Rumblefish,, after some re-search,,, Man this can keep on going,SO MUCH INVOLVED....EXOTIC METALS SOME I have`nt heard of,i`ll by-pass those...BUUUUT,main componet is carbon, more carbon content higher tensile strenght....CAST IRON-70,000-80,000 P.S.I. NODULAR IRON-95,000 P.S.I. CAST...