Patent ID: 9284617
Filing Date: 2016-03-15
CPC Classification: C21C,C22C

Claim Text:
1. A method to obtain a gray iron alloy, in an induction furnace, wherein the method comprising: a) deoxidizing of a liquid metal in a furnace by: increasing the furnace temperature inside a range of 1370° C.-1400° C., the silicon dioxide (SiO2) equilibrium temperature; turning off power to the furnace about for at least 5 minutes in order to promote flotation of coalesced oxides and other impurities; spreading an agglutinating agent on the surface of the liquid metal then removing said agglutinant material, now saturated with coalesced oxides from the liquid metal, leaving a cleaner liquid metal inside the furnace; b) by pre-nucleating: pouring from 15% to 30% of the liquid metal on a specific ladle; during operation, inoculating from 0.45% to 0.60% in % weight of a granulated inoculant of Fe—Si—Sr or Fe—Si—Ba—La alloys, right on a stream of the liquid metal; pouring back over inoculated liquid metal from the ladle to the furnace, in order to mix over inoculated metal from the ladle with the uninoculated metal remained into the furnace; wherein during this last operation, the furnace must be kept on “turn on” phase; and from thermal analysis, the product of pre-nucleating has two thermal parameters from the cooling curves with: a eutectic under cooling temperature, TSE, greater than or equal to 1115° C. and a range of eutectic recalescence, ΔT, with a maximum of 6° C., wherein TSE and ΔT are two thermal parameters from the cooling curves during solidification; during pouring an allowed temperature for HPI casts (Tp) is +/−10° C., in order to obtain a global cast modulus inside a range between 1.38 and 1.52; and the eutectoidic phase, the HPI microstructure presents graphite content on its matrix ≦2.3%, calculated by lever rule taking as reference the equilibrium diagram Fe—Fe3C.