US899713A - Heat treatment and quenching of alloyed steels. - Google Patents

Description

J. OHURGHWA RD. HEAT TREATMENT AND QUENGHING OF APPLICATION FILED SEPT. 18;

ALLOYBD STEBLS.

Patented Sept. 29, 1908.

gating or retardation are.

JAMES GHUROHWARD, OF NEW YORK, N. Y.

HEAT TREATMENT AND QUENCHTNG 0F ALLOYED STEELS.

I Speeificationof Letters Patent.

' Patented Sept. 29, 1908.

Application filed September 18, 1907. Serial No. 393,489.

uct is rendered of-extr'aordinary toug ness and hardness.

Each successive heat or heat-wave is carried to a point a little below either the segrepoints of the corresponding alloying metal, the mass being cooled or quenched after each successive heat or heat-wave.

For affording a better understanding to those versed in the art, I have shown in the accompanying drawing a diagram illustrating the different phases of the metal under a rising temperature.

In this drawing A is a period of restoration I where the alloying metal renters the mass particle.

B is the retardation point. At this oint the alloying metal has been complete y restored and enters in a period of rest or retarded activity.

HC is the period. of rest or inactivity of the a oy.

D is the segregating point. 'Here a reversechemical action takes place and the mass particle again siveats or throws out from itself the alloying metal.

E is the period of segregations, which commences at the segregating point and continues on to the melting point. a

If the temperature is carried to within 100 F. of the retardation oint of the alloying metal and'tlie' mass 0 metal allowed to soak for a while at this temperature, toration will be accomplished but not in so perfect a manner as if the temperature were carried to a point nearer the retardation point. It is very dangerous to attempt to carry a restoration temperature beyond the retardation point and into the zone of rest or inactivity. This period oftime is so short, that it is more than likely'that such treatthe res mentwould be extended beyond the segregating point and then the restoration would only be partial.

All quenchings given above the retarda tron point of manganese should bewith a view of toughening only, and oils are thebest substances for this use. brought into a proper or fit state for hardening until the temperature is stopped at the retardation point of the manganese contained in the steels. This point is generally known as the recalescent point. There are two actions occurring wit iin the body of the metal at this point, namely z-a thermochemical action which forces a physical actlon, whereby the manganese 18 caused. to

release its bond or grip on the mass particle, the mass particle thereupon assuming a new shape or form, and the carbon contained in the particle working its way out to the surfaces of the particle, leaving little or no carbon in the center thereof. This brings the hardening element-carbon-to the surface, a position where it can receive the chill and shock from the bath, causing the particle to collapse, shrink in size and harden, and, as the mass is an aggregation of particles this hardening is conveyed to the whole mass. Further hardening can be done by a lurality of quenchings, if they follow down rom the retardation oint of manganese. The car: bon will not e re-arranged in the particle by any subsequent temperature provided, such subsequent tem erature or temperatures being all below the retardation point of the manganese, but if a subsequent temperature is carried beyond the retardation point of the manganese the particle will again re-form and go back into its old shape, carrying the carbon in with it.

By quenching in any ordinary or suitable manner two operations are conducted under one heat, namely the restoration of the alloy ing metal and the toughening and hardening of the mass itself by the quenching. This very materially reduces the cost of productionfand is of great value to manufacturers of alloyed steels. The degree of hardness of the product can also be governed. If allowed to atmospherically cool it will be hard, but not nearly so hard as when quenched and yet harder than hen cooled more slowly.

This invention is amodification of that described and claimed in my Letters Patent The metal is not a little below the retardation point of the al No. 855,756, dated June 4th, 1907. a For more detailed statement of steps and temperatures employed see this patent.

Having thus described my invention I claim I. The herein described method'of heattreating and hardening alloyed steels, which consists in subjecting the mass of metal to a series of heats or heat Waves of successively decreasing maximum temperature, designed to affect the alloying metals in order of their res ective segregating points, the first heat or eat-Wave being carried to a temperature a little below the segregating point of the alloying metal having the highest segregating point, and each successive heat or heat-wave to a temperature a little below the segrega ing point of the corresponding alloying metal and quenching the mass after each successive heat or heat-Wave.

2. The herein described method of heattreating and hardening alloyed steels, which consists in subjecting the mass of metal to a series of heats or heat-Waves of successively decreasing maximum tem erature, designed to affect the alloying meta s in order of their respective retardation points, the first heat or heat-Wave being carried to a temperature l l I l lojying metal having the highest retardation point, and each successive heat or a little below the-"retarto a temperature dation point ofthe corresponding alloying metal and quenching the mass after each successive heat or heat-wave.

decreasing maximum temperature, designedto affect the alloying meta s in order of their respective retardation points, the first heat or ieat-wave being carried to a temperature within 100 F. of the retardation point of the alloying metal having'the highest retardation point, and each successive heat or heat- Wave to a temperature Within 100 F. of the retardation point of the corresponding alloying metal, and quenching the mass successive heat or heat-Wave.

In Witness whereof I have hereunto signed my name this 17th day of September 1907, in

the presence of two subscribing witnesses.

JAMES CHURCHWARD.

Witnesses: J. DPOAPLINGER, F. W. WIMAN.

heat-Wave

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