US1497889A - Method of making high-speed steel - Google Patents

Description

Patented lune l7, isaa VIILLIAI'JE BERTIN BROOKFIELID, OFSYRACUSE, NEW YORK.

METHOD OF MAKING HIGH-SPEED STEEL.

No Drawing.

1 0 all whomz'zf may concern:

Be it known that I, YVILLIAM B. BROOK4 FIELD, a citizen of the United States of America, and a resident of Syracuse, in the county of Onondaga, in the State of New York, have invented new and useful Improvements in Methods of Making High- Speed Steel, of whichthe following is a full, clear, and exact description.

This invention relates to the manufacture of steel for high-speed metal-cutting tools and analogous uses requiring a high degree of inherent and uniform resistance to Wear and breakage.

The methods most commonly employed for producing steel of this character are: the electric and the crucible and it is Well known by those skilled in this art that steels produced by the electric processes under the most skillful treatment contain varying quantities of non-metallic substances or inclusions Which may or may not be disclosed under the usual microscopic or chemical tests but nevertheless destroy the perfect homogeneity of the product and frequently appears in the completed tools in the form of chipping or breakage When subjected to more or less stress and strain in use.

In the crucible process, the materials are melted in a considerable number (24 or more) crucibles in the same furnace and it is found to be practically impossible to obtain the same quality of steel in the several units due to the inability of applying a uniform melting heat to the separate units or to different parts of the same unit.

Furthermore, While the electric melting process has the advantage of producing a more uniform grade of steel than that produced by the crucible process, the materials must be treated in relatively large masses and cast into correspondingly large ingots Which must be cogged or reduced into smaller sections before they can be Worked into stock.

Application filed June is, 1922.

Serial No, 568,864.

has an advantage over the electric process in that the molten metal may be cast into relatively small molds which may be readily Worked into the required stock Without decarbonization or excess loss by oxidation.

The main object of my process is to obtain the advantages of both the'electric and crucible processes and at the same time to eliminate their disadvantages and thereby to produce a better and more uniform grade of steel than can be by either of those processes.

This is accomplished by first reducing a relatively large quantity of the raW materials to a molten state in an electric furnace under proper slag conditions and sufficient temperature to assure a product of produced maximum homogeneity and then transferlarge quantities of the cheaper grades of base materials in the electric furnace and thereby to secure a molten steel product having a nore uniform chemical analysis than is possible by the crucible process,

While the additional heat treatn'ient of this molten product in reduced quantities in the separate and relatively small crucible units greatly assists in securing a uniform temperature in all of the units and permits the elimination of the non-metallic inclusions Which are unavoidably present in the electric furnace product so that the product resulting from the two heat treatments is not only free from non-metallic substances but possesses a maximum degree of homogeneity and uniformity of chemical analysis required for various tools and other uses and reduces to a minimum the liability of chipping or breaking of the tools when put to use.

The real merit of the invention as distinguished from the prior art is that after the electric furnace product has been introduced into the crucibles, a sufficient amount of slag is introduced into the molten metal in the crucibles to seal the same against oxidizing influences of the air or furnace heat during which time and for a definite period of say twenty or thirty minutes, this molten metal in the crucibleu'nits"is maintained at approximately. its original temper,-

ature (electric furnace temperature) to allOW the non-metallic inclusions vhich Were in the original electric furnace product to rise to the surface and to unite with the added slag and eventually be skimmedotf before pouring, thereby leaving a better and cleaner product substantially free from nonmetallic inclusions and therefore of more uniform grade or qualitythan has hereto-c smaller heated crucibles in a-crucible furnace v adding a sufiicient amount of extra slag to the molten metal in the crucibles to seal the same against oxidizing influences of the airor furnace heat andto expedite the collections of the non-metallicinclusions on the surface of the molten metal, retaining the molten metal in the crucible at approximately its original temperature and for a period of time as Will cause the non-metallic inclusions therein to rise to'the surface and to unite With the added slag, then skimming oil the slag with the non-metallic inclusions thereinand finally pouring the mo ten metal from the crucibles into relatively small molds.

I In Witness Where'ofI have hereunto set my hand this 12th day of" June, 1922.

' l/VILLIAM BERTIN BROOKFIELD. -Witnesses:

H; E; CHASE,

M. C. RILL'.