Reduced oxygen content of PM HIP materials for nuclear power plants

Purpose and goal

Powder metallurgy is an attractive, alternative method to manufacture large components for nuclear power plants. Yet, the method gives relatively high oxygen content for the material combined with impaired impact toughness values. The aim of the project is to develop methods as an integrated part in the powder metallurgical manufacturing process to achieve minimum, homogenous oxygen content for products weighting up to several tons. The goal was successfully reached with a hydrogen-based reduction process.

Expected results and effects

A new technique resulting in a reduced oxygen content of PM HIP materials has been developed. The availability of this new technique has improved competitiveness of Swedish powder industry, in a form of new available services. The PM HIP components can now gain from improved toughness which is of interest in nuclear applications. Once the use of PM HIP materials becomes accepted in nuclear power plants, many benefits will be available for the end-uses such as shorter, effective security controls and shorter stand stills.

Planned approach and implementation

The project was carried out in three phases characterized by very active participations of all partners. First, a method to minimize the oxygen content of the powdered raw material was elaborated. There after the parameters for an oxygen reduction process, conducted by a gas treatment of the powder, was be elaborated for increasingly larger powder volumes and for different alloys. Finally, the validity and repeatability of the process and achieved results (homogeneity of oxygen reductions in large volumes) was confirmed to become closer for the commercialization of the process.