KR0000541 KAERl/AR-570/2000 Hydrogen Embrittlement and Galvanic Corrosion of Titanium Alloys 31/47 Please be aware that all of the Missing Pages in this document were originally blank pages 2000. 6. 30. ^ A • AS 71 ^- 300 "C £7]- ef 2000 ppm PWR 5 of 700 ppm eq -8-Sfe- ^ 120 ppm nfl^-ofl 4. 1/10 S. 60^) ppm 200 °C jl-g-5l«H SI7] xt))^ - 11 - 3 1 7fl -S- 3 2 3 1. 3 2. 4 3. 6 4. 11 3 14 41 41 1. 41 2. 41 3. 42 4. 43 5. 45 47 56 58 - in - 2-1 A comparison of crack growth rates observed in AISI-4130 2 steel (a y = 1330 mn/m ) exposed to three different hydrogen containing environments, all other parameters being identical 20 - iv - =L m 2-1 Schematics of possible transport reaction steps involved in the embrittlement of a structural alloy by an external molecular hydrogen environment 21 2-2 Hydrogen induced, stage II slow crack growth in a high strength martensitic AISI-4340 exposed to various hydrogen -containing environments 22 2-3 Schematics of crack growth in a high strength steel 23 2-4 Schematics of the hydrogen-sweep model for concentrating hydrogen 24 2-5 Schematics of crack growth by hydrogen-lattice-bond interactions 25 2-6 Schematic diagram of cavity nucleation and growth by diffusion of hydrogen from a supersaturated metal lattice 26 2-7 General form of the rate by hydrogen-induced slow crack growth as a function of applied stress intensity 27 2-8 The relationship between the nature of the interaction of hydrogen with metals and the position of the metals in the periodic table 28 2-9 General form of the rate oh hydrogen-induced slow crack growth as a function of applied stress intensity 29 2-10 Schematic diagram of fatigue crack growth in a hydrogen environment • 30 2-11 The phase diagram of Ti-H binary system 31 2-12 Primitive unit cell of a hep metal (open circles) with tetrahedral (full circles) and octahedral (open squares) interstitial site •••• 32 2-13 The effect of displacement rate on the tensile reduction in area of the Ti-140A alloy containing 375ppm hydrogen 33 - v - 2-14 Temperature dependence of crack growth rate in the Ti-6A1 alloy and the Ti-6A1-4V alloy containing different bulk hydrogen concentrations 34 2-15 The fracture surface of the Ti-6A1-4V alloy having an acicular microstructure and failed in gaseous hydrogen at a pressure of 90.6 kN/m2 35 2-16 The hydrogen pressure dependence of the embrittlement ratio observed in the Ti-6A1-4V alloy heat treated to give a continuous a phase and continuous ft phase matrix 36 2-17 Hydrogen-induced cracking observed in Ti-6A1-4V alloy having a continuous ft -phase matrix with acicular a phase platelets 37 2-18 Titanium potentials in 10 % NaCl solution at 25 V after standing 48 hours natural aeration 38 2-19 Hydrogen absorption of titanium in synthetic sea water at increasing cathodic potential 39 2-20 Schematics of the central role of the passive film on titanium and the consequences of film breakdown under various conditions 40 3-1 Activation polarization curves for a reversible electrode system 50 3-2 Polarization behavior of iron in 1.0 N Sodium sulfate 51 3-3 Mixed potential behavior of galvanically coupled Metals A and B 52 3-4 Factors affecting galvanic corrosion • 53 3-5 The galvanic series of various metals in flowing water at 2.4 to 4.0 m/s for 5 to 15 days at 5 to 30 °C 54 3-6 The effect of coupling of titanium to other metals on corrosion rates in seawater 55 - vi - M pickling, electroplating, stripping -§-£} Sj-S)- (delayed failure) 1875id Johnson [1] <*fl *H ^4: ^-fr ^^7loflA-1 Tda^l «V^ ^-8-A] ^I^JIE ^4. n ^ 1965^d NASA(National Aeronautics and Space Administration) ^^ 5000psi -§--§- gaseous hydrogen storage vessel ^ ^^^ti 4^1- ##$ . ^-^^- w>7ll£l$i4 [2,3]. ^12:, ^^ ^ -g-g-^1 ^i (perturbation) 7]- ^ ZL - 1 - noble t!r - 2 - 2 g- ^ ±: m 717|| 2-1 171 2-1 3 5171- XI 2 ^ 1. ^r^^l -B-2fl(The origin of hydrogen) S^ bulk *1)jS. (screened proton) ^^S. ^^fl§ ^ 5tl4. .. o _. r Safe 41 fetfl €-S-tb 61^ £-5- #31 (transport reaction step) 2-1 [5,6]. «rdi £^7li£ 4s.JL ^-g- -S-^7j-iE (applied stress intensity), . S 2-1 £7]- ^±. £*} ^^71^] ^^oi] tilffl 103~104 "r^i-g-^ -S-J13J-8- 71^- JEfe ^r4i #]S|- (hydrogen degradation) M^ 2-1 41 ^-i- 2. ^r^M °1* (The transport of hydrogen) ^ o\7)t}^ ifl^- ^t ^-^ - 4 - W (screened proton) fe £113 1/3 >§j£S. a ^xfl^ ^^ ^^- 2xiO'6m3/gatom ^ partial molar volume -i: ^fe^al g-B^ &4 [7]. lXlO'6m 7> Hls^ 3. partial molar volume^ £^4^ J£tHr ^^^ ^-31^ octahedral JEfe tetrahedral [8]. (chemisorption) &$t: ^°14. ^-^ 2-2 [9]. kinetics <fl 4^ n^ 2-2 ^ <^5^ tiV-g- ^^^ fi- «>.§- ^-417H Gaseous [5]. -rdh^^^: ^> ^r^ precursor #3|1- ^r-g- [10] ^ - 5 - H2 (gas) *•* H2* 2 (H-M) precursor H2* £>4 precursor tflJf ^- ^.7] ^^/fugacity, -8-^, tfl^- 2-3 [11] ^-8- kinetic ^-g-^r ^-fe- gaseous X\ ^014. 3. -8-5:4-8-, ^fc-3*l- ^ -8-5:4-8-, ifl €^8: M-^^fe ^11 7} [12]. 7^ -8-S:4-8- 71^-^ ^±-Q 0]%^*] ^&2\ partial molar volume ^r ^^13 °l^^r °1^7ll «ffe- Cottrell-type atmosphere 7^ ofl [13]. (crack tip) XBS3 3-3 7ov£# ^^M?145l-^ ^1°J: [14] £ - 7 - fractographic 2-4 [14] <% °}£\$: 4=1 ^^^r 7H^=^^.S u|-E|-ifl^t)- ^1^- smooth sH facet 5L [151 °l^ al-g-35. (solubility limit) [16] ^LS. H% 2-5 <fl on ^11- sweep 4. 1950\3tj| ^ [17], o]^ decohesion 7]^-S. A]Q^9X^ [18]. decohesion 7)^ -g-^^ ^^.S ^4 [19]. n^ 2-6 ofl ^ 71 ^-# #31*1-8- 7l^fe 1940^ iflofl electrolytically cathodically charged ^r^°)l ^^& #3 ^1^ 7i^# ^^ wtol-S.^xl3L ^JO.^ [20], [21-23]. 2-7 <>)$•$: &* £fe ^li^t^l ^^ ^ 7} decohesion - 9 - 551^. ^^^-^-S. 7flS baking A|_ 3. Tft°. [24,25]. 2-8 ^•°] ionic, transition, intermediated covalent =:rS}--i- [26]. ^i^^-i- o|=7lS>fe- ^Sj-1-1-^ tB^-^- transition 8 li transition occluder notch - 10 - 4. fe crack initiation, slow crack growths- rapid unstable failure 4 ^^ *T 9X^. SI ?1W #31^ =1-8.3. ^-fecfl n]4i S^ (Fracture process zone, FPZ) SUrEfl [3,27], 5°|^6i ^-g- -g ^. Mode I loading^ (stress intensity factor) i& , B, fl Kic 71 o) ^-g- - 11 - sat)-. 71 S>\ "II-f «B>S t Engineering °>71 2-9 [3] . -g-3 7J-3E. threshold 51 ^ stage I, 51 stage H ^ Kic 51 stage HI 7} SX^n 1 9X4. Threshold -§ 51 ^^/fugacity ^-^4 [28] a *)^Ti-2) %•$• Kth Stage I 5 nonkinetics kinetics 5LS. Stage II H^ 51 - 12 - , stage opening/closing 2-10 [3] synergistic 37] 3 ^S>, 51 # ^-l" 7l^ofl $J14. ^f^ ^r^ ^>7l SI 711 Al^ 51-i- 51 - 13 - 3 !=]•%• a ^^^^r *}€- M^ ^ occluder $<^4 nJ-^Ms. Jl fe 10"3 at.% ^^ 2-11 [30]. I7l<3-SH 300-600 °C ^rS^^^^ife tflH? 2000wppm ^£^1^ 300 °C 600 °C <^l^H]Ai^ ^-^^1 7^ff <Q ^ ^T^-. ^tiV^o.^ ^^1 ^db^ yV^-^1 &xln> ^i ^^7lofl^ tfl^= 450 °C r±7\ tetrahedral ^^ 2-12 [31]. a >8-tfl^H ^#^}fe * habit ^^ ^^^^ll; ^^.^ [32,33] 18% > [34]. ^ 5X10""9 cmcm2/s7} <S<H^4 [35]. exp(-61,500/i?T) [36] tfl fugacityofl ^n I^^AS ^sl-l-^ ^^^ 7>^§}cf [37] - 14 - fe ^ 30 at.% 0 Ci] ^ HjEl-^ofl^ ^^^ ^AKg- rf^-4 ^-o] 14^^ ^ $X°-*\ 200°C i ^ 7X10"6 cm2/s7l- ^^^tf [38]. 3 exp(-21,500/i?T) [39] ^ ^}^^ ^^. ^£ofl 4ef & (impact embrittelment) Q *i^^£.#l^ (low strain rate embrittlement) 711 ^#*4. ^i^^£) ££011 « T?!^-^^- ^r^i ul-8-S. [40]. oi - 15 - [39]. Hj7}^-^ 0 Jl-g-S. [41]. 6ls|$: -r^-1-^ ^tt ^rifl^^ impact loading DBTT (ductile to brittle transition temperature) 7> ^o>^1rf [42]. £§)- fe^: impact loading^ <=fl ^ 2-13 o)l DBTT 7} fe^lfe ^^^: 44 - 16 - t\) ©l-i- sustained load cracking sustained load cracking ^ lOOppm [44] .2.3. ^ife- ^3. 2Lt\- ^fl [45]. ^^ 2-14 41 or + iff H]E(-^ ^•^•i) sustained load cracking [44]. *^#^y iff [2]. <a^^^l a -8-4- ^fe "W?57} #}^-41 -el o]si^ ^^-#S| cleavage 4] iff a # platelet 7> $7fl§l-fe s.-^-^ SJ-JZ) morphology ^ 2-15 4] u)-Bl-tfl^4 [46]. s^^oi ^-^-^o] 5^ Jl JlSTfl &S.& facets #3 ^l^-^^l terrace terrace ^2:fe terrace 2-16 [48] 41 i-l-Ehfl&^-ol ^^41 n}-e)- a/0 •c- transgranular 5" 141 a #°1 &A% ^^ T^^7r a - 17 - 2-17 [48] a a ^># W transgranular PH 2-18 ^1 ^-^r^l^ 10 % NaCl -g-^ pH t 0 14 S. ^^1^1- nfl^l ASTM Gr. 2 18 pH ^^^A-1 ^7]^^- §^71- i«# ^^11 ^^l^-i- ^ ^r 584. ^r, ^-^ 3 °]^fy 12 oi^-oij pH 2-18 <^1^ Ji^ol 3 °1*H4 12 ^1^-^ pH } ^<H^lfe ^ 1- ^ 5U4. sfl^1^ ^^ 4 rtfl pH, SI4. ^^^^-S- ^ ^^^1 [51-53]. - 18 - *}s. & 7} ^ Slfe 80 °C ) ^ si pH 7> 3 ^1^> S^ 12 ol-S-M^- ^^7]- -0.70 volts (vs. SCE) ^ SUrtfl n^ 2-19 [54]. _0<7 volts 80 °C [55]. ^.^ 2-19 °)H Ji^-ol ^-^^ (anodizing) ^ "g-7] #$• (air oxidizing) ^ ^'± ^^1- ^-^^1 ^i^l^-i- ^ ^r $14 [54].