US1190937A - Process of tempering or hardening steel. - Google Patents

Description

UNITED STATES PATENT OFFICE.

JOHN B. MOORE, OF LATROBE, PENNSYLVANIA.

PROCESS OF TEMPERING OR HABDENING STEEL.

No Drawing.

To all whom it may concern Be it known that I, JOHN B. MOORE, a citizen of the United States, residing at Latrobe, in the county of Westmoreland and State of Pennsylvania, have invented new and useful Improvements in Processes of Tempering or Hardening Steel, of which the following is a specification.

This invention is a process for treat ng steel, to effect the hardening or tempering thereof, and the object of the invention is to so treat the metal, that scaling or decarbonization thereof, is avoided during the process by which the hardening or tempering is accomplished. It is well known that when tools, made of high speed steel, are hardened or tempered by the methods now in common practice, scaling or decarbonization of the metal takes place to a greater or lesser extent, resulting in a corresponding weakening of the metal structure of the tool. This weakening or deterioration of the metal may be prevented by the following process, to witzg -lhe tool or piece of metal to be tempered is cleaned to free it from oil, greases, and the like, and all scale is removed in any preferred manner. Then, while the tool or metal is perfectly cold, it is immersed in water, and while wet after withdrawal from the water, it is rolled in powdered boric acid. The tool or metal is then subjected to the desired tempering heat and then cooled in a suitable bath. Or, if desired, the tool or metal, coated with boric acid, applied as vabove stated, may be preheated slowly to a temperature of about 1200 Fahrenheit, then removed from the furnace at this heat and again rolled in powdered boric acid, after which it may be brought up quickly to the proper temperature for high speed steel, about 2500 Fahrenheit, and finally cooled in a suitable bath.

Under the action of the heat, in the fore going process, the moisture in the boric acid is driven off, leaving boron trioxid, which is a thick viscid substance that will adhere to the metal, and will remain unchanged to near the melting point of steel. Boric acid and boron trioxid are neutral with regard to steel in that they will not attack either the metal or the carbon, and the effect of heating the boric acid upon the metal, as above described, is to provide the metal with a protecting coating which will not Withdraw any of the carbon from the steel, or attack the metal in any manner, and which will protect Specification of Letters Patent.

Patented July 11, 1916.

Application filed February 24. 1915. Serial No. 10,263.

the surface of the metal from decarbonization due to the action of air, furnace gases, or other extraneous source. hand, while boric acid and boron trioxid are neutral withrespect to steel, they have great aflinity for other substances, and it is desirable in carrying out the foregoing process, that the tool or metal being tempered, be kept from contact with the fire brick lining the furnace, or from coming in contact with any object not constructed of iron or steel, To protect the tool or metal under these conditions, it is preferred to place the same upon a suitable support of neutral material, during the heating operation, so as to prevent the protecting covering from being attacked. Said support may be made of any metal, neutral with respect to boric acid or llooron trioxid, capable of withstanding the ieat.

After the tempered tool or metal has been cooled, the boron trioxid will still adhere thereto like a glaze, and may be removed in any suitable manner. For instance, if left exposed to the atmosphere. the boron trioxid will take up moisture and assume the form of a powder which may be readily brushed off. The boron trioxid may be more quickly removed, however, by soaking the tool or metal in cold water, but great care must be taken to insure that the tool or metal is per fectly cold, before being immersed in the water, as otherwise it may crack.

I claim as my invention 1. A process of hardening high speed steel which consists in cleaning the metal, wetting the same with water, covering the wet surface with boric acid, whereby the water will cause the acid to stick, heating the coated metal to a degree to convert the boric acid into a glaze covering the surface of the metal, then increasing the temperature until the metal reaches a white heat, and finally quenching.

2. The process of hardening high speed steel which comprises cleaning the metal, causing a coating of boric acid to adhere to the cleaned metal, heating the coated metal to a degree to cause the boric acid to form a glaze covering the surface of the metal, increasing the temperature until the metal reaches a white heat, and finally quenching.

3. The process of hardening high speed steel which comprises cleaning the metal, causing a coating of boric acid to adhere to the cleaned metal, preheating the coated On the other matal tu form a glamm'or the surface there- In testimony whereof I havv hrrvunto sub uf applymg a second coatmg of home new], my hand 1n presence of two subscrllnng \vltagram hoatmg to convert the second coatmg nesses.

into a glaze t m'oring the first glaze, continu- JOHN B. MOORE. 5 mg to mcrvaso the temperature untll the W1tnesses:

metal reaches a \vhlte heat, and finally JAs T. HUGHES,

I quenching. IRA B. SIIALLENBERGER.