Dog-Bone Studies In U-Mo-Zry-4 Miniplates Fabrication Process CNEA developments in U-Mo-Zry-4

IGORR Conference - 17 -21 November 2014 - Bariloche, Argentina
Dog-Bone Studies In U-Mo-Zry-4 Miniplates
Fabrication Process
CNEA developments in U-Mo-Zry-4
miniplates and plates co-rolling control
M. LÓPEZ1, F.R. GRIBALDO2, E.N. OLIVAR2, B. PICCHETTI1 , H. TABOADA1
1Gerencia
del Ciclo de Combustible Nuclear, CAC, CNEA
2Departamento de Ensayos No Destructivos y Estructurales, CAC, CNEA
Avenida General Paz 1499 - Argentina
INTRODUCTION
Smaller Dog Bone
Thinner interdifussion layer
Bigger Dog Bone
Thicker interdifussion layer
INTRODUCTION
Low compressive stress
High compressive stress
371-2394 MPa
4372-29152 MPa
INTRODUCTION
Low compressive stress
High compressive stress
371-2394 MPa
4372-29152 MPa
INTRODUCTION
Low compressive stress
High compressive stress
371-2394 MPa
4372-29152 MPa
Smaller Dog Bone
Thinner interdifussion layer
Bigger Dog Bone
Thicker interdifussion layer
INTRODUCTION
Three different experiments were tested:
• co-rolling process with constant reductions
(0.25 mm)
• co-rolling process with constant percentage
reduction (5%)
• co-rolling process with a decrease reduction
method (from 15% to 5%)
MATERIALS
&
METHODS
MATERIALS & METHODS
Picture and frame process
Coupons are cut with linear precision saw
Fuel core is covered with zircalloy-4
Polish up to cloth with diamond paste
UMo alloys provided by INL
Assemble and TIG welding
Depleted Uranium
Co-rolling at 650 ºC
Figure 1: Zry-4 frame and sheets.
MATERIALS & METHODS
1
Reduction
Steps
Temperature
Compressive Stress
0.25 mm
2
3
5%
15% x3
10% x2
7% x2
5% x13
20
650 ºC
371-2394 MPa
Table 1: co-rolling conditions for each sample.
RESULTS
RESULTS: 0,25 mm reduction
4
16
8
20
12
Figure 2: X-Ray images obtained for selected steps of the co-rolling process of sample 1.
RESULTS: 0,25 mm reduction
12
20
Figure 3: X-Ray images obtained for steps 12 and 20 of the co-rolling process of sample 1.
RESULTS: 0,25 mm reduction
Left
Centre
Figure 4: SEM images obtained for sample 1 of centre and edges. Mag: 200x.
Right
RESULTS: 0,25 mm reduction
Thickness difference between centre and edges (%)
Step
Reduction
Accumulate
Reduction
Core
Reduction
4
3.38 %
14.19 %
-
8
3.21 %
29.25 %
-
12
5.72 %
45.18 %
-
16
6.98 %
61.30 %
-
6% - 5%
-
20
16.0 %
75.31 %
~66 %
48% - 33%
57% - 56%
GV Method
Difference is
not
considerable
SEM Method
-
-
Table 2: Dog-Bone obtained for sample 1 by comparison of the center and edges Grey
Value; is also shown in this table the core thickness, measured on the SEM image.
RESULTS: 5% reduction
3
10
15
6
11
18
9
13
20
Figure 5: X-Ray images obtained for selected steps of the co-rolling process of sample 2.
RESULTS: 5% reduction
11
20
Figure 6: X-Ray images obtained for steps 11 and 20 of the co-rolling process of sample 2.
RESULTS: 5% reduction
Left
Centre
Figure 7: SEM images obtained for sample 2 of center and edges. Mag: 200x.
Right
RESULTS: 5% reduction
Thickness difference between centre and edges (%)
Step
Reduction
Accumulate
Reduction
Core
Reduction
3
4.70 %
13.22 %
-
-
6
1.73%
25.88 %
-
-
9
3.06 %
35.01 %
-
-
10
6.59 %
39.29 %
-
11
4.60 %
42.09 %
-
13
4.38 %
47.11 %
-
15
3.31 %
51.02 %
-
-
18
5.04 %
57.91 %
-
-
20
2.25 %
59.59 %
~61 %
15% - 1%
GV Method
Difference
is not
considerable
SEM Method
-
Table 3: Dog-Bone obtained for sample 2 by comparison of the center and edges Grey
Value; is also shown in this table the core thickness, measured on the SEM image.
RESULTS: Decreasing reductions
21
Figure 8: X-Ray image obtained for sample 3, of the final co-rolling step.
RESULTS: Decreasing reductions
Left
Centre
Figure 9: SEM images obtained for sample 3 of center and edges Mag: 90x.
Right
RESULTS: Decreasing reductions
Thickness difference between centre and edges (%)
Step
Reduction
Accumulate
Reduction
Core
Reduction
GV Method
SEM Method
21
2.05 %
75.72%
~73%
12% - 10%
65% - 73%
Table 4: Dog-Bone obtained for sample 3 by comparison of the center and edges
Grey Value; is also shown in this table the core thickness, measured on the SEM
image.
RESULTS: Comparison
170
120
Sample 1
Sample 2
165
110
160
100
155
Grey Value
Grey Value
90
80
70
135
medio
min
max
50
40
1400
1600
1800
2000
2200
2400
2600
2800
190
180
170
160
GV medio
GV min
GV max
1400
1600
1400
1500
1600
1700
1800
1900
2000
2100
Figure 10: Grey Value vs. x (horizontal
shifting on the core) for each sample.
200
140
1200
1300
X (pixels)
Sample 3
150
medio
min
max
130
X (pixels)
Grey Value
145
140
60
210
150
1800
2000
2200
X (pixels)
2400
2600
2800
THEORETICAL
CALCULATION
THEORETICAL CALCULATION
From the point of view of fabrication it is
desirable to have a relationship linking the
deformation rate and strength shield of each
material at co-rolling temperature to assess
final dimensions of plate and core without
stopping each co-rolling step for X-ray checking.
THEORETICAL CALCULATION
a p * Lp  a p * R  ( R 
2
e0  e f
2
) 2  a p * R(e0  e f )
Taking into account the acting forces:
e
e   R   
R
2
 
Figure 11: Acting forces during rolling
process scheme
e
R
 1
ap: plate width
Lp: plate lenght
e0, ef: initial and final thickness
∆e: e0 - ef
THEORETICAL CALCULATION
Rolling Force
 . R.en
F   .a. R.en .1 
en1  en

_
Strengh shield
 _

.en 
   .a. R.en .1 

e

e
n 1
n


THEORETICAL CALCULATION
Rolling Force
 . R.en
F   .a. R.en .1 
en1  en

_
Rolling Surface
 _

.en 
   .a. R.en .1 

e

e
n 1
n


THEORETICAL CALCULATION
Rolling Force
 . R.en
F   .a. R.en .1 
en1  en

_
 _

.en 
   .a. R.en .1 

e

e
n 1
n


Variable factor involving the friction parameter between the
piece and the rollers, and the pre and post thickness
THEORETICAL CALCULATION
Rolling Force
 . R.en
F   .a. R.en .1 
en1  en

_
 _

.en 
   .a. R.en .1 

e

e
n 1
n


 
e
R
THEORETICAL CALCULATION
Rolling Force
 . R.en
F   .a. R.en .1 
en1  en

_
Applied Power
P  F .vt ; vt  Lp.  Lp.2
 _

.en 
   .a. R.en .1 

e

e
n 1
n


THEORETICAL CALCULATION
Rolling Force
 . R.en
F   .a. R.en .1 
en1  en

_
 _

.en 
   .a. R.en .1 

e

e
n 1
n


Applied Power
P  F .vt ; vt  Lp.  Lp.2

.en 
P  2  .a.R.en .1 

e

e
n 1
n

_
THEORETICAL CALCULATION
Rolling Force
 . R.en
F   .a. R.en .1 
en1  en

_
 _

.en 
   .a. R.en .1 

e

e
n 1
n


Applied Power
P  F .vt ; vt  Lp.  Lp.2

.en 
P  2  .a.R.en .1 

e

e
n 1
n

_

1  n 
P  2  .a.R.en .1  

1  n 

_
en
n 
en 1
THEORETICAL CALCULATION
Cancelling common factors and taking into account en possible
values it stands:

en 





en   en  
  en 
U  Mo
U  Mo
Zry  4
Zry  4
Zry  4
U  Mo

e e 

e  e 
Zry  4
0
f
U  Mo
0
f
THEORETICAL CALCULATION
Essay
(1)
Miniplate thickness
difference (mm)
(2)
(3)=0.5*[(1)-(2)]
(3)/(2)
Core thickness Cover thickness
Difference ratio
difference (mm) difference (mm)
1
4,48
0,636
1,922
3,024
2
4,55
0,592
1,979
3,343
3
4,826
0,72
2,053
2,853
4
4,83
0,713
2,059
2,889
5
4,6
0,65
1,975
3,037
6
5,13
0,661
2,234
3,379
7
4,96
ST. DEVIATION:
0,731
0,218
2,114
AVERAGE:
2,892
3,060
Table 5: Experimental miniplate thickness and estimated core thicknes for each corolled miniplate.
en1  en Zry4  e0  e f Zry4
en1  en U Mo e0  e f U Mo
 3.06  0.22
THEORETICAL CALCULATION
e
MP
F
 e
MP
F F 1
e0  eF Zry4
 ...  


e

e

e 
1
F
i 1 i
U  Mo
0  ef
MP
F
eF
U  Mo
MP
0
e
F 1
MP
i 1 i 0

U  Mo
0
F
U  Mo
MP
F
e
MP
F


1
F
i 1 i


1

f
  3.06  0.22
 1 e  e 
U  Mo
0
U  Mo
2e0  eF 

e 

MP
F
e
 e   e  e 
2e  e 
MP
F
0

 e
MP
0

1
F
i 1 i

7.56
F
 e
1
0
U  Mo
 eF
U  Mo

e 

MP
F

1
F
i 1 i

6.68

1
DISCUSSION
DISCUSSION
• When reductions are under 5% the core thickness stays homogeneous
during the co-rolling process. A disadvantage of this is that the process
requires more steps to reach the desire thickness.
• A new co-rolling protocol was developed in order to minimize both the
Dog Bone and the number of steps. A commitment between these
characteristics is obtained with decreasing percent reductions. The results
obtained for this protocol shows that the final dimensions of the plate, the
core thickness in particular, are not optimum for irradiation.
• It can be concluded that the co-rolling process can be done with constant
percent reductions: up to a 5% reduction or less are suggested.
• Based on theoretical calculation, given the final product specification for
both phases (and so for the miniplate) it is possible to reconstruct initial
(and at any stage) length and thickness if co-rolling strategy εn is provided.
Thank You!
Marisol López – [email protected]
Bianca Picchetti – [email protected]
Horacio Taboada – [email protected]
Fernando Gribaldo
Emilio Olivar
`