Method of making thin-walled ductile iron castings

摘要

A method is disclosed for making ductile iron castings having thin walls. Molten grey iron (preferably 3.5-4.2%C, 1.5-2.4% Si, and no greater than 0.65% carbide formers) is introduced to a mold assembly and nodularized/inoculated in such assembly prior to passing into the mold cavity of the assembly. The treated molten iron is fed into the mold cavity and into one extremity of a thin space thereof (0.2 inches thick or less and a length of at least 12 times the thickness). The treated molten metal is additionally mixed by vortical or turbulent flow immediately downstream of the treatment chamber as it is being conveyed to the mold cavity. While continuing to feed the treated molten iron to fill the mold cavity, a reservoir of the treated molten iron is created at a midstation of the thin space. The reservoir acts to conserve the heat of the molten metal and thus feed hotter molten metal to the remainder of the thin space and other connected cavity portions. The reservoir space also serves to define an integral functional part of the casting when solidified.