High saturation cobalt-iron magnetic alloys and method of preparing same

Claim 2

A WORKED AND HEAT TREATED ALLOY HAVING A SUBSTANTIALLY FLAT SURFACE AND WHICH ALLOY MEMBER IS SUITABLE FOR USE AS A TRANSFORMER CORE MATERIAL, CONSISTING ESSENTIALLY OF FROM ABOUT 4 TO ABOUT 6% COBALT, UP TO ABOUT 1.5% SILICON, UP TO ABOUT 0.3% ALUMINUM, UP TO ABOUT 0.8% CHROMIUM, UP TO ABOUT 0.3% MANGANESE, UP TO ABOUT 0.03% SULFUR, UP TO ABOUT 0.05% NITROGEN, LESS THAN ABOUT 0.03% CARBON AND THE BALANCE ESSENTIALLY IRON WITH INCIDENTAL IMPURITIES, THE ALLOY HAVING AN ORIENTATION IN WHICH OVER 50% BY VOLUME OF THE GRAINS HAVE A UNIT CUBE ORIENTATION SELECTED RORM THE GROUP CONSISTING OF (110) AND (100) IN WHICH THE SELECTED PLANE IS PARALLEL TO WITHIN 15* OF THE PLANE OF THE SURFACE OF THE ALLOY AND IN WHCH TWO OF THE CUBE EDGES OF THE SELECTED PLANE ARE ALIGNED PARALLEL TO WITHIN 15* OF THE WORKING DIRECTION, THE ALLOY ALSO HAVING A RESISTIVITY IN EXCESS OF 30 MICROOHM-CENTIMETERS.

Claim 3

The alloy of claim 1 in which the silicon content is within the range of between 1 and 1.5%.

Claim 4

The alloy of claim 1 in which the total of silicon and aluminum is within the range of between about 1.5% and about 1.8%.

Claim 5

The alloy of claim 1 in which the cobalt content is maintained within the range of between about 5 and about 6% and the total silicon and aluminum content is within the range of between about 1.5 and about 1.8%.

Claim 6

The alloy of claim 1 in which the cobalt content is between about 4 and about 5%, the silicon content is between about 1 and 1.5%, the aluminum content is between about 0.1 and about 0.3%, and the nitrogen content does not exceed about 0.005%.

Claim 7

A worked and heat treated alloy having a substantially flat surface and which alloy member is suitable for use as a transformer core material, consisting essentially of from about 4 to about 6% cobalt, from about 1.3 to about 1.5% silicon, up to about 0.3% aluminum, up to about 0.8% chromium, up to about 0.3% manganese, up to about 0.03% sulfur, up to about 0.05% nitrogen, less than about 0.03% carbon and the balance being iron with incidental impurities, the alloy having an orientation in which over 50% by volume of the grains have a unit cube orientation selected from the group consisting of (110) and (100) in which the selected plane is parallel to within 10* of the plane of the surface of the alloy and in which two of the cube edges of the selected plane are aligned parallel to within 10* of the working direction, the alloy having a resistivity in excess of 30 microohm-centimeters.

Claim 8

A worked and heat treated alloy having a substantially flat surface and which alloy member is suitable for use as a transformer core material, consisting essentially of from about 4 to about 6% cobalt, from about 1.3 to about 1.5% silicon, up to about 0.3% aluminum, up to about 0.8% chromium, up to about 0.3% manganese, up to about 0.03% sulfur, up to about 0.05% nitrogen, less than about 0.03% carbon and the balance being iron with incidental impurities, the alloy having an orientation in which over 50% by volume of the grains have a unit cube orientation selected from the group consisting of (110) and (100) in which the selected plane is parallel to within 10* of the plane of the surface of the alloy and in which two of the cube edges of the selected plane are aligned parallel to within 10* of the working direction, the alloy having a resistivity in excess of 30 microohm-centimeters.

Claim 9

The alloy of claim 6 in which the total of silicon and aluminum is within the range of between about 1.5 and about 1.6%.

Claim 10

The alloy of claim 6 in which the cobalt content is between about 5 and about 6% and the total of silicon and aluminum is within the range of between about 1.5% and about 1.6%.

Claim 11

The alloy of claim 6 in which the cobalt content is within the range of between about 4 and about 5%, the total of silicon and aluminum is within the range of between about 1.5 and about 1.6% and the nitrogen content does not exceed 0.005%.

Claim 12

A worked and heat treated alloy having a substantially flat surface and which alloy is suitable for use as a transformer core material, consisting essentially of from about 4 to about 6% cobalt, from about 1 to about 1.5% silicon, from about 0.1 to about 0.8% chromium, less than about 0.01% sulfur, less than about 0.03% carbon and the balance beinG iron with incidental impurities, the alloy having an orientation in which over 50% by volume of the grains have a unit cube orientation selected from the group consisting of (110) and (100) in which the selected plane is parallel to within 10* of the plane of the surface of the alloy and in which two of the edges of the selected plane are aligned parallel to within 10* of the working direction, the alloy also having a resistivity of at least 30 microohm-centimeters.

Claim 13

A worked and heat treated alloy having a substantially flat surface and which alloy is suitable for use as a transformer core material, consisting essentially of from about 4 to about 6% cobalt, from about 1 to about 1.5% silicon, from about 0.1 to about 0.8% chromium, less than about 0.01% sulfur, less than about 0.03% carbon and the balance beinG iron with incidental impurities, the alloy having an orientation in which over 50% by volume of the grains have a unit cube orientation selected from the group consisting of (110) and (100) in which the selected plane is parallel to within 10* of the plane of the surface of the alloy and in which two of the edges of the selected plane are aligned parallel to within 10* of the working direction, the alloy also having a resistivity of at least 30 microohm-centimeters.

Claim 14

The alloy of claim 10 in which the sum of the silicon and chromium content does not exceed about 2%.

Claim 15

The alloy of claim 10 in which the cobalt content is within the range of between about 4% and 5%.

Claim 16

A worked and heat treated alloy having a substantially flat surface and which alloy is suitable for use as a transformer core material consisting essentially of from about 4 percent to about 6% by weight of cobalt, up to about 1.5% silicon, up to about 0.8% chromium, up to about 0.3% aluminum, up to about 0.3% manganese, up to about 0.03% sulfur, up to about 0.05% nitrogen, the aluminum, manganese, nitrogen and sulfur being selected within the respective ranges stated to provide effective amounts of at least one inoculant of the group consisting of manganese sulfide and aluminum nitride, less than about 0.03% carbon and the balance iron with incidental impurities, the grains of the alloy having an orientation in which over 50% by volume of the grains have a unit cube orientation in which the (110) plane is parallel to within 15* of the plane of the surface of the alloy and in which two of the cube edges of the (110) plane aligned within 15* of the working direction, the alloy being further characterized by a secondary recrystallized microstructure, a resistivity in excess of 30 microohm-centimeters and a saturation induction of at least 21,500 gauss.

Claim 17

A worked and heat treated alloy having a substantially flat surface and which alloy is suitable for use as a transformer core material consisting essentially of from about 4 percent to about 6% by weight of cobalt, up to about 1.5% silicon, up to about 0.8% chromium, up to about 0.3% aluminum, up to about 0.3% manganese, up to about 0.03% sulfur, up to about 0.05% nitrogen, the aluminum, manganese, nitrogen and sulfur being selected within the respective ranges stated to provide effective amounts of at least one inoculant of the group consisting of manganese sulfide and aluminum nitride, less than about 0.03% carbon and the balance iron with incidental impurities, the grains of the alloy having an orientation in which over 50% by volume of the grains have a unit cube orientation in which the (110) plane is parallel to within 15* of the plane of the surface of the alloy and in which two of the cube edges of the (110) plane aligned within 15* of the working direction, the alloy being further characterized by a secondary recrystallized microstructure, a resistivity in excess of 30 microohm-centimeters and a saturation induction of at least 21,500 gauss.

Claim 18

The alloy of claim 13 in which the cobalt content is within the range between about 4 and about 5% and the inoculant is manganese sulfide.

Claim 19

The alloy of claim 13 in which the cobalt content is within the range between about 4% and about 5%, the inoculant is manganese sulfide and in which the alloy contains up to 0.3% aluminum and a nitrogen content of less than about 0.005%.

Claim 20

The alloy of claim 13 in which the silicon content is within the range of between about 1% and about 1.5%.

Claim 21

The alloy of claim 13 in which the cobalt content is within the range between about 4 and about 5%, the inoculant is aluminum nitride and the sulfur content is less than 0.01%.

Claim 22

A worked and heat treated alloy having a substantially flat surface and which alloy is suitable for use as a transformer core material consisting essentially of from about 4 to about 6% cobalt, from about 1.0 to about 1.5% silicon, at least one inoculant selected from the group consisting of manganese sulfide and aluminum nitride, the respective amounts of the components of the inoculants being limited to from about 0.05 to about 0.3% manganese with a corresponding sulfur content of between about 0.01% and about 0.03% where manganese sulfide is the inoculant and between about 0.02% and about 0.3% aluminum with a corresponding nitrogen content of between about 0.005% and about 0.05% nitrogen where aluminum nitride is the inoculant, less than 0.03% carbon and the balance iron with incidental impurities; the alloy having an orientation in which over 50% by volume of the grains have a unit cube orientation in which the (110) plane is parallel to within 10* of the plane of the surface of the alloy and in which two of the cube edges of the (110) plane are aligned parallel to within 10* of the working direction, the alloy being furtHer characterized by a secondary recrystallized microstructure, a resistivity in excess of 30 microohm-centimeters and a saturation induction of at least about 21,500 gauss.

Claim 23

A worked and heat treated alloy having a substantially flat surface and which alloy is suitable for use as a transformer core material consisting essentially of from about 4 to about 6% cobalt, from about 1.0 to about 1.5% silicon, at least one inoculant selected from the group consisting of manganese sulfide and aluminum nitride, the respective amounts of the components of the inoculants being limited to from about 0.05 to about 0.3% manganese with a corresponding sulfur content of between about 0.01% and about 0.03% where manganese sulfide is the inoculant and between about 0.02% and about 0.3% aluminum with a corresponding nitrogen content of between about 0.005% and about 0.05% nitrogen where aluminum nitride is the inoculant, less than 0.03% carbon and the balance iron with incidental impurities; the alloy having an orientation in which over 50% by volume of the grains have a unit cube orientation in which the (110) plane is parallel to within 10* of the plane of the surface of the alloy and in which two of the cube edges of the (110) plane are aligned parallel to within 10* of the working direction, the alloy being furtHer characterized by a secondary recrystallized microstructure, a resistivity in excess of 30 microohm-centimeters and a saturation induction of at least about 21,500 gauss.

Claim 24

The alloy of claim 18 in which the cobalt content is within the range between about 4 and about 5%, the inoculant is manganese sulfide and the alloy contains from about 0.1% to about 0.3% aluminum and not more than 0.005% nitrogen.

Claim 25

A worked and heat treated alloy having a substantially flat surface and which alloy is suitable for use as a transformer core material consisting essentially of from about 4 to about 6% cobalt, up to about 1.5% silicon, up to about 0.8% chromium, up to about 0.3% aluminum, up to about 0.3% manganese, less than 0.01% sulfur, less than about 0.005% nitrogen, less than about 0.03% carbon and the balance iron with incidental impurities, the alloy having an orientation in which at least 50% by volume of the grains have a unit cube orientation in which the (110) plane is parallel to within 15* of the surface of the alloy and in which two of the cube edges of the (110) plane are aligned within 15* of the working direction, the alloy being further characterized by a primary recrystallized microstructure and a resistivity in excess of 30 microohm-centimeters.

Claim 26

A worked and heat treated alloy having a substantially flat surface and which alloy is suitable for use as a transformer core material consisting essentially of from about 4 to about 6% cobalt, up to about 1.5% silicon, up to about 0.8% chromium, up to about 0.3% aluminum, up to about 0.3% manganese, less than 0.01% sulfur, less than about 0.005% nitrogen, less than about 0.03% carbon and the balance iron with incidental impurities, the alloy having an orientation in which at least 50% by volume of the grains have a unit cube orientation in which the (110) plane is parallel to within 15* of the surface of the alloy and in which two of the cube edges of the (110) plane are aligned within 15* of the working direction, the alloy being further characterized by a primary recrystallized microstructure and a resistivity in excess of 30 microohm-centimeters.

Claim 27

The alloy of claim 20 in which the silicon content is within the range between about 1 and about 1.5%.

Claim 28

The alloy of claim 20 in which the total silicon and chromium content is within the range between about 1 and about 2%.

Claim 29

The alloy of claim 20 in which the cobalt content is within the range between about 4 and about 5% and the total silicon and chromium content is within the range between about 1.5% and about 1.8%.

Claim 30

A worked and heat treated alloy having a substantially flat surface and which alloy is suitable for use as a transformer core material consisting essentially of from about 4 to about 5% cobalt, from about 1 to about 1.5% silicon, up to 0.8% chromium, less than 0.01% sulfur, less than 0.005% nitrogen, less than 0.03% carbon and the balance iron with incidental impurities, the alloy having an orientation in which at least 50% by volume of the grains have a unit cube orientation in which the (110) plane is parallel to within 10* of the surface of the alloy and in which two of the cube edges of the (110) plane are aligned parallel to within 10* of the working direction, the alloy being further characterized by a primary recrystallized microstructure and a resistivity of at least 30 microohm-centimeters.

Claim 31

A worked and heat treated alloy having a substantially flat surface and which alloy is suitable for use as a transformer core material consisting essentially of from about 4 to about 5% cobalt, from about 1 to about 1.5% silicon, up to 0.8% chromium, less than 0.01% sulfur, less than 0.005% nitrogen, less than 0.03% carbon and the balance iron with incidental impurities, the alloy having an orientation in which at least 50% by volume of the grains have a unit cube orientation in which the (110) plane is parallel to within 10* of the surface of the alloy and in which two of the cube edges of the (110) plane are aligned parallel to within 10* of the working direction, the alloy being further characterized by a primary recrystallized microstructure and a resistivity of at least 30 microohm-centimeters.

Claim 32

The alloy of claim 24 in which the chromium content is within the range of between about 0.5% and about 0.8%.

Claim 33

A worked and heat treated alloy having a substantially flat surface and which alloy is suitable for use as a transformer core material consisting essentially of from about 4 to about 6% cobalt, up to about 1.5% silicon, up to about 0.8% chromium, up to about 0.3% aluminum, less than 0.01% sulfur, less than 0.005% nitrogen, less than about 0.03% carbon and the balance iron with incidental impurities, the alloy having an orientation in which over 50% by volume of the grains have a unit cube orientation in which the (100) plane is parallel to within 15* of the surface of the alloy and in which two of the cube edges of the (100) plane are aligned parallel to within 15* of the working direction, the alloy being further characterized by a primary recrystallized microstructure and a resistivity of at least 30 microohm-centimeters.

Claim 34

A worked and heat treated alloy having a substantially flat surface and which alloy is suitable for use as a transformer core material consisting essentially of from about 4 to about 6% cobalt, up to about 1.5% silicon, up to about 0.8% chromium, up to about 0.3% aluminum, less than 0.01% sulfur, less than 0.005% nitrogen, less than about 0.03% carbon and the balance iron with incidental impurities, the alloy having an orientation in which over 50% by volume of the grains have a unit cube orientation in which the (100) plane is parallel to within 15* of the surface of the alloy and in which two of the cube edges of the (100) plane are aligned parallel to within 15* of the working direction, the alloy being further characterized by a primary recrystallized microstructure and a resistivity of at least 30 microohm-centimeters.

Claim 35

The alloy of claim 26 in which the chromium content does not exceed 0.3% in the absence of silicon.

Claim 36

The alloy of claim 26 in which the coBalt is within the range between about 4 and about 5% and the total of silicon and chromium content does not exceed about 2%.

Claim 37

The alloy of claim 26 in which the total silicon and chromium content is within the range between about 1 and about 2%.

Claim 38

In the process for producing (110) (001) texture in an alloy suitable for use as a transformer core material, the steps comprising, hot working a casting having a composition including less than 0.03% carbon, less than 0.01% sulfur, from about 4% to about 6% cobalt, up to about 1.5% silicon, up to about 0.3% aluminum, up to about 0.8% chromium, less than 0.005% nitrogen and the balance iron with incidental impurities, the hot working of the casting being at a temperature within the range of between about 1,000*C and about 1,100*C, cold working the hot worked material in two or more operations to finish gauge, the last cold working operation effecting a reduction in cross-sectional area of between 50 and 75% with an intermediate anneal interposed between successive cold working operation, said intermediate anneal being at a temperature within the range between about 800*C and the Ac1 temperature of the composition, and thereafter annealing the finish guage material at a temperature within the range between about 800*C and the Ac1 temperature of the composition, the material exhibiting a preponderance of the grains having a (110) (001) orientation, a primary recrystallized microstructure and normal grain growth.

Claim 39

In the process for producing (110) (001) texture in an alloy suitable for use as a transformer core material, the steps comprising, hot working a casting having a composition including less than 0.03% carbon, less than 0.01% sulfur, from about 4% to about 6% cobalt, up to about 1.5% silicon, up to about 0.3% aluminum, up to about 0.8% chromium, less than 0.005% nitrogen and the balance iron with incidental impurities, the hot working of the casting being at a temperature within the range of between about 1,000*C and about 1,100*C, cold working the hot worked material in two or more operations to finish gauge, the last cold working operation effecting a reduction in cross-sectional area of between 50 and 75% with an intermediate anneal interposed between successive cold working operation, said intermediate anneal being at a temperature within the range between about 800*C and the Ac1 temperature of the composition, and thereafter annealing the finish guage material at a temperature within the range between about 800*C and the Ac1 temperature of the composition, the material exhibiting a preponderance of the grains having a (110) (001) orientation, a primary recrystallized microstructure and normal grain growth.

Claim 40

The process of claim 30 in which part of the cold working takes place at a temperature between room temperature and about 500*C.

Claim 41

The process of claim 30 in which the final annealing is a box anneal for a time period of between 24 and 48 hours in a reducing atmosphere having a dew point of less than about - 40*C.

Claim 42

The process of claim 30 in which the final cold working operation to finish gauge effects a reduction in cross-sectional area within the range between about 60 to 70%.

Claim 43

In the process for producing (100) (001) texture in an alloy suitable for use as a transformer core material, the steps comprising casting a melt having a composition including less than 0.03% carbon, less than 0.01% sulfur, from about 4 to about 6% cobalt, up to about 1.5% silicon, up to 0.3% aluminum, up to about 0.8% chromium, less than about 0.005% nitrogen and the balance iron with incidental impurities, hot working the casting at a temperature within the range between about 1,000*C and 1, 100*C, cold working the hot worked material in two or more operations to finish gauge, at least the cold working operation effecting a reduction in cross-sectional area in excess of about 75% with an intermediate anneal interposed between each cold working operation, said intermediate anneal being at a temperature within the range between about 800*C and the Ac1 temperature of the composition, and final annealing the finish gauge material at a temperature within the range between about 800* C and the Ac1 temperature of the composition, the material exhibiting a preponderance of the grains having a (100) (001) orientation, a primary recrystallized microstructure and normal grain growth.

Claim 44

In the process for producing (100) (001) texture in an alloy suitable for use as a transformer core material, the steps comprising casting a melt having a composition including less than 0.03% carbon, less than 0.01% sulfur, from about 4 to about 6% cobalt, up to about 1.5% silicon, up to 0.3% aluminum, up to about 0.8% chromium, less than about 0.005% nitrogen and the balance iron with incidental impurities, hot working the casting at a temperature within the range between about 1,000*C and 1, 100*C, cold working the hot worked material in two or more operations to finish gauge, at least the cold working operation effecting a reduction in cross-sectional area in excess of about 75% with an intermediate anneal interposed between each cold working operation, said intermediate anneal being at a temperature within the range between about 800*C and the Ac1 temperature of the composition, and final annealing the finish gauge material at a temperature within the range between about 800* C and the Ac1 temperature of the composition, the material exhibiting a preponderance of the grains having a (100) (001) orientation, a primary recrystallized microstructure and normal grain growth.

Claim 45

The process of claim 34 in which the final annealing is a box anneal for a time period of between 24 and 48 hours in a reducing atmosphere having a dew point of less than about - 40*C.

Claim 46

In the process for producing (110) (001) texture in an iron base alloy suitable for use as a transformer core material, the steps comprising, casting a melt having a composition from about 4 to about 6% by weight of cobalt, Up to about 1.5% silicon, up to about 0.8% chromium, up to about 0.3% aluminum, up to about 0.3% manganese, up to about 0.03% sulfur, up to about 0.05% nitrogen, the aluminum, manganese, nitrogen and sulfur being selected within the respective ranges stated to provide effective amounts of at least one inoculant of the group consisting of manganese sulfide and aluminum nitride, less than about 0.03% carbon and the balance iron with incidental impurities, hot working the cast melt at a temperature within the range between about 1,250*C and the highest possible temperature without causing burning, cold working the hot worked material in two or more operations to finish gauge, at least the last cold working operation effecting a reduction in cross sectional area of between about 50 and about 75%, with an intermediate anneal interposed between said cold working operations, said intermediate anneal being at a temperature within the range between 800*C and the Ac1 temperature of the composition, decarburize annealing at a temperature within the range between about 760*C and about 870*C in a hydrogen atmosphere of hydrogen having a dew point in excess of about +4*C and box annealing the decarburized finish gauge material at a temperature within the range between about 800*C and the Ac1 temperature of the alloy, the material exhibiting a preponderance of the grains having a (110) (001) orientation, and a secondary recrystallized microstructure.

Claim 47

In the process for producing (110) (001) texture in an iron base alloy suitable for use as a transformer core material, the steps comprising, casting a melt having a composition from about 4 to about 6% by weight of cobalt, Up to about 1.5% silicon, up to about 0.8% chromium, up to about 0.3% aluminum, up to about 0.3% manganese, up to about 0.03% sulfur, up to about 0.05% nitrogen, the aluminum, manganese, nitrogen and sulfur being selected within the respective ranges stated to provide effective amounts of at least one inoculant of the group consisting of manganese sulfide and aluminum nitride, less than about 0.03% carbon and the balance iron with incidental impurities, hot working the cast melt at a temperature within the range between about 1,250*C and the highest possible temperature without causing burning, cold working the hot worked material in two or more operations to finish gauge, at least the last cold working operation effecting a reduction in cross sectional area of between about 50 and about 75%, with an intermediate anneal interposed between said cold working operations, said intermediate anneal being at a temperature within the range between 800*C and the Ac1 temperature of the composition, decarburize annealing at a temperature within the range between about 760*C and about 870*C in a hydrogen atmosphere of hydrogen having a dew point in excess of about +4*C and box annealing the decarburized finish gauge material at a temperature within the range between about 800*C and the Ac1 temperature of the alloy, the material exhibiting a preponderance of the grains having a (110) (001) orientation, and a secondary recrystallized microstructure.