PSI - Issue 13

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

00 (2018) 000–000

ScienceDirect Available online at www.sciencedirect.com Av ilable o line at ww.sciencedire t.com ienceDirect Structural Integrity Procedia 00 (2016) 000 – 000 Procedia Structu al Integrity 13 (2018) 619–624 00 (2018) 000–000 00 (2018) 000–000 00 (2018) 000–000 Available online at www.sciencedirect.com 00 (2018) 000–000 Available online at www.sciencedirect.com 00 (2018) 000–000 Available online at www.sciencedirect.com 00 (2018) 000–000 .sci c ir ct.c 00 (2018) 000–000 00 (2018) 000–000 00 (2018) 000–000 ECF22 - Loading and Environmental e ff ects on Structural Integrity Brittle fracture analysis of Dissimilar Metal Welds between low-alloy steel and stainless steel at low temperatures Ghassen Ben Salem a,b,c, ∗ , Ste´phane Chapuliot a , Arnaud Blouin a , Philippe Bompard b , Cle´mentin Jacquemoud c a FRAMATOME, 1 Pl. Jean Millier, 92400 Courbevoi , France b Laboratoire MSSMat, UMR CNRS 8579, Centr leSupelec, 3 Rue J liot Curie, 91190 Gif-sur-Yvette, France c DEN-Service d´ e´tudes me´caniques et thermiques (SEMT), CEA, Univ rsite´ Paris-Saclay, F-91191 G f-sur-Yvette, France Abstract Dissimilar Metal Welds (DMW) between low-alloy steel (A533 steel) and austenitic 316L stainless steel are widely used within the French nuclear power plants where they connect the main components to the primary circuit pipes. In th se DMW, the w lding process and the post-weld heat-treatment g nerat a hard thin lay r of carburized martensite and austenite in the vicinity of the fusi n line (FL), resulting in a he eroge eous microstructure with high mechanical properties gradient, hence potentiall , a high r se sitivity to b ittle fracture in th hard layer. The present study aims to evaluate the brittle behavior of the DMW at low temperatures and more particularly of the interfac between the carburized mart nsite and au tenite (MA ter ace). Fracture t ughness tests were carri d out at temperatures betw en − 120 ◦ C and − 50 ◦ C, with a precr ck tip loca d on the ferritic side near the FL (i. ., bet een the ferritic st el and he tainless steel butt ring). The analysis of th fracture behavior of the DMW w s based on a SEM examination of CT (C mpact T nsion) specimens fract re surfaces. Coupled with a 2D plane strain numerical simulation of the tests, the results show th t th presence of austenite in the fatigue precrack fron and subs qu t uct l tearing towards FL p oduced higher solicitati n on th hard layer and c used i tergranula f acture o the MA interface, resulting in lower toughness values for the spec men. To model the brittle behavi r of the MA interface, a stress b sed crit rion was used. Tensil t on axisymmetric spec men, which re ma h ned to initiat int rgranular racture in he MA interfac and tested at − 170 ◦ C, wer used to d fine a threshold stress ( σ th ), below which brit le f acture cannot occur. Th n, a cr terion to evaluate the i tl fractur i k of t e DMW was proposed and applied to the CT specim n. c 2018 The Authors. Published by Elsevier B.V. Peer-review under responsib lity of the ECF22 organizers. Keywords: Dis imilar Metal welds; Martensite-Austenite interface; Fusion Lin ; Hard layer; intergranular fracture; arbides; threshold stress; Notched Tensile Sp cimen ECF22 - Loading and Environmental e ff ects on Structural Integrity Brittle fracture analysis of Dissimilar Metal Welds between low-alloy steel an stainless ste l at low temperatures Ghassen Ben Salem a,b,c, ∗ , Ste´phane Chapuliot a , Arnaud Blouin a , Philipp Bompard b , Cle´mentine Jacquemoud c a FRAMATOME, 1 Pl. Jean Millier, 92400 Courbevoi , France b Laboratoire MSSMat, UMR CNRS 8579, CentraleSupelec, 3 Rue Joliot Curie, 91190 Gif-sur-Yvette, France c DEN-Service d´ e´tudes me´caniques et thermiques (SEMT), CEA, Universite´ Paris-Saclay, F-91191 Gif-sur-Yvette, France Abstract Dis imilar Metal Welds (D W) between low-alloy steel (A533 st el) and austenitic 316L stainless st el are widely used within the French nuclear power plants where they connect the main compone ts to the primary circuit pipes. In these DMW, the welding process and the post-weld heat-treatment generate a hard thin layer of carburized martensite and austenite in the vicinity of the fusion line (FL), resulting in a heterogeneous microstructure with high mechanical properties gradient, hence potentially, a higher sensitivity to brittle fracture in the hard layer. The present study aims to evaluate the brittle behavior of the DMW at low temperatures and more articularly of the interfa e between the carburized martensite and austeni (MA in erface). Frac ure toughness test we e carried out at temperatures between − 120 ◦ C and − 50 ◦ C, with a pr cr ck tip locate on the f rritic side near the FL (i.e., between th ferritic st el and the stainless s eel buttering). The an lysis of the fractur beh vior of th DMW was based on a SEM examina ion of CT (Compact Ten ion) specimens fracture surfaces. Cou led with a 2D plane strain numerical simulation of th tests, the results show that the presence of austenite in the fatigue precrack front and subs quent duct le tearing toward FL produced higher solicitations on the hard laye and caused intergra ular frac ure on th MA interface, resulti g in lower toughness values for the sp cimen. To model t e brittle behavi r of the MA interface, a s ress based criterion was used Tensile tests n ax symmetric s e im , which were machined to initiate int rgranular fracture in he MA interfac and tested at − 170 ◦ C, wer used o define a threshold stress ( σ th ), b low which brittle fracture cannot occur. Then, a criterion to eval e the brittle fracture risk of t e DMW was propo ed and applied to the CT specimen. c 2018 The Author . Published by Elsevier B.V. Peer-review un er res onsibility of the ECF22 or anizers. K ywords: Dissimilar Metal welds; Martensite-Austenite interface; Fusion Line; Hard layer; intergranular fracture; carbides; threshold stress; Notched ensile Specimen 2452-3216 © 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of PCF 2016. The present study aims to evaluate the brittle behavior of the DMW at low temperature and more particularly at the location of the Fusion Line (FL) between the ferritic steel and austenitic weld metal, where the highest mi crostructural and mechanical heterogeneities are concentrated. Section.1 presents the evolution of the microstructure across the ferritic / austenitic steel interface after the welding process and the Post-Weld Heat Treatment (PWHT). In this regard, stainless steel Dissimilar Metal Welds (SS DMW) are critical for the integrity of the currently operating reactors, since they represent singularities in the microstructure, stress gradients and residual stresses in the powerplant primary circuit. Therefore, their highly heterogenous microstructure and mechanical properties must be studied. The p ent study a ms to evaluate the brittle behavior of the DMW at low temperature and more particularly at the location of the Fusion Line (FL) between the ferritic steel and austenitic weld metal, where the highest mi crostructural and mechanical heterogeneities are concentrated. Section.1 presents the evolution of the microstructure across the ferritic / austenitic steel interface after the welding process and the Post-Weld Heat Treatment (PWHT). Dissimilar Metal Welds (DMW) between low-alloy steel 18MND5( ∼ A533) and austenitic 316L stainless steel are widely used within the French nuclear power plants, where they connect the main components to the primary circuit pipes (Fig.1(a)). In order to extend the operating nuclear powerplant lifespan, it is necessary to verify that each component is able to withstand brutal changes in temperature and pressure for all situations, taking into account the e ff ect of thermal ageing on the material behavior. In this regard, stainless steel Dissimilar Metal Welds (SS DMW) are critical for the integrity of the currently operating eactors, sinc they repre ent singularities in the microstructure, stress gradients and residual stress s in the powerplant primary circuit. Therefore, their highly heterogenous microstructure and mechanical properties must be studied. The present study aims to evaluate the brittle behavior of the DMW at low temperature and more particularly at the location of the Fusion Line (FL) between the ferritic steel and austenitic weld metal, where the highest mi crostructural and mechanical heterogeneities are concentrated. Section.1 pr sents the evolution of the microstructure across the ferritic / austenitic st el interface after the welding pro ess and th Post-Weld Heat Treatment (PWHT). Abstract Dissimilar Metal Welds (DMW) between low-alloy steel (A533 steel) and austenitic 316L stainless steel are widely used within the French nuclear power plants where t ey connect the main components to the primary circui pipes. In these DMW, the welding process and the post-weld heat-treatment gen rate a hard thin layer of carburized marten ite and auste ite in the vicinity of the fusion line (FL), resulting in a heterogeneous microstructure with high mechanical properties gradient, hence potentially, a higher sensitivity to brittle fracture in the hard layer. The present study aims to evaluate the brittle behavior of the DMW at low temperatures and more particularly of the interface between the carburized martensite and austenite (MA interface). Fracture toughness tests were carried out at temperatures betwe n − 120 ◦ C and − 50 ◦ C, with a precrack tip located on the ferritic side near he FL (i.e., between the ferritic steel and the stainless steel buttering). The analysis of the fracture behavior of the DMW was based on a SEM examination of CT (Compact Tension) specimens fracture surfaces. Coupled with a 2D plane strain numerical simulation of the tests, the results show that th presence of austenite in the fatigue precrack f ont and subs quent ductile tearing towards FL produced higher solicitations on the hard layer and caused intergranular fracture on t MA interface, resulting in lower toughness values for the specimen. To model the brittle behavior of the MA interface, a stress based criterion w s used. Tensile tests on axisymmetric specimen, which were mac ined to initiate intergranular fracture in the MA interface and tested at − 170 ◦ C, were used to define a threshold stress ( σ th ), below which brittle fracture cannot occur. Then, a criterion to evaluate the brittle fracture risk of the DMW was proposed and applied to the CT speci en. c 2018 Th Authors. Publish d by Elsevier B.V. Peer-revi w under responsibi ity of the ECF22 organizers. Keywords: Dissimilar Metal welds; Martensite-Austenite interface; Fusion Line; Hard layer; intergranular fracture; carbides; threshold stress; Notched Tensile Specimen 1. Introduction Dissimilar Metal Welds (DMW) between low-alloy steel 18MND5( ∼ A533) and austenitic 316L stainless steel are widely used within the French nuclear power plants, where they connect the main components to the primary circuit pipes (Fig.1(a)). In order to extend the operating nuclear powerplant lifespan, it is n cessary to verify that each component is able to withstand brutal changes in temperature and pressure for all situations, taking into account t e e ff ect of thermal ageing on the material behavior. In this regard, stainless steel Dissimilar Metal Welds (SS DMW) are critical for the integrity of the currently operating reactors, since they represent singularities in the microstructure, stress gradients and residual stresses in the powerplant primary circuit. Therefore, their highly heterogenous microstructure and mechanical properties must be studied. The pres nt study aims to evaluate the brittle behavior of the DMW at low temp rature and more particularly at the location of the Fusion Line (FL) between the ferritic steel and austenitic weld metal, where the highest mi crostructural and mechanical heterogeneities are concentrated. Section.1 presents the evolution of the microstructure across the ferritic / austenitic steel interface after the welding process and the Post-Weld Heat Treatment (PWHT). ECF22 - Loadi g and Environmental e ff ects on Structural Integrity Brittle fracture analysis of Dissimilar Metal Welds between lo -alloy steel and stainl ss steel at low temperatures Ghassen Ben Salem a,b,c, ∗ , Ste´phane Chapuliot a , Arnaud Blouin a , Philippe Bompard b , Cle´mentine Jacquemoud c a FRAMATOME, 1 Pl. Jean Millier, 92400 Courbevoie, France b Laboratoire MSSMat, UMR CNRS 8579, CentraleSupelec, 3 Rue Joliot Curie, 91190 Gif-sur-Yvette, France c DEN-Service d´ e´tudes me´caniques et thermiques (SEMT), CEA, Universite´ Paris-Saclay, F-91191 Gif-sur-Yvette, France Abst act Dissimilar Metal Welds (DMW) betwe n low-alloy st el (A533 steel) and aust nitic 316L stainless steel are wid ly us d within the French ucl ar power plants where they connect the main components to the primary ci cuit pipes. In thes DMW, the welding process and the post-weld heat-treatment generate a hard thin layer of carburized martensite and austenite in the vicinity of the fusion line (FL), resulting in a heterogeneous microstructure with high mechanical properties gradient, hence potentially, a higher sensitivity to brittle frac ure in the hard layer. The present study aims to evaluate the brittle behavior of the DMW at low temperatures and more particularly of the interface between the carburized martensite and us enite (MA interf ce). Fracture oughness tests were carried out at temperatures betwe n − 120 ◦ C and − 50 ◦ C, with a prec a k tip located on the ferritic side near the FL (i.e., between the ferritic steel and the stainless ste l buttering). The analysis of the fracture behavior of the DMW was ba ed on a SEM examination of CT (Compact Tension) specimens fracture surfaces. Coupled with a 2D plane strain numerical simulation of the tests, the results show that the presence of austenite in t e fatigue precrack front and subsequent ductile tearing towards FL produced higher solicitatio s on t e hard layer and caused intergranular fracture on the MA interface, resulting in lower toughness values for the specimen. To model the brittle behavior of the MA interface, a stress based criterion w s used. Tensile tests on axisymm tric specimen, which were machined to initiate intergranular fracture in the MA interface and tested at − 170 ◦ C, were used to define a threshold stress ( σ th ), below which brittle fracture cannot occur. Then, a criterion to evaluate the brittle fracture r sk of the DMW was proposed and applied to the CT specimen. c 2018 The Authors. Pub ished by Elsevi r B.V. Peer-review under responsibility of the ECF22 organizers. Keywords: Dissimilar Metal welds; Martensite-Austenite interface; Fusion Line; Hard layer; intergranular fracture; carbides; threshold stress; Notched Tensile Specimen 1. Introduction Dissimilar Metal Welds (DMW) between low-alloy steel 18MND5( ∼ A533) and austenitic 316L stainless steel are widely used within the French nuclear power plants, where they connect the main components to the primary circuit pipes (Fig.1(a)). In order to extend the operating nuclear powerplant lifespan, it is necessary to verify that each component is able to withstand brutal changes in temperature and pressure for all situations, taking into account the e ff ect of thermal ageing on the material behavior. In this regard, stainless steel Dissimilar Metal Welds (SS DMW) are critical for the integrity of the currently operating reactors, since they represent singularities in the microstructure, stress gradients and residual stresses in the powerpla t primary circuit. Therefore, their highly heterogenous microstructure and mech ical properties must be studied. The present study aims to evaluate the brittle behavior of the DMW at low temperature and more particularly at the location of the Fusion Line (FL) between t ferritic steel and austenitic weld metal, where th highest mi crostructural and mechanical heterogeneities are concentrated. Section.1 presents the evolution of the microstructure across the ferritic / aust nitic steel interface after the welding process and the Post-Weld Heat Treatment (PWHT). ECF22 - Loadi g and Environmental e ff ects on Structural Integrity Brittle fracture an lysi of Dis imilar Metal Welds between low-alloy steel and stainless steel at low temperatures Ghassen Ben Salem a,b,c, ∗ , Ste´phane Chapuliot a , Arnaud Blouin a , Philippe Bompard b , Cle´menti e Jacquem ud c a FRAMATOME, 1 Pl. Jean Millier, 92400 Courbevoie, Fr nce b Laboratoire MSSMat, UMR CNRS 8579, CentraleSupelec, 3 Rue Joliot Curie, 91190 Gif-sur-Yvette, France c DEN-Service d´ e´tudes me´caniques et thermiques (SEMT), CEA, Universite´ Paris-Saclay, F-91191 Gif-sur-Yvette, France Abstract Dissimilar M tal Welds (DMW) between low-alloy st el (A533 steel) and austenitic 316L stainless steel are widely used within the French nuclear power pla ts where they connect the main components to the primary circuit pipes. In thes DMW, the welding process and the post-weld heat-treatment generate a hard thin layer of carburized martensite and austenite in the vicinity of the fusion line (FL), resulting in a heterogeneous microstructure with h gh mecha ical properti s gradient, h nce potentially, a higher ensitivity to brittle fracture in the hard layer. The present study aims to evaluate the brittle behavior of the DMW t low temperatures and more particularly of the interface between the carburized martensite and austenite (MA interface). Fracture toughness tests were carried out at temperatures between − 120 ◦ C and − 50 ◦ C, with a precrack tip located on the ferritic side near the FL (i.e., between the f rritic steel and the stainless ste l buttering). The analysis of the fractu e behavior of the DMW was based on a SEM examination of CT (Compact Tension) specimens fracture surfaces. Coupled with a 2D plane strain numerical simulation of the ests, the results show that the presence of austenite in the fatigue precrack front and sub equ nt ductile te ring towards FL produced higher solicitations on the hard layer and caused interg anular fracture on the MA interface, resulting in lower toughness values for the specimen. To model the brittle behavior of the MA interface, a stress based criterion was us d. Tensile tests on axisymmetric specimen, which were machined to initiate intergranular fracture in the MA interface and tested at − 170 ◦ C, were used to define a threshold stress ( σ th ), below wh ch brit le frac ure cannot occur. Then, a criterion to evaluate the brittle fr cture risk of the DMW was proposed and applied to the CT spe imen. c 2018 The Aut ors. Publish d by Elsevi r B.V. Peer-review under responsibility of the ECF22 organizer . Keywords: Dissimilar Metal welds; Martensite-Austenite interface; Fusion Line; Hard layer; intergranular fracture; carbides; threshold stress; Notched Tensile Specimen 1. Introduction Dissimilar Metal Welds (DMW) between low-alloy steel 18MND5( ∼ A533) and austenitic 316L stainless steel are widely used within the French nuclear power plants, where they connect the main components to the primary circuit pipes (Fig.1(a)). In order to extend the operati g nuclear powerplant lifespan, it is necessary to verify that each component is able to withstand brutal c anges in temperature and pressure or all situations, taking into accoun the e ff ect of thermal ageing on the material behavior. In this regard, stainless steel Dissimilar Metal Welds (SS DMW) are critical for the integrity of the currently operating reactors, since they represent singularities in the microstructure, stress gradients and residual stress s in the powerpla t p imary circuit. Therefore, their highly heterogenous microstructure and mecha ical properties must be studied. The present study aims to evaluate the brittle behavior of the DMW at low temperature and more partic larly t the locatio of the Fusion Line (FL) between t f rritic steel and austenitic weld metal, where th highest mi crostructural and mechanical heterogeneities are concentrated. S ction.1 presents the evolution of the icrostructure across the ferritic / auste itic steel interface after the welding pro ess and the Post-Weld Heat Treat ent (PWHT). tr t r l I t rity acture analysi o i e t een Ghassen Ben Salem a,b,c, ∗ , Ste´phane Chapuliot a , Arnaud Blouin a , Philippe Bompard , le´mentine Jacquemoud c a T , 1 l. Jean illier, 92400 ourbevoie, France b Laboratoire SS at, S 8579, entraleSupelec, 3 ue Joliot urie, 91190 if-sur-Yv tte, rance c DEN-Service d´ e´tudes me´caniques et thermiqu s (SEMT), CEA, Universite´ Paris-Saclay, F-91191 if-sur-Yvette, rance stract issi ilar etal elds ( ) bet een lo -alloy steel ( 533 s eel) and austenitic 316 stainless steel are idely used ithin the rench nuclear po er plants here they connect the ain co ponents to the pri ary circuit pipes. In these , the elding process and the post- eld heat-treat ent generate a hard thin layer of carburized artensite and austenite in the vicinity of the fusion line ( ), resulting in a heterogeneous icrostructure ith high echanical properties gradient, hence potentially, a higher sensitivity to brittle fracture in the hard layer. he present study ai s to evaluate the brittle behavior of the at lo te peratures and ore parti ularly of the interface bet een the carburized artensite and austenite ( inter ace). racture toughness tests were carri d out at te peratures bet een 120 ◦ and 50 ◦ , ith a precrack tip located on the ferritic side near the (i.e., bet een the ferritic steel and the stainless steel buttering). he analysis of the fracture behavior of the as based on a exa ination of ( o pact e sion) speci ens fracture surfaces. oupled ith a 2 plane strain nu erical si ulation of the tests, the results sho that the presence of austenite in the fatigue precrack front a s se e ctile te ri g to ar s produc d higher solicitations on the hard layer and caused intergranular fractur on the interface, resulting in lo er toughness values for the speci en. o odel the brittle behavior of the interface, a stress based criterion was used. Tensile tests on axisy etric specimen, which were machined to initiate intergranular fracture in the interface and tested at − 170 ◦ , ere used to de ne a threshold stress ( th ), below which brittle fracture cannot oc ur. hen, a criterion to evaluate the brittle fracture risk of the as proposed and applied to the CT specimen. c 2018 he ut ors. ublished by lsevier B.V. er-revie under responsibility of th 22 organ zers. ey ords: issimilar Metal welds; Martensite-Austenite interface; Fusion ine; ard layer; intergranular fracture; carbides; threshold stress; otched ensile Speci en . I tr cti ssi ilar etal el s ( ) et ee l -all steel ( ∼ ) a a ste itic stai less steel are i el se it i t e re c clear er la ts, ere t e c ect t e ai c e ts t t e ri ar circ it i es ( i . (a)). I r er t e te t e eratin clear er la t lifes a , it is ecessar t erif t at eac c e t is a le t i sta r tal c a es i te erat re a ress re f r all sit ati s, ta i i t acc t t e e ff ect f t er al a ei t e aterial e a i r. I t is re ar , stai less steel issi ilar etal el s ( ) are critical f r t e i te rit f t c rre tl erati react rs, si ce t e re rese t si larities i t e icr str ct re, stress ra ie ts a resi ual stresses in t e er la ri ar circ it. eref re, t eir i l eter e s icr str ct re a ec ical r erties st e st ie . The present study aims to evaluate t rittle e a i r f t e at l te erature a r artic larl t t e l cati f t e si i e ( ) et e t ferritic steel a a st itic el etal, ere t e i est i cr str ct ral and mecha ical h terog neities are concentrated. Se tion. rese ts t e e l ti f t e icr str ct re acr ss t e ferritic / a ste itic steel i terface after t e el i r cess a t e st- el eat reat e t ( ). E F22 - Loading and Environ ental e ff ects on Structural Integrity rittle fract re a al sis f issi ilar etal el s etween lo -all steel a stai less steel at l te erat res Ghassen Ben Sale a,b,c, ∗ , Ste´phane hapuliot a , rnaud louin a , Philipp Bo pard b , le´ entine Jacque oud c a FRAMATOME, 1 Pl. Je Mill er, 92400 Courbevoie, France b Laboratoire MSSMat, UMR CNRS 8579, Centr leSupelec, 3 Rue Joliot Curie, 91190 Gif-sur-Yvette, France c DEN-Service d´ e´tudes me´caniques et thermiques (SEMT), CEA, Universite´ Paris-Saclay, F-91191 Gif-sur-Yvette, France Abstract Dissimilar etal elds (D ) between low-alloy steel (A533 steel) and austenitic 316L stainless steel are widely used within the French nuclear power plants where they connect the main components to the primary circuit pipes. In these D , the welding process and the post-weld heat-treatment generate a hard thin layer of carburized martensite and austenite in the vicinity of the fusion line (FL), resulting in a heterogeneous microstructure with high mechanical properties gradient, hence potentially, a higher sensitivity to brittle fracture in the hard layer. The present study aims to evaluate the brittle behavior of the DMW at low temperatures and more particularly of the interface between the carburized martensite and austenite (MA interface). Fractur toughness test were carried out at temperatures between − 120 ◦ C and − 50 ◦ C, with a precrack tip located on the f rritic side near the FL (i.e., bet een the ferritic steel and the stainless steel buttering). The analysis of the fracture behavior of the D was based on a SEM examination of CT (Compact Tension) specimens fracture surfaces. Coupled with a 2D plane strain numeric l simulation of the tests, the results show t at the presence of austenite in the f tigue precrack front and subsequent ductile tearing towards FL p oduced higher solicitations on the hard layer and caused intergranular fracture on the MA interface, resulting in lower toughness values for the specimen. To model the brittle behavior of the MA interface, a stress based criterion was used. Tensile tests on axisymmetric s ecimen, which were machined to initiate intergranular fracture i the A interface and tested at − 170 ◦ C, wer used to define a threshold stress ( σ th ), below which brittle fracture cannot occur. Then, a criterion to evaluate the brittle fracture risk of t e DMW was proposed and applied to the CT specimen. c 2018 The Authors. Published by Elsevier B.V. i ilit f the F 2 organizers. Keywo ds: Dissimilar Metal welds; Mar ensite-Austenite interface; Fusion Line; Hard lay r; intergranular fracture; carbides; threshold stress; Notched T nsile Specimen 1. Introduction Dissi ilar etal elds (DMW) between low-alloy steel 18 ND5( ∼ A533) and austenitic 316L stainless steel are widely used within the French nuclear power plants, where they connect the main co ponents to the pri ary circuit pipes (Fig.1(a)). In order to extend the operating nuclear powerplant lifespan, it is necessary to verify that each co ponent is able to withstand brutal changes in temperature and pressure for all situations, taking into account th e ff ect of thermal ageing on the material behavior. In this regard, stainless steel Dissi ilar etal elds (SS DMW) are critical for the int grity of he currently operating reactors, since they represent singularities in the microstructure, stress gradients and residual stresses in powerplant pri ary circuit. Therefore, their highly heterogenous icrostructure and mechanical properties must be studied. The present study ai s to evaluate the brittle behavior of the D at low te perature and ore particularly at the location of the Fusion Line (FL) between the ferritic steel and austenitic weld etal, where the highest i crostructural and echanical heterogeneities are concentrated. Section.1 presents the evolution of the icrostructure across the f rritic / austenitic steel interface after the welding process and the Post-Weld Heat Treatment (PWHT). ∗ Corresponding author. T l.: + 33-610-68-1105 E-mail address: ghassen.ben-salem@ecp.fr ECF22 - Loading and Environmental e ff ects on Structural Integrity Brittle fracture a alysis of Dissimilar Metal Welds between low-alloy steel and tainless steel at low temperatures Ghassen Ben Salem a,b,c, ∗ , Ste´phane Chapuliot a , Arnaud Blouin a , Philippe Bompard b , Cle´mentin Jacquemoud c a FRAMATOME, 1 Pl. Je n Mill er, 92400 Courbevoie, France b Laboratoire MSSMat, UMR CNRS 8579, Centr leSupelec, 3 Rue Joliot Curie, 91190 Gif-sur-Yvette, France c DEN-Service d´ e´tudes me´caniques et thermiques (SEMT), CEA, Universite´ Paris-Saclay, F-91191 Gif-sur-Yvette, France Abstract Dissimilar Metal Welds (DMW) between low-alloy steel (A533 steel) and austenitic 316L stainless steel are widely used within the French nuclear power plants where they connect the main components to the primary circuit pipes. In these DMW, the welding process and the post-weld heat-treatment generate a hard thin layer of carburized martensite and austenit in th vicinity of the fusion lin (FL), r sulti g in a heterogeneous microstructure with high mechanical properties gradient, henc potentially, a higher sensitivity to brittle fracture in the hard layer. The present study aims to evaluate th brittle behavior of the DMW at low temperatures and more particularly of the interface between th carburized arte site and aust nite (MA int rface). Fracture toughnes te ts wer carried out at temperatures between − 120 ◦ C and − 50 ◦ C, with a precrack tip loca d on the f rritic side near L (i.e., between the ferritic steel and the stai less ste l butt ring). The an lysis of th fracture beh vior of th DMW was based on a SEM examination of CT (C mpact Tension) specimens fract re surfaces. Coupled with 2D plan str in numerical simulation of the t sts, the results show that the presence of austen e in t e fatigue p e rack fron nd subsequent ductile tearing towards FL produced higher solicitations the hard layer and caused intergranular fractur on the MA interfa e, resulting in lower toughness values for the specimen. To model brittle be avior of th MA interface, a stress b s d criterion was used. Tensile tests on axisymmetric specim , which were machined to initiate intergranular fracture in th MA int rface and tested at − 170 ◦ C, were used to d fine a thresho d tress ( σ th ), below which brittle fracture cannot occur. Then, a criterion to evaluate the brittl fracture risk of th DMW was proposed and applied o the CT specimen. c 2018 T Au hors. P blished by Elsevier B.V. Peer-review under respo sibility of the ECF22 orga izers. Keywo ds: Dissimilar Metal welds; Martensit -Au tenite interface; Fusion Line; Hard layer; intergranular fracture; carbides; threshold stress; Notched T nsile Sp cimen 1. Int oduction Dissimilar Metal Welds (DMW) between l w-alloy steel 18MND5( ∼ A533) and austenitic 316L stainless steel are widely used within the French nuclear power plants, where they connect the main components to the primary circuit pipes (Fig.1(a)). In order to extend the operating nuclear powerplant lifespan, it is ne essary to verify hat each component is able to withstand rutal changes in temp rature and pressure for all situations, taking into account th e ff ect of thermal agei g on the mat rial behavior. In this regard, stainles s eel Dissimilar Metal Weld (SS DMW) a critical for the in egri y of he currently operating reactors, sinc they represent singularit es in the microstru ture, s ress gr dients a d residual stresses in t powerplant primary circuit. Ther fore, their highly heterog nous microstructure and mechan cal prop rties mus be studied. The prese study aims t evaluate the brittle behavior of the DMW at low temperature d mo e particularly at the location of the Fu ion Line (FL) between the ferritic steel and austen weld metal, where the highest mi crostructu al and mechanical heteroge eities are conce trated. Section.1 present the evolution of the microstructure across the ferritic / austeniti steel interfac after the welding proce s nd the Post-W ld H at Treatm nt (PWHT). ∗ Correspondi g author. T l.: + 33-610-68-1105 E-mail address: gh ssen.ben-salem@ecp.fr 1. Introduction Dissimilar Metal Welds (DMW) between low-alloy steel 18MND5( ∼ A533) and austenitic 316L stainless steel are widely used within the French nuclear power plants, where they connect the main components to the primary circuit pipes (Fig.1(a)). In order to extend the operating nuclear powerplant lifespan, it is necessary to verify that each component is able to withstand brutal changes in temperature and pressure for all situations, taking into account th e ff ect of thermal ageing on the materi l behavior. In this regard, s a less steel Dissimilar Metal Weld (SS DMW) are critical for the integrity of the cu rentl operating reactors, since they represent singularities in the microstructure, stress gradients a d residual stresses in t powerplant primary circuit. Ther fore, their highly heterogenous microstructure and mechanical properties us be studi d. The presen study aims to evaluate the brittle behavior of the DMW at low temperature and m re particularly at the location f the Fusion Line (FL) be ween h ferritic steel and austen i weld metal, where the highest mi cros ructural and mechanical heterogeneities are concentrated. Section.1 present the evolution of the microstructure across the ferritic / austeniti st el int rface after th welding pro ess and h Post-W ld H at Tr at ent (PWHT). ∗ Correspondi g author. Tel.: + 33-610-68-1105 E-mail address: ghassen.ben-salem@ecp.fr 2210-7843 c 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ECF22 organ zers 1. Introduction Dissimilar Metal Welds (DMW) b tween low-alloy steel 18MND5( ∼ A533) and ustenitic 316L stainless steel are widely used within the French nuclear power plants, where they connect the main components to the primary circuit pipes (Fig.1(a)). In order to extend the operating nuclear powerplant lifespan, it is necessary to verify that each component is able to withstand brutal changes in temperature and pressure for all situations, taking into account the e ff ect of therm ag ing on the material behavior. In this regard, s a less steel Dissimilar Metal Welds (SS DMW) are cri ical for the integrity of the cu rentl opera ing reactors, since they repres nt singularities the microstructure, stress gradient and residual stresses in the powerplant primary circuit. Therefore, their highly heterogenous micro tructu e and mechanical properties must be studied. The present study aim to valuate the brittle behavior of the DMW at low temperature and more particularly at t e location of the Fusion Line (FL) between the ferritic steel and a stenitic weld me al, where the highest mi crostructural and mechan cal heterogeneities are concentrated. Section.1 presents the evolution of the microstructure across the ferritic / austenitic steel interface after the welding process and the Post-Weld Heat Treatment (PWHT). ∗ Corresponding author. Tel.: + 33-610-68-1105 E-mail address: gh ssen.ben-salem@ecp.fr 2210-7843 c 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ECF22 organizers. 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 e ff ects on Structural Integrity Brittle fracture analysis of Dissimilar Metal Welds between low-alloy steel and stainless steel at low temperatures Ghassen Ben Salem a,b,c, ∗ , Ste´phane Chapuliot a , Arnaud Blouin a , Philippe Bompard b , Cle´mentine Jacquemoud c a FRAMATOME, 1 Pl. Jean Millier, 92400 Courbevoie, France b Laboratoire MSSMat, UMR CNRS 8579, CentraleSupelec, 3 Rue Joliot Curie, 91190 Gif-sur-Yvette, France c DEN-Service d´ e´tudes me´caniques et thermiques (SEMT), CEA, Universite´ Paris-Saclay, F-91191 Gif-sur-Yvette, France Abstract Dissimilar Metal Welds (DMW) between low-alloy steel (A533 steel) and austenitic 316L stainless steel are widely used within the French nuclear power plants where they connect the main components to the primary circuit pipes. In these DMW, the welding process and the post-weld heat-treatment generate a hard thin layer of carburized martensite and austenite in the vicinity of the fusion line (FL), resulting in a heterogeneous microstructure with high mechanical properties gradient, hence potentially, a higher sensitivity to brittle fracture i the hard layer. The present study aims to evaluate the brittle behavior of the DMW at low temperatures and more particularly of the interface between the carburized martensite and austenite (MA interface). Fracture toughness tests were carried out at temperatures between − 120 ◦ C and − 50 ◦ C, with a precrack tip located on the ferritic side near the FL (i.e., between the ferritic steel and the stainless steel buttering). The analysis of the fracture behavior of the DMW was based on a SEM examination of CT (Compact Tension) specimens fracture surfaces. Coupled with a 2D plane strain numerical simulation of the tests, the results show that the presence of austenite in the fatigue precrack front and subsequent ductile tearing towards FL produced higher solicitations on the hard layer and caused intergranular fracture on the MA interface, resulting in lower toughness values for the specimen. To model the brittle behavior of the MA interface, a stress based criterion was used. Tensile tests on axisymmetric specimen, which were machined to initiate intergranular fracture in the MA interface and tested at − 170 ◦ C, were used to define a threshold stress ( σ th ), below which brittle fracture cannot occur. Then, a criterion to evaluate the brittle fracture risk of the DMW was proposed and applied to the CT specimen. c 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ECF22 organizers. Keywords: Dissimilar Metal welds; Martensite-Austenite interface; Fusion Line; Hard layer; intergranular fracture; carbides; threshold stress; Notched Tensile Specimen ECF22 - Loading and Environmental e ff ects on Structural Integrity Brittle fracture analysis of Dissi ilar Metal Welds bet een lo -alloy steel and stainless steel at low temperatures Ghassen Ben Salem a,b,c, ∗ , Ste´phane Chapuliot a , Arnaud Blouin a , Philippe Bompard b , Cle´mentine Jacquemoud c a FRAMATOME, 1 Pl. Jean Millier, 92400 Courbevoie, France b Laboratoire MSSMat, UMR CNRS 8579, CentraleSupelec, 3 Rue Joliot Curie, 91190 Gif-sur-Yvette, France c DEN-Service d´ e´tudes me´caniques et thermiques (SEMT), CEA, Universite´ Paris-Saclay, F-91191 Gif-sur-Yvette, France Abstract Dissimilar Metal Welds (DMW) between low-alloy steel (A533 steel) and austenitic 316L stainless steel are widely used within the French nuclear power plants where they connect the main components to the primary circuit pipes. In these DMW, the welding process and the post-weld heat-treatment generate a hard thin layer of carburized martensite and austenite in the vicinity of the fusion line (FL), resulting in a heterogeneous microstructure with high mechanical properties gradient, hence potentially, a higher sensitivity to brittle fracture in the hard layer. The present study aims to evaluate the brittle behavior of the DMW at low temperatures and more particularly of the interface between the carburized martensite and austenite (MA interface). Fracture toughness tests were carried out at temperatures between − 120 ◦ C and − 50 ◦ C, with a precrack tip located on the ferritic side near the FL (i.e., between the ferritic steel and the stainless steel buttering). The analysis of the fracture behavior of the DMW was based on a SEM examination of CT (Compact Tension) specimens fracture surfaces. Coupled with a 2D plane strain numerical simulation of the tests, the results show that the presence of austenite in the fatigue precrack front and subsequent ductile tearing towards FL produced higher solicitations on the hard layer and caused intergranular fracture on the MA interface, resulting in lower toughness values for the specimen. To model the brittle behavior of the MA interface, a stress based criterion was used. Tensile tests on axisymmetric specimen, which were machined to initiate intergranular fracture in the MA interface and tested at − 170 ◦ C, were used to define a threshold stress ( σ th ), below which brittle fracture cannot occur. Then, a criterion to evaluate the brittle fracture risk of the DMW was proposed and applied to the CT specimen. c 2018 Th Authors. Published by Elsevier B.V. Peer-review under responsibility of the ECF22 organizers. Keywords: Dissimilar Metal welds; Martensite-Austenite interface; Fusion Line; Hard layer; intergranular fracture; carbides; threshold stress; Notched Tensile Specimen ECF22 - Loading and Environmental e ff ects on Structural Integrity Brittle fracture analysis of Dissimilar Metal Welds between low-alloy steel and stainless steel at low temperatures Ghassen Ben Salem a,b,c, ∗ , Ste´phane Chapuliot a , Arnaud Blouin a , Philippe Bompard b , Cle´mentine Jacquemoud c a FRAMATOME, 1 Pl. Jean Millier, 92400 Courbevoie, France b Laboratoire MSSMat, UMR CNRS 8579, CentraleSupelec, 3 Rue Joliot Curie, 91190 Gif-sur-Yvette, France c DEN-Service d´ e´tudes me´caniques et thermiques (SEMT), CEA, Universite´ Paris-Saclay, F-91191 Gif-sur-Yvette, France Abstract Dissimilar Metal Welds (DMW) between low-alloy steel (A533 steel) and austenitic 316L stainless steel are widely used within the French nuclear power plants where they connect the main components to the primary circuit pipes. In these DMW, the welding process and the post-weld heat-treatment generat a hard thin lay r of carburized martensite and austenite in the vicinity of the fusi n line (FL), resulting in a he erogeneous microstructure with high mechanical properties gradien , hence potent all , a higher sensitivity to b ittle fracture in the hard layer. The present study aims to evaluate the brittle behavior of the DMW at low temperatures and more parti ularly of the interface betw en the arburized martensite and austenite (MA interface). Fracture t ughness tests were carried ou at temperatures betw en − 120 ◦ C and − 50 ◦ C, with a precrack tip loca d on the ferritic side near the FL (i.e., betw en the ferritic steel and he stainless steel buttering). The analysis of the fracture behavior o the DMW was based on a SEM examination of CT (Compact Tension) specimens fracture surfaces. Coupled with a 2D plane strain numerical simulation of the tests, the results show th t the presence of austenite in the fatigue precrack front and subsequent ductile tearing towards FL produc d higher solicitations on th hard layer and caused intergranular ac ure on the MA interface, r sulting in lower toughness values for the specimen. To model the brittle behavior of the MA interface, a stress based criterion was used. Tensile ests on axisymmet ic specimen, which were mach ned to initiate intergranular fr cture in the MA interface and te ted at − 170 ◦ C, were used to define a threshold stress ( σ th ), below which brittle fracture cannot occur. Then, a criterion to evaluate the brittle fractu ri k of th DMW wa proposed and applied to t e CT specimen. c 2018 The Authors. Published by Elsevier B.V. Peer-review under respons bility of the ECF22 organizers. Keywords: Dissimilar Metal welds; Martensite-Austenite interface; Fusion Line; Hard layer; intergranular fracture; carbides; threshold stress; Notched Tensile Specimen © 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ECF22 organizers. ECF22 - Loadi g and Environmental e ff ects on Structural Integrity Brittle fracture analysis of Dissimilar Metal Welds between low-alloy steel and stainl ss steel at low temperatures Ghassen Ben Salem a,b,c, ∗ , Ste´phane Ch pul ot a , Arnaud Blouin a , Philippe Bompard b , Cl´mentine Jacquemoud c a FRAMATOME, 1 Pl. Jean Millier, 92400 Courbevoie, France b Laboratoire MSSMat, UMR CNRS 8579, CentraleSupelec, 3 Rue Joliot Curie, 91190 Gif-sur-Yvette, France c DEN-Service d´ e´tudes me´caniques et thermiques (SEMT), CEA, Universite´ Paris-Saclay, F-91191 Gif-sur-Yvette, France 2 - i ir t l t © 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 In this regard, stainless steel Dissimilar Metal Welds (SS DMW) are critical for the integrity of the currently operating reactors, since they represent singularities in the microstructure, stress gradients and residual stresses in the powerplant primary circuit. Therefore, their highly heterogenous microstructure and mechanical properties must be studied. Dissimilar Metal Welds (DMW) between low-alloy steel 18MND5( ∼ A533) and austenitic 316L stainless steel are widely used within the French nuclear power plants, where they connect the main components to the primary circuit pipes (Fig.1(a)). In order to extend the operating nuclear powerplant lifespan, it is necessary to verify that each component is able to withstand brutal changes in temperature and pressure for all situations, taking into account the e ff ect of thermal ageing on the material behavior. 1. Introduction 1. Introduction 1. Introduction Dissimilar Metal Welds (DMW) between low-alloy steel 18MND5( ∼ A533) and austenitic 316L stainless steel are widely used within the French nuclear power plants, where they connect the main components to the primary circuit pipes (Fig.1(a)). In order to extend the operating nuclear powerplant lifespan, it is necessary to verify that each component is able to withstand brutal changes in temperature and pressure for all situations, taking into account the e ff ect of thermal ageing on the material behavior. v il l li t www.elsevier.com/locate/procedia

2452-3216  2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ECF22 organizers. 10.1016/j.prostr.2018.12.102 ∗ Corresponding author. Tel.: + 33-610-68-1105 E-mail address: ghassen.ben-salem@ecp.fr ∗ Corresponding author. Tel.: + 33-610-68-1105 E-mail address: ghassen.ben-salem@ecp.fr ∗ Corresponding author. Tel.: + 33-610-68-1105 E-mail address: ghassen.ben-salem@ecp.fr ∗ Corresponding author. Tel.: + 33-610-68-1105 E-mail address: ghassen.ben-salem@ecp.fr ∗ Corresponding author. el.: 33-610-68-1105 - ail ad ress: ghassen.ben-sale ecp.fr 2210-7843 c 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ECF22 organizers. 2210-7843 c 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibi ity of the ECF22 organizers. 2210-7843 c 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ECF22 organizers. 2210-7843 c 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ECF22 organizers. 2210-7843 c 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ECF22 organizers. ∗ Corresponding author. Tel.: + 33-610-68-1105 E-mail address: ghassen.ben-salem@ecp.fr ∗ Corresponding author. Tel.: + 33-610-68-1105 E-mail address: ghassen.ben-salem@ecp.fr 2210-7843 c 2018 The Authors. Published by Elsevier B.V.