US1370020A - High-speed steel - Google Patents

Description

umrno STATES PATENT. OFFICE;

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To all whom it'may co'rwim: I

Be it known that I, Omnnns M. J ormson,

residing at Avalon, in the. county of A llegheny and State of Pennsylvania, a citizen of the United States, have invented or discovered certain new and useful Improvements in Hi -Speed Steel, of .which 1mprovementst e following is a specification.

My invention :relates to high-speed steels, and proceeds from the discovery that, consequent upon the presence of the two elements molybdenum and vanadium within certain ranges of percentage,asteel of high cutting efficiency may be'pro'duced without resort to some of the more expensive alloying metals such as cobalt and uranium, a steel which in 'performanceexcels all hi hspeed steels knownto me-'-cven those whlch depend for excellence'upon'the'presence of other expensive ingredients;

1 refer particularlyinwhat has just been said to cobalt and uranium. In general estimation atprese'nt, high-speed steel compounded withcobalt in quantities up to 5% is considered the steel is relatively very costly, because cobaltis anzexpensive ingredient, and

I because ofits cost'this cobalt steel is less widely-used than otherwiseit would be." I have just intimated the steel of my'mvention, lacking colni still excels cobalt .steel.

Study of the manytests of these high-speed steels leii *me to observe that those containing molybdenum were, some of them, very excellent, while others were not; and that those which were very excellent invariably contained vanadium while those which were inferior did not contain vanadium and, finally, that steels conta' vanadium but no molybdenum, when classe together, were not so remarkable. observations led to a study of the molybdenum-vanadium combination, with the resultingdiscovery that if vanadium be present in percentages of 1.10 and greater (preferabl 1.15-1.50) accompanied by molybdenum, I preferably in quant ties less than 1%, the com osition conforming 9therwise to recognize standards for highchrospeeiflcation of Letters Patent.

best. And this cobalt These p steel, the product .under test reveals outmiu'm, vanadium, tungsten, andoccasionally molybdenum; sometimes cobalt in amounts ranging up to 5%, and sometimes relatively third the specific composition of a typical specimen'oi my improved steel- 20-15% .e0-.70 .3540 es-.55 e3 .s5-.55 .s5-.ss 44 3-5 3.75-5 4.71 1.10-1.50 Lao-n40 1.20 .254 .eo-. .eo

Molybdenum, if present in percentages greater than those recommended, has, I find,

Patented Mar. 1', 1921. Application filed December 12, 1818. Serial No. 344,880. a

the tendency to cause the steel to chip at the cutting edges; if the percentage is very much greater than recommended, then the molybdenum tends to volatilize and to leave the steel with softened surface.

I Und'erexisting conditions this tendency to volatilize- .tion' of molybdenum appears as the molybdenum content approaches and exceeds one per cent, and it becomes more pronounced the, molybdenum content increases in "value beyond that point. Under existing conditions my invention will not be realized ifthe molybdenum content greatly exceeds one per cent. .and will certainly not be realized if it rises as high as two per cent.

I On the other hand by keeping within .the --limits defined, the results will excel other steels of the same components as heretofore compounded in aratio of 9:6 or 9: 8. Steel has not heretofore been compounded of the elements and 'in the proportions which I have given the foregoing analysis.

". A specific test will illustrate what has been said; A specimen of steel of my invention distanced "all competitors and gave under test a totaltravel of 58%" its nearest com titor, 'acobalt steel, gave 53%" while the. fieldfall high-grade high-speed steels,

followed, .with these records: 475, 43}, 43%,

fit gg t, 9, 8,

in a companion application for Letters Patent, erial-No. 344,329 I have described and claimed a method of producing highspeed steel, beginning with high-speed scale,

and proceeding in uninterrudpted operation to the finished product. I 0 not mean to limit my invention to any particular method of production, but in order to give full advice, how my improved steel may be produced, I give the following description.

A furnace charge of the following composition is introduced into and smelted within an electrical furnace:

The powdered molybdenum and powdered tungsten just mentioned are in metallic form, uncombinod and unalloyed. The powder is adulterated chiefly with iron, also in metallic form, and there are minor impurities such as carbon and silica present,

in quantities less than one per cent.

When the reactions have occurred the metal is tested and, according to test, carbon is added in the form of coke introduced through the slag and stirred into the bath, until the carbon content reaches about .50%. Finally, just before tapping, the following 7 ingredients are added- Ferro-silicon, silicon) 3 pounds Form-manganese, (7 O to 80% manganese) 2 pounds Ferro vanadium (39% vana dium) 5% pounds The carbon test employed is preferably the fracture test.

The furnace of the run of the foregoing specific figures was heated by a current of a pressure of 40-45 volts; the operation continued through 6 to 7 hours; the current 'consumption for the complete run amounted to about 400 kilowatt-hours; the resultant ingot wei bed 225 poiiiiidgbesides the test ieces, w ich aggregated 15' pounds more. a

he anal sis of the product is that given in tlfie thi' column ofthe first tabulation a ove.

additions of molybdeum and of tungsten made to the initial charge, and the final and proportion of non-ferrous components,

exclusive of vanadium and molybdenum.

I claim as my invention:

1. A high-speed steel of the following composition, so far as concerns the elements namedz' carbon, .20%-.75%; silicon, .35- .80%; manganese, .35-.55%; tungsten, 12- 18%; chromium, 35%; vanadium, 1.10- 1.50%; molybdenum, .251%.

2. A high speed steel including inits composition vanadium and molybdenum each in some one of the percentages that will form high speed steel, the vanadium content exceeding 1.1% and the molybdenum content ranging from a minimum where its presence is revealed in increased toughness of product to a maximum where volatilization under the hardening operation begins, substantially as described. I

In testimony whereof'i have hereunto set my hand.

CHARLES M. JOHNSON. Witnesses:

BAYARD H. CHRISTI, FnANcmJ. Tomesorr.