Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
249 words
A method of manufacturing a permanent magnet comprising forming a workpiece of an alloy having the following composition by weight: ______________________________________
Chromium 22.5 to 25.5%
Cobalt 15.0 to 17.5%
Molybdenum 2.0 to 4.0%
Silicon 0.1 to 0.8%
Oxygen less than 0.10%
Effective carbon
less than 0.06%
Remainder iron and unavoidable impurities,
______________________________________ where effective carbon is defined as carbon content plus 0.86 times nitrogen content, and subjecting the workpiece to: (a) a homogenising annealing for 15 minutes to 3 hours at 1230° C. to 1280° C., followed by quenching in liquid; then to (b) a treatment comprising treating the workpiece for 10 to 30 minutes at 720° C. to 740° C., followed by the application for 10 to 120 minutes in a preferred axial direction of a magnetic field of 80 to 240 kA/m at a temperature of 630° C. to 650° C., followed by cooling in air; and subsequently to (c) an age-hardening treatment in the following stages: (ci) maintaining the workpiece at 590° C. to 625° C. for 0.25 to 10 hours (cii) maintaining the workpiece at 555° C. to 585° C. for 0.5 to 30 hours, and (ciii) maintaining the workpiece at 500° C. to 540° C. for 0 to 50 hours; thereby to form a permanent magnet which has the following properties, measured in the direction of magnetisation; coercive field strength B H C at least 50 kA/m; remanence Br at least 1.2 T; and energy value (BH) max at least 39 kJ/m 3 .
Claim 2
Independent Claim
249 words
A method of manufacturing a permanent magnet comprising forming a workpiece of an alloy having the following composition by weight: ______________________________________
Chromium 22.5 to 25.5%
Cobalt 15.0 to 17.5%
Molybdenum 2.0 to 4.0%
Silicon 0.1 to 0.8%
Oxygen less than 0.10%
Effective carbon
less than 0.06%
Remainder iron and unavoidable impurities,
______________________________________ where effective carbon is defined as carbon content plus 0.86 times nitrogen content, and subjecting the workpiece to: (a) a homogenising annealing for 15 minutes to 3 hours at 1230° C. to 1280° C., followed by quenching in liquid; then to (b) a treatment comprising treating the workpiece for 10 to 30 minutes at 720° C. to 740° C., followed by the application for 10 to 120 minutes in a preferred axial direction of a magnetic field of 80 to 240 kA/m at a temperature of 630° C. to 650° C., followed by cooling in air; and subsequently to (c) an age-hardening treatment in the following stages: (ci) maintaining the workpiece at 590° C. to 625° C. for 0.25 to 10 hours (cii) maintaining the workpiece at 555° C. to 585° C. for 0.5 to 30 hours, and (ciii) maintaining the workpiece at 500° C. to 540° C. for 0 to 50 hours; thereby to form a permanent magnet which has the following properties, measured in the direction of magnetisation; coercive field strength B H C at least 50 kA/m; remanence Br at least 1.2 T; and energy value (BH) max at least 39 kJ/m 3 .
Claim 3
Independent Claim
249 words
A method of manufacturing a permanent magnet comprising forming a workpiece of an alloy having the following composition by weight: ______________________________________
Chromium 23.0 to 24.7%
Cobalt 15.5 to 17.0%
Molybdenum 2.0 to 3.5%
Silicon 0.2 to 0.6%
Oxygen less than 0.08%
Effective carbon
less than 0.06%
Remainder iron and unavoidable impurities,
______________________________________ where effective carbon is defined as carbon content plus 0.86 times nitrogen content, and subjecting the workpiece to: (a) a homogenising annealing treatment for 30 to 60 minutes at 1250° C. to 1270° C., followed by quenching in liquid; then to (b) a treatment comprising maintaining the workpiece at 725° C. to 735° C. for 10 to 20 minutes, followed by applying to it for 20 to 80 minutes in a preferred axial direction, a magnetic field of 120 to 200 kA/m at a temperature of 635° C. to 645° C., followed by cooling in air; and subsequently to (c) an age-hardening treatment in the following stages: (ci) maintaining the workpiece at 595° C. to 605° C. for 0.5 to 1 hour (cii) maintaining the workpiece at 560° C. to 570° C. for 1 to 20 hours, and (ciii) maintaining the workpiece at 500° C. to 530° C. for 0 to 30 hours; thereby to form a permanent magnet which has the following properties, measured in the direction of magnetisation; coercive field strength B H C at least 50 kA/m; remanence Br at least 1.2 T; and energy value (BH) max at least 39 kJ/m 3 .
Claim 4
Independent Claim
249 words
A method of manufacturing a permanent magnet comprising forming a workpiece of an alloy having the following composition by weight: ______________________________________
Chromium 23.0 to 24.7%
Cobalt 15.5 to 17.0%
Molybdenum 2.0 to 3.5%
Silicon 0.2 to 0.6%
Oxygen less than 0.08%
Effective carbon
less than 0.06%
Remainder iron and unavoidable impurities,
______________________________________ where effective carbon is defined as carbon content plus 0.86 times nitrogen content, and subjecting the workpiece to: (a) a homogenising annealing treatment for 30 to 60 minutes at 1250° C. to 1270° C., followed by quenching in liquid; then to (b) a treatment comprising maintaining the workpiece at 725° C. to 735° C. for 10 to 20 minutes, followed by applying to it for 20 to 80 minutes in a preferred axial direction, a magnetic field of 120 to 200 kA/m at a temperature of 635° C. to 645° C., followed by cooling in air; and subsequently to (c) an age-hardening treatment in the following stages: (ci) maintaining the workpiece at 595° C. to 605° C. for 0.5 to 1 hour (cii) maintaining the workpiece at 560° C. to 570° C. for 1 to 20 hours, and (ciii) maintaining the workpiece at 500° C. to 530° C. for 0 to 30 hours; thereby to form a permanent magnet which has the following properties, measured in the direction of magnetisation; coercive field strength B H C at least 50 kA/m; remanence Br at least 1.2 T; and energy value (BH) max at least 39 kJ/m 3 .