Processing of Bimetallic Inconel 625-16Mo3 Steel Tube via Supercritical Bend: Study of the Mechanical Properties and Structure

Ci a ion: Ba enyi, I.; Slany, M.; Kou il, K.; Zouha , J.; Kolomy, S.; Sedlak, J.; Maje ik, J. P ocessing o Bime allic Inconel 625-16Mo3 S eel Tube ia Supe c i ical Bend: S udy o he Mechanical P ope ies and S uc u e. Ma e ials 2023,16, 6796. h ps://doi.o g/10.3390/ ma16206796 Academic Edi o : Toshio Ogawa Recei ed: 2 Oc obe 2023 Re ised: 18 Oc obe 2023 Accep ed: 19 Oc obe 2023 Published: 21 Oc obe 2023 Copy igh : © 2023 by he au ho s. Licensee MDPI, Basel, Swi ze land. This a icle is an open access a icle dis ibu ed unde he e ms and condi ions o he C ea i e Commons A ibu ion (CC BY) license (h ps:// c ea i ecommons.o g/licenses/by/ 4.0/). ma e ials A icle P ocessing o Bime allic Inconel 625-16Mo3 S eel Tube ia Supe c i ical Bend: S udy o he Mechanical P ope ies and S uc u e Igo Ba enyi 1, Ma in Slany 2,* , Ka el Kou il 2, Jan Zouha 2, S epan Kolomy 2, Jose Sedlak 2 and Joze Maje ik 1 1Facul y o Special Technology, Alexande Dubcek Uni e si y o T encin, 911 06 T enˇcín, Slo akia; igo [email p o ec ed] (I.B.); [email p o ec ed] (J.M.) 2Facul y o Mechanical Enginee ing, Ins i u e o Manu ac u ing Technology, B no Uni e si y o Technology, 616 69 B no, Czech Republic; ka el.kou il@ u b .cz (K.K.); [email p o ec ed].cz (J.Z.); s epan.kolomy@ u b .cz (S.K.); [email p o ec ed].cz (J.S.) *Co espondence: slany[email p o ec ed].cz Abs ac : Incine a ion is cu en ly he s anda d way o disposing o municipal was e. I uses compo- nen s p o ec ed by high- empe a u e- esis an laye s o ma e ials, such as Inconel alloys. The e o e, he objec i e o he cu en pape is o s udy he mechanical p ope ies and s uc u e o a bime allic Inconel 625-16Mo3 s eel ube. The Inconel 625 laye was 3.5 mm hick and was applied o he su ace o he ube wi h a wall hickness o 7 mm ia he cold me al ans e me hod. The bime allic ube was ben using a supe c i ical bend (d ≤ 0.7D). This pape is ocused on he in es iga ion o he ma e ial changes in he Inconel 625 laye a eas in luenced by he maximum ensile and comp essi e s esses a e he bend. The change in laye hickness a e he bend was e alua ed and compa ed o he non-de o med ube. In addi ion, he local mechanical p ope ies (nanoha dness, Young modulus) ac oss he indica ed in e acial a eas using quasis a ic nanoinden a ion we e in es iga ed. Subse- quen ly, a ho ough mic os uc u e obse a ion was ca ied ou in a eas wi h maximum ensile and comp essi e s esses o de e mine changes in he mo phology and size o dend i es ela ed o he e ec o ensile o comp essi e s esses induced by bending. I was ound ha he g ain ea u ed a s e ched seconda y dend i e axis in he a ea o ensile s ess, bu comp essi e s ess impa ed a p olonga ion o he p ima y dend i e axis. Keywo ds: Inconel 625; bime allic ma e ial; welding; mechanical p ope ies; mic os uc u e; supe - c i ical bend 1. In oduc ion In ecen yea s, he incine a ion o municipal was e has become a a o able al e na- i e o adi ional was e land illing. In addi ion o was e disposal, incine a ion has o he bene i s. The gene a ed hea ene gy can be used o c ea e elec ici y o o hea ing. Despi e i s ad an ages, he incine a ion p ocess also poses a p oblem ha mus be sol ed. The empe a u e when incine a ing o dina y municipal was e is abou 800 o 900 ◦ C, and o haza dous was e, empe a u es up o 1300 ◦ C a e used. The combus ion en i onmen is e y agg essi e, and he componen s mus wi hs and he high- empe a u e co osion caused by Cl, N 2 , O 2 , e c. One o he a ailable solu ions is o apply a p o ec i e Inconel 625 laye o he componen . The componen om which he expe imen al samples we e made is pa o an incine a ion chambe o municipal was e. I is a 16Mo3 s eel ube h ough which supe c i i- cal cooling wa e lows, and i s ou e su ace is unde he in luence o agg essi e condi ions. The main damage ac o is he high- empe a u e in luence (abou 500 ◦ C) and subsequen high- empe a u e co osion in a chemically agg essi e en i onmen . The e o e, he ube is coa ed wi h an Inconel 625 laye wi h esis ance o hese condi ions [ 1 , 2 ]. The laye is Ma e ials 2023,16, 6796. h ps://doi.o g/10.3390/ma16206796 h ps://www.mdpi.com/jou nal/ma e ials Ma e ials 2023,16, 6796 2 o 15 made using he cold me al ans e (CMT) me hod. CMT welding is a modi ied MIG/MAG welding p ocess based on a sho -ci cui ing ans e p ocess de eloped by he Aus ian welding company F onius in 2004. This p ocess was de eloped based on he MIG/MAG welding p ocess bu di e s in he ype o d ople ans e me hod, which had no been p e iously encoun e ed [ 3 , 4 ]. The con en ional MIG/MAG p ocess uses sho -ci cui ing d ople ans e , while CMT employs a new mechanical d ople -cu ing me hod o ans e mol en me al o he weld [ 2 ]. Mo eo e , CTM uses shallow cu en s ha lead o a signi ican educ ion in hea gene a ion. A new ype o d ople ans e educes he Fe con en in he clad laye , leading o enhanced coa ing esis ance o high- empe a u e co osion [ 5 ]. The dissolu ion o he base me al in he clad laye is almos negligible, esul ing in a e y na ow usion zone and a na owe HAZ compa ed o he MIG/MAG p ocess [ 5 ]. The p inciple, ad an ages, limi a ions, and applica ions o he CMT echnique we e discussed by Lo enzin and Ru ili in de ail in hei wo k [ 4 ]. Du ing welding, empe a u e a ia ions in welds and pa en me als ha e impo an e ec s on ma e ial cha ac e is ics and esidual s esses, as well as on he dimensional and shape accu acies o welded p oduc s [ 6 , 7 ]. The CMT me hod has been e ec i ely used o he welding and cladding o Inconel, Aluminum, Ti anium alloys, s eels, and o he ma e ials [8–12]. The coa ed ube is ben by supe c i ical bending (d ≤ 0.7D; d is he diame e o he bend; D is he diame e o he ube) as pa o he manu ac u ing p ocess o he incine a o componen [ 13 , 14 ]. The pa ame e s and mechanical p ope ies o he bend we e analyzed, and a speci ic p ocedu e was de eloped o cold-bend he ube wi h he use o sand illing inside o bend i wi hou c acking and excessi e de o ma ion o i s c oss-sec ion [13,14]. Cold bending equi es a e y high alue o he yield s eng h o he ma e ial o cause a shape change in he ma e ial, which leads o he plas ic de o ma ion o he ma e ial. The ensile s eng h canno be exceeded o a oid ma e ial ailu e. In e nal s esses a ise in he ma e ial due o cold bending. The ac ing s esses and de o ma ions du ing ube cold bending (see Figu e 1) we e analyzed by se e al au ho s using ma e ials including he clad laye o Inconel 625 [ 15 – 18 ]. Du ing each bending p ocess, ensile s esses ( σ ) occu in he ou e laye s o he wo kpiece ela i e o he bending adius, and elonga ion o he ma e ial occu s in his a ea ( ε ). On he con a y, he inne laye s a e subjec ed o comp essi e s esses ( σc ), and he ma e ial is comp essed ( εc ) in his a ea. Among hem is he so-called non-de o med laye wi hou ac ing longi udinal s esses, whe e ε = 0 (neu al axis), and hus, he ma e ial e ains i s o iginal shape and olume. This laye does no copy he heo e ical bend adius bu is shi ed inwa d in he di ec ion o he bend axis. Fo his eason, ce ain elonga ion occu s du ing he bending p ocess o he ube, which can be de e mined by using a ma hema ical calcula ion. When bending a hollow ube wi h a cons an wall hickness, he men ioned s esses ha e an analogous e ec on he wall hickness. The e is a dec ease in he ou e adius ela i e o he heo e ical bending adius, and on he con a y, in he inne adius, he hickness o he wall inc eases. Ma e ials 2023, 16, x FOR PEER REVIEW 2 o 15 condi ions [1,2]. The laye is made using he cold me al ans e (CMT) me hod. CMT welding is a modi ied MIG/MAG welding p ocess based on a sho -ci cui ing ans e p ocess de eloped by he Aus ian welding company F onius in 2004. This p ocess was de eloped based on he MIG/MAG welding p ocess bu diffe s in he ype o d ople ans e me hod, which had no been p e iously encoun e ed [3,4]. The con en ional MIG/MAG p ocess uses sho -ci cui ing d ople ans e , while CMT employs a new me- chanical d ople -cu ing me hod o ans e mol en me al o he weld [2]. Mo eo e , CTM uses shallow cu en s ha lead o a signi ican educ ion in hea gene a ion. A new ype o d ople ans e educes he Fe con en in he clad laye , leading o enhanced coa ing esis ance o high- empe a u e co osion [5]. The dissolu ion o he base me al in he clad laye is almos negligible, esul ing in a e y na ow usion zone and a na owe HAZ compa ed o he MIG/MAG p ocess [5]. The p inciple, ad an ages, limi a ions, and appli- ca ions o he CMT echnique we e discussed by Lo enzin and Ru ili in de ail in hei wo k [4]. Du ing welding, empe a u e a ia ions in welds and pa en me als ha e impo an effec s on ma e ial cha ac e is ics and esidual s esses, as well as on he dimensional and shape accu acies o welded p oduc s [6,7]. The CMT me hod has been effec i ely used o he welding and cladding o Inconel, Aluminum, Ti anium alloys, s eels, and o he ma e- ials [8–12]. The coa ed ube is ben by supe c i ical bending (d ≤ 0.7D; d is he diame e o he bend; D is he diame e o he ube) as pa o he manu ac u ing p ocess o he incine a o componen [13,14]. The pa ame e s and mechanical p ope ies o he bend we e analyzed, and a speci ic p ocedu e was de eloped o cold-bend he ube wi h he use o sand illing inside o bend i wi hou c acking and excessi e de o ma ion o i s c oss-sec ion [13,14]. Cold bending equi es a e y high alue o he yield s eng h o he ma e ial o cause a shape change in he ma e ial, which leads o he plas ic de o ma ion o he ma e ial. The ensile s eng h canno be exceeded o a oid ma e ial ailu e. In e nal s esses a ise in he ma e ial due o cold bending. The ac ing s esses and de o ma ions du ing ube cold bend- ing (see Figu e 1) we e analyzed by se e al au ho s using ma e ials including he clad laye o Inconel 625 [15–18]. Du ing each bending p ocess, ensile s esses (σ ) occu in he ou e laye s o he wo kpiece ela i e o he bending adius, and elonga ion o he ma e ial occu s in his a ea (ε ). On he con a y, he inne laye s a e subjec ed o comp essi e s esses (σc), and he ma e ial is comp essed (εc) in his a ea. Among hem is he so-called non-de o med laye wi hou ac ing longi udinal s esses, whe e ε = 0 (neu al axis), and hus, he ma e ial e ains i s o iginal shape and olume. This laye does no copy he he- o e ical bend adius bu is shi ed inwa d in he di ec ion o he bend axis. Fo his eason, ce ain elonga ion occu s du ing he bending p ocess o he ube, which can be de e - mined by using a ma hema ical calcula ion. When bending a hollow ube wi h a cons an wall hickness, he men ioned s esses ha e an analogous effec on he wall hickness. The e is a dec ease in he ou e adius ela i e o he heo e ical bending adius, and on he con a y, in he inne adius, he hickness o he wall inc eases. Figu e 1. Ac ing s esses and de o ma ions du ing he bending p ocess. The au ho s Guo, X. e al. [19] ca ied ou simula ions and eal expe imen s on H62 b ass ube bends wi h diffe en pa ame e s and in es iga ed he in luence o hese σ +σ -σ ε +ε -ε ε c σ c neu al axis Figu e 1. Ac ing s esses and de o ma ions du ing he bending p ocess. The au ho s Guo, X. e al. [ 19 ] ca ied ou simula ions and eal expe imen s on H62 b ass ube bends wi h di e en pa ame e s and in es iga ed he in luence o hese pa am- e e s on he bending p ope ies. As pa o hei expe imen s, hey also in es iga ed he Ma e ials 2023,16, 6796 3 o 15 dependence o he bending a io, R/D 0 (R—bending adius; D— ube diame e ), on he esul ing s esses and he a io o he pipe wall hickness be o e and a e bending. Thei expe imen s p o ed ha wi h he inc ease in he bending a io, he alue o in e nal s esses caused by bending dec eased exponen ially. Also, he wall hickness a io be ween he o iginal ube and he ben ube dec eased wi h he inc easing bending a io R/D 0 [ 19 ]. The au ho s e alua ed he men ioned pa ame e s a he place o maximum comp essi e s esses in he lowe pa o he bending a c. Du ing he cold bending o he ube, plas ic de o ma ion o he ma e ial occu s, which causes s ain ha dening. This is a undamen al ac o in assessing ha dness changes in he a eas o he ma e ial mos a ec ed by bending s esses. The au ho s Ka suji Tosha e al. [ 20 ] di ec ly e alua ed he e ec o comp essi e and ensile s esses on he inal ha dness o ben shee s in a su ace laye a e he shee bending o C45 s eel. Thei esul s show ha ha dness alues a e bending dec ease wi h inc easing ensile s esses bu inc ease wi h inc easing comp essi e s esses. Howe e , wo k ha dening in bo h a eas wi h ensile s ess and comp essi e s ess has a no iceable in luence. In he a eas whe e he ensile s ain is o e 1%, he alue o he ha dness inc emen wi h wo k ha dening is la ge han he ha dness dec emen caused by he ensile s esses hemsel es [ 20 ]. The ha dness inc eases wi h he comp essi e s ess in he elas ic s ain s age and inc eases apidly a e he comp essi e s ess eaches he plas ic s ain s age due o wo k ha dening. In gene al, in egions o bends wi h plas ic de o ma ion and subsequen wo k ha dening, whe he by ensile o comp essi e s esses, ha dness alues inc ease. The highes ha dness alues we e measu ed in he a ea o he highes comp essi e s esses, whe e he e ec o s ain ha dening is combined wi h he ac ion o comp essi e s esses [20]. Se e al au ho s ha e used nanoinden a ion o e alua e he nanomechanical beha io and local mechanical p ope ies o laye s and coa ings [ 21 – 24 ]. Quasis a ic nanoinden a ion es s in ol e pushing a diamond- ipped inden e head in o a ma e ial unde ei he load o displacemen con ol. The inden a ion esponse o he subsu ace laye s o he ma e ial can be in luenced by a change in i s plas ic beha io caused by in e nal s esses [ 25 ]. Resea che s [ 25 , 26 ] no ed he in luence o in e nal s esses on he pe manen plas ic dep h de e mined a e inden a ion and he con ac su ace. This in luence is smalle when using sha p inden a ion ips, such as hose wi h Be ko ich- ype geome y. Also, me hods we e de eloped o measu e and e alua e in e nal s esses using nanoinden a ion [ 25 ] based on di e ences in con ac a ea measu emen s. These small di e ences should co espond o in e nal s esses. P e ious wo ks by he au ho s’ collec i e [ 13 , 14 ] we e ocused on he s udy o he abili y o c ea e c i ical and supe c i ical bends in bime al pipes (i.e., bends smalle han 1D, speci ically 0.7D) wi h Inconel 625 cladding, and his solu ion has no been published in any o he s udy so a . While hese p e ious s udies mainly deal wi h he echnological pa ame e s o he bending p ocess in ela ion o he p esence o possible de ec s, his wo k is ocused on he de ailed ma e ial in es iga ion o he mic os uc u e and nanomechanical p ope ies (nanoha dness, educed modulus) o an Inconel 625 cladding laye in di e en a eas a ec ed by s esses caused by he bending p ocess. The main goal is o ob ain a comp ehensi e o e iew o he beha io o he laye ma e ial du ing bending wi h he possibili y o u he in es iga ing he damage mechanism o he laye by high- empe a u e and chemically agg essi e condi ions. 2. Ma e ials and Me hods 2.1. Expe imen al Ma e ials As men ioned abo e, a ben 16Mo3 s eel ube wi h an Inconel 625 weld o e lay was used o expe imen s. The subs a e, 16Mo3 middle-alloyed s eel, is hea - esis an s eel o use a highe empe a u es and p essu es. I has good o mabili y, weldabili y, and co osion esis ance in a wa e apo en i onmen up o 530 ◦ C. I is supplied in a s a e a e annealing, whe e he esul ing s uc u e is e i e and pea li e (Figu e 2a). Ma e ials 2023,16, 6796 4 o 15 The mic os uc u e was obse ed in he cen e a ea o he ube wall. The basic chemical composi ion and mechanical p ope ies o 16Mo3 s eel a e shown in Table 1. Ma e ials 2023, 16, x FOR PEER REVIEW 4 o 15 annealing, whe e he esul ing s uc u e is e i e and pea li e (Figu e 2a). The mic os uc- u e was obse ed in he cen e a ea o he ube wall. The basic chemical composi ion and mechanical p ope ies o 16Mo3 s eel a e shown in Table 1. Table 1. Chemical composi ion and mechanical p ope ies o 16Mo3 s eel. w .% C Mn Si Mo Al P S Fe 16Mo3 s eel min. 0.1 0.5 0.15 0.25 -- -- -- Balance max. 0.20 0.8 0.37 0.35 0.015 0.04 0.04 Tensile s eng h R m (MPa) Yield poin R p0,2 (MPa) Duc ili y A (%) Ha dness HB 440 380 30 150 (a) (b) Figu e 2. (a) SEM mic os uc u e image o 16Mo3 s eel (subs a e)— he cen e o he ube wall; (b) SEM mic os uc u e image o Inconel 625 clad laye (wi hou bend). Inconel 625 is a hea - esis an and c eep- esis an nickel alloy (NiC 22Mo9Nb). The chemical composi ion and mechanical p ope ies o Inconel 625 a e lis ed in Table 2. The alloy is subs i u ionally s eng hened by Ni, bu Nb and o he p esen elemen s can cause addi ional p ecipi a ion s eng hening. The basic mic os uc u e o Inconel 625 cladding is homogeneous, con aining only g ains o γ solid solu ion (Figu e 2b) in he o m o den- d i es. The e a e also some seconda y phases—p ecipi a es o γ’ and γ’’ on he g ain bounda ies [27]. The Nb p ecipi a es in he γ” phase, while Ti and Al o m he γ’ phase. The γ” phase con ibu es mo e o he ha dening effec han he γ’ phase [28]. The mic o- s uc u e and mechanical p ope ies o Inconel 625 supe alloy a e desc ibed in mo e de ail by o he au ho s [29,30]. Inconel 625 wi e, 1 mm in diame e , was used o o e weld he laye on he subs a e using he CMT me hod. The diame e o he basic ube was D = Ø38 mm, while i s wall hickness was 7 mm. Addi ionally, he o e welded ou e laye o Inconel 625 had an a - e age hickness o 3.5 mm. Table 2. Chemical composi ion and mechanical p ope ies o Inconel 625. w .% C Mo Co Nb Ti Fe C Mn Si Al P S Ni Inconel 625 (NiC 22Mo9Nb) min. 20 8 -- 3.15 -- -- -- -- -- -- -- -- Balance max. 23 10 1 4.15 0.4 5 0.1 0.5 0.5 0.4 0.015 0.015 Tensile s eng h R m (MPa) Yield poin R p0,2 (MPa) Duc ili y A (%) Ha dness HV 965 490 50 200 2.2. Expe imen al Sample P epa a ion The ube was ben using a supe c i ical bend, whe e d ≤ 0.7D (d is he diame e o he bend; D is he diame e o he ube) a ambien empe a u e wi h an applied bending Figu e 2. ( a ) SEM mic os uc u e image o 16Mo3 s eel (subs a e)— he cen e o he ube wall; (b) SEM mic os uc u e image o Inconel 625 clad laye (wi hou bend). Table 1. Chemical composi ion and mechanical p ope ies o 16Mo3 s eel. w .% C Mn Si Mo Al P S Fe 16Mo3 s eel min. 0.1 0.5 0.15 0.25 -- -- -- Balance max. 0.20 0.8 0.37 0.35 0.015 0.04 0.04 Tensile s eng h Rm(MPa) Yield poin Rp0,2 (MPa) Duc ili y A (%) Ha dness HB 440 380 30 150 Inconel 625 is a hea - esis an and c eep- esis an nickel alloy (NiC 22Mo9Nb). The chemical composi ion and mechanical p ope ies o Inconel 625 a e lis ed in Table 2. The alloy is subs i u ionally s eng hened by Ni, bu Nb and o he p esen elemen s can cause addi ional p ecipi a ion s eng hening. The basic mic os uc u e o Inconel 625 cladding is homogeneous, con aining only g ains o γ solid solu ion (Figu e 2b) in he o m o dend i es. The e a e also some seconda y phases—p ecipi a es o γ ’ and γ ” on he g ain bounda ies [ 27 ]. The Nb p ecipi a es in he γ ” phase, while Ti and Al o m he γ ’ phase. The γ ” phase con ibu es mo e o he ha dening e ec han he γ ’ phase [ 28 ]. The mic os uc u e and mechanical p ope ies o Inconel 625 supe alloy a e desc ibed in mo e de ail by o he au ho s [29,30]. Table 2. Chemical composi ion and mechanical p ope ies o Inconel 625. W .% C Mo Co Nb Ti Fe C Mn Si Al P S Ni Inconel 625 (NiC 22Mo9Nb) min. 20 8 -- 3.15 -- -- -- -- -- -- -- -- Balance max. 23 10 1 4.15 0.4 5 0.1 0.5 0.5 0.4 0.015 0.015 Tensile s eng h Rm(Mpa) Yield poin Rp0,2 (Mpa) Duc ili y A (%) Ha dness HV 965 490 50 200 Inconel 625 wi e, 1 mm in diame e , was used o o e weld he laye on he subs a e using he CMT me hod. The diame e o he basic ube was D = Ø38 mm, while i s wall hickness was 7 mm. Addi ionally, he o e welded ou e laye o Inconel 625 had an a e age hickness o 3.5 mm. Ma e ials 2023,16, 6796 5 o 15 2.2. Expe imen al Sample P epa a ion The ube was ben using a supe c i ical bend, whe e d ≤ 0.7D (d is he diame e o he bend; D is he diame e o he ube) a ambien empe a u e wi h an applied bending momen o 25.5 kNm. The c oss-sec ion o he ben ube pa used o he p epa a ion o he expe imen al sample is shown in Figu e 3. The samples we e aken om wo a eas wi h he g ea es in e nal ensile and comp essi e s esses a e bending (see Figu e 1). The place wi h maximum ensile s esses, ma ked as OR (ou e adius), is loca ed a he op o he bending a c. The place wi h maximum comp essi e s esses, ma ked as IR (inne adius), is loca ed a he bo om o he bending a c. Ma e ials 2023, 16, x FOR PEER REVIEW 5 o 15 momen o 25.5 kNm. The c oss-sec ion o he ben ube pa used o he p epa a ion o he expe imen al sample is shown in Figu e 3. The samples we e aken om wo a eas wi h he g ea es in e nal ensile and comp essi e s esses a e bending (see Figu e 1). The place wi h maximum ensile s esses, ma ked as OR (ou e adius), is loca ed a he op o he bending a c. The place wi h maximum comp essi e s esses, ma ked as IR (in- ne adius), is loca ed a he bo om o he bending a c. The samples p epa ed om he ma ked places we e hen p ocessed by using a s and- a d me allog aphic sample p epa a ion p ocedu e, including p essing in o a bakeli e mix- u e, g inding, polishing, and e ching. Glyce egia (50% HCl, 33% glyce ol, and 17% HNO3) was used as an e chan o he Inconel 625 laye mic os uc u e. The inal samples we e used bo h o nanoinden a ion measu emen and o ligh mic oscopic s uc u al obse a ions. Ligh mic oscopic analysis, including some quan i a i e mic oscopy pa am- e e s (dend i e dimensions), was pe o med using a con ocal lase measu emen mic o- scope Olympus Lex OLD5100, Olympus IMS, Webs e (Olympus, T encin, Slo akia) and i s analy ical so wa e—S eam e sion 2.4. The s uc u es in luenced by ensile and com- p essi e s esses we e obse ed ia he ULTRA PLUS scanning elec on mic oscope (Ca l Zeiss, Homb ech ikon, Swi ze land). EBSD analysis was pe o med ia EBSD NORDLYS (Ox o d Ins umen s, Abingdon, England), and NANO Binning was se o 4 × 4. The meas- u ing EHT ol age was se o 20 kV wi h a spo size o 120 µm, and he cu en was 3 nA. The scanning a ea o he samples was, in all cases, 1 × 0.75 mm. Figu e 3. C oss-sec ion o he ube pa used o expe imen al sample p epa a ion. 2.3. Quasis a ic Nanoinden a ion Quasis a ic nanoinden a ion is used o measu e he cou ses o nanoha dness and he educed Young modulus ac oss Inconel laye s om he su ace o a ce ain dep h. The me hod was i s in oduced by Oli e and Pha [31] and is based on pushing a diamond- ipped inden e head in o a ma e ial, whe e he displacemen (h) as a unc ion o he load (F) is moni o ed du ing bo h he loading and unloading cycles o he inden a ion p ocess. The esul ing ela ion F-h is called he nanoinden a ion cu e (Figu e 4a). The loading pa o he cu e is used o e alua e nanoha dness H, which is de ined as he con ac p essu e unde he inden e [32]: 𝐻=𝐹 𝐴  (1) whe e F is he load, and Ac is he p ojec ed con ac a ea calcula ed a a dep h o inden a ion h. The unloading pa is ela ed o eco e ing elas ic de o ma ion and can be used o cal- cula e he Young modulus o he ma e ial. The ini ial slope (S) o he unloading cu e can be ela ed o he elas ic modulus o he ma e ial using he equa ion [32]: 𝑆=𝑑𝐹 𝑑ℎ =2𝐸  𝐴  √ 𝜋 (2) whe e S is he ini ial slope o he unloading cu e o con ac s iffness, F is he applied load, and E is he educed Young modulus. Figu e 3. C oss-sec ion o he ube pa used o expe imen al sample p epa a ion. The samples p epa ed om he ma ked places we e hen p ocessed by using a s anda d me allog aphic sample p epa a ion p ocedu e, including p essing in o a bakeli e mix u e, g inding, polishing, and e ching. Glyce egia (50% HCl, 33% glyce ol, and 17% HNO 3 ) was used as an e chan o he Inconel 625 laye mic os uc u e. The inal samples we e used bo h o nanoinden a ion measu emen and o ligh mic oscopic s uc u al obse a ions. Ligh mic oscopic analysis, including some quan i a i e mic oscopy pa ame e s (dend i e dimensions), was pe o med using a con ocal lase measu emen mic oscope Olympus Lex OLD5100, Olympus IMS, Webs e (Olympus, T encin, Slo akia) and i s analy ical so wa e— S eam e sion 2.4. The s uc u es in luenced by ensile and comp essi e s esses we e obse ed ia he ULTRA PLUS scanning elec on mic oscope (Ca l Zeiss, Homb ech ikon, Swi ze land). EBSD analysis was pe o med ia EBSD NORDLYS (Ox o d Ins umen s, Abingdon, England), and NANO Binning was se o 4 × 4. The measu ing EHT ol age was se o 20 kV wi h a spo size o 120 µ m, and he cu en was 3 nA. The scanning a ea o he samples was, in all cases, 1 ×0.75 mm. 2.3. Quasis a ic Nanoinden a ion Quasis a ic nanoinden a ion is used o measu e he cou ses o nanoha dness and he educed Young modulus ac oss Inconel laye s om he su ace o a ce ain dep h. The me hod was i s in oduced by Oli e and Pha [ 31 ] and is based on pushing a diamond- ipped inden e head in o a ma e ial, whe e he displacemen (h) as a unc ion o he load (F) is moni o ed du ing bo h he loading and unloading cycles o he inden a ion p ocess. The esul ing ela ion F-h is called he nanoinden a ion cu e (Figu e 4a). The loading pa o he cu e is used o e alua e nanoha dness H, which is de ined as he con ac p essu e unde he inden e [32]: H=F Ac(1) whe e Fis he load, and A c is he p ojec ed con ac a ea calcula ed a a dep h o inden a ion h. The unloading pa is ela ed o eco e ing elas ic de o ma ion and can be used o calcula e he Young modulus o he ma e ial. Ma e ials 2023,16, 6796 6 o 15 Ma e ials 2023, 16, x FOR PEER REVIEW 6 o 15 (a) (b) Figu e 4. (a) Nanoinden a ion cu e o eal ma e ial and (b) loading cu e used o he expe imen . The con en ional Young modulus o he sample (E s ) can be ela ed o he educed modulus (E ) using Equa ion (3), p o ided ha he inden e modulus (E i ) and Poisson’s a ios o he specimen and inden e (ν s and ν i , espec i ely) a e known o can be es ima ed [32]: 1 𝐸=1𝜈   𝐸1𝜈   𝐸 (3) Quasis a ic nanoinden a ion measu emen s we e pe o med wi h a Hysi on T i- boinden e TI950 (Ma e ials Resea ch Labo a o y, U bana, IL, USA), whe e he expe i- men al esul s we e analyzed using i s so wa e, Hysi on T iboscan e sion 1.0. A s and- a d apezoid wi h maximum o ce F = 10,000 µN and holding ime = 2 s was chosen as he loading cu e o e e y ealized inden a ion poin , as is shown in Figu e 4b. A Be ko- ich inden a ion ip was used o he expe imen , which has sufficien sha pness o he used expe imen al ma e ials. The numbe o nanoinden a ion poin s was chosen speci i- cally o each Inconel laye a ea ype sepa a ely in a way o co e he en i e hickness o he laye in he a ea. The s ep (dis ance) be ween poin s was cons an —150 µm. 3. Resul s 3.1. Change in Laye Dep h a e Bending The change in he hickness o he welded laye due o bending was analyzed as pa o he expe imen s, oo. The measu emen was ca ied ou wi h a ligh mic oscope and i s e alua ion so wa e on mac os uc u e pho og aphs. The achie ed esul s a e shown in Figu e 5a. Figu e 5b shows he esul s in pola coo dina es, including changes in he o al wall hickness o he ube. The pola coo dina e iew displays he comple e scheme o he bending a c and allows he isualiza ion o he ube wall de o ma ion, including Inconel laye s on bo h sides o he ube. The eg ession equa ions modeled on he basis o expe i- men al da a o hicknesses (Figu e 5a) clea ly indica e he maximum o minimum hick- ness a he op o he bend, whe e α = 90°. As a esul o bending, he welded Inconel laye on he ou e a c o he bend became hinne due o he ensile s esses p esen . The maximum hinning is a he op o he ou e a c (α = 90°, 73% o he o iginal hickness o he laye ). A sample labeled OR was aken om his a ea. In con as , he hickening o he Inconel laye occu ed due o he p esence o comp essi e s esses in he lowe bend a c. The Inconel laye on his side o he a c o he bend has he maximum hickness (α = 90°, 149% o he hickness o he o iginal laye ). A sample labeled IR was aken om his a ea o he bending a c. The laye hickness changes a e bending a e ela ed o he ypes o in e nal s esses and hei dis ibu ion wi hin he Inconel 625 laye . h p h e h max h F max F dF dh Loading Unloadin g Figu e 4. (a) Nanoinden a ion cu e o eal ma e ial and (b) loading cu e used o he expe imen . The ini ial slope (S) o he unloading cu e can be ela ed o he elas ic modulus o he ma e ial using he equa ion [32]: S=dF dh =2E √Ac √π(2) whe e Sis he ini ial slope o he unloading cu e o con ac s i ness, Fis he applied load, and E is he educed Young modulus. The con en ional Young modulus o he sample (E s ) can be ela ed o he educed mod- ulus (E ) using Equa ion (3), p o ided ha he inden e modulus (Ei) and Poisson’s a ios o he specimen and inden e (νsand νi, espec i ely) a e known o can be es ima ed [32]: 1 E =1−ν2 s ES +1−ν2 i Ei (3) Quasis a ic nanoinden a ion measu emen s we e pe o med wi h a Hysi on T iboin- den e TI950 (Ma e ials Resea ch Labo a o y, U bana, IL, USA), whe e he expe imen al esul s we e analyzed using i s so wa e, Hysi on T iboscan e sion 1.0. A s anda d apezoid wi h maximum o ce F = 10,000 µ N and holding ime = 2 s was chosen as he loading cu e o e e y ealized inden a ion poin , as is shown in Figu e 4b. A Be ko ich inden a ion ip was used o he expe imen , which has su icien sha pness o he used expe imen al ma e ials. The numbe o nanoinden a ion poin s was chosen speci ically o each Inconel laye a ea ype sepa a ely in a way o co e he en i e hickness o he laye in he a ea. The s ep (dis ance) be ween poin s was cons an —150 µm. 3. Resul s 3.1. Change in Laye Dep h a e Bending The change in he hickness o he welded laye due o bending was analyzed as pa o he expe imen s, oo. The measu emen was ca ied ou wi h a ligh mic oscope and i s e alua ion so wa e on mac os uc u e pho og aphs. The achie ed esul s a e shown in Figu e 5a. Figu e 5b shows he esul s in pola coo dina es, including changes in he o al wall hickness o he ube. The pola coo dina e iew displays he comple e scheme o he bending a c and allows he isualiza ion o he ube wall de o ma ion, including Inconel laye s on bo h sides o he ube. The eg ession equa ions modeled on he basis o expe imen al da a o hicknesses (Figu e 5a) clea ly indica e he maximum o minimum hickness a he op o he bend, whe e α= 90◦. As a esul o bending, he welded Inconel laye on he ou e a c o he bend became hinne due o he ensile s esses p esen . The maximum hinning is a he op o he ou e a c ( α = 90 ◦ , 73% o he o iginal hickness o he laye ). A sample labeled OR was aken om his a ea. In con as , he hickening o he Inconel laye occu ed due o he p esence o comp essi e s esses in he lowe bend a c. The Inconel laye on his side o he a c o Ma e ials 2023,16, 6796 7 o 15 he bend has he maximum hickness ( α = 90 ◦ , 149% o he hickness o he o iginal laye ). A sample labeled IR was aken om his a ea o he bending a c. The laye hickness changes a e bending a e ela ed o he ypes o in e nal s esses and hei dis ibu ion wi hin he Inconel 625 laye . Ma e ials 2023, 16, x FOR PEER REVIEW 7 o 15 (a) (b) Figu e 5. Inconel laye hickness depends on he posi ion angle in he bending a c (a), (b) he de- pendence displayed in pola coo dina es, including o al wall hickness changes. 3.2. Mechanical P ope ies ac oss Inconel 625 Laye s The cou ses o he local nanoha dness H and educed Young modulus E we e meas- u ed ac oss he Inconel 625 laye o he ube wi hou a bend (NB) and he ube wi h he bend in a eas o maximum ensile s esses (OR) and maximum comp essi e s esses (IR). I can be assumed ha ha dness alues will be in luenced by in e nal s esses h ough inden a ion dep h measu emen s du ing he nanoinden a ion p ocess. The measu emen s do no include he in e ace be ween he laye and he subs a e o he s ep change in he local mechanical p ope ies wi h he alues o he subs a e. The measu emen s o he ube wi hou he bend a e shown in Figu e 6. Bo h nanoha dness and he educed Young mod- ulus a e cons an in he en i e measu ed laye c oss-sec ion. This was also p o en by a eg ession analysis o he da a. The laye is homogeneous wi hou changes in H o E . Figu e 6. Nanoha dness and educed Young modulus cou ses ac oss he Inconel 625 laye on he ube wi hou bend (NB). The ben ube was analyzed by nanoinden a ion in wo a eas (see Figu e 3). The i s a ea is a he op o he bending a c (OR), whe e he Inconel 625 laye hickness is mini- mum, which means maximum ensile s esses. The second a ea is a he bo om o he bending a c (IR), whe e he Inconel laye hickness is maximum due o maximum com- p essi e s esses. Figu e 5. Inconel laye hickness depends on he posi ion angle in he bending a c ( a ), ( b ) he dependence displayed in pola coo dina es, including o al wall hickness changes. 3.2. Mechanical P ope ies ac oss Inconel 625 Laye s The cou ses o he local nanoha dness H and educed Young modulus E we e mea- su ed ac oss he Inconel 625 laye o he ube wi hou a bend (NB) and he ube wi h he bend in a eas o maximum ensile s esses (OR) and maximum comp essi e s esses (IR). I can be assumed ha ha dness alues will be in luenced by in e nal s esses h ough inden a ion dep h measu emen s du ing he nanoinden a ion p ocess. The measu emen s do no include he in e ace be ween he laye and he subs a e o he s ep change in he local mechanical p ope ies wi h he alues o he subs a e. The measu emen s o he ube wi hou he bend a e shown in Figu e 6. Bo h nanoha dness and he educed Young modulus a e cons an in he en i e measu ed laye c oss-sec ion. This was also p o en by a eg ession analysis o he da a. The laye is homogeneous wi hou changes in H o E . Ma e ials 2023, 16, x FOR PEER REVIEW 7 o 15 (a) (b) Figu e 5. Inconel laye hickness depends on he posi ion angle in he bending a c (a), (b) he de- pendence displayed in pola coo dina es, including o al wall hickness changes. 3.2. Mechanical P ope ies ac oss Inconel 625 Laye s The cou ses o he local nanoha dness H and educed Young modulus E we e meas- u ed ac oss he Inconel 625 laye o he ube wi hou a bend (NB) and he ube wi h he bend in a eas o maximum ensile s esses (OR) and maximum comp essi e s esses (IR). I can be assumed ha ha dness alues will be in luenced by in e nal s esses h ough inden a ion dep h measu emen s du ing he nanoinden a ion p ocess. The measu emen s do no include he in e ace be ween he laye and he subs a e o he s ep change in he local mechanical p ope ies wi h he alues o he subs a e. The measu emen s o he ube wi hou he bend a e shown in Figu e 6. Bo h nanoha dness and he educed Young mod- ulus a e cons an in he en i e measu ed laye c oss-sec ion. This was also p o en by a eg ession analysis o he da a. The laye is homogeneous wi hou changes in H o E . Figu e 6. Nanoha dness and educed Young modulus cou ses ac oss he Inconel 625 laye on he ube wi hou bend (NB). The ben ube was analyzed by nanoinden a ion in wo a eas (see Figu e 3). The i s a ea is a he op o he bending a c (OR), whe e he Inconel 625 laye hickness is mini- mum, which means maximum ensile s esses. The second a ea is a he bo om o he bending a c (IR), whe e he Inconel laye hickness is maximum due o maximum com- p essi e s esses. Figu e 6. Nanoha dness and educed Young modulus cou ses ac oss he Inconel 625 laye on he ube wi hou bend (NB). The ben ube was analyzed by nanoinden a ion in wo a eas (see Figu e 3). The i s a ea is a he op o he bending a c (OR), whe e he Inconel 625 laye hickness is minimum, Ma e ials 2023,16, 6796 8 o 15 which means maximum ensile s esses. The second a ea is a he bo om o he bending a c (IR), whe e he Inconel laye hickness is maximum due o maximum comp essi e s esses. Figu e 7shows he cou se o nanoha dness and he educed Young modulus ac oss he a ea OR. The educed modulus is also cons an in his case. This indica es he absence o any phase ans o ma ion o he o ma ion o a new phase ac oss he laye . Howe e , he nanoha dness H dec eases om he su ace. I s alues close o he su ace a e bigge and g adually dec ease wi h dep h o he alues measu ed on he ube wi hou he bend. Ma e ials 2023, 16, x FOR PEER REVIEW 8 o 15 Figu e 7 shows he cou se o nanoha dness and he educed Young modulus ac oss he a ea OR. The educed modulus is also cons an in his case. This indica es he absence o any phase ans o ma ion o he o ma ion o a new phase ac oss he laye . Howe e , he nanoha dness H dec eases om he su ace. I s alues close o he su ace a e bigge and g adually dec ease wi h dep h o he alues measu ed on he ube wi hou he bend. Figu e 7. Nanoha dness and educed Young modulus cou ses ac oss he Inconel 625 laye on he ben ube— he a ea wi h maximum ensile s esses (OR). Figu e 8 shows he cou se o nanoha dness and he educed Young modulus ac oss he IR a ea. The educed modulus is again cons an . The nanoha dness H inc eases om he su ace o he deepe a eas. I s alues g adually inc ease om he su ace and almos double in alue compa ed o he nanoha dness o he ube wi hou he bend. Figu e 8. Nanoha dness and educed Young modulus cou ses ac oss he Inconel 625 laye on he ben ube— he a ea wi h maximum comp ess s esses (IR). 3.3. Analysis o Clad Laye Mic os uc u e a e Bending The mic os uc u e o Inconel 625 laye s affec ed by he bending p ocess is docu- men ed in Figu e 9, which was gene a ed using a con ocal mic oscope (Olympus Lex Figu e 7. Nanoha dness and educed Young modulus cou ses ac oss he Inconel 625 laye on he ben ube— he a ea wi h maximum ensile s esses (OR). Figu e 8shows he cou se o nanoha dness and he educed Young modulus ac oss he IR a ea. The educed modulus is again cons an . The nanoha dness H inc eases om he su ace o he deepe a eas. I s alues g adually inc ease om he su ace and almos double in alue compa ed o he nanoha dness o he ube wi hou he bend. Ma e ials 2023, 16, x FOR PEER REVIEW 8 o 15 Figu e 7 shows he cou se o nanoha dness and he educed Young modulus ac oss he a ea OR. The educed modulus is also cons an in his case. This indica es he absence o any phase ans o ma ion o he o ma ion o a new phase ac oss he laye . Howe e , he nanoha dness H dec eases om he su ace. I s alues close o he su ace a e bigge and g adually dec ease wi h dep h o he alues measu ed on he ube wi hou he bend. Figu e 7. Nanoha dness and educed Young modulus cou ses ac oss he Inconel 625 laye on he ben ube— he a ea wi h maximum ensile s esses (OR). Figu e 8 shows he cou se o nanoha dness and he educed Young modulus ac oss he IR a ea. The educed modulus is again cons an . The nanoha dness H inc eases om he su ace o he deepe a eas. I s alues g adually inc ease om he su ace and almos double in alue compa ed o he nanoha dness o he ube wi hou he bend. Figu e 8. Nanoha dness and educed Young modulus cou ses ac oss he Inconel 625 laye on he ben ube— he a ea wi h maximum comp ess s esses (IR). 3.3. Analysis o Clad Laye Mic os uc u e a e Bending The mic os uc u e o Inconel 625 laye s affec ed by he bending p ocess is docu- men ed in Figu e 9, which was gene a ed using a con ocal mic oscope (Olympus Lex Figu e 8. Nanoha dness and educed Young modulus cou ses ac oss he Inconel 625 laye on he ben ube— he a ea wi h maximum comp ess s esses (IR). 3.3. Analysis o Clad Laye Mic os uc u e a e Bending The mic os uc u e o Inconel 625 laye s a ec ed by he bending p ocess is documen ed in Figu e 9, which was gene a ed using a con ocal mic oscope (Olympus Lex OLS5100, Ma e ials 2023,16, 6796 9 o 15 Olympus IMS, Webs e , TX, USA). The s uc u e o he o iginal laye una ec ed by bending is shown in Figu e 9a o compa e changes a e bending in he OR (Figu e 9b) o IR a ea (Figu e 9c). As desc ibed in mo e de ail in Sec ion 2.1, he mic os uc u e o he laye is p ima ily o med by dend i es o he γ phase. The shape and mo phology o dend i es a e he mos signi ican indica o s o mic os uc u al changes due o bending. Ma e ials 2023, 16, x FOR PEER REVIEW 9 o 15 OLS5100, Olympus IMS, Webs e , TX, USA). The s uc u e o he o iginal laye unaffec ed by bending is shown in Figu e 9a o compa e changes a e bending in he OR (Figu e 9b) o IR a ea (Figu e 9c). As desc ibed in mo e de ail in Sec ion 2.1, he mic os uc u e o he laye is p ima ily o med by dend i es o he γ phase. The shape and mo phology o den- d i es a e he mos signi ican indica o s o mic os uc u al changes due o bending. In he a ea whe e ensile s esses a e ac ing, he dend i es a e s e ched in he di ec- ion o hei seconda y axes, called a ms (see Figu e 9b). The p ima y dend i e axes a e also na owe bu emain s aigh , wi hou de o ma ion o cu a u e. In he a ea o com- p essi e s esses (depic ed in Figu e 9c), he mic os uc u e is no iceably mo e affec ed compa ed o OR. The a ms o he dend i es a e almos indis inc as a esul o de o ma ion by comp essed s esses. The dend i e axes a e no longe s aigh bu ben wi h a ce ain cu a u e. (a) (b) (c) Figu e 9. Mic os uc u e o Inconel 625 clad laye and i s change a e bending. (a) Sample wi hou bend (NB), (b) a ea o maximum ensile s esses (OR), and (c) a ea o maximum comp essi e s esses (IR). The men ioned conclusions a e also con i med by he quan i a i e mic os uc u e anal- ysis pe o med using he analy ical so wa e S eam o he Olympus Lex OLS5100 (Table 3). The o iginal mic os uc u e pho og aphs we e p ocessed in o de o highligh dend i e bounda ies h ough hei ans o ma ion o he wo-colo scheme, which is mos sui able o he quan i a i e analysis. A e p ocessing, he dend i es we e mo e p onounced wi h sha pe bo de s. The in e dend i ic space was simpli ied o a ma ix, neglec ing he p esence o seconda y phases. The geome ic pa ame e s o he dend i es (wid h, leng h) we e hen e alua ed. In he case o he IR egion, he leng h o he a c in which he dend i es we e de o med was conside ed o be he leng h o he dend i e. Addi ionally, phase analysis was pe o med o de e mine he sha e o dend i es and he ma ix. The wid h o he dend i es ollows he ype o applied s ess. I is signi ican ly la ge in he ensile a ea and, con e sely, smalle in he p essu e a ea. The leng hs o he den- d i es do no change signi ican ly in indi idual in es iga ed cases, e en hough, in he IR egion, hey a e de o med in o he shape o an a c. In e ms o he phase sha e, he e was a dec ease in he p opo ion o he in e dend i ic space (ma ix) in bo h a e -bending cases compa ed o he s a e wi hou bending. In wo a e -bending cases, dend i es a e diffe en ly de o med acco ding o he applied s ess. Howe e , he sha e o he dend i ic a ea is almos he same in bo h cases. Table 3. Quan i a i e mic oscopy pa ame e s o in es iga ed dend i es. Pa ame e NB OR IR Dend i e wid h (µm) 9.93 ± 1.11 17.7 ± 0.8 4.75 ± 1.24 Dend i e leng h (µm) 51.39 ± 1.68 48.94 ± 2.8 52.72 ± 7.45 A ea o he dend i es (%) 42.38 54.03 56.75 Ma ix (%) 57.62 45.97 43.25 Figu e 9. Mic os uc u e o Inconel 625 clad laye and i s change a e bending. ( a ) Sample wi h- ou bend (NB), ( b ) a ea o maximum ensile s esses (OR), and ( c ) a ea o maximum comp essi e s esses (IR). In he a ea whe e ensile s esses a e ac ing, he dend i es a e s e ched in he di ec ion o hei seconda y axes, called a ms (see Figu e 9b). The p ima y dend i e axes a e also na owe bu emain s aigh , wi hou de o ma ion o cu a u e. In he a ea o comp essi e s esses (depic ed in Figu e 9c), he mic os uc u e is no iceably mo e a ec ed compa ed o OR. The a ms o he dend i es a e almos indis inc as a esul o de o ma ion by comp essed s esses. The dend i e axes a e no longe s aigh bu ben wi h a ce ain cu a u e. The men ioned conclusions a e also con i med by he quan i a i e mic os uc u e analysis pe o med using he analy ical so wa e S eam o he Olympus Lex OLS5100 (Table 3). The o iginal mic os uc u e pho og aphs we e p ocessed in o de o highligh dend i e bounda ies h ough hei ans o ma ion o he wo-colo scheme, which is mos sui able o he quan i a i e analysis. A e p ocessing, he dend i es we e mo e p onounced wi h sha pe bo de s. The in e dend i ic space was simpli ied o a ma ix, neglec ing he p esence o seconda y phases. The geome ic pa ame e s o he dend i es (wid h, leng h) we e hen e alua ed. In he case o he IR egion, he leng h o he a c in which he dend i es we e de o med was conside ed o be he leng h o he dend i e. Addi ionally, phase analysis was pe o med o de e mine he sha e o dend i es and he ma ix. Table 3. Quan i a i e mic oscopy pa ame e s o in es iga ed dend i es. Pa ame e NB OR IR Dend i e wid h (µm) 9.93 ±1.11 17.7 ±0.8 4.75 ±1.24 Dend i e leng h (µm) 51.39 ±1.68 48.94 ±2.8 52.72 ±7.45 A ea o he dend i es (%) 42.38 54.03 56.75 Ma ix (%) 57.62 45.97 43.25 The wid h o he dend i es ollows he ype o applied s ess. I is signi ican ly la ge in he ensile a ea and, con e sely, smalle in he p essu e a ea. The leng hs o he dend i es do no change signi ican ly in indi idual in es iga ed cases, e en hough, in he IR egion, hey a e de o med in o he shape o an a c. In e ms o he phase sha e, he e was a dec ease in he p opo ion o he in e dend i ic space (ma ix) in bo h a e -bending cases compa ed o he s a e wi hou bending. In wo a e -bending cases, dend i es a e di e en ly de o med acco ding o he applied s ess. Howe e , he sha e o he dend i ic a ea is almos he same in bo h cases.