Study of cracking and microstructure in Co-free valve seat hardfacing
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Nuclear Materials and Energy, Volume 31
AbstractFor reducing the radiological hazard, Co-free hardfacing alternatives have been used to replace the traditional Co-based hardfacing alloys in nuclear power plant applications. However, manufacturing a defect-free Co-free hardfacing is challenging. Reduced galling resistance and mechanical properties exhibited by common replacement alloys in some conditions limit the application. This issue is important for the operating nuclear power plants with lifetime extension and also for the new builds. In this paper, a failed industrial hardfacing was studied. Through-the-thickness cracks of the Co-free hardfacing deposit with NOREM 02 on a nuclear swing check plug were detected. The potential cause of the brittle interdendritic cracking was studied and the detailed microstructure of the Co-free hardfacing analysed. The solidification defects during the manufacturing and the lacking of ferrite phase in the microstructure together with the potentially non-optimized handling procedures are concluded to be the causes of the observed cracking.
Hardfacing, Cobalt-free, Valve, Nuclear, Microstructure, WEAR-RESISTANCE, GALLING RESISTANCE, FRACTURE-TOUGHNESS, IRON, ALLOYS, STEEL, TEMPERATURE, PERFORMANCE, HARDNESS
Que , Z , Ahonen , M , Virkkunen , I , Nevasmaa , P , Rautala , P & Reinvall , H 2022 , ' Study of cracking and microstructure in Co-free valve seat hardfacing ' , Nuclear Materials and Energy , vol. 31 , 101202 . https://doi.org/10.1016/j.nme.2022.101202