Grain refinement of steels is important because as-cast steels are prime examples of materials where the properties achieved depend upon the characteristics of the solidification microstructure. In general, a coarse columnar grain structure will inevitably evolve upon solidification if potent heterogeneous nucleation sites ahead of the solidifying front are absent. In the presence of effective seed crystals, fine equiaxed grains form directly in the melt.

SINTEF is developing specials addition alloys for steels that contain a fine dispersion of effective seed crystals within a project called DISvaDRI. The project is focussing both on the as-cast structure of stainless steels that do not have a solid-state phase transformation, as well as on tailoring the right inclusions for nucleation of acicular ferrite. The alloys are produced through rapid solidification techniques as well as through solid state processing of mixtures of fine powders.

SINTEF is working on grain refinement of steels in close co-operation with the Norwegian ferroalloy industry and the European steel industry.

Example of the effect of a grain refiner on the microstructure of cast AISI 329 stainless steel.

Recent publications related to this work:
Conference paper Electric Furnace Conference 2001
Conference paper MS&T 2004

 Contact: Casper van der Eijk