High strength ductile hot rolled nitrogenized steel

Claim 1

The method of producing a high yield strength steel comprising the steps of: heating an aging low carbon steel to a temperature within the alpha plus gamma region of the iron carbon phase diagram for a time sufficient to dissolve a substantial proportion of the carbon into the ferrite of said steel and to form a predetermined proportion of said steel into austenite, quenching said steel to substantially retain the solubilized carbon in solution and to transform at least the major proportion of said austenite into a form selected from the group consisting of martensite and bainite, tempering said steel, plastically deforming the steel an amount equivalent to at least 2 percent on the tensile stress-strain diagram, aging said deformed steel for time sufficient to develop a desired superior yield strength, said predetermined proportion of austenite being an amount necessary to provide the aged steel with said yield strength when said steel is deformed at least the equivalent of 2 percent on the tensile stress-strain diagram, said temper providing the said quenched steel with sufficient ductility for subsequent forming without preventing the development of said desired yield strength.

Claim 2

The method of producing a high yield strength steel comprising the steps of: heating an aging low carbon steel to a temperature within the alpha plus gamma region of the iron carbon phase diagram for a time sufficient to dissolve a substantial proportion of the carbon into the ferrite of said steel and to form a predetermined proportion of said steel into austenite, quenching said steel to substantially retain the solubilized carbon in solution and to transform at least the major proportion of said austenite into a form selected from the group consisting of martensite and bainite, tempering said steel, plastically deforming the steel an amount equivalent to at least 2 percent on the tensile stress-strain diagram, aging said deformed steel for time sufficient to develop a desired superior yield strength, said predetermined proportion of austenite being an amount necessary to provide the aged steel with said yield strength when said steel is deformed at least the equivalent of 2 percent on the tensile stress-strain diagram, said temper providing the said quenched steel with sufficient ductility for subsequent forming without preventing the development of said desired yield strength.

Claim 3

The method of producing a high yield strength nitrogenized low carbon steel comprising the steps of: rapidly heating an aging low carbon nitrogenized steel to a temperature within the alpha plus gamma region of the phase diagram for a time sufficient to dissolve a substantial proportion of the carbon and nitrogen into the ferrite of said steel and to form a predetermined proportion of said steel into austenite, quenching said steel to substantially retain the solubilized carbon and nitrogen in solution and to transform at least the major proportion of said austenite into a form selected from the group consisting of martensite and bainite, tempering said quenched steel, plastically deforming the steel an amount equivalent to at least 2 percent on the tensile stress-strain diagram, aging said deformed steel for a time sufficient to develop a minimum yield strength of 80,000 psi, said predetermined proportion of austenite being an amount necessary to provide the aged steel with the yield strength of about 80,000 psi when said steel is deformed at least the equivalent of 2 percent on the tensile stress-strain diagram, said temper providing said quenched steel with sufficient ductility for subsequent forming without preventing the development of said minimum yield strength.

Claim 4

The method of producing a high yield strength nitrogenized low carbon steel comprising the steps of: rapidly heating an aging low carbon nitrogenized steel to a temperature within the alpha plus gamma region of the phase diagram for a time sufficient to dissolve a substantial proportion of the carbon and nitrogen into the ferrite of said steel and to form a predetermined proportion of said steel into austenite, quenching said steel to substantially retain the solubilized carbon and nitrogen in solution and to transform at least the major proportion of said austenite into a form selected from the group consisting of martensite and bainite, tempering said quenched steel, plastically deforming the steel an amount equivalent to at least 2 percent on the tensile stress-strain diagram, aging said deformed steel for a time sufficient to develop a minimum yield strength of 80,000 psi, said predetermined proportion of austenite being an amount necessary to provide the aged steel with the yield strength of about 80,000 psi when said steel is deformed at least the equivalent of 2 percent on the tensile stress-strain diagram, said temper providing said quenched steel with sufficient ductility for subsequent forming without preventing the development of said minimum yield strength.

Claim 5

The method of producing a high yield strength nitrogenized low carbon steel comprising the steps of: rapidly heating a hot rolled aging low carbon nitrogenized steel to a temperature within the alpha plus gamma region of the phase diagram for a time sufficient to dissolve a substantial proportion of the carbon and nitrogen into the ferrite of said steel and to form a predetermined proportion of said steel into austenite, quenching said steel to substantially retain the solubilized carbon and nitrogen in solution and to transform at least the major proportion of said austenite into a form selected from a group consisting of martensite and bainite, tempering said quenched steel, plastically deforming the steel an amount equivalent to at least 2 percent on the tensile stress-strain diagram, aging said deformed steel for a time sufficient to develop a minimum yield strength of 80,000 psi, said predetermined proportion of austenite being an amount necessary to provide the aged steel with a yield strength of about 80,000 psi when said steel is deformed at least the equivalent of 2 percent on the tensile stress-strain diagram, said temper providing said quenched steel with sufficient ductility for subsequent forming without preventing the development of said minimum yield strength.

Claim 6

The method of producing a high yield strength nitrogenized low carbon steel comprising the steps of: rapidly heating a hot rolled aging low carbon nitrogenized steel to a temperature within the alpha plus gamma region of the phase diagram for a time sufficient to dissolve a substantial proportion of the carbon and nitrogen into the ferrite of said steel and to form a predetermined proportion of said steel into austenite, quenching said steel to substantially retain the solubilized carbon and nitrogen in solution and to transform at least the major proportion of said austenite into a form selected from a group consisting of martensite and bainite, tempering said quenched steel, plastically deforming the steel an amount equivalent to at least 2 percent on the tensile stress-strain diagram, aging said deformed steel for a time sufficient to develop a minimum yield strength of 80,000 psi, said predetermined proportion of austenite being an amount necessary to provide the aged steel with a yield strength of about 80,000 psi when said steel is deformed at least the equivalent of 2 percent on the tensile stress-strain diagram, said temper providing said quenched steel with sufficient ductility for subsequent forming without preventing the development of said minimum yield strength.

Claim 7

The method of producing a high yield strength nitrogenized low carbon hot rolled steel comprising the steps of: rapidly heating an aging low carbon steel to a temperature within the alpha plus gamma region of the iron carbon phase diagram in the range of about 1,319° to 1,420°F. for a time sufficient to dissolve a substantial proportion of the carbon and nitrogen into the ferrite of said steel and to form a predetermined proportion of said steel into austenite, quenching said steel to substantially retain the solubilized carbon and nitrogen in solution and to transform at least the major proportion of said austenite into a form selected from the group consisting of martensite and bainite, tempering said quenched steel, plastically deforming the steel an amount equivalent to at least 2 percent on the tensile stress-strain diagram, aging said deformed steel for time sufficient to develop a minimum yield strength of 80,000 psi, said predetermined proportion of austenite being an amount necessary to provide the aged steel with the yield strength of about 80,000 psi when said steel is deformed at least the equivalent of 2 percent on the tensile stress-strain diagram, said temper providing said quenched steel with sufficient ductility for subsequent forming without preventing the development of said minimum yield strength.

Claim 8

The method of producing a high yield strength nitrogenized low carbon hot rolled steel comprising the steps of: rapidly heating an aging low carbon steel to a temperature within the alpha plus gamma region of the iron carbon phase diagram in the range of about 1,319° to 1,420°F. for a time sufficient to dissolve a substantial proportion of the carbon and nitrogen into the ferrite of said steel and to form a predetermined proportion of said steel into austenite, quenching said steel to substantially retain the solubilized carbon and nitrogen in solution and to transform at least the major proportion of said austenite into a form selected from the group consisting of martensite and bainite, tempering said quenched steel, plastically deforming the steel an amount equivalent to at least 2 percent on the tensile stress-strain diagram, aging said deformed steel for time sufficient to develop a minimum yield strength of 80,000 psi, said predetermined proportion of austenite being an amount necessary to provide the aged steel with the yield strength of about 80,000 psi when said steel is deformed at least the equivalent of 2 percent on the tensile stress-strain diagram, said temper providing said quenched steel with sufficient ductility for subsequent forming without preventing the development of said minimum yield strength.

Claim 9

The method of producing a high yield strength nitrogenized low carbon hot rolled steel comprising the steps of: rapidly heating an aging low carbon steel to a temperature within the alpha plus gamma region of the iron carbon phase diagram in the range of about 1,319° to 1,420°F. for a time period of 3 to 60 seconds to dissolve a substantial proportion of the carbon and nitrogen into the ferrite of said steel and to form a predetermined proportion of said steel into austenite, quenching said steel to substantially retain the solubilized carbon and nitrogen in solution and to transform at least the major proportion of said austenite into a form selected from the group consisting of martensite and bainite, tempering said quenched steel, plastically deforming the steel an amount equivalent to at least 2 percent on the tensile stress-strain diagram, aging said deformed steel for time sufficient to develop a minimum yield strength of 80,000 psi, said predetermined proportion of austenite being an amount necessary to provide the aged steel with the yield strength of at least about 80,000 psi when said steel is deformed at least the equivalent of 2 percent on the tensile stress-strain diagram, said temper being such as to provide the quenched steel with sufficient ductility to permit a tensile deformation of about 18 percent without preventing the development of the said 80,000 psi final yield strength.

Claim 10

The method of producing a high yield strength nitrogenized low carbon hot rolled steel comprising the steps of: rapidly heating an aging low carbon steel to a temperature within the alpha plus gamma region of the iron carbon phase diagram in the range of about 1,319° to 1,420°F. for a time period of 3 to 60 seconds to dissolve a substantial proportion of the carbon and nitrogen into the ferrite of said steel and to form a predetermined proportion of said steel into austenite, quenching said steel to substantially retain the solubilized carbon and nitrogen in solution and to transform at least the major proportion of said austenite into a form selected from the group consisting of martensite and bainite, tempering said quenched steel, plastically deforming the steel an amount equivalent to at least 2 percent on the tensile stress-strain diagram, aging said deformed steel for time sufficient to develop a minimum yield strength of 80,000 psi, said predetermined proportion of austenite being an amount necessary to provide the aged steel with the yield strength of at least about 80,000 psi when said steel is deformed at least the equivalent of 2 percent on the tensile stress-strain diagram, said temper being such as to provide the quenched steel with sufficient ductility to permit a tensile deformation of about 18 percent without preventing the development of the said 80,000 psi final yield strength.