US1773793A - Permanent magnet - Google Patents

Description

Patented Aug. 26, 1930 UNITED STATES- PATENT" ol-"rlca cam. sa'rrnnn, or xnnrnnn, GERMANY, Assmuon To run rum nnu'rscan'nnnm s'mnnwnnxn AKTIENGESELLSOEAI'T, or xnarnnn, mm!

PERMANENT MAGNET Io Drawing. Application gum February 19, 1980,8erla1 no. 429332, and in Germany larch a, 1m.

Up to nowmagnetic chromium and magnetic tungsten steels have been principal y used for the production of permanent mag- "nets. Since about ten yearsthe magnetic cobalt steel has been added to satisfy greater demands. The latter, as a rule, being pro;

Q duced with a cobalt content of, over 3%. In order to satisfy particularly great demands the cobalt content is being raised to 10, 15, 20 and Cobalt is still very ex. pensive and the use of magnetic cobalt'steel is still a very limited one. Since years the electro-technical industry is in search of a magnetic steel 'for use on a large scale which is not considerably more expensive than.

tungsten steel, "yet surpasses the latter as regards thema netic ower. The present invention provi essue a magnetic steel.

This new magnetic steel is based upon the combination of steel alloys which, in additionto 1.3 to 6.5% of chromium as the basic alloying constituent, contain tungsten or molybdenum or vanadium or copper or cobalt or manganese era mixture of two or more or all of these alloying metals. The

presence of at least two of these alloying metals increases the'coercive force of the magnetic steel. In order to prove this two alloys had been made one of which contained 0.61% C, 5.5% W and 2.13% Cr in addition to 0.35% Mn. As a counter-proof a tungsten steel had been produced with 0.60% C, 5.8%. W, and 0.33% Mn. In the In carrying out a number of other tests in.

which in addition to chromium, tungsten or molybdenum or both were present, 1t has been found that the addition of one or both these metals increases the coercive force coning steel containm M addition to chromimand manganese .tung;

siderably as compared with the corres 0ndonly chromium. f in sten alone is addedf'it will be necessary, wit 3 a chromium content of only 1.3 to about 1.9%, to add at least 0.8% of tungsten for the purpose of obtaining the highest-mag;

netic efficiency. With a chromium content of 4.5% and more a smaller amountof tungsten "may be added.

If in addition to chromium and man molybdenum alone is added, the molyb enum nese content has to amount to at least 0.8% with to secure the beneficial action bf the molybdenum all the same, it will r'ove of advantage to use smaller amountsoihholybdenumabout 0. 3 to 0.6%-adding thereto tungsten or cobalt or copper either separately or in suitable combination. By properly regulat ing the proportions of tungsten and molybdenum relatively to the.chromium content,

one is enabled to produce} with a suitable carbon content which has'tolrange' from 0.65 to 1.25%, magnetic steels having a particularly high degree of remanence together with a perfectly satisfactory coercive force or alternately, steels having a particularl high coercive force together with a satis actory degree of remanence. If the coercive force rises above 80 gauss up to 100 gauss, theremanence will drop below 10000 gauss. Yet by suitably proportioning the content of carbon, chromium tungsten'and molybdenum, it becomes posslble to raise the remanence to above 10000- gauss and the coercive force up to 80 gauss, i. e. to secure a magnetic power factor of Br. He. 10"= .800 (Gumlichs numbers), in contradistinction to the best tungsten steels which scarcely ive better results than Br. I-Ic. 10"=760. increase in the magnetic power factor is more easily brought about by the addition of cobalt in quantities already as small as up to 3%. A magnetic steel-with about 3% of chromium and- 2% of cobalt is, by way ofexample, not consid erably more expensive than a 6% tungsten.

steel, yet by farits superior as regards the magnetic properties.

the other-hand, the manufacturing costs chromium and 1% of tung'stenor of a-magnetic steel containing about 2% of chromium,

of a magnetic steel containing about. 2% of are less by more than 20% than those of a 6% tungsten steel, yet its magnetic properties are equal to those of the best tungsten steel. Similar conditions will prevail if with a chromium content of 1.3 to 6.5% copper in amounts of about 0.5% is added in the place of tungsten or molybdenum. Also copper or vanadium or these metals together with tung-' sten and molybdenum and with cobalt may be added at the same time. All these metals will considerably increase the coercive force of a magnetic steel having a chromium content as alloying basis. Thus a test piece containing 4.75% Cr. and 1.57% Mo. had a coercive force of 79 gauss.

Having thus described my invention what claim as new and desire to secure by Letters Patent is:

1. Permanent magnets characterized by the fact that they are produced from steel alloys which contain 0.65% to 1.25% of carbon and about 0.25 to 1% of manganese and in addition to 1.3% to 6.5% of chrominum one of the following alloying constituents: tungsten (0.5 to 3%), molybdenm (0.5% to 1 5%), copper (0.5 to 1%) and cobalt (0.5 to 3% 2. Permanent magnets characterized by the fact that they are produced from steel alloys which contain 0.65 to 1.25% of carbon and about 0.25 to 1% of man anese and in addition to 1.3% to 6.5% of c romium several of the following alloying constituents: tungsten (up to 3%), molybdenum (up to 1.5%), copper (up to 1%) and cobalt (up to 3%), the total percentage of said allo ing constituents amounting to a minimum imit of 0.6 and a maximum limit of 7%.

3. Permanent magnets according to claim 1 in which the alloying metals tungsten, molybdenum, cop er and cobalt are replaced at least partially y vanadium.

4. Permanent magnets according to claim 2 in which the alloying metals tunsten, mo-.

lybdenum', copper and cobalt are replaced at least partially by vanadium. CARL SATTLER.