US1071937A - Process for surface-hardening metal. - Google Patents

Description

' ment of a temperature of about 6000 deperature in practice venien't support and the JOHN H. MQCORMICK,

or c oLumBus, 01110.

r'aocnss roe suarAon-nmmnmue METAL.

No Drawing.

Specification of Letters Patent. Application filed May as, 1910. Serial No. 582,799.

Patented Sept. 2, 1913.

To all whom it may concern.

Be it known that I, JOHN H. MoConMIoK, a citizen of the United States, residing at Columbus, in the county of Franklin and State of Ohio, have invented certain new and useful Improvements in Processes for Surface-Hardening Metal, of which the following is a specification.

My invention. consists in an improved process whereby malleable and similar iron and steel, containing a necessary amount of free or combined carbon, ma be surface hardened to a desired depth without changing the character of the interior or main body of the metal; to accomplish this object in a simple, rapid and convenient manner and to admit of the hardening of a portion only or the whole of the surface of a metal body.

To this end, my process consists in apply ing to the surface to be hardened, the flame produced by ignitin oxygen and acetylene gases in any desirab e proportions to attain a flame of very intense heat, or to otherwise subject the surface to a very intense heat to very rapidly bring the surface against which the heat is directed, to a hardcnin temperature before the body metal un er the surface against which the flame is directed, has reached this temperature, and then quickly chilling the same before the interior of the body metal is heated by conduction. It will thus be noted that I employ heating means of high intensity to very rapidly bring the surface metal to be hardened to the correct hardening temperature which has been variously estimated to be between 1300 and 1500 degrees F., but which temis usually determined by the eye when the metal has reached what is known in the art as'a cherry red. In a number of the claims, I have referred to the hardening temperature by which I mean that the surface metal has reached a tempering heat, or, in other words, it is at a cherry red. I

In carrying out this process, it has been found that it is necessary to subject the article to be surface hardened, to a temperature of over 4000 degrees Fahrenheit, the best results being obtained by the employgrees. In carrying out this. rocess, the metal body, the surface of whichis to be treated, may be given any suitable or conflame directed dition existing before to the metal surface thereon from any suitable or well known form of burner or nozzle which is carried at the end of a gas conducting hose or pipe. The surface of the body belng sufficiently heated, the flame is removed therefrom and the metal body quickly chilled either by inserting the same into a bath of cold water, or by directing a stream of cold water on to the heated surface.

It will be understood that owing to the character of the heat generated by a flame of the gases mentioned, the surface of the metal body may be heated to a high temperature in the fraction of a minute and before the heat can penetrate to an undesirable distance beneath the surface, thus leaving the interior of the metal body so far as its chemical composition and condition is concerned, unchanged.

Heretofore surface or case hardening has been confined to wrought iron or steel having a very low per cent. of carbon and which was therefore not capable of being tempered. By my method, metals that are subject to tempering or hardening, may be surface hardened, but which if treated by the ordinary tempering methods, consisting of heating in a tempering flame and chilling, would result in hardenlng throughout the body. It will thus be seen that my improved process not only leaves the interior of the metal body in its normal condition, or in the conof the surface of heating, but it admitsa metal body being hard le ened to the desired depth within such a;

short period of time, as to produce a great savlng in time, labor and expense.

What I claim, is- 1. A process for surface hardening iron and steel containing a necessaryfper cent. of

carbon, consistin first, in sub ecting the surface to be har ened to the heat from the flame of gas or combined gases at a temperature of over 4000 degrees Fahrenheit, second, discontinuing the application of the heat before the body of metal is heated beyond=the depth of metal to be hardened, and third, quickly subjecting said heated surface to a chilling process.

2. A process for surface hardemng metal containing the necessary hardening in.- gredients consisting, first, in subjecting'the surface metal to be hardened to the action of a heat sufliciently intense vto rapidly bring the surface metal to a hardening temperature before the sub-surface metal has been so affected; second, discontinuing the application of heat and subjecting the heated surface metal to a rapid chilling process While at the hardening temperature.

3. A process for surface hardening metal containing the necessary hardening ingredients consisting, first, in subjecting the surface metal to be hardened to a flame of iron melting intensity, second, discontinuing the heating process as soon as the surface metalhas reached the hardening temperature and before the sub-surface metal has been so affected and applying a rapid chilling process to the surface metal While at the hardening temperature.

In testimony whereof I affix my signature in presence of two Witnesses.

JOHN H. MCCORMICK.

Witnesses:

C. C. SHEPHERD, A. L. PHELPS. V