Hydrogen Embrittlement and Galvanic Corrosion of Titanium Alloys

Home , Hydrogen embrittlement

KR0000541

KAERl/AR-570/2000

31/47 Please be aware that all of the Missing Pages in this document were originally blank pages 2000. 6. 30.

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- 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

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- 19 - Table 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.

Environment Crack growth Comments (P = 45 Torr) rate (m/s)

Molecular hydrogen, Efe 9.0xl0~b Extrapolated from high pressure Hydrogen sulfide, H2S 8.0 X10"3 at P = 45 ton- Dissociated hydrogen, H 1.2 X10"2 Extrapolated from low pressure

- 20 - THE PATH (HYDROGEN TRANSPORT REACTIONS AND INTERACTION MECHANISMS)

THE BEGINNING THE END (ORIGIN AND FORM (CHANGE IN ALLOY OF HYDROGEN) BEHAVIOR) TIME, DISTANCE. OR EXTENT OF DEGRADATION

Fig. 2-1 Schematics of possible transport reactions steps involved in the embrittlement of a structural alloy by an external molecular hydrogen environment.

- 21 - oooooooooo ooooo ooooo t HYDROGEN MOLECULE ooooo • HYDROGEN ATOM OFERROUS ATOM 008

REACTION STEPS b GAS-PHASE DIFFUSION C PHYSISORPTION AND DISSOCIATION d ADATOM MIGRATION AND CHEMISORPTION e SOLUTION f LATTICE DIFFUSION

Fig. 2-2 Hydrogen induced, stage II slow crack growth in a high strength martensitic AISI-4340 exposed to various hydrogen-containing environments. Also indicated are the apparent hydrogen transport reactions controlling embrittlement in each environment. Rate-controlling process: (a) diffusion (b) gas-phase transport (c) surface reaction (H2-metal) (d) surface reaction (H20-metal)

- 22 - TEMPERATURE {"CJ- 140120 CO 80 60 40 20 0 -20 -40 1 i I I r r i i i i

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2.5 4.0

Fig. 2-3 Schematics of crack growth in a high strength steel, (a) without hydrogen present crack growth occurs by microvoid coalescence within a large plastic zone about the crack tip. (b) with hydrogen present deformation becomes easier and crack growth occurs as a result of severely localized deformation at crack tip.

- 23 - LOAD LOAD t

(a) (b)

Fig. 2-4 Schematics of the hydrogen-sweep model for concentrating hydrogen, (a) a Cottrell-type hydrogen atmosphere is associated with a moving dislocation, (b) hydrogen is stripped from the dislocation as it passes particles and concentrates at the particle-matrix interface, (c) the dislocation moves on and the process is repeated.

- 24 - (a) (0

Fig. 2-5 Schematics of crack growth by hydrogen-lattice-bond interactions, (a) the adsorption mechanism where hydrogen adsorbs on the surface of the crack tip weakens the lattics bonds and the crack tip moves forward in a continuous manner, (b) the decohesion mechanism where hydrogen interacts to weaken the lattics bonds ahead of the crack tip (at the point of maximum stress) and the nucleated crack moves backward to the crack tip, the process is repeated and the crack tip moves forward in a discontinuous manner.

- 25 - Hn ••

(a) (b)

Fig. 2-6 Schematic diagram of cavity nucleation and growth by diffusion of hydrogen from a supersaturated metal lattics. Ceq is the lattice hydrogen concentration in equilibrium with molecular hydrogen in the gas-filled cavity, dotted line, initial hydrogen supersaturation; dashed line, hydrogen profile at void nucleation; solid line, hydrogen profile after diffusion and void growth.

- 26 - DISTANCE-

Fig. 2-7 General form of the rate of hydrogen-induced slow crack growth as a function of applied stress intensity.

- 27 - GROUP PERIOD IA HA HIB DZB 3ZB SIB SOB illllU IB HB IHA BTA 3TA J3A 2DA 0

n Be 13 14 15 16 17 18 m Al Cl 19 34 35 Se Br 38 50 53 Sn 85 3ZI At IONIC TRANSITION INTER COVALENT MEDIATE

EXOTHERMIC HYDROGEN OCCLUDERS ENDOTHERMIC HYDROGEN OCCLUDERS

Fig. 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 - STAGE

o cc CD 3 cc o O CO IX. O STAGEI LU

KIC APPLIED STRESS INTENSITY, K|

Fig. 2-9 General form of the rate of hydrogen-induced slow crack growth as a function of applied stress intensity.

- 29 - I

5 o

ALTERNATING (AK() OR MAXIMUM (K|) STRESS INTENSITY

Fig. 2-10 Schematic of fatigue crack growth in a hydrogen environment when the mechanical and chemical degradation processes are acting independently. Fatigue crack growth in hydrogen is the simple sum of the mechanical and chemical components, dashed line, static/hydrogen environment; dotted line, fatigue/inert environment; solid line, fatigue/hydrogen environment.

- 30 - Weight Percent Hydrogen 0.5 1 1.5 8

20 30 tO 50 Ti Atomic Percent Hydrogen

Fig. 2-11 The phase diagram of Ti-H binary system.

- 31 - Fig. 2-12 Primitive unit cell of a hep metal (open circles) with tetrahedral (full circles) and octahedral (open squares) interstitial site. The arrows indicate four different types of jump paths for the hydrogen, where the jumps of type 2, 3 and 4 cross a common octahedral site. The two different lattice parameters a and c are also indicated.

- 32 - PLATEN SPEED, m/i A /) 4.2 X 10"* B D 2.1x10"* C A 2.1 x 10"5 D O 1.0x10-5 E O 2.1 x 10"6

-200 -150 -100 -50 0 50 100 150 TEMPERATURE CO

Fig. 2-13 The effect of displacement rate on the tensile reduction in area of the Ti~140A alloy containing 375ppm hydrogen.

- 33 - io~8r

49.5 < K < 59.0 MPa ~ 100 ppm H2

9 UJ 10-

DC o l0-10 o o

-250 -200 -150 -100 -50 50 TEMPERATURE (°C)

Fig. 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 - Fig. 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. Arrows indicate the probable direction of local crack growth.

- 35 - Fig. 2-16 The hydrogen pressure dependence of the embrittlement ratio

(stress intensity factor at the onset of slow crack growth KSCg divided by the nonstandard critical stress intensity factor KQ) observed in the Ti-6A1-4V alloy heat treated to give a continuous a phase (•) and continuous 0 phase matrix(O) T = 24 °C; D = 8.9X10"8 m/s.

- 36 - Fig. 2-17 Hydrogen-induced cracking observed in Ti-6A1~4V alloy having a continuous 0 -phase matrix with acicular a phase platelets: (a) tested at a hydrogen pressure of 9.06 X104 N/m2 and (b) tested at a hydrogen pressure of 1.3 xlO1 N/m2.

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1 1 1 I 1 1 0 2 4 6 8 K) 12 14 pH

Fig. 2-18 Titanium potentials in 10 % NaCl solution at 25 "C after standing 48 hours natural aeration.

- 38 - s c br a 200 " br o

Fig. 2-19 Hydrogen absorption of titanium in synthetic seawater at increasing cathodic potential.

- 39 - Mechanical [No Embfilllemenl Chemical ± r(No Hydrogen Plckupj Material Repasstvaies oiN Repassivalton depending on ^y Oxygen Supply Llmlleo siress/siraln level ) ( 1 • propagalton is provenled , Film Breakdown

^8y Stress/Strain) ., ^By Crevlcs Corrosion}

/T)mesl'lct80 Hydiogen Eniry V. (applied negailve polenllals)

Radlolysls provides source ol hydrogen

Fig. 2-20 Schematics of the central role of the passive film on titanium and the consequences of film breakdown under various conditions. On the left are mechanical film rupture events, on the right are chemical effects.

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- 50 - -0.7

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- 51 - A) '°-"2 ,4 TOTAL REDUCTION RATE

''corr.A i

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\ "7 TOTAL OXIDATION RATE T 'o.B

LOG CURRENT DENSITY

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- 52 - TYPE OF JOIN - welded -rostencrs • separated with external connection ELECTRODE POTENTIALS TOTAL GEOMETRY

- standard potential of metal In solution - area ratio - galvanic potential between metals - distances involved - surface shape - surface condition - number of galvanic cells

REACTION KMETICS BULK SOLUTION PROPERTIES

- metal absolution - Oj content - 0} reduction overvoltage -pll - Hj evolution overvollage Metal A | Metal D - conductivity 1 1 - corrosivity - pollutant level

ALLOY COMPOSITION BULK SOLUTION ENVIRONMENT

- major constituents - temperature - minor constituents - Dow rate - impurities - volume • height above surface PROTECTIVE FILMKCtlARACTERBTICS MASS TRANSPORT - potential dependence - migration - pH dependence - diffusion - solution dependence - convection

Fig. 3-4 Factors affecting galvanic corrosion.

- 53 - ttCTVQ VOLTS VERSUS SATURATED CALOMEL REFERENCE ELECTRODE

-1.6 -1.4 -1.2 -1.0 -0.8 -0.6 -0.4 -0.2 0 +0.2

GRAPHITE) !>LATlWUMr~l Nl-Cr-Mo ALLOY C| TITANIUM NI-Cr-Mo-Cu-SI ALLOY NICKEL-IRON CHROMIUM ALLOY (25 ALLOY "20 STAINLESS STEELS, CAST AMD WROUGHT STAINLESS STEEL - TYPES 316, 31iWKM I CZ NICKEL-COPPER ALLOYS 400. K-SOol I STAINLESS STEEL TYPES 302. 304, 321, 347MB I C SILVERl I NICKEL 200 I SILVER BRAZE ALLOYS I NICKEL -CHROMIUM ALLOY «OoBBi Q NICKEL-ALUMINUM BROHZrr I 70-30.COPPER NICKEL CD LEADCZJ STAINL SS STEEL TYPE 430| BO-20 COPPER N CKELC 90-10 COPPER HICKELCH NICKEL SILVER O

STAINLESS STEEL • TYPE ; 4io. 41 B| TIN BRONZES (C*M) CD SILICON BRONZED MANGANESE BRONZE CD

IDMIRALTY BRASSS,. iALUMINUM Pb-Sn SOLDER (50/50) d) COPPERlZD TIND NAVAL BRASS. YELLOW BRASS. RED BRASS ALUMINUM BRONZE CIZ] STENITIC NICKEL.CAST IRON LOW ALLOY STEELCP MILO STEEL. CAST IR CAOMIUMO A UMINUM ALLOYSl. BERYLIUMQ ZINCCJ C MAGNESIUM

Fig. 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 - 1 - LOW CARBON STEEL I 2 - GUNMETAL (88/10/2) 3 • ALUMINUM 4-70 CU-30NI 5-80 CU-20 Ni 6 • MONEL 9*7/31/1/1) 7 - ALUMINUM BRONZE *14 I • 60/40 BRASS (MUNTZ METAL) 9 - ALUMINUM BRASS (ALLOY 687) 10 • 18/8 STAINLESS (304)

2500 HOUR IN SEAWATER

10/1 1/10

ANODE/CATHODE AREA RATIO

(mm/yj

GALVANIC 10- -(.254) ATTACK ADDITION

NORMAL UNCOUPLED a - -(103) CORROSION

(--(.152)

4- (.102)

2 --(.0*1)

o-'-o

Fig. 3-6 The effect of coupling of titanium to other metals on corrosion rates in seawater.

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1. W. H. Johnson, Proc. R. Soc. London, 23 (1875) 49. 2. H. G. Nelson, NASA TN D-6691, National Aeronautics and Space Administration, Washington, D. C. (1972). 3. H. G. Nelson, Treatise on Materials Science and Technology, eds. by C. L. Briant and S. K. Banerji, Academic Press, NY, (1983) 275. 4. C. G. Hancock and H. H. Johnson, Trans. TMS-ATME, 236 (1966) 513. 5. D. P. Williams and H. G. Nelson, Metall. Trans., 1 (1970) 63. 6. H. G. Nelson et al., Metall. Trans., 2 (1971) 953. 7. R. A. Oriani, Trans. TMS-AIME, 235 (1966) 1386. 8. R. A. Oriani, NACE, Houston, (1969) 32. 9. H. G. Nelson, ASTM STP 543, Philadelphia, Pennsylvania, (1974) 152. 10. M. R. Shanabarger, Phys. Rev. Lett., 43 (1979) 1964 11. R. P. Wei, AIME, NY, (1981) 677. 12. P. Bastien and P. Azou, Proc. World Metall. Cong., 1st American Society of Metals, (1951) 535. 13. J. P. Hirth, Metall. Trans. A., 11A (1980) 861. 14. C. D. Beachem, Metall. Trans., 3 (1972) 437. 15. S. P. Lynch, Met. Forum, 2 (1979) 189. 16. J. K. Tien et al., Metall. Trans., 7A (1976) 821. 17. N. O. Petch and P. Stables, Nature (London), 169 (1952) 842. 18. W. J. Barnett and A. R. Troiani, J. Met. Trans. AIME, 209 (1957) 486. 19. R. A. Oriani, Ann. Rev. Met. Sci., 8 (1978) 327. 20. C. A. Zapffe and C. E. Sims, J. Met. Trans. AIME, 145 (1941) 225. 21. F. A. de Kazinczy, J. Iron Steel Inst, 177 (1954) 85. 22. B. A. Bilby and J. Hewitt, Acta Metall., 10 (1962) 587.

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- 60 - SL <9=

INIS

KAEWAR-570/2000

2000 Vl p.66 O ), A4 BIBLIOGRAPHIC INFORMATION SHEET Performing Org. Sponsoring Org. Standard Report No. ENIS Subject Code Report No. Report No. KAERI/AR-570/2000 Title / Subtitle Hydrogen embrittlement and galvanic corrosion of titanium alloys Project Manager Jeong Ryong Soh, Development of New Cladding Materials and Department Researcher and Department Y. H. Jeong, B. K. Choi, J. H. Baek and D. Y. Hwang (Development of New Cladding Materials) B. S Choi and D. J. Lee (Advanced Reactor System Technology Team)

Publication Publication Daejeon Publisher KAERI 2000 Place Date Page p.66 111. & Tab. Yes(O), No ( ) Size A4 Note Classified Open(O), Restricted( ), Report Type Technical Report Class Document Sponsoring Org. Contract No.

Abstract :

The material properties including the fracture behavior of titanium alloys used as a steam generator tube in SMART can be degraded due to the hydrogen embrittlement and the galvanic corrosion occurring as a result of other materials in contact with titanium alloys in a conducting corrosive environment. In this report the general concepts and trends of hydrogen embrittlement are qualitatively described to adequately understand and expect the fracture behavior from hydrogen within the bulk of materials and under hydrogen containing environments because hydrogen embrittlement may be very complicated process. And the characteristics of galvanic corrosion closely related to hydrogen embrittlement is qualitatively based on simple electrochemical theory.

Subject Keywords "• Hydrogen embrittlement, galvanic corrosion, titanium alloys