STP1175: Annealing Experiments on Irradiated NiCrMo Weld Metal

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

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

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

    Pages: 11    Published: Jan 1994


    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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