Ford Motor Company Limited

Applied Process, Inc.

Atmosphere Group

Bela V Kovacs

John R Keough

Herschel B Smartt

Roman M Nowicki

Gerald S Cole

Robert A Sensoli

Douglas M Pramstaller

Charles A Stickels

William R Keough

Sand castings are removed from their molds before cooling and reheated in a heat treating booster furnace. The castings are transferred from the booster furnace to a rotary drum filled with agitation media. As the castings pass through the media drum, they are simultaneously cleaned of sand particles and down-quenched by the agitation media. The system is particularly suited for austempering cast iron parts.

Combination sand cleaning and heat treating apparatus for sand casted

A method for producing a selectively surface hardened cast iron part includes the steps of (a) heating the part to a desired austempering temperature of between about 450.degree. F. and about 800.degree. F. until the entire cast iron part possesses the desired austempering temperature substantially uniformly throughout it; (b) heating only the surface of the cast iron part to an austenitizing temperature of between about 1500.degree. F. and about 1800.degree. F. by immersing the cast iron part in a molten lead or tin bath until a desired thickness of an austenite layer is formed on the surface of the cast iron part, without substantial heating of the interior of the cast iron part; (c) quenching the surface-heated cast iron part in a non-liquid quenching bath atmosphere, i.e. a gaseous atmosphere maintained at the desired austempering temperature, for a time adequate to transform the surface austenite layer to an ausferritic structure; and (d) cooling the cast iron part before bainite is formed in the heat-treated surface layer. In this manner, only the heat-treated surface layer of the cast iron part is hardened, because it is quenched from both sides simultaneously from two sources: self-quenching by the interior of the part, and external quenching by the austempering atmosphere. Typical heating times in step (a) are between about 10 minutes and about 10 hours, and in step (b) are between about 3 seconds and about 10 minutes. The quenching time in step (c) is typically between about 15 minutes and about 8 hours.

Method for producing a selectively surface hardened cast iron part

A method for preparing an austempered cast iron which includes an ausferritic matrix, the cast iron having a silicon content of from about 1.6 to about 2.4 weight percent, and a carbon content of from about 1.6 to about 2.2 weight percent, such that the carbon equivalent of the cast iron is from about 2.1 to about 3.0 weight percent. The method includes (a) melting the cast iron composition; (b) pouring the melt into a mold to form a casting having eutectic carbide particles; (c) altering the temperature of the casting to about 1650.degree.-1900.degree. F. and maintaining the temperature of the casting at about 1650.degree.-1900.degree. F. until substantially all of the eutectic carbide particles convert to temper graphite nodules to form a temper graphite-containing casting; (d) cooling the temper graphite-containing casting to about 1500.degree.-1750.degree. F. and maintaining the temperature of the tempered graphite-containing casting at about 1500.degree.-1750.degree. F. until a fully austenitic matrix is achieved; (e) quenching the austenitic matrix casting to a temperature of between about 460.degree. to about 750.degree. F. and maintaining that temperature until the entire casting is transformed to an ausferritic matrix; and (f) cooling the ausferritic matrix casting to room temperature before bainite is formed.

Method for preparing high silicon, low carbon austempered cast iron

A method for producing a selectively surface hardened cast iron part includes uniformly heating the surface of the part by immersion into a molten metallic bath until a desired thickness of surface austenite is produced, and thereafter quenching the heated cast iron part in a liquid quenching bath which is maintained at a temperature of between about 450.degree. to about 800.degree. F. for about 10 minutes to about 4 hours. The resultant selectively surface hardened cast iron part is surface hardened with the bulk of the body of the part remaining untempered. An apparatus for performing this process includes a molten metal bath chamber for containing the molten metal and a molten salt bath quenching chamber for quenching the cast iron parts with a conveyor means extending between the molten metal bath and the molten salt bath chambers. A second conveyor means removes the parts from the molten salt bath chamber.

Method and apparatus for surface austempering of cast iron parts

An austemperable cast iron which includes an ausferritic matrix, the cast iron having a silicon content of from about 1.6 to about 2.4 weight percent, and a carbon content of from about 1.6 to about 2.2 weight percent, such that the carbon equivalent of the cast iron is from about 2.1 to about 3.0 weight percent. The austempered cast iron is prepared by melting the cast iron composition; to about 1650.degree.-1900.degree. F. and maintaining the temperature of the casting at that temperature until substantially all of the eutectic carbide particles convert to temper graphite nodules to form a temper graphite-containing casting, then cooling the temper graphite-containing casting to about 1500.degree.-1750.degree. F. and maintaining the temperature of the tempered graphite-coating at about 1500.degree.-1750.degree. F. until a fully austenitic matrix is achieved, and then quenching and cooling the ausferritic matrix casting to room temperature before bainite is formed.

High silicon, low carbon austemperable cast iron

A closed mold assembly having a mold cavity therein, an ingate extending from the mold cavity through the mold assembly with an opening having an outer wall for immersion into a bath of molten metal, and an expendable cap fitting around the outer wall of the ingate having a continuously upward tapering dimension to urge the top larger of the molten metal in a bath away from the ingate opening during the immersion process to minimize impurity inclusion in the mold. The expendable cap is preferably made from a non-contaminating sacrificial material intended to be melted after immersion into the molten metal bath without being detrimental to the quality of the workpiece. The closed mold assembly may also include upflow channels formed within the bottom of the mold assembly to further urge impurities in the top layer to flow away from the ingate opening and may further include downwardly extending ribs in the mold assembly with flat surfaces on the bottom to form a level surface to facilitate easy mold handling such that the molds may be stacked upon one another.

Expendable cap device to minimize dross inclusions in the vacuum casting

A method is disclosed for making gray iron having both increased wear resistance and impact toughness, comprising: (a) solidifying a hypoeutectic gray iron melt (i) to which has been added a eutectic carbide forming agent in an amount of 0.3-0.8% by weight, selected from the group consisting of Ti, V and Cr, and, advantageously, a high carbon austenite/ferrite forming agent in an amount of 0.5-3.0%, by weight, selected from the group consisting of nickel and copper, and at a solidification rate to form an austenite matrix with a mixture of flake graphite and eutectic carbide particles suspended in said matrix; and (b) heat treating the solid by (i) heating to a temperature and for a period of time to fully austenitize the solid, (ii) quenching the solid to a temperature level and for a period of time to decompose austenite to form a high carbon austenite and ferrite matrix, and (iii) air cooling the solid to room temperature. The hypoeutectic gray iron contains less than 4.35% carbon equivalent and preferably comprises, by weight, 2.5-2.95% carbon, 2.0-2.5% silicon, 0.5-0.90% manganese, and the remainder iron.

Gray cast iron having both increased wear resistance and toughness

A method is disclosed which comprises: (a) forming a ferrous alloy melt consisting essentially of by weight, 3-4% carbon, 2.0-3.0% silicon, 0.1-0.9% manganese, up to 0.02% phosphorus, up to 0.002% sulphur, up to 1% contaminants or impurities, 0-0.4% molybdenum, 0-3.0% nickel or copper, and the reminder essentially iron, the melt being subjected to a graphite modifying agent in an amount and for a period of time effective to form either ductile or semiductile iron upon solidification; (b) heat treating the solidification of said melt by austempering to form a matrix consisting substantially of high carbon austenite and ferrite and a cell boundary having unreacted low carbon austenite; (c) heating said austempered iron to a pearlite forming temperature (1200.degree.-1300.degree. F.) and holding (2-5 minutes) at said temperature to permit the unreacted low carbon austenite to form pearlite; and (d) cooling said heat treated iron to room temperature.

Machinable ductile or semiductile cast iron and method

A method is disclosed for forming a surface hardenable cast iron article by development of metastable retained austenite in the cell boundary of a ductile or semiductile cast iron. The method comprises (a) controlling the solidification of a cast iron melt to extend the eutectic arrest time to 4-12 minutes, the melt having by weight percent a carbon equivalent (carbon plus one-third silicon) equal to 4.3-5.0, manganese 0.55-1.2, nickel 0.5-3.0, and the remainder essentially iron, the melt having been treated to form cell boundaries in the solidified iron with a high proportion of the manganese being segregated in the cell boundaries; (b) subjecting the solidified cast iron to an austempering heat treatment to permit the segregated manganese in the cell boundaries to form metastable retained austenite; and (c) terminating the heat treatment prior to the conversion of the metastable austenite to a stable microstructure. To obtain the benefits of wear resistance, the method further comprises using the heat treated cast iron by stressing a surface region thereof and transforming the microstructure of such surface region to martensite.

Hardenable cast iron and the method of making cast iron

A method is disclosed for making compacted graphite cast iron of improved strength and hardness while retaining excellent thermal conductivity, low shrinkage, and excellent damping characteristics. A ferrous alloy is melted consisting essentially of, by weight, 3-4% C, 2-3% Si, 0.2-0.7% Mn, 0.25-0.4 Mo, 0.5-3.0% Ni, up to 0.002% sulfur, up to 0.02% phosphorus, and impurities or contaminants up to 1.0%, with the remainder being essentially iron. The melt is subjected to a graphite modifying agent to form compacted graphite upon solidification. The solidified casting is heat treated by austempering and quenching to produce an iron having a matrix of bainite and austenite.

Method of making CG iron

Method of making ductile cast iron with improved strength

Method of making high strength ferritic ductile iron parts

A method is disclosed of making as-cast ductile iron wherein an iron melt having a chemistry capable of forming gray iron having flake graphite is treated with a nodularizing agent and solidified to provide a microstructure consisting substantially of a pearlite matrix containing uniformly distributed graphite nodules surrounded by ferrite. The iron melt is alloyed with: (a) at least one of 0.02-0.06% Sb and 0.02-0.08% Sn, (b) 0.001-0.0015% each of Ce and La, and (c) 0.5-1.0% Mn.

Method for increasing mechanical properties in ductile iron by alloy

A method and apparatus for continuously stream treating molten metal is disclosed. A controlled vortex flow of the molten metal is stimulated and a stream of particulate treating agent, such as magnesium ferrosilicon, or pure magnesium mixed with other ferro alloys, is directed onto a predetermined zone of the vortical flow. A stream choke is employed downstream of the vortex flow to control dwell time of the flow in the vortex and to regulate downstream mixing. This method increases magnesium recovery, provides flexibility to change charge weights, eliminates residue in treating apparatus, and promotes dissolution of the treating agent within a desired zone.

Continuous stream treatment of ductile iron

A method and apparatus for producing modified grey iron, and particularly nodular cast iron, is disclosed. The apparatus comprises refractory elements including an inclined flow course for continuous reception of molten grey iron, a V-shaped inclined receptacle interposed in said course into which a predetermined supply of modifying agent, such as magnesium, is injected to react with said iron, and means for controlling the egress of iron from the receptacle in order to sequentially stage the build-up and dissipation of a pool of iron in said receptacle facilitating chemical reactions and thorough mixing for attaining and improving the homogeneity of the modified iron elements. The product and composition uniquely is characterized by about 3.5 carbon, by weight, 2.5% silicon, 0.2-0.9Mn sulfur no greater than 0.015%, the remainder being essentially iron; the composition is devoid of carbide and dross or slag and has a graphite nodule count of at least 400 per square millimeter in a 1/2inch section.

Growing community of inventors

Bloomfield Hills, MI, United States of America

Bela V Kovacs