sub-surface corrosion research on rock bolt system

Publications (YM) Yucca Mountain

1-18-2007

Sub-surface corrosion research on rock bolt system, perforated Sub-surface corrosion research on rock bolt system, perforated

SS sheets and steel sets for Yucca Mountain Repository SS sheets and steel sets for Yucca Mountain Repository

Dhanesh Chandra University of Nevada, Reno, [email protected]

Jaak J.K. Daemen University of Nevada, Reno, [email protected]

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Part of the Civil and Environmental Engineering Commons, and the Metallurgy Commons

Repository Citation Repository Citation Chandra, D., Daemen, J. J. (2007). Sub-surface corrosion research on rock bolt system, perforated SS sheets and steel sets for Yucca Mountain Repository. Available at:Available at: https://digitalscholarship.unlv.edu/yucca_mtn_pubs/12

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YM-DOE Program Review -DRI, Reno 1-18-07

YM –DOE Review Meeting At DRI, Reno January 18, 2006 (1 – 1.25 pm)

Dhanesh Chandra* - PIJaak Daemen** - Co-PIRaul B. Rebak***- National Laboratory Collaborator (LLNL)Michael Mohorich*- MS Graduate Student Anjali Talekar*- Ph.D Graduate StudentSuresh Divi*- Ph.D Graduate StudentJosh Lamb*- Ph.D Graduate Student*Metallurgical & Materials Engineering, University of Nevada, Reno 89557**Mining Engineering, University of Nevada, Reno 89557***Lawrence Livermore National Laboratory, Livermore CA 94551

Sub-surface Corrosion research on Rock Bolt system, Perforated SS Sheets and

Steel Sets for Yucca Mountain Repository

- Presented to -

YM Project Program Review Panel Members


• Metallurgical Issues in Underground Repository Reinforcement Support for Nuclear Materials Storage in simulated Yucca Mountain Environment used for Corrosion Issues

• Issues related to I-beams (Low Carbon) and Rock Bolts (Med. Carbon)

• Experimental

• Results

1. Corrosion Tests- Effect of Ionic Concentration (1x,10x,100x), Temperature, concentration and aeration/deaeration effects in YMwaters (RB and I-Beam)

2. Hydrogen Permeation Tests

3. Environmentally Assisted Corrosion Tests - Stress Corrosion Cracking/Hydrogen Embrittlement in 100x YM water concentration at Room Temperature and 85oC (I-Beams)

Outline

* Dynamic Strain Aging - Portevin–LeChatelier Effect (PLC) under induced Potentials

Subsurface Facilities Criterion:a)thermal-mechanical stressesb)loads from constructionc)loads from repository operationsd)in situ loads from the overlying rocks e)loads from seismic occurances

Emplacement tunnels:• 18ft diameter• 52 required to emplace 70,000 metric tons• 35 miles total length

• Rock bolts will be installed for structural integrity of the tunnel

• Typical rock bolt for this application is 10 ft long

YM - Subsurface Design

Friction Rock Bolt


Rockbolts

I-Beam

Rock Bolt and Steel Sets in Yucca Mountain (YM) Environment

Waste Packages

Objective of Study:Determine Corrosion Rates Aerated/Deaerated

Simulated Environment Stress Corrosion Cracking Effects and Hydrogen

embrittlement Behavior in YM Nuclear Repository

Background

Tubular

Solid - w/small diameter hole


Summary of Task ORD-FY04-019

In ProgressStress corrosion cracking (SCC) research

(Major Task to be started)

Task 2Task 2

CompletedFor Rock bolts

Electrochemical Corrosion (Polarization and Impedance)

studies

Task B1(Additional Task of

Impedance Spectroscopy was

carried out at UNR in this task)

In progress for rock bolts and steel

Salt Spray MethodTaskA1 (1.4)

CompletedFor rock bolts

Aqueous CorrosionTaskA1 (1.3)

In ProgressFor rock bolts

Humid Air CorrosionTaskA1 (1.2)

In ProgressDry OxidationTaskA1 (1.1)Task 1

StatusTaskSIP Task No.


Tasks (Cont’d)

Completed for Rock bolts and more work is

in progress.

X-ray Photoelectron Spectroscopy (XPS)

Task 3.3 (Additional task carried out to study the oxide film formed, this task is not mentioned in SIP)

Completed for Rock bolts and further work

is in Progress

Scanning Electron Microscopy and Energy Dispersive analysis (SEM-

EDX)

Task 3.3

Needs to be done. Scoping studies

already performed

Atomic Force Microscopy (AFM)Task 3.3

Majority work done, in a process of

completion for steel sets

Hydrogen Permeation ResearchTask 3.2

Hydrogen Embrittlement (HE) Research

Task 3.1\


Materials and Methods Used for Sub-surface Reinforcing Corrosion Study

Materials

Rock Bolts

Williams Hollow Core MC Steel

(From YM Site)

Split Sets (HSLA)

Swellex Rock Bolts (HSLA)

CT Rock Bolts

Sub-Surface Support Liners

Steel Sets (I-Beam from YM Site )

Bernold Shields (4340 Steels)

Other Alloys

Alloy 22 (Ni Base Alloys)

Methodologies Used to Determine Corrosion rates and other

Properties1. Potentiodynamic Method

2. Potentiostatic Method

3. Electrochemical Impedance Studies

4. Immersion Studies

(ASTM G-31)

5. Cyclic Humidity Studies (ASTM-G-60)

6. Water Spray test (Modified Water Spray G-85 tests)

7. Stress Corrosion Cracking/Hydrogen Permeation Studies


Swellex Rock Bolts Plastically deformed and Inflated (with water Pressure) Rock Bolt

Cross sectionafter expansion

A >> B

B

300bar

High pressure water is insertedto expand the hollow bolt. In the final stagesthe water is forced out by airpressureforce water out of the inlet hole

.Swellex bolt is insertedinside the drill hole with a FACE plate until the plateis tight against the rock

Cross section beforeexpansion

Rock BoltBefore

After

As Received-Sectioned

Materials


Hollow Core Rock Bolts and Steel Sets (I-Beam) From YM Repository Site

Steel Compositions

Rock bolt I-BeamC 0.44 0.08

S 0.31 0.05

Mn 1.57 0.84

P 0.013 0.020

Si 0.27 0.12

Cu 0.19 0.34

Mo 0.03 0.02

Ni 0.06 0.09

Cr 0.08 0.08

8”

Rock Bolts: From the Nuclear Rep. Site

Steel Sets: I-Beam From the YM Site

Materials


Split Set Rock Bolts and Bernold ShiedPotentiodynamic scans - SS46 type rock bolts - aerated simulated 1x YM water at different temperatures.

0

1000

2000

3000

4000

5000

6000

20 30 40 50 60 70 80 90 100

Temperature (0C)

Cor

rosi

on R

ate

( μm

/y)

-0.70

-0.60

-0.50

-0.40

-0.30

-0.20

-0.10

0.00

1.00E-08 1.00E-07 1.00E-06 1.00E-05 1.00E-04 1.00E-03 1.00E-02

Current Density (A/cm2)

App

lied

Pote

ntia

l (V)

25C

45C

90C

65C

Radial Pressure exerted Against the Rock

slotted & tapered steel tube with Face Plateslotted & tapered steel tube with Face Plate

Slotted and Tapered Tube Driven in the rock

Materials

Bernold Shield


Specimens were ground and polished

Examples of RB/I-Beam Specimens Before Corrosion/SCC Tests

IB

IBRBIB

Materials


100 μm 100 μm

Rock Bolt

0.44%C

I-Beam

0.08%C

Example of the Microstructure of the Underground Support Materials Materials

EDS Analysis - MnS inclusions in I-Beam

EDS Spectra60μm


pH: 8.32 8.21

Na+: 61.3 51.0

SiO2: 70.5 66.4

Ca2+: 101 14.0

K+: 8.0 4.9

Mg2+: 17.0 2.0

HCO3-: 200 120

Cl-: 117 7.5

(SO)42-: 116 22.0

F-: 0.86 2.2

CO2: 85.2

*Yucca Mountain

Water (mg/l)

J-13 Well Water Chemicals Used to prepare the 1x YM waters(mg/l)

2 Na+ 1.09

F- 0.9

210 Na+ 33.6

SiO3- 56.2

200 Na+ 54.0

HCO3- 146.0

50 K+ 19.5

HCO3- 30.5

196 Ca2+ 52.9

Cl- 94.1

210 Ca2+ 48.3

SO42- 117.6

100 Mg2+ 12.0

Cl- 35.0

50 Mg2+ 5.0

SO42- 19.5

Drainage Water of Nuclear repository Water Composition, Comparison with J-13, and Preparation

*This Research DTN: LB0011DSTTHCR1.001[147120]

Electrolytes used


Gas Flow Meter

Purging Element

Lugg

in P

robe

Plat

inum

Cou

nter

Ele

ctro

de

To the Potentiostat, Gamry Instruments,

Model: PC4(750) DC 105

85.0 C

PIDTemperature

Controller

Gas

Ther

moc

oupl

e G

auge

Fritt

ed P

urgi

ng E

lem

ent

Gas Trap

Heating Mantle

Electrochemical Cell Set-Up for Potentiodynamic and Impedance Scans

Specimen


Electrochemical Cell for Standard Corrosion Tests Potentiodynamic Test Apparatus

1corri

CR K EWρ

=

icorr = B/Rp

B = βa. βc / [2.3(βa+ βc)]

Measurement of Corrosion Rate

Where, K1 = 3.27×10-3 mm.g/μA.cm.yearicorr = μA/cm2

ρ = 8.69 g/cm3

EW = 23.28 (unitless)ρ = 7.83 g/cm3

EW = 27.82 (unitless)ρ = 7.86 g/cm3

EW = 27.24 (unitless)

Alloy 22

Split Set

βa= βc=0.12Volt/D

Weight loss method → Long term tests

Electrochemical tests → corrosion properties of the material in a short period of time

Polarization method (ASTM G 59)→ widely accepted because of their reliability and fast data acquisition

Polarization resistance → is defined as the slope of electrode potential vs. current in the linear axis

ASTM G 102

y = 280.17x - 0.4731R2 = 0.9963

-0.49

-0.48

-0.48

-0.47

-0.47

-0.46-4.0E-05 -3.0E-05 -2.0E-05 -1.0E-05 0.0E+00 1.0E-05 2.0E-05 3.0E-05 4.0E-05 5.0E-05

-0.54

-0.52

-0.50

-0.48

-0.46

-0.44

-0.42

-0.40

1.0E-07 1.0E-06 1.0E-05 1.0E-04 1.0E-03 1.0E-02Current Density (A/cm2)

App

lied

Pote

ntia

l (V

vs. A

g/A

gCl)

Swellex Mn 24


Stress Corrosion Cracking Tests on Yucca Mountain I-Beam Supports Low Carbon Steel (0.08%C) Using SSRT Universal

Testing Machine

-1.2

-1

-0.8

-0.6

-0.4

-0.2

0

1.E-07 1.E-05 1.E-03 1.E-01Log I(A/cm2)

Pote

ntia

l (V)

; vs

Ag/A

gCl

Ecorr

- 620mV- 680mV

AnodicRegion

Cathodic Region

SSRT/Stress Corrosion/HIC

Apparatus


Environmentally Assisted Electromechanical Tests

Using Simulated YM Waters

Dynamic Strain Aging effects Due to

Coupled Electrochemical and Mechanical


Schematic of Hydrogen Permeation Cell

tentiostat I Anodic Chamber

Steel Sample (1.5 mm Thick)

Pt ElectrodeAg/AgCl Reference Electrode

Potentiostat IICathodicChamber

Ag/AgCl Reference Electrode

H2O + e- Hads+ OH- (1)

Hads + Hads H2 (g) (2)

Hads + H2O + e- H2 (g) OH- (3)or


Summary of Corrosion Rates (CR) Determined by Electrochemical and Immersion Methods

I-Beams (0.08%C)• Aerated Conditions: High CR at ~45oC and

Low at RT and 85oC• Deaerated Conditions: Generally Low

Corrosion Rates (22o- 85oC)

0

200

400

600

800

1000

1200

1400

1600

0 20 40 60 80 100

Temp erature (C)

μ

273 293 313 333 353 373

Temp erature (K)

1x (Nit rogenat ed))

10x (Nit rogenat ed)


1x (Oygenat ed)

10x (Oygenat ed)

100x (Oygenat ed)

YM Wat er Spray

Cyclic Humidit y

K

C H- 12 6 5

Y M WS - 9 70

LONG-TERM TES TS (Fille d S ymbols) YMWS = YM Wa t e r S pra y (1x)CH= Cyc lic Humidit y (1x)

Nitrogenated

Oxygenated

Oxy

gena

ted

I-Beams (0.08%C)

Rock Bolts (0.44%C)• High CR at 45oC and Low at 22o and 85oC

(YM water Concentration:100x)• Increasing CR With Temperature (YM

Waters: 1x, 10x)

0

200

400

600

800

1000

1200

1400

1600

0 20 40 60 80 100

Temp erature (C)

μ

273 293 313 333 353 373

Temp erature (K)

1x (Nitrogenated)10x (Nit rogenated)100x (Nitrogenated)1x (Oygenated)10x (Oygenated)100x (Oygenated)Immersion Tests-AirYM W. Spray Cyclic HumidityK

C H- 8 8 7

Y M W S - 8 14

N I- 513

P I- 9 6 0

C I- 2 0 0

C I- 4 5

LONG-TERM TES TS (Fille d S ymbols) YMWS = YM Wa t e r S pra y (1x)CH= Cyc lic Humidit y (1x)P I= P a rt ia lly Imme rse d (1x)NI= Non Imme rse d (1x)CI= Comple t e ly Imme rse d (1x)

Nitrogenated

Oxygenated

Oxy

gena

ted

Rock Bolts (0.44%C)


Temperature Effects on CR of Rock Bolts (0.44%C) in Aerated (Oxygenated) YM waters

0

200

400

600

800

1000

1200

20 30 40 50 60 70 80 90

Temperature (degree of celcius)

Cor

rosi

on R

ate

(mic

ron/

year

)

1X10X100X

Ix and 10x YM waters → Similar Behavior

100x → Different Behavior with a Maxima at~45oC

Corrosion Rates vs Temperature in AERATED YM Waters

Potentiodynamic Polarization of aerated 1x YM Water

-1-0.9-0.8-0.7-0.6-0.5

-0.4-0.3-0.2-0.1

0

1.E-07 1.E-06 1.E-05 1.E-04 1.E-03 1.E-02 1.E-01

Current Density(A/cm2)

Pote

ntia

l(V);v

s Ag

/AgC

85oC

25oC1X YM Water

Tem.Eff in 100xo

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

1.E-08 1.E-06 1.E-04 1.E-02 1.E+00

Curent Density(A/cm2)

Pote

ntia

l(V)

25456585

Rock Bolt Potentiodynamic Scans Showing Temperature Effect on Icorr

45oC

100X YM Water

-1.0

-0.9

-0.8

-0.7

-0.6

-0.5

-0.4

1.0E-09 1.0E-07 1.0E-05 1.0E-03


Appl

ied

Pote

ntia

l (V)

25oC

85oC

75oC

45oC

90oC


I-Beam-Baseline Studies Potentiostatic and Dynamic Test

0.00E+00

2.00E-07

4.00E-07

6.00E-07

8.00E-07

1.00E-06

1.20E-06

0 10000 20000 30000 40000 50000 60000 70000 80000

Time (sec)

Perm

eati

on C

urre

nt (I

p, a

mp/

cm2 ) HCO3

- SiO32-

HCO3- +SiO3

2-

Baseline scan

Potentiodynamic Curves in water (0% NaCl) (A) With no extra added Ions (B) 0.01 M SiO3

2- (C) 0.5 M HCO3-, (D)

0.01 M SiO32- + 0.5 M HCO3

-

Silicate Ions do not play any role in passivation when present with Bicarbonate ion in Plain DI water

-1.5

-1

-0.5

0

0.5

1

1.5

2

1.00E-08 1.00E-07 1.00E-06 1.00E-05 1.00E-04 1.00E-03 1.00E-02 1.00E-01 1.00E+00

log I (A/cm2)

E (v

) vs A

g/A

gCl

0.5 M HCO3

-

0.01 M SiO32- + 0.5 M

HCO3-

With No Additions

0.01 M SiO3

2-

IcorrSilicate Icorr Bicarbonate

IcorrCombined

Ref. V. Deodeshmuk, et al. Corr. Science 2003

Monitoring of Potential -Effect of silicate and Bicarbonate ions on in

3.5 % NaCl Solution


0

1

2

3

4

5

6

278280282284286288290292294

Carbon, C(1s)

***

*****

***

C-H

0

0.5

1

1.5

2

2.5

3

522524526528530532534536538542544

Binding Energy (eV)

Oxygen O(1s)

***

*****

***

Intensity x 104

Fe(Hydroxide)

Intensityx 105

7007057107157207257307357400

0.5

1

1.5

***

**

Fe (2p3/2)

Fe (2p1/2)

Fe(Hydroxide) (Feo

)

Binding Energy (eV)

Iron Fe (2p)

-1

-0.9

-0.8

-0.7

-0.6

-0.5

-0.4

-0.3

-0.2

-0.1

0

1E-08 1E-07 1E-06 0.00001 0.0001 0.001 0.01 0.1 1log i

E(V

)vsA

g/A

gCl

0.01 M SiO32- + 0.5

M HCO3-

XPS spectra at pre-passivation potential in 0.01 M SiO32- + 0.5 M HCO3

-

120.4

51.6

36.9230.9625.820.6415.4810.32 5.16

0Fe HydroxideAnd Silica

FeCO3 +SiO2

Feo

DEPTH PROFILESFeCO3

SiO2

FeCO3

FeCO3

Sputter Depth (nm)

0 50

150

200

250

300

0

O1s

Fe2p

C1s

Si2p

102030405060708090

100

Ato

mic

Con

cent

ratio

n (%

)

0.01 M SiO32- + 0.5 M HCO3

-


Hydrogen Permeation In Steel sets and Rock Bolts

Permeability (J∞L)mols/cm.s x 10-11

Deff (cm2/s)x 10-7

Solubility Co (ppm)

Density of Trapping

Sites (N) x 1021/cm3

Steel sets (1st

transient)5.94 5.18 114.7 3.2

Steel sets (2nd

transient)

5.54 7.43 58.03 1.5

Rock Bolt (1st

Transient)

2.65 1.64 161.6 14.2

Rock Bolt (2nd

Transient)

3.2 2.42 132.2 7.9

lageff t

LD6

2

=effDLJC ∞=0

eff

L

DDCN

3°=

FAILJ /∞

∞ =

MATERIAL PROPERTY

Example of Immersion test-75oC-Corrosion rates Swellex RBImmersion test (first set)@750C in 1X YM Water-Aerated (Oxygen)

Fully-Immersed

Non-Immersed

Half-Immersed

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

0 100 200 300 400 500 600

Time(Hours)

Nor

mal

ised

Mas

s L

oss(

gm)

Corrosion rates@75oC in aerated(Air) for MCS and SwellexMn24

0

500

1000

1500

2000

2500

3000

1 2 3

1:Non-Immersed, 2:Half-Immersed ,3:Fully-Immersed

Cor

rosi

on R

ates

( μm

/yea

r)CR at 75C(MCS-Yilmaz) CR at 75C(SwellexMn24-Divi)

• Full Immersion

• Half Immersion

• Non Immersed

Immersion Corrosion test of Swellex Mn24 in 1X YM water @25oC-Nitrogenated

0.9982

0.9984

0.9986

0.9988

0.999

0.9992

0.9994

0.9996

0.9998

1

1.0002

0 100 200 300 400

Time(hours)

Nor

mal

ized

Mas

s Los

s (gm

)

Half-Immersed

Non-Immersed

Fully-Immersed

Normailzed Mass Loss at 250C in 1X YM Water-Aerated(Oxygen)

Sample#b(Non-Immersed)

Sample#a(Fully-Immersed)

Sample#c(Half-Immersed)

0.85

0.9

0.95

1

1.05

0 200 400 600

Time(Hours)

Nor

mal

ized

Mas

s (gm

)

Immersion of Swellex Mn 24 was done according to ASTM G-32.

For aerated and de-aerated specimens at room temperature, the highest corrosion rate is 622 and 50 μm/year respectively.

At 75oC in oxygen, the corrosion rate for fully immersed specimen is 885 μm/year.

For both MCS and Swellex Mn 24 steels the highest corrosion rate is observed for half immersed specimens as 1000 and 2598 μm/year.

Corrosion Rate (μm/year) 75oC (oxygen) 25oC(Oxygen) 25oC(Nitrogen) Swellex Mn 24 MCS Swellex Mn 24 Swellex Mn 24 Non-Immersed 1135 510 467 38 Half-Immersed 2598 1000 622 50 Fully-Immersed 885 200 264 16

Example of Swellex Mn 24-Immersion test-25oC-Corrosion Rates


0.955

0.96

0.965

0.97

0.975

0.98

0.985

0.99

0.995

1

1.005

0 1 2 3 4 5 6 7 8Time(days)

Mas

s(g)

Rockbolt

Steel set

0.994

0.995

0.996

0.997

0.998

0.999

1

1.001

0 5 10 15 20 25

Time(Days)

Mas

s(g)

Rock Bolt

Steel Set

Salt Spray and Humidity tests of Rock Bolt and I-Beam

Salt spray Fog Tests

Weight Loss

Humidity Chamber

Weight Loss

I beam corrosion rates are lower than that of rock-bolt in both in spray (Fog) conditions and Humid Environments of 1xYM water. The CR difference is higher in salt spray tests due to

the concentration cell effects.

I-Beam CR ~19 μm/yr

RB CR ~45 μm/yr

I-Beam CR ~910 μm/yr

RB CR ~800 μm/yr


“Static” - Strain Aging Phenomenon

Recovery of Yield Point due to Aging for a long time (months) to create Cottrell atmospheres.

This process can be accelerated with Temperature as it controls diffusion of atoms ( In Steels usually T < 400oC recovery is observed)

Cottrell – Bilby

f = Solute segregated to a Dislocation in time t

f = α. ρ.(A.D.t / kT)2/3

A= Interaction constant

D= Diffusion Coeeficient

ρ = Total Length of dislocation /unit volume

Harper

f = Solute segregated to a Dislocation in time t

f = 1- exp [α. ρ.(A.D.t / kT)2/3]

Stre

ss

Strain Strain

Strain Aging

• When Aging Occurs During deformation, the phenomenon is termed Dynamic Starinaging

• Dynamic Strain aging work hardening rate is abnormally high and also dependent on the Temperature and Strain rate.

• Increasing Temperature also increases the maximum work hardening

Dynamic Strain Aging Phenomenon


100xn85 Ecorr

0

100

200

300

400

500

600

700

800

0 1 2 3 4 5

Position(m m )

Load

(kg)

I-Beam (100xYM Water) at 85oC and at Ecorr

Lüder Bands

285

295

305

315

325

335

345

355

0.3 0.4 0.5 0.6 0.7Elongation(mm)

Load

(kg)

A

630

640

650

660

670

680

690

700

710

3.8 4 4.2 4.4Elongation(mm)

Load

(kg)

B

Dynamic Strain Aging (DSA) Occurred At 85°C at Ecorr Open Circuit Potential Portevin LeChatelier Effect

I-Beam in 100x YM water at Ecorr

-0.8

-0.6

-0.4

-0.2

0

Pote

ntia

l (V)

; vs

Ag/A

gCl

Ecorr

Plastic flow tends to become unstable leading to serrations


0

100

200

300

400

500

600

700

0 0.05 0.1 0.15 0.2 0.25Strain

Stre

ss (

MPa

)

85oC(+50 mV)I-Beam (100x YM waters)

25oC(+50 mV)

Stress Strain Curves of I-Beams At RT and 85 °C

25°C Ductile Failure with Secondary

Cracks85 °C Brittle

Failure

Dynamic Strain Aging (DSA) Occurred At 85°C at -650 mV (Ecorr~-700mV)

Portevin LeChatelier Effect

25 °C 85 °C

85oC (-650 mV)

25oC (-650 mV)


300

350

400

450

500

550

600

650

0 0.05 0.1 0.15 0.2 0.25Strain

Stre

ss(M

Pa)

MechanicalTest

-600 mVEcorr

-750 mV

-900 mV

-1200 mV

-650 mV

SSRT Behavior of I-Beam At Various Potentials in

100x YM Water

Ecorr -700mV

85 °C


250

300

350

400

450

500

550

0 0.05 0.1 0.15 0.2 0.25

Strain

Stre

ss(M

Pa)

Glycerine

-750-1200

-700 (Ecorr)

-900 -650-600

Inert environment

Effect of High Cathodic Charging in

100x YM Waters

Room Temperature Scans at Various Potentials Showing No Dynamic StrainAging Effects on the Low Carbon Steel in 100x YM Deaerated Waters

Room Temperature


0

100

200

300

400

500

600

700

0 0.05 0.1 0.15 0.2 0.25 0.3Strain

Stre

ss(M

Pa)

25 oC

85 oC

Areas which are the measure of ductilities at 25 oC and 85 oC

Figure 4c.12. Ductility differences of LCS revealed by mechanical tests at RT and 85 oC in air with the strain rate 10-6/s . The difference in the rectangular surface areas as a measure of ductility shows the increased embrittlement in the steel due to strain aging, or PLC effect.

Metallurgical and Materials Engineering University of Nevada, Reno Results


-6.E-04

-5.E-04

-4.E-04

-3.E-04

-2.E-04

-1.E-04

0.E+00

1.E-04

2.E-04

0 20000 40000 60000 80000 100000 120000Time(s)

Cur

rent

(A)

-0.0077

-0.0067

-0.0057

-0.0047

-0.0037

-0.0027

-0.0017

-0.0007

0.0003

Cur

rent

(A)

-600 mV

-650 mV

- 700 mV

-750mV

-900 mV

-1200 mV (refer to right hand side axis)

-600

-650

-750-900

-1200

25°C

-5.0E-05

-4.0E-05

-3.0E-05

-2.0E-05

-1.0E-05

0.0E+00

1.0E-05

2.0E-05

0 20000 40000 60000 80000 100000 120000

Time(s)

Cur

rent

(A)

-650 mV

-600 mV-700 mV

-750 mV

These two curves are referred to the right hand side axis

-1.6E-03

-1.2E-03

-8.0E-04

-4.0E-04

-6.0E-02

-4.0E-02

-2.0E-02

0.0E+00

-650-700

-600

-750

-900

-1200

85°C

Possible SCC

Secondary Cracks, SCC

Current Transients at RT and 85 °C

Time(s)


620

640

660

680

700

720

740

760

31000 36000 41000 46000 51000 56000 61000 66000 71000Time(s)

Loa

d(kg

)

-0.71

-0.69

-0.67

-0.65

-0.63

-0.61

-0.59

32700 42700 52700 62700 72700

Pote

ntia

l(V),

vs A

g/A

gCl

Correlated Ecorr change with the serration amplitudes of PLC effect in Low Carbon Steel during SSRT in YW water caused a large amount of potential change at the interface of LCS and the Test Solution.

Plots of Load vs Elongation and Ecorr vs Time (sec) during a SSRT A Test in YW water at the Constant Strain Rate of 1.6x10-6/s

Potential

85oC

50oC 55oC65oC

85oC

Specimen Failure

Load

1.3 1.8 2.3 2.8 3.3 3.8 mm

600

620

640

660

680

700

720

740

1.3 1.8 2.3 2.8Elo ngat io n(mm)

Load vs Elongation Curve

Elongation

70oC


10

20

30

40

50

60

70

80

1.0E-07 1.0E-06 1.0E-05 1.0E-04 1.0E-03 1.0E-02

Strain Rate(1/s)

Red

uctio

n of

Are

a(%

)

85 oC

25 oC

Embrittlement by Strain Aging and Hydrogen

Stress Corrosion Cracking

Measure of Ductility by R of A Obtained At Various Slow Strain Rates Ranging From 10-3/s to 10-7/s at 25oC and 85oC

for I-Beam Supports at Ecorr -700 mV

Metallurgical and Materials Engineering, University of Nevada, Reno Results


General Cracking Modes of I-Beam (1.6x10-7/sec) 25 °C, Air

Ductile Failure85°C Elec-Mech

Inner Longitudinal

Cracks

Load

Load

T G

I G

T G

I G

25°C Elec-Mech.

Secondary Cracks

25oC (@Ecorr = *-700mV)

25oC (*Potential -900oC)

*Potential Reference Ag/AgCl Electrode


Fracture Morphology of I-Beam at 25°C and 85 °C


Ductile FailureSSRT Air - 25 °C

Quasi cleavage-slip Mode

SSRT 85°C 100xYM Waters

Transgranular Cracks

The ridges are due to PLC effect. Average length ~0.4 mm

SSRT 25°C 100xYM Waters

Semi-planar Transgranular cracking mode


0

10

20

30

40

50

60

70

-1300 -1200 -1100 -1000 -900 -800 -700 -600 -500 -400Potential(mVAg/AgCl)

Rof

A(%

)

25 oC85 oC

19

21

23

25

27

29

31

33

-1300 -1200 -1100 -1000 -900 -800 -700 -600 -500 -400

Potential(mVAg/AgCl)

Elo

ngat

ion(

%)

25 oC

85 oC

Measure of ductility by Reduction of Area values of I-Beam Under

various specimen Potentials at Room Temperature and 85oC

Measure of Ductility of I-Beam Under Various Specimen Potentials at Room temperature and 85 oC

Measure of ductility by % Elongation of LCS under various

specimen potentials at Room Temperature and 85oC



OXIDATION KINETIC STUDIES OF ROCK BOLTS

nWy ktA

⎛ ⎞⎜ ⎟⎝ ⎠

= =Oxidation Rate Law: (W/A) is the weight gain per unit area at time t,

k is the rate constant, and

n is the time exponent of the rate law.

Isothermal and non-isothermal kinetics can be given by:

)().( αα fTkdtdr ==

α is the extent of reaction,

k(T) is the temperature dependent rate constant (a constant value for isothermal experiments)

0 expaEk k

RT⎛ ⎞−Δ

= ⎜ ⎟⎝ ⎠

The rate constant follows an Arrhenius expression

( )0( ) sin 2avg TT t T t A t Pβ π= + + ⋅

Temperature profile in a typical modulated thermogravimetric analysis:

βavg = underlying heating rate = 0 (isothermal)

( )sin 2TA t Pπ ⋅ (A time varying perturbation to the isothermal T0temperature )


2.22 x 10-4

2.67 x 10-40.7709

0.7900

7.122 x 10-5

6.5 x 10-50.7013

0.7825

9.27 x 10-5

6.24 x 10-50.6685

0.7750

0.41775.04

1.60 x 10-5

4.05 x 10-50.7859

0.7675

Mn-24

9.35 x 10-4a

2.71 x 10-40.5828a

0.7900

2.3212 x 10-4

1.433 x 10-40.7302

0.7825 3.693b92.81b

2.44 x 10-5

6.72 x 10-50.7968

0.7750SS-46

ko(kg2m-

4s-0.7)

Activation energy

(kJ/mol)b

Rate constant (k)(kg.m-2s-n)a

Index of Rate

Law (n)

T(oC)

Material

Time constants (n), Rate constants (k), activation energies and pre-exponential factors (k0) for the HSLA steels in the first oxidation regime.


SUMMARY

Effect of Temperature Under Electrochemical EnvironmentDynamic Strain Aging Effects (Portevin Le Chatelier Effect) occurs at ~70°C contributing to significant embrittlement under YM simulated repository environmentsCorrosion rates of Rock bolts and I-beams

Hydrogen Permeation

Oxidation Studies

Salt Spray and Immersion Tests

Future Studies

•Mechanistic –XPS Studies

•Stress Corrosion Cracking further

•Oxidation Kinetic Studies

•Potentiodynamic and Potentiostatic studies


Thank you

Metallurgical and Materials Engineering University of Nevada, Reno

We Thank YM US DOE for Support of this Project

We also thank DOE Program Managers and HRC Directors and QA staff for their Cooperation and Help on the project


YM Water (Salt) Spray Tests

Specimens shown after 48 hour exposure

period.

After

C.Rate = ____________K x WA x T x D

The corrosion rates have been determined from the weight loss measurements of rock bolt and I-beam coupon specimens for 35oC.

Rate of Rock Bolt: 814 μm/year

Rate of I-Beam: 970 μm/year

CR values are close to the Partial immersion values. Coupon surfaces in this case were exposed to YM water partially too, during the entire fog type exposure time.

Before

Rock Bolt Specimens

I-Beam


Figure 3.1.2 Potentiodynamic scans for SS46 type rock bolts in aerated simulated 1x YM water at different temperatures.

Figure 3.1.3. Corrosion rate as a function of temperature (aerated) in 1x YM water.

0

1000

2000

3000

4000

5000

6000

20 30 40 50 60 70 80 90 100

Temperature (0C)

Cor

rosi

on R

ate

( μm

/y)

-0.70

-0.60

-0.50

-0.40

-0.30

-0.20

-0.10

0.00

1.00E-08 1.00E-07 1.00E-06 1.00E-05 1.00E-04 1.00E-03 1.00E-02


App

lied

Pote

ntia

l (V)

25C

45C

90C

65C


The films formed in the aerated YM waters are different in nature with compared to the deaerated ones; They are not see through, thick and softer.

Etched outrock bolt

Metal

Surface Film Formation and Pitting in 100x YM waters at 85oC

Results



Precipitate layers formed on I-Beam at 25°C in 100x YM waters at RT. The scale peals of easily when they meet dry air after taken out of the cell. However the high temperature films are non porous and see through.

85°CRT


The precipitate layer at 25 °C,

Porous scale lets EDX electrons to enter Fe

underneath

Mostly chloride and oxide scales with less

solubility at Low temperatures

The precipitate layer at 85°C,

Nonporous and more protective layer

Possible Silicon oxide or magnesium chloride

Mn and Fe absence

Scale differences at RT and 85°C on I-Beam Tensile Specimen


25 oC 85 oC



SUMMARY (Cont’d)

Environmentally Assisted Cracking of I-Beams (0.08%C)

100x YM waters

I-Beams are susceptible to SCC at 25°CEffect of Temperature Under Electrochemical Environment•Dynamic Strain Aging Effects (Portevin Le Chatelier Effect) occurs at ~70°C contributing to significant embrittlement under YM simulated repository environments

Isothermal Tests

High Temperature (85oC)

•Dynamic Strain Aging Effects occur at electrochemical potentials in I-Beams

•Hydrogen Induced Cracking occurs at the cathodic interface potentials; and also hydrogen blistering

Room Temperature•Stress Corrosion Cracking occurs under applied potentials in I-Beams

Metallurgical and Materials Engineering University of Nevada, Reno


Repeatability test of the Set-Up with SS 304 in NaOH

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

1.00E-08 1.00E-07 1.00E-06 1.00E-05 1.00E-04 1.00E-03 1.00E-02 1.00E-01 1.00E+00

Current Density(A/cm2)

Pote

ntia

l vs

SCE,

(V)

F432 inTap Water, Aerated by Air as 150ml/min

-1.4

-1.2

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.0000001 0.000001 0.00001 0.0001 0.001 0.01 0.1 1


Pote

ntia

l vs

SCE

(V)

Repeability of the Experimental Set-Up

Repeatibility tests are the preliminary experiments which should be done to make sure the results are able to be produced with in acceptable accuracy range. In our case it is less than 20 mV voltage change range which is well accepted by the ASTM Stardards.



Summary of the Rates (micron/year)Electrochemical RB (Deaerated) Immersion RB (1x) YM Water

spray (1x)

1x

10x

100x

25oC 45oC 65oC 85oC

35 55 110 160

50 65 109 162

45 62 107 159

Electrochemical (Aerated)

1x

10x

100x

25oC 45oC 65oC 85oC

100 250 550 1100

101 300 710 1050

210 480 220 150

75oC200

513

960

fully

Hum.air

partially

35oC

814

970

RB

I-Beam

Aer

ated

Aer

ated

ambi

ent

Aer

ated

Humidity Chamber

19

45

Dea

erat

ed

RB

SS

25oC 75oC

45 200



Taken out before the pitting potentials. Deaerated 65oC YM water. Shows protective film formation over the surface

Continued scan over the pitting potentials, and observed pitting

Surface Films Formed on Rockbolts in Deaerated Waters

Results



Deaerated

Film formations specimens YM Waters

Inclusions


Aerated

White Precipitate


Polarization plots of I beam samples in Nitrogenated 100x solution

-1.2-1

-0.8-0.6-0.4-0.2

0

-8 -6 -4 -2 0

Log (i) A/cm2

Ecor

r (V

) vs

Ag/

AgC

l

25oC (Blue)

45oC (Purple)

85oC (Brown)

65oC (Dark Green)

-6 -4 -2 0

log (i) A/cm2

25oC (Blue)

45oC (Purple)85oC (Brown)

65oC (Dark Green)

Polarization plots of I beam samples in Oxygenated 100x solution

-1-0.8-0.6-0.4-0.2

00.2

-8 -6 -4 -2 0

Log (i) A/cm2Ec

orr(

V) v

s A

g/A

gCl

25oC (Blue)

45oC (Purple)

85oC (Brown)

65oC (Dark Green)


Polarization Plots of I-Beam in 1x Oxygenated Solution


100xn85 Ecorr

0

100

200

300

400

500

600

700

800

0 1 2 3 4 5

Position(mm)

Load

(kg)

I-Beam (100xYM Water) at 85oC and at Ecorr

Lüder Bands

0

100

200

300

400

500

600

700

0 0.05 0.1 0.15 0.2 0.25Strain

Stre

ss (

MPa

)

85oC(+50 mV)I-Beam (100x YM waters)

25oC(+50 mV)


Lüder Band and Dynamic Strain Aging Effect at 85 °C

I-Beam in 100x YM water at Ecorr

Open circuit Potential Portevin LeChatilierEffect


Polarization Plots of I-Beam in YM 1x Solution


-1.2-1

-0.8-0.6-0.4-0.2

0

-8 -6 -4 -2 0

Log (i) A/cm2

Ecor

r (V

) vs

Ag/

AgC

l

25oC (Blue)

45oC (Purple)

85oC (Brown)

65oC (Dark Green)

Polarization plots of I beam in 1x nitrogenated solution

-1.2-1

-0.8-0.6

-0.4-0.2

0

-8 -6 -4 -2 0

log (i) A/cm2

Ecor

r (V

) vs

Ag/

AgC

l

25oC (Blue)

45oC (Purple)

85oC (Brown)

65oC (Dark Green)



-1

-0.8

-0.6

-0.4

-0.2

0

0.2

-8 -6 -4 -2 0

log (i) A/cm2Ec

orr

(V) v

s A

g/A

gcl


-1-0.8-0.6-0.4-0.2

00.2

-8 -6 -4 -2 0

Log (i) A/cm2

Ecor

r(V

) vs

Ag/

AgC

l

25oC (Blue)

45oC (Purple)85oC (Brown)

65oC (Dark Green)

igure 2. Polarization plots of steel set samples measured in YM water under deaerated conditions at different temperatures. (top left) 1x (bottom left)1

igure 3. Polarization plots of steel set samples measured in YM water under aerated conditions at different temperatures. (Top right A) 1x (Bottom Ri


YM-DOE Program Review -DRI, Reno 1-18-07Metallurgical and Materials Engineering, University of Nevada, Reno Results


Figure 4c.4. SSRT Fracture characteristics of LCS strained at a constant rate of 1.6X10-

6/s in air and 100X deaerated YM water at 25 oC and 85 oC. Columns A, B, and C show mechanical test at RT, environmental test at 25 oC, and

environmental test at 85 oC, with imposed Ecorr(-700 mVAg/AgCl). The first row shows half of the fracture surface and the second shows the gauge length

portion at the fracture location.


Mech. test 25oC 85oC


Inner wall details of QC modes in I-Beam Failed by SSRT at 85oC. The ridges observed with PLC effect, and they showed an average length around 0.4 micron.



B


SCC tested YM I-beam specimens tested at100x YM water concentration at 85oC.

(A) Ecorr (B): 50mV above Ecorr, and (C) 100 mV above Ecorr

Scanning electron micrographs of steel sets strained at the rate 10-6/s: (A) Failed in air (B) Using 100x YM water environment.


Figure 4c.7. Quasi-cleavage(A) and discontinuous planar cleavage(B) crackingmodes of LCS at 85 oC.



50

55

60

65

70

75

80

85

90

500 700 900 1100 1300

Ti ( i t )

Tem

pera

ture

(oC

)

1

23

4

56

-0.74

-0.72

-0.7

-0.68

-0.66

-0.64

-0.62

-0.6

-0.58

550 650 750 850 950 1050

Time(s)

Pote

ntia

l(V);

vs

Ag/

AgC

l

1

2 3

4

56



During strain aging, the interface potential shifts to more cathodvalues. There are precise correlations determined between the amplitudes of serrations and the interface potential, and also corresponding current. This result from this work on I-beam maapply to the other metals as well and the methods can be used investigation tools for understanding PLC effects in depth.

Summary

Electro-mechanical tests methods we used can be useful for investigating PLC Effects in the other metals and alloys.



Section xx

x x

8”

A B C


Stress Corrosion Cracking Tests on Yucca Mountain I-Beam Supports Low Carbon Steel (0.08%C) Using SSRT Universal

Testing Machine

-1.2

-1

-0.8

-0.6

-0.4

-0.2

0

1.E-07 1.E-05 1.E-03 1.E-01Log I(A/cm2)

Pote

ntia

l (V)

; vs

Ag/A

gCl

Ecorr

- 620mV- 680mV

AnodicRegion

Cathodic Region


Actual Swellex Rock bolt-Before Expanding

Idealized Shape before and After Expanding

2B.3

2B.2 (a) 2B.2 (c)

2B.2 (b) 2B.2 (d)

2B.2 (e)

Expanded StateAs Received


US DOE Sub surface Materials Support Program for the YM Nuclear Materials Storage

DOE Designs

DOE- Approves

Sub surface Metallurgical Materials Evaluation Mainly:

Universities (UNR) –Independent Evaluation of

Various Properties

DOE Site License –Nuclear Regulatory

Commission

Canisters for Nuclear Materials Storage

US National Laboratories –

Lawrence Livermore National Laboratory and

Sandia National Laboratory

Technical Advisory and Scaled testing of Materials

Quality Assurance Program Monitored BY DOE for all our

research


Nuclear Repository Site Tunnel Configuration

At Yucca Mountain Near Las Vegas, Nevada

Background

Water Table

800’ below

1200 feet


-1.2

-1

-0.8

-0.6

-0.4

-0.2

0

1.E-08 1.E-07 1.E-06 1.E-05 1.E-04 1.E-03 1.E-02 1.E-01


Pot

entia

l (V

); vs

Ag/

AgC

l

25oC45oC 65oC

85oC

Potentiodynamic Scans for Rock Bolt at Various Temperatureswith Deaeration by Nitrogen

Anodic

Cathodic

Potentiodynamic Scans for Rock Bolt in Simulated YM Waters(1x)

Effect of Temperature Potentiodynamic Results –Temp.


-1.2

-1

-0.8

-0.6

-0.4

-0.2

0

1.E-08 1.E-06 1.E-04 1.E-02 1.E+00

Curent Density (A/cm2)

Pote

ntia

l (V)

; vs

Ag/

AgC

l

Polarization of rockbolt in 1X YM water at 25,45,65,85 oC

0

500

1000

1500

2000

2500

3000

3500

4000

0 1000 2000 3000 4000 5000

Re Z(ohms)

Im Z

(ohm

s)

25oC

45oC

65oC

85oC

Impedance Spectra Taken at Ecorr=~-0.75 V

βa. βcB =

2.3 (βa+βc)

Rock Bolt Temperature Effects and Complementary Impedance Spectroscopy on

Medium Carbon Steel (0.44%C) - Deaerated Conditions

Decreasing semi circle radius(polarization resistance) with temperature

Increasing Icorr(Corrosion Rate) with temperature

25oC45oC

65oC

85oC

icorr= B/Rp

Stern-Geary Equation


-1.2

-1

-0.8

-0.6

-0.4

-0.2

0

1.0E-09 1.0E-07 1.0E-05 1.0E-03 1.0E-01 1.0E+01


Pote

ntia

l(V);v

s A

g/A

gCl

Rock Bolt Concentration Effects of Deaerated Yucca Mountain Waters on at Room Temperature

Polarization of Rockbolts Using 1x,10x and 100x YM waters at 25oC

As expected, there is some Effect of Concentration on Corrosion Behavior of Rock Bolt (RB) in DEAERATED YM waters. CR’s increased slightly with ionic concentration

1x10x

100x

0

500

1000

1500

2000

2500

3000

3500

0 1000 2000 3000 4000Real Z(ohms)

Im Z

(ohm

s)

Impedance Spectra at Ecorr(-0.760 V) for 1x,10x, 100x YM Waters

1x

10x

100x


020406080

100120140160180

10 20 30 40 50 60 70 80 90 100

Temperature (oC)

Corr

osio

n Ra

te (m

icro

n/ye

ar)

10X

100X1X

Corrosion Rates Showing Temperature and Concentration Effects (Rock Bolts-RB)

Rate (25oC): 30 to 45 μm/yr

Rate (85oC) :160 to 165 μm/yr

Corrosion Rates vs Temp. In the DEAERATED YM Waters With Different Concentrations

Expected small Changes in Corrosion Rates from the 1x to 100x Deaerated YM waters at a given temperature from RT to 85 oC.

25 85

Rate = ___________C. EW. icorr

D

Deaerated



-1-0.8-0.6-0.4-0.2

00.2

-8 -6 -4 -2 0

Log (i) A/cm2

Ecor

r(V

) vs

Ag/

AgC

l

25oC (Blue)

45oC (Purple)

85oC (Brown)

65oC (Dark Green)

Temperature Effects on Icorrof I-Beam Using 100x YM

Deaerated/Aerated WatersResults Show CR Peaking at ~45oC Trend for all the YM Concentrations Similar (to RB) in the Next Slide


-1.2-1

-0.8-0.6-0.4-0.2

0

-8 -6 -4 -2 0

Log (i) A/cm2

Ecor

r (V

) vs

Ag/

AgC

l

45oC (Purple)

85oC (Brown)

65oC (Dark Green) 25oC (Blue)


0

200

400

600

800

1000

1200

1400

1600

0 20 40 60 80 100

Temperature (C)

μ

273 293 313 333 353 373

Temperature (K)

1x (Nitrogenated)10x (Nit rogenated)100x (Nitrogenated)1x (Oygenated)10x (Oygenated)100x (Oygenated)Immersion Tests-AirYM W. Spray Cyclic HumidityK

C H- 8 8 7

Y M WS - 8 14

N I- 513

P I- 9 6 0

C I- 2 0 0

C I- 4 5

LONG-TERM TES TS (Fille d S ymbols) YMWS = YM Wa t e r S pra y (1x)CH= Cyc lic Humidit y (1x)P I= P a rt ia lly Imme rse d (1x)NI= Non Imme rse d (1x)CI= Comple t e ly Imme rse d (1x)

Nitrogenated

Oxygenated

0

200

400

600

800

1000

1200

1400

1600

0 20 40 60 80 100

Temp erature (C)

μ

273 293 313 333 353 373

Temp erature (K)


10x (Nit rogenat ed)


1x (Oygenat ed)

10x (Oygenat ed)

100x (Oygenat ed)

YM Wat er Spray

Cyclic Humidit y

K

C H- 12 6 5

Y M W S - 9 70

LONG-TERM TES TS (Fille d S ymbols) YMWS = YM Wa t e r S pra y (1x)CH= Cyc lic Humidit y (1x)

Nitrogenated

Oxygenated

Figure 1(left) Effect of temperature and electrolyte concentration (1,10, and 100x), and oxygen (aerated/deaerated) concentration on the corrosion rate (μm/year) of Rock bolts. Note: the data points in bold symbols with corrosion rates inμm/year are of the conventional (long-term) ASTM Immersion experiments, YM water spray and humidity tests on rock bolt samples.

Figure 1(right) Effect of temperature and electrolyte concentration (1,10, and 100x), and oxygen (aerated/deaerated) concentration on the corrosion rate of I-beam. Note the data points of long-term YM water spray and humidity tests.

Wiliam’s Rock Bolt Low Carbon Steel I–beam from YM site

Summary of Corrosion Rates - 1


The precipitate layer at 25 °C

Porous scale lets EDX electrons to enter Fe

underneath

Mostly chloride and oxide scales with less

solubility at Low temperatures

The precipitate layer at 85°C

Nonporous and more protective layer

Possible Mg-Si oxide or magnesium chloride

Mn and Fe absence

Scale differences at RT and 85°C on I-Beam Tensile Specimen

Split set-Potentiostatic Scans – Effect of Potential

- 700 mV -600 mV - 400 mV

+200 mV

Fluctuation of current at -700mV and -600mV suggests a formation of unstable pitAt -400mV further increase in current represent a stable pit formation

Results -27

25°C

Swellex Mn24 rock bolt –Potentiodynamic scan-Corrosion Rates Corrosion Rate of Swellex Mn 24 rock bolt in 1X YM water

0

500

1000

1500

2000

2500

25 45 65 90

Temperature(oC)

Cor

rosi

on R

ate

( μm

/yea

r)

De-aerated (Nitrogen)

Aerated (Oxygen)

Corrosion Rate of Swellex Mn 24 rock bolt in YM water concentrations

0

50

100

150

200

250

300

1 10 100

YM water concentration (X times)

Cor

rosi

on R

ate

( μm

/yea

r)

De-aerated (Nitrogen)

Aerated ( Oxygen)

Corrosion rates of Swellex Mn24 rock bolt in aerated conditions are higher at all temperature than in de-aerated conditions.

At ambient conditions, rock bolt corrodes at 30μm/year in de-aerated 1X YM water and 145μm/year in aerated 1X YM water. At 90oC, corrosion rates are 227 and 2269 μm/year for de-aerated and aerated respectively.

In de-aerated and aerated conditions, corrosion rate of rock bolt increased with the concentration. Highest corrosion rate in de-aerated and aerated conditions was observed in 100X solution as 110 and 240 μm/year respectively.


2.3

2.32

2.34

2.36

2.38

2.4

2.42

2.44

2.46

2.48

0 10 20 30 40 50 60 70 80 90 100 110 120

Time (days)

Mas

s (g

r)

Mass Loss of Rock Bolt in 1x Yucca Mountain Waters at 25oC

Corrosion Rate: 45 micron/year

C

Rate = ____________K x WA x T x D

Experimental set-up

Basic Laboratory Immersion Corrosion Experiment at Room Temperature (25oC)


Weight Loss of Rockbolt In YM Water at 75 oC.

0.7

0.75

0.8

0.85

0.9

0.95

1

1.05

0 100 200 300 400 500 600

Time(hours)

Mas

s(g)

Effect of Immersion Position at 75oC 1x YM Water

513 μm/yr

960 μm/yr

200 μm/yr

Concentration Cell Effects increases the corrosion rates of rock bolt at the YM water-Humid air borders.• Full Immersion

• Half Immersion

• Non Immersed

sub-surface corrosion research on rock bolt system

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