Effect of helium on tensile properties and microstructure in 9%Cr–WVTa–steel after neutron irradiation up to 15dpa between 250 and 450°C

Effect of 16.3dpa neutron irradiation on fatigue lifetime of the RAFM steel EUROFER97

“…In analogy to the tensile test results, the fatigue tests revealed a pronounced irradiation hardening at the low irradiation temperature of 250 • C [3]. This can be observed during fatigue testing in the stress-strain hysteresis loops in Fig.…”

“…The results obtained with respect to the tensile and instrumented Charpy properties under this irradiation condition were published earlier [3,4].…”

“…Irradiationinduced dislocation loops and small ␣'-precipitates are responsible for this hardening effect. They were detected in the microstructure by TEM investigations [3]. Several helium bubbles were observed, too, but the concentration was too low to influence the structural properties.…”

“…At coolant incoming temperatures at and below ∼300 • C, significant irradiation hardening of many hundred MPa has been observed in various types of steels, leading to a pronounced reduction of uniform elongation and to fracture toughness degradation [2][3][4]. The investigation presented here was aimed at finding out whether this irradiation hardening will also affect the microstructure, the fracture behavior as well as the fatigue life of the European reference steel EUROFER97.…”

Tensile behavior of EUROFER ODS steel after neutron irradiation up to 16.3 dpa between 250 and 450 °C

“…This effect could not be found in the EUROFER97 steel. This irradiation induced dislocation loops and point defect block the mobility of the dislocations with the result of decreasing ductility [14]. For future, further microstrutural investigations by TEM of EUROFER97 ODS HIP and EUROFER97 steel are necessary to understand better the mechanism of the different microstructures.…”