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Annealing Experiments on Irradiated NiCrMo Weld Metal

Leitz, C
Manager, deputy director and manager,Power Generation Group KWU, SIEMENS AG,

Klausnitzer, EN
Manager, deputy director and manager,Power Generation Group KWU, SIEMENS AG,

Hofmann, G
Manager, deputy director and manager,Power Generation Group KWU, SIEMENS AG,


Pages: 11    Published: Jan 1994


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Source: STP1175-EB


Abstract

Charpy-V impact, tensile, drop weight and fracture mechanics specimens from a NiCrMo weld metal with a relatively high copper content (0.27 %) were irradiated at about 315 °C to neutron fluences between 2 and 7 x 1019 cm-2 (E > 1 MeV). Post-irradiation annealing experiments on all the above mentioned types of specimens were conducted at an annealing temperature of 450 °C, which was selected after recovery experiments on hardness and impact test specimens only, performed at annealing temperatures in the range 350 – 550 °C and with annealing times of up to 168 h. Annealing at 550 °C, a temperature which is not applicable to a reactor pressure vessel (RPV) in situ, yielded impact properties better than the pre-irradiation values. After annealing at 450 °C, which can be applied in annealing of RPVs, residual shifts of transition temperature of 40 to 50 K remained. Another weldment of similar composition irradiated at about 285 °C reached the same post-anneal level of residual shift. Some specimens were re-irradiated after irradiation and subsequent 450 °C/60 h annealing. They reached the same total transition temperature shift after an additional fluence of the same magnitude as the fluence of the primary irradiation. After a second 450 °C annealing the residual shift again was about 40 K.


Keywords:
neutron irradiation, annealing, reactor pressure vessel, low alloy steel, weld metal, mechanical properties

Paper ID: STP23946S
Committee/Subcommittee: E10.08
DOI: 10.1520/STP23946S
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