A reliable welding method producing joint properties as similar to those of the base materials as possible is needed in sealing the copper corrosion barrier of the final disposal canister for spent nuclear fuel. Friction stir welding (FSW) and electron beam welding (EBW) are currently the two potential methods. FSW is a new and innovative joining method. It is a solid state method, where the detrimental phenomena related to melting do not occur. Other advantages include small and uniform grain size, equiaxed grains, random texture, as well as good mechanical properties of the joints. Friction stir processing (FSP) is a variation of FSW, and it is used to e.g. heal casting defects and improve corrosion properties. The work in this Doctoral Thesis concentrated on FSW of copper and the microstructure of the welds as well as on the formation of the microstructure. The studied subjects include recrystallization, banding, as well as entrapped oxide particles and their influence on the localization of deformation. The results indicate that the microstructure and mechanical properties of the FSW welds are very similar to those of the base materials (unlike EB welds), making FSW a preferable method for sealing the canisters for spent nuclear fuel.
|Translated title of the contribution||Kuparin kitkahitsaus pyörivällä työkalulla ja hitsien mikrorakenne ja ominaisuudet|
|Publication status||Published - 2012|
|MoE publication type||G4 Doctoral dissertation (monograph)|
- friction stir welding
- oxide particles