Gray iron Investment castings ndi zinthu zotayira zomwe zimatsanuliridwa ndi kutayika kwa phula popanga zitsulo. Gray iron (kapena imvi cast iron) ndi mtundu wa iron-carbon alloy (kapena Ferrum-Carbon Alloy) yomwe ili ndi graphite microstructure. Amatchulidwa ndi mtundu wa imvi wa fracture yomwe imapanga. 
