Surface layer inoculation of a sand cast hypoeutectic gray iron melt

•A suspension consisting of a powdered inoculation agent was developed.•The suspension's application as mold coat leads to an inoculated gray iron melt.•Hardness measurements show the statistically significant reproducibility.•A grain size of 100–200 μm is most suitable for the lowest hardness.•The low costs and easy application make this procedure very attractive for practical use.

A suspension containing a powdered inoculating agent was developed and sprayed onto the surface of the sand mold's cavity prior to casting. Metallographic examinations and Brinell hardness measurements show that by this method an inoculated microstructure containing mainly type A graphite can be reproducibly achieved from an untreated hypoeutectic gray iron melt. This effect can be shown in the whole specimen and is statistical significant in the focused specimens regions next to the surface and center. An inoculating agent's powder size of 100–200 μm is most suitable to achieve a large amount of type A graphite and homogeneous low Brinell hardness.