t t i l iti of ma i ittl t. : i tr t t l ; r rittl t; fr t r i 1. i n l Cell systems are a poten i l next-generation energy syste . t i t t, t i i t t t t t iti l tems and ma erials previousl e t t t l t to allow delivering l rger hydrogen quanti ies in an efficient w y, us ng higher ydrogen pressu es, up to M [ ]. The best economical solution would be the use of medium and high-strength l i t t t i i e els and t t i l c t. . l t t family o r-M steel and are frequ ntly us d in the quenched and tempered condition when a good combinatio of strengt t n i i . t l , it i ll o t t thes t l iti t ittl t t l t t t l , t i susceptibility incr it t t t l l t t l , . e d a a i n h l h o v t i t t r d l C ms e a poten e t e te thes © 2017 Th Authors. Published by Elsevi r B.V. Peer-review under responsibility of the Scientific Committee of ICSI 2017 © 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. i it t t t l

2452-3216 © 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of PCF 2016. 2452-3216  2017 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of ICSI 2017 10.1016/j.prostr.2017.07.105 © 2017 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of ICSI 2017. © 2017 The Authors. Published by Elsevier B.V. Peer review under r sponsibility of the Scientific Committee of ICSI 2017. © 2017 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of ICSI 2017. * Corresponding author. Tel.: +0034-985-182-024. E-mail address : belzunce@uniovi.es © 2017 The Authors. Published by Elsevi r B.V. Peer-review under responsibility of the Scientific Committee of ICSI 2017. * Corresponding author. Tel.: +0034-985-182-024. E-mail address : belzunce@uniovi.es t r . li l ier . . i ilit t i ti i itt . rr i t r. l.: - - - . E-mail address : belzunce@uniovi. s © 2017 The Authors. Published by Els vier . . Peer-review under respo si ilit f t e cie tific ittee f I I . © 2017 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of ICSI 2017. * Corresponding author. Tel.: +0034-985-182-024. E-mail address : belzunc @uniovi.es t r . bli l i r . . eer-review under responsibility of the Scientific Committee of IC . Corr i t r. el.: +0034-9 - 8 - . - il : l i i. © * Corresponding author. Tel.: +351 218419991. E-mail address: amd@tecnico.ulisboa.pt * Corresponding author. Tel.: +0034-985-182-024. E-mail address : belzunce@uniovi.es * Corresponding author. Tel.: +0034-985-182-024. E-mail address : belzunce@uniovi.es * Corresponding author. el.: 0034-985-182-024. - ail address : belzunce uniovi.es i