Charpy impact properties of martensitic 10.6% Cr steel (MANET-I) before and after neutron exposure (original) (raw)
Related papers
Journal of Nuclear Materials, 2007
Irradiation embrittlement studies rely very often on Charpy impact data, in particular the ductile-to-brittle transition temperature (DBTT). However, while the DBTT-shift is equivalent to the increase of the fracture toughness transition temperature of ferritic steels, it is not the case for ferritic/martensitic steels. The aim of this study is to critically assess experimental data obtained on a 9%Cr-ferritic/martensitic steel, Eurofer-97, to better understand the underlying mechanisms involved during the fracture process. More specifically, a dedicated analysis using the load diagram approach allows to unambiguously reveal the actual effects of irradiation on physically rather than empirically based parameters. A comparison is made between a ferritic and ferritic/martensitic steel to better identify the possible similarities and differences. Tensile, Charpy impact and fracture toughness tests data are examined in a global approach to assess the actual rather than apparent irradiation effects. The adequacy or inadequacy of the Charpy impact test to monitor irradiation effects is extensively discussed.
Effect of specimen size on the impact properties of neutron irradiated A533B steel
Journal of Nuclear Materials, 1995
A new methodology is proposed to correlate the upper shelf energy (USE) of full-size and subsize Charpy specimens of a nuclear reactor pressure vessel plate material. The methodology appears to be more satisfactory than those methodlogies proposed earlier. The USE was normalized by a normalization factor involving the dimensions of the Charpy specimen, the elastic stress concentration factor, and the plastic constraint at the notch root. The normalized values of the USE were found to be invariant with speciment size. In addition, it was also found that the ratio of the USE of unirradiated to that of irradiated materials was approximately the same for full-, half-, and third-size specimens. The ductile-to-brittle transition temperture (DBTT) increased due to irradiation at 150°C to a nominal fluence of 1.0 × 1019 n/cm2 (E >MeV) by 78, 83 and 70°C for full-, half-, and third-size specimens, respectively. These shifts in DBTT appeared to be independent of specimen size and notch geometry.
Tensile and Charpy Impact Properties of Irradiated Reduced Activation Ferritic Steels
Effects of Radiation on Materials: 18th International Symposium, 1999
Tensile tests were conducted on eight reduced-activation Cr-W steels after irradiation to 15-17 and 26-29 dpa, and Charpy impact tests were conducted on the steels irradiated to 26-29 dpa. Irradiation was in the Fast Flux Test Facility at 365°C on steels containing 2.25-12% Cr, varying amounts of W, V, and Ta, and O.l%C. Previously, tensile specimens were irradiated to 6-8 dpa and Charpy specimens to 6-8, 15-17, and 20-24 dpa. Tensile and Charpy specimens were also thermally aged to 20000 h at 365°C. Thermal aging had little effect on the tensile behavior or the ductile-brittle transition temperature (DBTT), but several steels showed a slight increase in the upper-shelf energy (USE). After =7 dpa, the strength of the steels increased (hardened) and then remained relatively unchanged through 26-29 dpa (Le., the strength saturated with fluence). Postirradiation Charpy impact tests after 26-29 dpa showed that the loss of impact toughness, as measured by an increase in DBTT and a decrease in the USE, remained relatively unchanged from the values after 20-24 dpa, which had been relatively unchanged from the earlier irradiations. As before, the two 9Cr steels had the most irradiation resistance.
Charpy impact properties of low activation alloys for fusion applications after neutron irradiation
Journal of Nuclear Materials, 1996
The MANITU irradiation and fracture-toughness testing program although initially foreseen to clarify the early dose-saturation of ADBIT for commercial ferritic steels has been extended to include the medium temperature ( 2 250°C) irradiation hardening behaviour of promising low-activation alloys. The results after a first 0.8 dpa irradiation clearly show a much better behaviour of the new alloys in any respect (e.g. DB'IT after irradiation always below +5O"C for subsize specimens, for the ORNL steel even below -20°C). The complexity of temperature dependency is probably caused by the transition range in dose accumulation, and should therefore not be 'over-interpreted'.
Engineering Failure Analysis, 2019
The mechanical performance of reactor pressure vessel (RPV) materials is an important factor in determining the safety and economics of the operation of a nuclear power plant. The ductile-tobrittle transition temperature (DBTT) tested by Charpy impact test is an important parameter for evaluating the RPV embrittlement. In this paper, the Charpy impact test of RPV steel prior and after irradiation was carried out at different temperatures. The fracture morphology was observed by scanning electron microscopy. The irradiation effect on the impact fracture behavior was analyzed in the DBTT temperature zone. Results show that in the DBTT range, the crack initiation and propagation energy are obviously reduced for the irradiated material. After irradiation, the dimple area on the fracture surface is significantly reduced, and the distance from the crack initiation source to the gap is decreased. For the RPV steel with low Cu steel content, matrix damage becomes the main factor on material irradiation embrittlement.
Impact behavior of reduced-activation steels irradiated to 24 dpa
Journal of Nuclear Materials, 1996
Charpy impact tests were previously conducted on eight chromium-tungsten steels after irradiation at 365°C to 6-8 and 15-17 dpa in the Fast Flux Test Facility. These same steels, which range in chromium concentration from 2.25 to 12 wt% (all steels contained O.l%C>, have now been irradiated to 20-24 dpa under the same conditions. Post-irradiation Charpy impact tests after 20-24 dpa showed that the loss of impact toughness, as measured by an increase in the ductile-brittle transition temperature (DBTT) and a decrease in the upper-shelf energy, remained relatively unchanged from the values after 15-17 dpa. As before, the most irradiation-resistant steels were two 9% Cr steels: the DBTT of a 9Cr-2W-0.25V steel increased 59"C, and for the same composition with an addition of 0.07% Ta, the DB'IT increased only 2 1°C. The other steels developed shifts in DBTT of 100 to 300°C. A 2.25% Cr steel with 2% W and 0.25% V was less severely affected by irradiation than 2.25% Cr steels with 0.25% V and no tungsten, 2% W and no vanadium, and with 1% W and 0.25% V. Steels with 5 and 12% Cr, 2% W, and 0.25% V had properties between those of the 2.25Cr and 9Cr steels.
Journal of Nuclear Materials, 2000
The objective of this work is to examine the susceptibility to hardening and embrittlement of Fe7.5/11CrWTaV reduced-activation (RA) and conventional 9/12Cr±Mo martensitic steels as a function of¯uence up to 10 dpa and irradiation temperature in the range of 250±450°C. For this purpose, materials were irradiated in the Osiris Reactor (Saclay) at 325°C for various doses ranging from 0.8 dpa to a maximum dose of 8±9 dpa. Available data concern the evolution of tensile properties for doses from 0.8 to 3.4 dpa. On the other hand, RA-steels were irradiated as Charpy V and tensile specimens in the high¯ux reactor (HFR) at Petten at temperatures ranging from 250°C to 450°C with a dose of about 2.4 dpa. Ó
Materials Science and Technology, 2003
The Charpy impact energies of a reactor pressure vessel steel in the as received and several thermally embrittled conditions have been tentatively correlated to three J fracture toughness parameters derived under quasi-static loading regimen. Very good correlation has been achieved over the whole fracture resistance range of the structural steel, as obtained by the application of special heat treatments. It has been established that the parameters controlling the impact energy absorption capacity of the materials are the equivalent grain size of dual phase (ferrite/bainite) annealed microstructures and the bainite packet size of single phase quenched and tempered materials. The dependence of the Charpy impact energy of precracked, side grooved bend bars on the representative grain size of the microstructures tested has been disclosed as a Hall-Petch relationship. MST/5744
Fracture toughness of irradiated modified 9Cr–1Mo steel
Journal of Nuclear Materials, 2009
The effects of irradiation on fracture toughness of modified 9Cr-1Mo steel in the transition region were investigated. Half size precracked Charpy specimens were irradiated up to 1.2 Â 10 21 n/cm 2 (E > 0.1 MeV) at 340°C and 400°C in the Korean research reactor. The irradiation induced transition temperature shift for a modified 9Cr-1Mo was evaluated by using the Master Curve methodology. The T 0 temperature for the unirradiated specimens were measured as À67.7°C and À72.4°C from the tests with standard PCVN (precracked charpy V-notch) and half sized PCVN specimens, respectively. The T 0 shifts of specimens after irradiation at 340°C and 400°C were 70.7°C and 66.1°C, respectively. The Weibull slopes for the fracture toughness data obtained from the unirradiated and irradiated modified 9Cr-1Mo steels were determined to confirm the applicability of master curve methodology to modified 9Cr-1Mo steel.