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Fatigue tests on the ITER PF jacket
Cryogenics 52 (2012) 486–490
Contents lists available at SciVerse ScienceDirect
Cryogenics journal homepage: www.elsevier.com/locate/cryogenics
Fatigue tests on the ITER PF jacket Jinggang Qin a,⇑, Klaus-Peter Weiss b, Yu Wu a, Zhixiong Wu c, Laifeng Li c, Sheng Liu d a
Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui 230031, PR China Institute for Technical Physics, Karlsruhe Institute of Technology, Karlsruhe D-76344, Germany c Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, PR China d China International Nuclear Fusion Energy Program Execution Center, Beijing 100862, PR China b
a r t i c l e
i n f o
Article history: Received 22 November 2011 Received in revised form 20 May 2012 Accepted 26 May 2012 Available online 18 June 2012 Keywords: ITER PF jacket Fatigue properties 316L
a b s t r a c t This paper focuses on fatigue tests on the ITER Poloidal Field (PF) jacket made of 316L stainless steel material. During manufacture, the conductor will be compacted and spooled after cable insertion. Therefore, sample jackets were prepared under compaction, bending and straightening in order to simulate the status of PF conductor during manufacturing and winding. The fatigue properties of materials were measured at T < 7 K, including S–N and fatigue crack growth rate (FCGR). The testing results show that the present Chinese PF jacket has good fatigue properties, which conclude that the results are accordant with the requirements of ITER. Ó 2012 Elsevier Ltd. All rights reserved.
1. Introduction The ITER is a joint international research and development project [1,2] that aims to demonstrate the scientific and technical feasibility of fusion power. The ITER magnet system is made up of four main sub-systems: The 18 Toroidal Field coils, referred to as TF coils; the Central Solenoid, referred to as CS; the six Poloidal Field coils, referred to as PF coils; and the Correction Coils, referred to as CCs. All coils with different dimensions use Cable-In-Conduit Conductors (referred to as CICC). There are three kinds of PF conductors, which are PF1/6, PF2/3/4 and PF5. China is responsible for the manufacture of PF2/3/4 and PF5 conductors. One of the key-points for these CICC is to characterize the properties of the steel jacket. The modified 316L stainless steel materials are used as the PF jacket [3]. The PF jacket is ‘‘round-in-square’’ shape, shown in Fig. 1. The superconducting cable was inserted into the jacket and afterwards compacted to the final dimension forming the CICC, and one kind of PF conductor (PF5) was shown in Fig. 1. After reception at the coil manufacturer site, the PF conductor unite lengths are bent to the coil radius, insulated, and wound into the final coil dimensions using appropriate tools. Since the conductor has to undergo the described compaction and bending, the effect of cold work on the mechanical properties of jacket shall be investigated. The mechanical properties of PF jacket (316L) are different from ⇑ Corresponding author. E-mail address: [email protected] (J. Qin). 0011-2275/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.cryogenics.2012.05.018
TF jacket (316LN) [4]. It is necessary to evaluate not only the tensile property but also fatigue property at low temperature because the CICC is subjected to warming up and cooling down, and operated at about 4.5 K. If the magnets quench, the jacket with high properties could make the equipment much safe. Mechanical tests on PF jacket performed by Liu et al. [5]. But only tensile properties and fracture toughness are reported. However, fatigue properties are also very important for PF jacket. This fatigue test is conducted in strain control mode and focuses on the nominal cycling stress required to cause a failure after a number of cycles. The test result is presented as a plot of stress (S) against the number of cycles to failure (N), which is known as an S–N test. To avoid heating of the specimen due to a high strain rate the standard test method recommends 0.4% s 1 or less, leading to a significant time to conduct the cycling especially at low stress levels connected to a high number of cycles. According to requirements [3] S–N tests are needed for all PF jackets, and the acceptance criterion shall be a fatigue limit of at least 500 MPa after a minimum of 30,000 cycles. But the following tests can be replaced by fatigue crack growth rate (FCGR) test, if the material of first batch meets the requirement. In China, the Institute of Plasma Physics of Chinese Academy of Sciences (ASIPP) is in charge of the research on PF jacket. The jacket is provided by Zhejiang Jiuli Hi-Tech Metals co., Ltd. In this paper, fatigue properties of Chinese PF jacket are reported. All tests are performed in CryoMak (Cryogenic–Materialtesting– Karlsruhe) laboratory at the Karlsruhe Institute of Technology (KIT) lab. The test results show that the present PF jacket has good fatigue properties, and meet the ITER requirements.
J. Qin et al. / Cryogenics 52 (2012) 486–490
487
Fig. 1. Cross section (left: PF jacket, right: PF5 conductor).
Table 1 PF jacket dimension.
Before compaction After compaction
Outer dimension
Inner diameter (mm)
Corner radius (mm)
54.2 54.2 51.9 51.9
38.0 35.3
4.0 4.0
2. Sample preparation and experimental procedure The testing jackets need compaction, bending and straightening in order to simulate the exact situation of PF conductor manufacture [3]. The dimension of tested jacket is shown in Table 1. The S–N and FCGR testing specimens shall be sectioned by ElectroDischarge-Machining (EDM), and dimensions are shown in Fig. 2. The S–N specimen dimensions shall conform to JIS Z2283 [6], and FCGR specimen dimensions shall conform to ASTM E647 [7]. The testing specimens shall be sectioned longitudinally from the center of one jacket face, corresponding to the maximum tensile or compressive strain during bending [8], as indicated in Fig. 3. The S–N testing specimens are from one remelting heat (ESR No. 09224020183–4), but FCGR specimens are from three different heats (ESR No. 09224020183–4, 09224010174–2, and 09224270 075–1). The chemical compositions are listed in Table 2. After compaction, the jacket had about 6% elongation. It was then bent to a radius of r = 2000 mm and straightened. The specimens were tested at cryogenic temperature (<7 K). The cryogenic testing samples were machined at KIT. 3. Results and discussion The metallographic phase analysis is reported (Fig. 4), including grain size and grain boundary sensitization. Micrographs
revealed no presence of ditches at grain boundaries and no visible ferrite content. Grain size measurement was performed, and the size number according to ASTM E112–96 (2004) e1 [9] is G = 6.0. All metallographic phases are required to ITER requirements [3]. Tensile tests at Technical Institute of Physics and Chemistry of Chinese Academy of Sciences (TIPC) were done before fatigue test, and results are summarized in Fig. 5. From the tensile test results, we found that the tensile properties of present PF jacket are good and stable, especially at cryogenic temperature. The fatigue specimens machined at KIT were shown in Fig. 6. The S–N tests were carried out according to JIS Z2283 [6]. Four specimens were prepared. All specimens were tested at R = 0.1, strain rate <0.4% s 1 and T < 7 K. The first specimen (SN1) was tested at a stress range of 700 MPa (Fig. 7), and the maximum number of cycles applied was 100,000 cycles. The specimen was loaded up to a maximum stress of 777 MPa, followed by two unloading sequences to analyze the necessary strain range. After that the specimen was cycled with a constant strain range. The specimen reacted fully elastic showing no hysteresis, shown in Fig. 7. The cycling was done at 0.6 Hz to stay below the maximum strain rate of 0.4% s 1 according to standard. According to the behavior of the specimen a higher frequency would be also possible (1–5 Hz). The specimen survived the 30,000 cycle limit, therefore specimen SN2 was tested at an increased stress range of 1000 MPa (max. 1111 MPa to min. 111 MPa, shown in Fig. 8 on the left). The specimen failed at 25,062 cycles, and the final curve of time versus stress–strain range is shown in Fig. 8 on the right. The timescale is not appropriate to resolve single stress cycles as in Fig. 7, but the main point is to show a stepwise collapse of the specimen while the feedback system of the tensile machine tried
Fig. 2. Specimen dimensions (left: S–N, right: FCGR).
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J. Qin et al. / Cryogenics 52 (2012) 486–490
Fig. 3. Sample location of S–N (left) and FCGR (right) specimens [8].
Table 2 Chemical composition of PF jackets from different remelting heat. Element 09224020183–4 09224010174–2 09224270075–1 ITER wt.% requirement C Si Mn P S Cr Ni Mo Co
0.016 0.317 1.46 0.029 0.003 16.3 13.96 2.1 0.047
0.013 0.314 1.45 0.029 0.003 16.26 13.95 2.09 0.049
0.021 0.345 1.41 0.027 0.0041 16.43 13.92 2.1 0.053
<0.03 <0.75 <2.0 <0.03 <0.01 16.0–18.50 11.0–14.0 2.0–2.50 <0.1
to recover the stress controlled maximum and minimum level until the full separation of the specimen. Other two specimens were tested at the stress range of 700 MPa and 800 MPa, respectively. The results are given in Table 3. The failed S–N specimen (SN2) is shown in Fig. 9. According to present standardization of mechanical test for PF jacket, the number of samples will be agreed between the DA and IO, based on early results indicating the amount of margin between the specification (30,000 cycles at 500 MPa) and the material performance on the first production heat. From the S–N test results, we can find that the present S–N specimens can survive 100,000 cycles at 700 MPa, much higher than the given specification. The FCGR tests were carried out according to ASTM E647 [7], and were also tested at KIT. Five specimens from different heats were prepared. The FCGR tests were carried out in helium gas at cryogenic temperatures (<7 K). A sinusoidal cyclic load at 30 Hz was applied. The samples were tested at force range of 5 kN and R = 0.1. Acceptance for FCGR shall be evaluated by assessing the da/dN parameter calculated from the Paris law constants (C and m values) derived from a line of best fit taken as an average of the two identical samples tested in each heat. The range of acceptable da/dN values shall be assessed in the range of 10–85 MPa-m1/2 and must remain less than or equal to the values shown in Table 4 [8]. The test results are shown in Fig. 10. In Fig. 10, it’s easily to be seen that all tested FCGR specimens are much less than standard value, and conform to the ITER requirements.
Fig. 4. Metallographic phase (left: grain size, right: intergranular corrosion).
Fig. 5. Tensile properties of PF jacket (EL: elongation, YS: yield strength, UTS: ultimate tensile strength).
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Fig. 6. Machined specimens (left: S–N, right: FCGR).
Fig. 7. SN1: Loading line (left), stress and strain cycles at the end at 101,000 cycles (right), r: stress, : strain, Dt: testing time, D: strain range.
Fig. 8. SN2: Loading line (left), stress and strain cycles at the end during failure (right), r: stress, : strain, Dt: testing time, D: strain range.
Table 3 S–N test results for PF jacket. Specimen
Cycles
Stress_range (MPa)
Stress_Max (MPa)
Stress_Min (MPa)
Remarks
SN1 SN2 SN3 SN4
>100,000 25,062 >100,000 >100,000
700 1000 800 700
777 1111 888 777
77 111 88 77
Survived Failed Survived Survived
490
J. Qin et al. / Cryogenics 52 (2012) 486–490
Fig. 9. Failure surface of SN2 after 25,000 cycles.
Table 4 FCGR acceptance limits.
DK (MPa m0.5) da/dN (m/cycle) DK (MPa m0.5) da/dN (m/cycle) DK (MPa m0.5) da/dN (m/cycle)
10 1.494E-08 40 7.962E-07 70 3.554E-06
15 5.511E-08 45 1.091E-06 75 4.274E-06
20 1.248E-07 50 1.446E-06 80 5.079E-06
25 2.266E-07 55 1.865E-06 85 5.973E-06
30 3.690E-07 60 2.354E-06
35 5.571E-07 65 2.915E-06
Acknowledgements The authors are very grateful to ITER IO for their help on the cryogenic test. They also wish to acknowledge the contribution of Zhejiang Jiuli Hi-Tech Metals co., Ltd. This work is partly supported by National Magnetic Confinement Fusion Science Program, Grant No. 2011GB112004. References
Fig. 10. Test results of FCGR.
4. Conclusions The ITER PF conductor jacket needs compaction and bending. The mechanical samples were prepared under compaction, bending and straightening according to the ITER requirements. The fatigue samples were tested at cryogenic temperature (T < 7 K). Four S–N and five FCGR specimens were tested. The test results were discussed, and showed that requirements were fulfilled.
[1] ITER Structural Design Criteria for Magnet Components (SDC-MC), N11 FDR 5001–07-05 R 0.1, NAKA, Japan; 2001. [2] ITER Final Design Report, IAEA Vienna and ITER IT team Design Description Document 1.1 Update; January 2004. [3] Technical Specification ANNEX B to Procurement Arrangement 1.1.P6C.CN.01; 2008. [4] Qin J, Wu Y, Weiss K, et al. Mechanical tests on the ITER TF jacket, Cryogenics; 2012;52:336–9. [5] Liu H, Wu Y, et al. Mechanical tests on the ITER PF 316L jacket after compaction. Cryogenics 2011;51:234–6. [6] Method of low cycle fatigue testing for metallic materials in liquid helium, JIS Z2283; 1998. [7] Standard test method for measurement of fatigue crack growth rates, ASTM E647; 2008. [8] Standardization of PF conductor jacket mechanical testing procedure v1.0, ITER internal document, IDM#ITERD659R44; 2011. [9] Standard test methods for determining average grain size, ASTM E112–96 (2004) e1; 2004.
Contents lists available at SciVerse ScienceDirect
Cryogenics journal homepage: www.elsevier.com/locate/cryogenics
Fatigue tests on the ITER PF jacket Jinggang Qin a,⇑, Klaus-Peter Weiss b, Yu Wu a, Zhixiong Wu c, Laifeng Li c, Sheng Liu d a
Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui 230031, PR China Institute for Technical Physics, Karlsruhe Institute of Technology, Karlsruhe D-76344, Germany c Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, PR China d China International Nuclear Fusion Energy Program Execution Center, Beijing 100862, PR China b
a r t i c l e
i n f o
Article history: Received 22 November 2011 Received in revised form 20 May 2012 Accepted 26 May 2012 Available online 18 June 2012 Keywords: ITER PF jacket Fatigue properties 316L
a b s t r a c t This paper focuses on fatigue tests on the ITER Poloidal Field (PF) jacket made of 316L stainless steel material. During manufacture, the conductor will be compacted and spooled after cable insertion. Therefore, sample jackets were prepared under compaction, bending and straightening in order to simulate the status of PF conductor during manufacturing and winding. The fatigue properties of materials were measured at T < 7 K, including S–N and fatigue crack growth rate (FCGR). The testing results show that the present Chinese PF jacket has good fatigue properties, which conclude that the results are accordant with the requirements of ITER. Ó 2012 Elsevier Ltd. All rights reserved.
1. Introduction The ITER is a joint international research and development project [1,2] that aims to demonstrate the scientific and technical feasibility of fusion power. The ITER magnet system is made up of four main sub-systems: The 18 Toroidal Field coils, referred to as TF coils; the Central Solenoid, referred to as CS; the six Poloidal Field coils, referred to as PF coils; and the Correction Coils, referred to as CCs. All coils with different dimensions use Cable-In-Conduit Conductors (referred to as CICC). There are three kinds of PF conductors, which are PF1/6, PF2/3/4 and PF5. China is responsible for the manufacture of PF2/3/4 and PF5 conductors. One of the key-points for these CICC is to characterize the properties of the steel jacket. The modified 316L stainless steel materials are used as the PF jacket [3]. The PF jacket is ‘‘round-in-square’’ shape, shown in Fig. 1. The superconducting cable was inserted into the jacket and afterwards compacted to the final dimension forming the CICC, and one kind of PF conductor (PF5) was shown in Fig. 1. After reception at the coil manufacturer site, the PF conductor unite lengths are bent to the coil radius, insulated, and wound into the final coil dimensions using appropriate tools. Since the conductor has to undergo the described compaction and bending, the effect of cold work on the mechanical properties of jacket shall be investigated. The mechanical properties of PF jacket (316L) are different from ⇑ Corresponding author. E-mail address: [email protected] (J. Qin). 0011-2275/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.cryogenics.2012.05.018
TF jacket (316LN) [4]. It is necessary to evaluate not only the tensile property but also fatigue property at low temperature because the CICC is subjected to warming up and cooling down, and operated at about 4.5 K. If the magnets quench, the jacket with high properties could make the equipment much safe. Mechanical tests on PF jacket performed by Liu et al. [5]. But only tensile properties and fracture toughness are reported. However, fatigue properties are also very important for PF jacket. This fatigue test is conducted in strain control mode and focuses on the nominal cycling stress required to cause a failure after a number of cycles. The test result is presented as a plot of stress (S) against the number of cycles to failure (N), which is known as an S–N test. To avoid heating of the specimen due to a high strain rate the standard test method recommends 0.4% s 1 or less, leading to a significant time to conduct the cycling especially at low stress levels connected to a high number of cycles. According to requirements [3] S–N tests are needed for all PF jackets, and the acceptance criterion shall be a fatigue limit of at least 500 MPa after a minimum of 30,000 cycles. But the following tests can be replaced by fatigue crack growth rate (FCGR) test, if the material of first batch meets the requirement. In China, the Institute of Plasma Physics of Chinese Academy of Sciences (ASIPP) is in charge of the research on PF jacket. The jacket is provided by Zhejiang Jiuli Hi-Tech Metals co., Ltd. In this paper, fatigue properties of Chinese PF jacket are reported. All tests are performed in CryoMak (Cryogenic–Materialtesting– Karlsruhe) laboratory at the Karlsruhe Institute of Technology (KIT) lab. The test results show that the present PF jacket has good fatigue properties, and meet the ITER requirements.
J. Qin et al. / Cryogenics 52 (2012) 486–490
487
Fig. 1. Cross section (left: PF jacket, right: PF5 conductor).
Table 1 PF jacket dimension.
Before compaction After compaction
Outer dimension
Inner diameter (mm)
Corner radius (mm)
54.2 54.2 51.9 51.9
38.0 35.3
4.0 4.0
2. Sample preparation and experimental procedure The testing jackets need compaction, bending and straightening in order to simulate the exact situation of PF conductor manufacture [3]. The dimension of tested jacket is shown in Table 1. The S–N and FCGR testing specimens shall be sectioned by ElectroDischarge-Machining (EDM), and dimensions are shown in Fig. 2. The S–N specimen dimensions shall conform to JIS Z2283 [6], and FCGR specimen dimensions shall conform to ASTM E647 [7]. The testing specimens shall be sectioned longitudinally from the center of one jacket face, corresponding to the maximum tensile or compressive strain during bending [8], as indicated in Fig. 3. The S–N testing specimens are from one remelting heat (ESR No. 09224020183–4), but FCGR specimens are from three different heats (ESR No. 09224020183–4, 09224010174–2, and 09224270 075–1). The chemical compositions are listed in Table 2. After compaction, the jacket had about 6% elongation. It was then bent to a radius of r = 2000 mm and straightened. The specimens were tested at cryogenic temperature (<7 K). The cryogenic testing samples were machined at KIT. 3. Results and discussion The metallographic phase analysis is reported (Fig. 4), including grain size and grain boundary sensitization. Micrographs
revealed no presence of ditches at grain boundaries and no visible ferrite content. Grain size measurement was performed, and the size number according to ASTM E112–96 (2004) e1 [9] is G = 6.0. All metallographic phases are required to ITER requirements [3]. Tensile tests at Technical Institute of Physics and Chemistry of Chinese Academy of Sciences (TIPC) were done before fatigue test, and results are summarized in Fig. 5. From the tensile test results, we found that the tensile properties of present PF jacket are good and stable, especially at cryogenic temperature. The fatigue specimens machined at KIT were shown in Fig. 6. The S–N tests were carried out according to JIS Z2283 [6]. Four specimens were prepared. All specimens were tested at R = 0.1, strain rate <0.4% s 1 and T < 7 K. The first specimen (SN1) was tested at a stress range of 700 MPa (Fig. 7), and the maximum number of cycles applied was 100,000 cycles. The specimen was loaded up to a maximum stress of 777 MPa, followed by two unloading sequences to analyze the necessary strain range. After that the specimen was cycled with a constant strain range. The specimen reacted fully elastic showing no hysteresis, shown in Fig. 7. The cycling was done at 0.6 Hz to stay below the maximum strain rate of 0.4% s 1 according to standard. According to the behavior of the specimen a higher frequency would be also possible (1–5 Hz). The specimen survived the 30,000 cycle limit, therefore specimen SN2 was tested at an increased stress range of 1000 MPa (max. 1111 MPa to min. 111 MPa, shown in Fig. 8 on the left). The specimen failed at 25,062 cycles, and the final curve of time versus stress–strain range is shown in Fig. 8 on the right. The timescale is not appropriate to resolve single stress cycles as in Fig. 7, but the main point is to show a stepwise collapse of the specimen while the feedback system of the tensile machine tried
Fig. 2. Specimen dimensions (left: S–N, right: FCGR).
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J. Qin et al. / Cryogenics 52 (2012) 486–490
Fig. 3. Sample location of S–N (left) and FCGR (right) specimens [8].
Table 2 Chemical composition of PF jackets from different remelting heat. Element 09224020183–4 09224010174–2 09224270075–1 ITER wt.% requirement C Si Mn P S Cr Ni Mo Co
0.016 0.317 1.46 0.029 0.003 16.3 13.96 2.1 0.047
0.013 0.314 1.45 0.029 0.003 16.26 13.95 2.09 0.049
0.021 0.345 1.41 0.027 0.0041 16.43 13.92 2.1 0.053
<0.03 <0.75 <2.0 <0.03 <0.01 16.0–18.50 11.0–14.0 2.0–2.50 <0.1
to recover the stress controlled maximum and minimum level until the full separation of the specimen. Other two specimens were tested at the stress range of 700 MPa and 800 MPa, respectively. The results are given in Table 3. The failed S–N specimen (SN2) is shown in Fig. 9. According to present standardization of mechanical test for PF jacket, the number of samples will be agreed between the DA and IO, based on early results indicating the amount of margin between the specification (30,000 cycles at 500 MPa) and the material performance on the first production heat. From the S–N test results, we can find that the present S–N specimens can survive 100,000 cycles at 700 MPa, much higher than the given specification. The FCGR tests were carried out according to ASTM E647 [7], and were also tested at KIT. Five specimens from different heats were prepared. The FCGR tests were carried out in helium gas at cryogenic temperatures (<7 K). A sinusoidal cyclic load at 30 Hz was applied. The samples were tested at force range of 5 kN and R = 0.1. Acceptance for FCGR shall be evaluated by assessing the da/dN parameter calculated from the Paris law constants (C and m values) derived from a line of best fit taken as an average of the two identical samples tested in each heat. The range of acceptable da/dN values shall be assessed in the range of 10–85 MPa-m1/2 and must remain less than or equal to the values shown in Table 4 [8]. The test results are shown in Fig. 10. In Fig. 10, it’s easily to be seen that all tested FCGR specimens are much less than standard value, and conform to the ITER requirements.
Fig. 4. Metallographic phase (left: grain size, right: intergranular corrosion).
Fig. 5. Tensile properties of PF jacket (EL: elongation, YS: yield strength, UTS: ultimate tensile strength).
489
J. Qin et al. / Cryogenics 52 (2012) 486–490
Fig. 6. Machined specimens (left: S–N, right: FCGR).
Fig. 7. SN1: Loading line (left), stress and strain cycles at the end at 101,000 cycles (right), r: stress, : strain, Dt: testing time, D: strain range.
Fig. 8. SN2: Loading line (left), stress and strain cycles at the end during failure (right), r: stress, : strain, Dt: testing time, D: strain range.
Table 3 S–N test results for PF jacket. Specimen
Cycles
Stress_range (MPa)
Stress_Max (MPa)
Stress_Min (MPa)
Remarks
SN1 SN2 SN3 SN4
>100,000 25,062 >100,000 >100,000
700 1000 800 700
777 1111 888 777
77 111 88 77
Survived Failed Survived Survived
490
J. Qin et al. / Cryogenics 52 (2012) 486–490
Fig. 9. Failure surface of SN2 after 25,000 cycles.
Table 4 FCGR acceptance limits.
DK (MPa m0.5) da/dN (m/cycle) DK (MPa m0.5) da/dN (m/cycle) DK (MPa m0.5) da/dN (m/cycle)
10 1.494E-08 40 7.962E-07 70 3.554E-06
15 5.511E-08 45 1.091E-06 75 4.274E-06
20 1.248E-07 50 1.446E-06 80 5.079E-06
25 2.266E-07 55 1.865E-06 85 5.973E-06
30 3.690E-07 60 2.354E-06
35 5.571E-07 65 2.915E-06
Acknowledgements The authors are very grateful to ITER IO for their help on the cryogenic test. They also wish to acknowledge the contribution of Zhejiang Jiuli Hi-Tech Metals co., Ltd. This work is partly supported by National Magnetic Confinement Fusion Science Program, Grant No. 2011GB112004. References
Fig. 10. Test results of FCGR.
4. Conclusions The ITER PF conductor jacket needs compaction and bending. The mechanical samples were prepared under compaction, bending and straightening according to the ITER requirements. The fatigue samples were tested at cryogenic temperature (T < 7 K). Four S–N and five FCGR specimens were tested. The test results were discussed, and showed that requirements were fulfilled.
[1] ITER Structural Design Criteria for Magnet Components (SDC-MC), N11 FDR 5001–07-05 R 0.1, NAKA, Japan; 2001. [2] ITER Final Design Report, IAEA Vienna and ITER IT team Design Description Document 1.1 Update; January 2004. [3] Technical Specification ANNEX B to Procurement Arrangement 1.1.P6C.CN.01; 2008. [4] Qin J, Wu Y, Weiss K, et al. Mechanical tests on the ITER TF jacket, Cryogenics; 2012;52:336–9. [5] Liu H, Wu Y, et al. Mechanical tests on the ITER PF 316L jacket after compaction. Cryogenics 2011;51:234–6. [6] Method of low cycle fatigue testing for metallic materials in liquid helium, JIS Z2283; 1998. [7] Standard test method for measurement of fatigue crack growth rates, ASTM E647; 2008. [8] Standardization of PF conductor jacket mechanical testing procedure v1.0, ITER internal document, IDM#ITERD659R44; 2011. [9] Standard test methods for determining average grain size, ASTM E112–96 (2004) e1; 2004.