In-the-Mold Additions

Adding selenium (Se) to stainless steel castings poured in green sand molds is effective in eliminating porosity. To evaluate the effect of controlled amounts of Zr and Se on porosity elimination in gray iron, small amounts were added (8% Zr as FeSiZr) to a 9-g in-the-mold inoculating tablet. A second experiment was run with an addition of 3.3% Se to an 8% Zr-modified in-the-mold inoculating tablet.

Castings made with either Zr or with both Se and Zr still contained some subsurface porosity, probably the result of insufficient treatment alloy. The microstructures of both castings treated with the 9-g inoculating tablets were somewhat improved, containing 100% Type A graphite, compared to the standard ladle inoculation with 75% foundry grade FeSi containing 0.75% Ca, which contained some Types B and D graphite.

Table of contents
[Paper Header]
[Porosity Study]
[Binder Ratio] [Binder Level] [Casting Temperature] [Section Size]
[Sand Effect] [Iron Oxide Additions] [ Binder Dispersion/Mixing]
[Metal Composition] [Core Age]
[Eliminating Porosity]
[Ti and Zr Additions] [In-the-Mold Additions] [ Core Washes]
[Core Post-Baking]
[Discussion]