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1
O AK RIDGE NATIONAL LABORATORY
U. S. D EPARTMENT OF ENERGY
Neutron Scattering for Engineering
Materials at HFIR - ORNL
Camden R. Hubbard
Residual Stress User Center
Diffraction and Thermophysical Properties Group
Materials Science and Technology Division
Oak Ridge National Laboratory
ANSWER Tour at ORNL
November 8, 2006
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O AK RIDGE NATIONAL LABORATORY
U. S. D EPARTMENT OF ENERGY
ORNL Residual Stress User Center’s Unique X-ray,
Synchrotron & Neutron Facilities for Stress Mapping
Determining stress at difficult locations in large and small specimens
at ambient or at elevated temperature and/or under applied load
• Large or small specimens
• Flat or curved
• Thin films or bulk
• Ambient or elevated
temperature or load
Contact: Camden Hubbard
http://html.ornl.gov
Neutron Kappa
Neutron XYZ
X-ray large
specimen
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O AK RIDGE NATIONAL LABORATORY
U. S. D EPARTMENT OF ENERGY
Outline
• HFIR upgrades and instruments for engineering materials
studies
• Design, construction, installation, and performance of
NRSF2 at HFIR
• Highlights of research projects (during commissioning)
• Summary
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O AK RIDGE NATIONAL LABORATORY
U. S. D EPARTMENT OF ENERGY
High Flux Isotope Reactor at ORNL is One of The
Two High Flux Reactor Facilities Worldwide
Commissioning of new scattering
instrument began in 2004. Goals is 15
new instruments.
HFIR Upgrades:
Be reflector replacement
new beam tubes
addition of cold source
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O AK RIDGE NATIONAL LABORATORY
U. S. D EPARTMENT OF ENERGY
Operating Instruments at HFIR by
April 2007
• Thermal Neutrons
− Triple axes instruments (HB1, HB1A, HB3)
− Neutron Residual Stress Mapping Facility (NRSF2)
− Wide Angle Neutron Diffractometer (WAND)
− Four Circle (Single Crystal) Diffractometer
• Cold Neutrons
− Small Angle Neutron Scattering (40 and 35-m SANS)
(light blue = commissioning phase)
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O AK RIDGE NATIONAL LABORATORY
U. S. D EPARTMENT OF ENERGY
Design, Construction,
Installation, and Performance
of the
2 nd Generation Neutron Residual
Stress Mapping Facility (NRSF2)
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O AK RIDGE NATIONAL LABORATORY
U. S. D EPARTMENT OF ENERGY
• Slits close to specimen (reactor - high
efficiency) define gage volume
• Measured strain component is in the
direction parallel to the scattering
vector Q
• XYZ translations for moving sample for
mapping throughout
• Specimen rotation or remounting
permits measurement of various strain
components
− Determination of either an individual strain
component or the full strain/stress tensor.
• Method is generally non destructive
and measures throughout the thickness
of the sample .
Measurement Volume in Neutron Diffraction
Mapping is Defined by the Neutron Optic Elements
Incident Beam
Incident Beam Slit
Diffracted Beam Slit
Detector
Specimen
Q
(Scattering Vector)
2 q
- -
- -
1
2
Sampling or gage volume
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O AK RIDGE NATIONAL LABORATORY
U. S. D EPARTMENT OF ENERGY
NRSF2 Is One of Four New Instruments to
be Installed Around HFIR’s HB-2 Tunnel
Dedicated location - 100%
of time for materials
science and engineering
New doubly focusing, Si
wafer monochromator
higher flux
five wavelengths
Large capacity XYZ
goniometer
Seven PSD detector array
high efficiency
Load frame
Furnaces
Huber phi-chi orienter
Advanced software
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O AK RIDGE NATIONAL LABORATORY
U. S. D EPARTMENT OF ENERGY
The Popovici-Stoica Stacked Si Wafers, Double Crystal,
Doubly Focusing Monochromator Provides Five Choices of l
from 1.45 to 2.67 Å and Major Flux and FWHM Enhancements
70 75 80 85 90 95 100 105 110
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
Ge(511)
Ge(422)
CaF
2
(420)
mbend 40
mbend 60
mbend 80
mbend 100
mbend 120
mbend 139
optimum eperimental limit
theoretical expectation
FWHM [ 0 ]
2 q [ 0 ]
Si 331
Ge(400)
CaF
2
(422)
Ge(331) Mo(211)
FWHM optimized by
changing the bending radius
0.6Al 311 6.3 6 3
Ni 220 16 15 0.69
Fe 211 11 12 0.54
FWHM
Ratio
Integrated
Intensity
Ratio
Peak
Intensity
Ratio
Phase
hkl
With addition of 7-detector
array the gains, depending
on wavelength, will be from
30 to 80x !
Performance enhancements compared
to first generation NRSF (1991-2000)
(both used single PSD detector)
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O AK RIDGE NATIONAL LABORATORY
U. S. D EPARTMENT OF ENERGY
X Y Z W & 2Q Stages Provide High Accuracy
with Flexibility for Small and Large Samples
• Mechanically rigid, highly
reproducible positioning
− 500 kg load directly on XY
− Rotation stages
2q accuracy of 0.001°
W accuracy of 0.003°
− Translation stages
X-stage - 400 mm
Y-stage - 200 mm
accuracy - 0.01 mm
• Accessories (HTML & CNS)
− Load frame (5000 lbs force)
− Huber chi-phi orienteer
− Vertical Z-stage (50 kg, 400 mm)
− Z-Elevator (450 kg, 200 mm)
− Furnaces(gas, vacuum, induction)
− 5T Superconducting magnet with
induction heater insert
Large area and 3T overhead crane for
mounting large specimens or accessories
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O AK RIDGE NATIONAL LABORATORY
U. S. D EPARTMENT OF ENERGY
System Calibration is Precise and Accurate
100 120 140 160 180 200 220 240 260 280 300
80.5
81.0
81.5
82.0
82.5
83.0
83.5
84.0
Value Error
-----------------------------------------------------
D2q /Dchannel 0.01921 1.27E-5
2 q
channel number
70 75 80 85 90 95 100 105 110
-0.005
-0.004
-0.003
-0.002
-0.001
0.000
0.001
0.002
0.003
0.004
0.005
RMS
2 q
Max error of
reference peak
positions ~0.002°2 q
PSD channel to
2 q conversion
very linear
Calibration powders:
• Ni, Fe, Mo, Ge, CaF 2 reference powders
• Accurate lattice parameters for each from XRD
with SRM Si standard and cell refinement
• Reproducible mount of calibration samples
Calibration Steps
• PSD intensity response
• Conversion of channel
number to angle
• Out of Plane detectors
• Finite detector height
• Fit 2q0 and l
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O AK RIDGE NATIONAL LABORATORY
U. S. D EPARTMENT OF ENERGY
Load Frame Developed via LDRD Project
for In-situ Deformation & Materials Behavior Studies
• An automated load frame has been
developed to study specimens
under large uniaxial loads for in-situ
deformation studies.
• Key features include:
– 5000 lbf. loading capacity
– Tension/compression (static)
– Low cycle fatigue (dynamic)
– Automated load control and macrostrain
recording
– Fast data collection (6 sec) allows
continuous strain rate experiments
– Z-elevator provides for mapping
about crack tips under loads
• A wet-chemical, environmental cell
is being developed for:
− hydrogen charging
− cathodic protection
− corrosion studies
Specimen
(-)
(+)
(ref)
Mechanical
Loading
Potentiostat
In-Situ
Neutron
Diffraction
(- )
Environmental cell
for electrochemical
charging
NRSF2’s
load frame
ready to be
lifted from
cart onto
XYZ unit
Tensile testing
sample geometry
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O AK RIDGE NATIONAL LABORATORY
U. S. D EPARTMENT OF ENERGY
AL2024 Continuous Loading Versus Step
Loading Yields Similar Results >50% Faster
Neutron data collection times:
• Step loading
• raise load, hold and count
• 2 min/point and 30 different
loads --> 60 min.
• Continuous loading
• 15 sec/point for 25 min.
• extended to greater strain
• eliminates potential creep 0.00 0.02 0.04 0.06 0.08 0.10 0.12
-0.001
0.000
0.001
0.002
0.003
0.004
0.005
0.006
Elastic Strain
Total Strain
No.8-cont.
No.4-step
Al2024 continuous and step loading comparison
Continuous loading enables neutron diffraction materials behavior
studies most comparable to conventional mechanical property testing
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O AK RIDGE NATIONAL LABORATORY
U. S. D EPARTMENT OF ENERGY
LabView NRSF2-MAP Developed For Users
with Great Flexibility and Reliability
NRSF2-MAP controls XYZ’s
mono, SPS and accessories
such as load frame, huber,
furnaces, …
Collection spread sheet
real axes-2Q, W, X, Y, Z, phi
pseudo axes- Si400, load, ..
time-sec, min, hours
monochromator and bend
notes
Edge Scans
automated collection
model fitting
Multiple instrument control
NRSF2
TEC
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O AK RIDGE NATIONAL LABORATORY
U. S. D EPARTMENT OF ENERGY
LabView Software NRSF2-VIEW Developed for
Real-Time Display
NRSF2-VIEW provides
Calibration
Real-time results display
Post experiment processing
User can take executable
code with them
Displays
Fitting of last profile
2D-Parameter vs axis, log#, …
3D-Parameter vs 2 axes
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O AK RIDGE NATIONAL LABORATORY
U. S. D EPARTMENT OF ENERGY
Highlights of Initial Projects
During Commissioning
To date there have been four themes for the NRSF2
Materials science and engineering studies
Residual stress mapping
Materials deformation behavior
Real time and in situ experiments
Phase and hydrogen content mapping
User Proposals: http://html.ornl.gov
Contact: Cam Hubbard, 865-574-4472,
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O AK RIDGE NATIONAL LABORATORY
U. S. D EPARTMENT OF ENERGY
NRSFNRSF2’s First Strain Mapping Project
Characterize New Weld Processes and Filler Metals
Baseline - tensile stresses
New weld processes - compressive
Results helped
improve & validate
stress models
Impact is enhanced
fatigue life!
• Caterpillar developing new
filler metals and weld
processes
• Validation of finite element
modeling was goal
• Cruciform steel plate samples
• Combined ND and XRD
stress mapping
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O AK RIDGE NATIONAL LABORATORY
U. S. D EPARTMENT OF ENERGY
Crack Opening (Transverse) Strains Mapped
along line of Compact Tension Specimen Crack
The perturbed plastic zones associated with cyclic fatigue and the
overload can be distinguished
-6 -4 -2 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30
-1400
-1200
-1000
-800
-600
-400
-200
0
200
400
600
800
1000
1200
1400
Lattice strain (10 -6)
Distance from overload point (mm)
1
2
3
4
5
6
7
20 30 40 50 60
Stress Intensity Range DK (MPam1/2)
N
R
N
R
Retardation Period
Pmax
Pmin
Poverload
cycle
load
5
4
3
2 6
7
1
7 specimens
examined ex situ
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O AK RIDGE NATIONAL LABORATORY
U. S. D EPARTMENT OF ENERGY
2-D Mappings of Four Overload Specimens with
Detailed Mapping Measured for Axial Strains
-10
-5
0
5
10
15
20
25
-10 -5 0 5 10 15 20 25 30
Along crack direction
Transverse direction
-10
-5
0
5
10
15
20
25
-10 -5 0 5 10 15 20 25 30
Along crack direction
Transverse direction
-5
0
5
10
15
20
Y
-200
-200
-200
-200
-50
-50
-50 110000
100
100
100
100
100
100
100
100
250
250
250
250
250
250
250
250
250
250250
250
250
250
250
250 250
250
250
250
400
400
400
400
400
400
400
-5 0 5 10 15 20 25
X SP1
-5
0
5
10
15
20
y
-500
-350
-200
-200
-200
-200
-200
-50
-50
100
100
100
100
100 100
100
100
100
100
100
100
250
250
250
250
250
250
400
400
400
400
400
400
550
700
-5 0 5 10 15 20 25
x SP2
-5
0
5
10
15
20
y
-350
-350
-350
-200
-200
-200
-200
-200
-200
-200
-200
-50 -50
-50 -50
-50
-50
-50
-50
-50
-50
100
100
100
100
100
100
100
100 100
250
250
250
250
250
400
400
550
550
700
-5 0 5 10 15 20 25
x SP6
Gage volume 4 mm 3, 1700 data points in four 2-D maps collected in 4 days
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O AK RIDGE NATIONAL LABORATORY
U. S. D EPARTMENT OF ENERGY
Arizona State Used In-situ Loading on NRSF2
ASU Goal is to Develop Models for Lightweight MMCs
Driveshafts
Cylinder liners
0
200
400
600
800
1000
1200
1400
0 0.01 0.02 0.03 0.04 0.05
Global Strain
Global Stress-Strain Curve
SiC Internal Stress
Al Matrix Internal Stress
2080Al-20vol.% SiC
5x5x5 mm 3
Phase sensitive!
Al-SiC Composites
Load
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O AK RIDGE NATIONAL LABORATORY
U. S. D EPARTMENT OF ENERGY
0
200
400
600
800
1000
1200
1400
0 0.01 0.02 0.03 0.04 0.05
Global Strain
Global Stress-Strain Curve
SiC Internal Stress
Al Matrix Internal Stress
2080Al-20vol.% SiC
FEM
FEM
FEM
Comparison of in-situ Loading Stresses from ND
With FEM Model Shows Need to Improve Models
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O AK RIDGE NATIONAL LABORATORY
U. S. D EPARTMENT OF ENERGY
–ZrH2 Identified in the Bulk
Zircalloy Rods by Neutron Diffraction
• Zr-4 rods charged with H gas in tube furnace:
at 430 °C and 13.8 kPa
for 30, 60, and 90 min.
• A hydride layer at the surface of the specimen was
observed for the 60 min. rod (Fig. 3)
• Neutron diffraction was used for identification of
-ZrH2 (Fig. 4):
increase in -ZrH2 peak intensities with charging
decrease in the Zr peak intensities
systematic increase in the overall background
• Neutron incoherent scattering was used for
measurement of total H content by quantifying the
change of the background signal:
large incoherent scattering from H
low from Zr-4
Fig 3. A cross-sectional fracture surface
(quadrant) showing a hydride layer with
a thickness of about 400 μm at the
surface of the specimen.
0.5 mm
Hydride layer
Fig 4. Neutron diffraction profiles of the asreceived
Zr-4 specimen and specimens
charged with H for 30, 60, and 90 min.
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O AK RIDGE NATIONAL LABORATORY
U. S. D EPARTMENT OF ENERGY
Hydrogen Distribution Mapped Within ThHydrogen The
Rod
• NRSF2 neutron incoherent scattering
Gage volume: 1 x 20 x 1 mm3
= 1.887 Å
2 = 74-78 deg., flat background region
• The mapping (Fig 6.) shows a H
concentration maximum near the surface
• Future work
Quantitative evaluation of the data taking
into account H attenuation, sample
geometry, and the gage volume.
Mapping ZrH2 phase fraction
Fig. 6. Variation of the background intensity along
the radius of as-received and 60-minute charged
E. Garlea, V. O. Garlea, H. Choo, C. R. Hubbard round-bar specimens.
and P. K. Liaw, “Neutron Incoherent Scattering
Measurements on Hydrogen-Charged Zircaloy-4”,
submitted to Materials Science Forum (2006).
Next - study hydrogen charging on
stresses around cracks and on basis
of changes in fatigue life
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O AK RIDGE NATIONAL LABORATORY
U. S. D EPARTMENT OF ENERGY
The Future for ORNL Engineering Diffraction
• NRSF2 full user program begins with HFIR Cycle 408 (April-May, 2007)
− Cycles 409 & 410 Summer 2007
− Goal is to run 8-10 fuel cycles (~23 days each) per fiscal year there after
• Vulcan commissioning 6/2008-12/2008
− Similar to ISIS level
− SNS reaches full power ~2010
8x ISIS
comparable time average flux to HFIR at full power
− VULCAN will have large detector solid angle
• Increasingly complex studies to be encouraged
− materials behavior under biaxial loads
− In situ and simulated processing
− real-time demands
− engineering stress mappings at increasingly finer resolution and pixel density
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O AK RIDGE NATIONAL LABORATORY
U. S. D EPARTMENT OF ENERGY
NRSF2 and VULCAN will work in
tandem to optimize user access
• NRSF2 & VULCAN will share
− “Off line/On line” alignment system
− Experiment simulation and planning software tools (SSscanSS)
• Proposal process will identify most appropriate instrument
− NRSF2 strengths
Spatial resolution mapping with one or a few hkl
Engineering residual stress mapping
Industrial focus (particularly EERE transportation related & WFO)
− VULCAN strengths
Materials deformation behavior (intergranular stresses, twinning, defects)
Spatial mapping with collection of the full pattern
Real-time, in situ studies requiring full pattern
Science focus
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O AK RIDGE NATIONAL LABORATORY
U. S. D EPARTMENT OF ENERGY
On-line/Off-line Sample and Instrument Alignment Systems
Procured, Initial Training Taken, Off-line Lab Being Set Up
• Four laser trackers (~$450K)
− Two for VULCAN building
− One for off-line alignment
− One for NRSF2
• Enables rapid and accurate
3D sample alignment
− accuracy to ~ 0.03 mm
− done off-line
− CMM capability
− input to SSscanSS for
optimize collection
− mounting plate transferable
to VULCAN, NRSF2, TEC
• For aligning accessories
− load frame
− vacuum and lamp furnaces
− sample orienter
− special (e.g. FSP system)
• For precise and fast
interchange of radial
collimators
Radial collimators
Laser tracker
system
VULCAN cave |
