Study of cracking and microstructure in Co-free valve seat hardfacing

Nuclear Materials and Energy

Matias Ahonen¹  Pekka Nevasmaa²  Paavo Rautala³  Iikka Virkkunen³  Zaiqing Que³  Hannu Reinvall⁴ 

[1] Corresponding author.;Department of Mechanical Engineering, Aalto University School of Engineering, Otakaari 4, 02150 Espoo, Finland;Nuclear Reactor Materials, VTT Technical Research Centre of Finland, Kivimiehentie 3, FI-02044 VTT, Finland;Teollisuuden Voima Oyj, 27160 Eurajoki, Finland;

关键词: Hardfacing;    Cobalt-free;    Valve;    Nuclear;    Microstructure;   

DOI  :  

来源: DOAJ

【 摘 要 】

For 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.

【 授权许可】

Unknown