Effect of Cold Working Effect of Cold Working on the Corrosion - - PowerPoint PPT Presentation
Effect of Cold Working Effect of Cold Working on the Corrosion Resistance of JPCA Steel on the Corrosion Resistance of JPCA Steel in Flowing Pb-Bi at 450C in Flowing Pb-Bi at 450C Abu Khalid Rivai , Shigeru Saito, Obayashi Hironari, Masao
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IWSMT10, Beijing-China, October 18-22, 2010
Abu Khalid Rivai, Shigeru Saito, Obayashi Hironari, Masao Tezuka, Chiaki Kato, Kenji Kikuchi JAEA - Japan Atomic Energy Agency
Effect of Cold Working Effect of Cold Working
in Flowing Pb-Bi at 450ºC in Flowing Pb-Bi at 450ºC
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Materials Issues: 1.Corrosion attack
2.Hydrostatic pressure of Pb-Bi. 3.Protons bombardment to beam window.
Developing Solutions: 1. JPCA steel: the candidate material for the proton beam window. 2. Cold worked-JPCA steel: expected to be stronger to endure protons bombardment and Pb-Bi`s pressure.
LBE (Pb-Bi eutectic) is the candidate for ADS (Accelerator Driven System) spallation target and core coolant (JAEA`s design).
Scale: mm
LBE
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Cold working (austenitic steel) process induces: 1. Increasing the strength and hardness. 2. Dislocation movement within the crystal. 3. Transformation from fcc austinite (γ) to bcc martensite (α`, magnetic). Cold working
JPCA (without cold working) 20% Cold worked-JPCA Cold work Strengthening of a metal by plastic deformation
Slip/deformation bands
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LBE temp. and flow velocity: ~450ºC and 1 m/s
To investigate the effect of cold working on the corrosion resistance of JPCA steel in flowing Pb-Bi at 450ºC of temperature and 1 m/s of flow velocity.
Proton beam window
Proton
LBE
Weld part Weld part ADS
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Parameter Conditions Type of liquid LBE (Pb-Bi eutectic) Flow velocity (m/s) 1
450 and 350 Oxygen concentration (wt.%)
~10-8
Time immersion (hrs) 1000 Materials 20% Cold worked (CW)-JPCA No CW-JPCA (as comparison)
Fe Ni Cr Mo Mn Si Ti C B P Co S N Balance
15.50 14.50
2.50 1.50 0.50 0.25 0.055 0.004 <0.035 <0.02 <0.01 <0.01
JPCA-Chemical Compositions (wt.%)
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200 300 400 500 600 700
ΔG
Temperature (ºC)
(1/3) Bi2O3 PbO NiO H2O (1/4) Fe3O4 (1/3) Cr2O3
ΔGo, Oxygen potential of oxides ΔG oxygen, Oxygen potential in LBE 10-9 10-8 10-7 10-6 10-5 10-4 10-3
450⁰C
Oxygen concentration:
~10-8 - ~10-9 wt.%
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JLBL-1 (JAEA Lead-Bismuth Loop for material corrosion)
450ºC, 1 m/s
No CW-JPCA 20%CW-JPCA
TIG welds 420 mm
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JPCA (no CW)
10µm Adhered Pb-Bi Bulk Pb-Bi penetration A layer?
10 20 30 40 50 60 70 80 90 100 1 2 3 4 5 6 7 8 9 Weight ( %) Analysis point Fe Cr Ni O Pb Bi
20%CW-JPCA
10µm Adhered Pb-Bi Bulk Pitting 1 3 5 7 9 2 4 6 8 10
Adhered Pb-Bi Oxide layer? 1µm
10 20 30 40 50 60 70 80 90 100 1 2 3 4 5 6 7 8 9 10 Weight ( %) Analysis point Fe Cr Ni O Pb Bi
Ferrite layer LBE penetration Fe-Cr oxide 10 1 2 3 4 5 6 7 8 9
1µm Adhered Pb-Bi Bulk Pb-Bi penetration A layer?
1 2 3 4 5 6 7 8 9
1µm Adhered Pb-Bi Bulk Pb-Bi penetration A layer?
JPCA (no CW)
20%CW-JPCA
Pb Pb M M 3. 3.0 0 µm Bi Bi M M 3. 3.0 0 µm 3. 3.0 µ 0 µm Fe Fe K K 3. 3.0 0 µm 3. 3.0 µ 0 µm Cr K Cr K 3. 3.0 µ 0 µm 3. 3.0 µ 0 µm Ni Ni K K 3. 3.0 0 µmPb Bi Fe-Pb-Bi Fe Cr Ni
LBE
Cr-Pb-Bi Ni-Pb-Bi
Adhered LBE Fe Fe LBE Adhered LBE Cr LBE Adhered LBE Ni Pb-Bi Pb-Bi Cr Pb-Bi Ni
Bi Bi M M 3. 3.0 0 µm Pb Pb M M 3. 3.0 0 µm 5. 5.0 µ µm O K O K 3. 3.0 0 µm Fe Fe K K 3. 3.0 0 µm Cr K Cr K 3. 3.0 0 µmBi Fe Cr O Pb Fe-Cr-O
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JPCA (no CW) 20%CW-JPCA
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200 400 600 800 1000 1200 1400 20 30 40 50 60 70 80 90 100 110 120 Intensity Diffraction angle (2θ)
α α α α α α α β α β ββ ββ
α: Austenite b: Pb-Bi oxide
α β β β β
200 400 600 800 1000 1200 20 30 40 50 60 70 80 90 100 110 120 Intensity Diffraction angle (2θ)
γ
α: Austenite β : Fe-Cr γ : (Fe-Cr) oxide δ : Pb-Bi oxide
α α α α α α β δ β β γ γ γ γ γ δ β β γ γγ γ γ γ γ γ γ γ γ δ δ δ δ δ δ γ δ g δ δ
JPCA (no CW)
20%CW-JPCA
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*Alternating voltage is applied to a conductive cantilever. The electromagnetic forces acting between the sample surface and the cantilever are detected to measure the potential across the sample surface. μ m μ m
Adhered Pb-Bi F e r r i t e l a y e r Pb-Bi penetration Bulk Pitting area Adhered Pb-Bi Bulk
JPCA (no CW)
20%CW-JPCA
Adhered Pb-Bi Bulk Adhered Pb-Bi Bulk 14
JPCA (no CW)
20%CW-JPCA
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*A magnetized probe is scanned at a constant distance from the sample surface. Magnetic forces due to the leakage field are detected and magnetic information about the sample surface is displayed visually.
100x100 µm 50x50 µm 100x100 µm 50x50 µm 100x100 µm 50x50 µm
Magnetic bands Magnetic bands
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*Porter DA, Easterling KE, “Phase transformations in metals and alloys”, 2nd edition: Chapman & Hall, London, 1993.
JPCA (without cold working) 20% Cold worked-JPCA
Slip/deformation bands
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Parameter 20% CW–JPCA No CW–JPCA Ferritization
Oxide layer .
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(localized)
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(localized)
. Corrosion behavior of 20%CW- JPCA and SA-JPCA in flowing Pb-Bi at 450ºC for 1000 hours
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In the present study, superficial ferritization accompanied with penetration of Pb-Bi through the ferrite layer occurred for JPCA without cold working. On the other hand, dissolution attack occurred only partially (localized superficial pitting) for the 20% cold worked-JPCA steel with no ferritization observed. Therefore, cold working limited a dissolution attack from flowing Pb-Bi. However, for the beam window material application the pitting corrosion problem has to be solved.
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