TY - JOUR
T1 - Fracture-mechanical properties of neutron irradiated ITER specification tungsten
AU - Caganidze, A.
AU - Chauhan, A.
AU - Schneider, Hans-Christian
AU - Terentyev, Dmitry
AU - Borghmans, Gitte
AU - Aktaa, Jarir
N1 - Score=10
PY - 2021/1/8
Y1 - 2021/1/8
N2 - The work focuses on the investigation of the influence of neutron irradiation on the fracture mechani- cal properties of ITER specification-conform, stress-relieved tungsten bar. The irradiation of miniaturized Three-Point Bend specimens was performed inside the fuel channel of the Material Test High Flux BR2 reactor of SCK • CEN in Mol. An irradiation damage dose close to 1 dpa (in tungsten) was achieved at 800 °C with active temperature cooling and constant on-line temperature monitoring. Thick-wall stainless steel capsules were implemented for shielding the thermal neutrons in order to reduce Re transmuta- tion down to ~2 at.% (and 0.2 at.% Os). The quasi-static fracture mechanical experiments were carried out following ASTM E399 aiming at the determination of plane strain fracture toughness K Ic . The post irradiation examination of the specimens irradiated at 800 °C reveals severe material embrittlement. At T test = T irr = 800 °C, a deformation free brittle fracture is observed. The fractographic investigations show a mixture of brittle transgranular cleavage and intergranular fracture. With increasing the test tempera- ture above 10 0 0 °C, the fracture mode is changed from the brittle to a ductile one. Blunting of the notch tip leads to a suppression of the crack initiation and propagation and consequently no failure of the spec- imens was observed up to severe deflection levels. In some cases, however, a ductile crack growth with a characteristic dimple formation was identified, in addition. Based on the obtained results, the Ductile to Brittle Transition Temperature shift induced by the neutron irradiation at 800 °C is evaluated to be 600-625 °C.
AB - The work focuses on the investigation of the influence of neutron irradiation on the fracture mechani- cal properties of ITER specification-conform, stress-relieved tungsten bar. The irradiation of miniaturized Three-Point Bend specimens was performed inside the fuel channel of the Material Test High Flux BR2 reactor of SCK • CEN in Mol. An irradiation damage dose close to 1 dpa (in tungsten) was achieved at 800 °C with active temperature cooling and constant on-line temperature monitoring. Thick-wall stainless steel capsules were implemented for shielding the thermal neutrons in order to reduce Re transmuta- tion down to ~2 at.% (and 0.2 at.% Os). The quasi-static fracture mechanical experiments were carried out following ASTM E399 aiming at the determination of plane strain fracture toughness K Ic . The post irradiation examination of the specimens irradiated at 800 °C reveals severe material embrittlement. At T test = T irr = 800 °C, a deformation free brittle fracture is observed. The fractographic investigations show a mixture of brittle transgranular cleavage and intergranular fracture. With increasing the test tempera- ture above 10 0 0 °C, the fracture mode is changed from the brittle to a ductile one. Blunting of the notch tip leads to a suppression of the crack initiation and propagation and consequently no failure of the spec- imens was observed up to severe deflection levels. In some cases, however, a ductile crack growth with a characteristic dimple formation was identified, in addition. Based on the obtained results, the Ductile to Brittle Transition Temperature shift induced by the neutron irradiation at 800 °C is evaluated to be 600-625 °C.
KW - Polycrystalline tungsten
KW - Fracture behaviour
KW - Neutron irradiation
UR - https://ecm.sckcen.be/OTCS/llisapi.dll/open/42312920
U2 - 10.1016/j.jnucmat.2020.152761
DO - 10.1016/j.jnucmat.2020.152761
M3 - Article
SN - 0022-3115
VL - 547
SP - 1
EP - 8
JO - Journal of Nuclear Materials
JF - Journal of Nuclear Materials
M1 - 152761
ER -