1. EN Division-Metallurgy and Metrology
Domaine / Field:
LHC –11T DS Dipole Project
Date:
N° EDMS EDMS Nr.:
Requérant / Customer:
D. Smekens (TE/MSC)
Liste de distribution / Distribution list:
M. Karppinen (TE/MSC) S. Sgobba (EN/MME)
Characterization of DISCUP C3/30 ODS Copper from Luvata OY/ECKA Granules for 11T DS Dipole project
Données expérimentales / Experimental data:
Samples :
2 x 600 mm long samples
Optical microscope: Microscope Digital KEYENCE; Quantimet Leica Q600
Hardness :Wolpert hardness machine
Tensile tests: UTS tensile test machine
SEM observations: ZEISS Sigma
Dimensional metrology: Digital level TESA
EN Division-Materials and Metrology
CERN/EN/MME-MM/NJ-EDMS

2. Sample description and tests performed
Two extruded and drawn shapes of approximately 600 mm long made of DISCUP C3/30 from Luvata OY/ECKA Granules have been characterized through different techniques:
Dimensional metrology
Optical and SEM observations
Hardness measurements
Tensile tests
The term “as received” (AR) refers to the shape prior to any heat treatment and “heat treated” (HT) following a Nb3Sn reaction type heat treatment (665 °C 50h) a b
View of the 2 shapes in the “as received” state
EN Division-Materials and Metrology
CERN/EN/MME-MM/NJ-EDMS

3. Macro observations Face Face A R30.1
Cross section in comparison with the plane provided (LHCMBHSP0023)
Presence of some stain on the surface in the “As received” state
EN Division-Materials and Metrology
CERN/EN/MME-MM/NJ-EDMS

4. Dimensional metrology
One of the shapes was cut into two halves of 300 mm length (Half 1 and Half 2) and a dimensional metrology was carried out in two of their surfaces (Face A and Face R30.1) to check the straightness in the “as received” and “heat treated” states
The curvature is slightly reduced after the heat treatment in all the samples but in “Half 2 Face A”
EN Division-Materials and Metrology
CERN/EN/MME-MM/NJ-EDMS

5. Electrical conductivity /%IACS
Temper state
Electrical conductivity /%IACS AR
88.7±0.1 HT
90.7±0.1
The electrical conductivity is slightly increased after heat treatment
Optical observations before etching AR HT
There is not visible porosity in any of the temper states
EN Division-Materials and Metrology
CERN/EN/MME-MM/NJ-EDMS

6. Optical observations after etching
Longitudinal
Transversal AR HT
EN Division-Materials and Metrology
CERN/EN/MME-MM/NJ-EDMS

7. Optical observations
For the longitudinal images (parallel to the extrusion direction) in the previous slide, we can state that the piece is ultra-fine grained and that shows a fibrous structure.
In the transversal images (perpendicular to the extrusion direction), the grains are equiaxed
The grain size is slightly increased after the heat treatment as visible in both longitudinal and transversal cross cuts
In left image, relative to the HT specimen, we can observe some recrystallization near the center region of the cross-cut, parallel to the extrusion direction
These large recrystallized grains are common in the annealing of the ODS coppers and are due to primary recrystallization.
EN Division-Materials and Metrology
CERN/EN/MME-MM/NJ-EDMS

8. Hardness measurements
Measurements parallel to the extrusion direction
Measures in cross section 1 3 2 A B
HRB (HV)
Temper 1 2 3 AR
70.7±1.5 (137)
71.7±0.6 (139)
70.3±1.5 (137) HT
59.7±0.6 (118)
61.7±0.6 (121)
62±1 (122)
Pure Cu
(O) 45
HV5
Temper A B AR
137.2±2.8
147.2±3.3 HT
124.3±5
125.8±6.3
The hardness does not vary in the length direction and is depressed by the heat treatment as expected
Before the heat treatment, the values of hardness in the thick part of the cross section (A) are lower than the thin part (B) close to the sharp edge, however, after the heat treatment they become similar (annealing phenomenon).
CW 60%
EN Division-Materials and Metrology
CERN/EN/MME-MM/NJ-EDMS

9. Tensile tests
The heat treatment reduces the yield and tensile strength and increases ductility
As expected, mechanical properties at cryogenic temperatures are improved including ductility
EN Division-Materials and Metrology
CERN/EN/MME-MM/NJ-EDMS

10. A common behavior for pure copper is that the elongation decreases when the temperature increases finding a minimum of elongation at around 250° C
% of flat fracture RT
4.2 K AR
66% 0% HT
33%

11. Comparison of results with supplier’s data and Glidcop (C15715)
According to the values of oxide content, the most similar ODS copper is C15715
The closest tensile properties are observed are for a CW55% C15715
CW 99% 4K RT
ECKA Granules
ASM
MME-MM
measurement AR (includes + CW15% by Luvata)
Reference (“fully cold worked” by Ecka)
C15715
(CW 55%)
Al oxide content (wt%)
Not available
0.60
0.70
UTS (MPa)
414
427
Yield strength (MPa)
397
407
Elongation (%)
9.21
15-20 18
HRB 71
65-70 68
Electrical conductivity (%IACS)
88.7
88-91 92
EN Division-Materials and Metrology
CERN/EN/MME-MM/NJ-EDMS

12. Conclusions
The dimensions of the shapes have to be improved. The cross section does not perfectly fit the planes and the straightness could be improved. This straightness in fact changes when the shape is heat treated and might lead to a problem of dimensional stability.
The mechanical properties are comparable to the ones of CW 55% C15715
Strength and ductility increase at cold
HT samples show a partial annealing
No porosity was found
The heat treatment have several effects in the properties:
Changes the curvature of drawn shapes
Increases the electrical conductivity
Increases the grain size and promote some local recrystallization
Homogenizes the hardness across the section
EN Division-Materials and Metrology
CERN/EN/MME-MM/NJ-EDMS