US1526513A - Process and apparatus for the thermic treatment of steels and in ceneral of all other alloys susceptible of hardening - Google Patents

Description

Feb. 17. 1925. 1,526,513

L. F. J. C. A. THIBAUDIER ET AL PROCESS AND APPARATUS FOR THE THERMIC TREATMENT OF STEELS AND IN GENERAL OF ALL 'OTHER ALLOYS SUSCEPTIBLE OF HARDENING Filed Dec. 15. 1921 w 2 Sheets-Sheet 1 JQW Feb. 17. 1925. 1,526,513

FOR THE THERMIC TREATMENT OF STEELS AND L. F. J. C. A. THIBAUDIER ET AL PROCESS AND APPARATUS IN GENERAL OF ALL OTHER ALLOYS SUSCEPTIBLE OF HARDENING Filed Dec. 15, 1921 2 Sheets-Sheet 2 3 pm .5 5 EN .LEH

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8m y m LDUIS FEANQOIS J CLAUDE AITTG'INE TEIBAUIDIER Alli D HENRI ill PARIS, FRANCE.

ZEBQCESS AND APPARATUS FOR THE THERMIC TEMTMENT G15 STEELEE arm Ill GEN- ERAL 01 ALL OTHER ALLOYS SUSCEPTIBLE 0F HARDELENG.

Application filed December 15, 1921. Serial No. 522,637.-

1 0 all whom it may concern:

Be it known that we, Louis FRANQOIS Josi-irnt CLAUDE AN'roINn THIBAUDIER' and Hnxnr VITEAUX, citizens of the Republic ot'France, and residing at Paris, Seine Department No. 19 Rue de la Rochefoucauld, in the Republic of France, have invented a certain new and useful Process and Appa- 'ratus for the Thermic Treatment of Steels and in General of all other Alloys Susceptible of Hardening, of which the following is the specification.

The thermic treatment of n'ietallurnical products is recognized to afford aconsiderable number of advantages, and such treatment will give rise to marked improvements in the mechanical properties of products of this class. This treatment which comprises in general a reheating operation followed by hardening. then a second reheating or annealing, has not however been adapted in current practice to theextent which it would appear to merit, for in fact in a considerable number of cases it is recognized that the operations required for the treatment, and especially forthe reheatingbefore or after the hardening, are too diiiicult to carry into efi'ect or will require an excessive out- In order to simplify these operations and more particularly to obviate the annealing after hardening it has been proposed to arrest the hardening before the said products have become entirely cooled. or on the other hand to carry out the hardening operation in'a limited volume of liquid. In the first case, the quantity of heat remaining in the piece after the hardening is stopped is sufficient to reheat the hardened parts and to aiiord the annealing. and in the second case, the heating of the hardening bath, whose mass is made proportional to the mass of the piece to be treated. will reduce the rate of heating and will afford a slow hardening which is adapted to produce similar results to those which would be obtained by a more energetic hardening with subsequent annealingf These simplified methods of treatment have not come into general use to the extent which might be supposed. by reasonv of the serious inconveniences which they present. In the first-mentioned process, the rate of cooling of the surfaces in contact with a considerable volume of liquid is so high that in order to obtain certain and regular results it would be necessary to arrest the hardening after a stated time within one second, but such exact operations are very diflicult to carry out in usual shop practice, whence it will follow that the results afforded by this method of treatment will have an uncertain and irregular character. On the other hand it becomes difficult with thismethod to carry out the hardening of the pieces to any great depth without an undue cooling of the surfaces, and the latter will thereby remain in a hard and brittle condition.

The method of hardening in a quantity of liquid proportional to the mass under treatment will permit of reducing the rate of cooling and will thus facilitate to determine the instant of stopping the tempering operation in order to obtain a given hardness. But it is recognized by numerous experimenters that the said process gave rise to a very irregular hardening not only between the various pieces but even throughout the mass of a single piece. Furthermore. and doubtless by reason of this lack of homogeneity and the consequent internal stresses, the pieces treated in this manner are much subject to developing interior cracks.

The difiiculties in the use of the above methods are due to the following circumstances: 1-The rate of cooling of the sur faces immersed in a considerable volume of cold liquid is large. 2-The rapid heating of a limited mass of liquid and the formation of bubbles of vapor within the said mass will constitute very irregular phenomena.

This invention consists in submitting the pieces under treatment and employed at a temperature above the critical temperature, to a stated number of short immersions in water or like liquid in the hot or cold state which is provided in a limited quantity and in proportion to the size oi the said pieces. Experience shows that it will now be possible to entirely obviate above-mentioned drawbacks while at the same time retaining the advantages of a partial hardening; as well as oi a hardening in a reduced volume of liquid. The quantity of liquid to be used. duration of the immersion and emersion. and the numher of these latter operations, are to be do ion termined by experience according to the size of the pieces under treatment and the results to be obtained in such manner that the said pieces shall be cooled from their initial temperaturewhich is above the critical temperatureto the temperature of the atmosphere according to a'la-w of variation of temperatures which is intermediate between the law of variation of temperatures corresponding to the integral cooling in a large volume of water and the law of Variation of temperatures corresponding to the cooling in the open air, the said law being of such character as to afford the modifications of structure corresponding to the properties which it is desired to obtain, in a single operation,

by the thermic treatment.

By law of variation of temperatures", we

-mean the connection existing between the inprocess forming the subject-matter of the present invention. I

The duration of the immersion and the volume of liquid used for the hardening bath are preferably determined in such manner that the bars orlike pieces to be treated shall be pern'iitt'ed' to cool in a sufficiently rapid manner to cover the stipulated time without however permitting the speed of cooling to attain the value above which interior or exterior cracking effects are to be apprehended. The time required for the einersion period is of sufficient length in order that durin g each of the said periods there will be produced an equalization of the temperature in the tempered regions. The number of inunersions is also chosen in such manner that the quantity of heat remaining in the mass of the said pieces after the last immersion is susceptible of heating the hardened parts to a temperature below the critical point but still sufli cient to efi'ectthe desired. annealing operation. In some cases it will not be necessary to effect the complete emersion of the pieces under treatment. he found preferable in certain cases to vary the depths or heights of immersion and emersion during the treatment.

The said method of operation will afiord the following advantages:

1. During each immersion, the surface portions of the pieces under treatment which have become tempered during the preceding immersion, are now slowly cooled by the air,

On the other hand it may variation which shall be intermediate be 7 tween the cooling in cold or more or less hot water and the cooling 1n the open air, and to confer upon the said parts in a single operationv the mechanical properties corresponding to the said law of cooling.

2. The emersions increase the duration of the treatment and also reduce the rate of cooling, and. in consequence it becomes; an

easy matter to determine the exact moment for arresting the treatment in order to obtain a given result. I

3. The reheating obtained during each emersion will act to neutralize in the tempered regions the inequalities of temperature resulting from the differences in cooling which may have been produced during the preceding immersion, the vapor bubbles formed within the liquid will disappear, and the bath which is stirred by the-immersion and removal of the pieces will assume a more uniform temperature, whence'it will follow thaeby reason of the separate and successive hardening operations there will be obtained results of an absolutely regular character in any given piece of work and between the various pieces of work, at'the 'sametime ob-' viating interior cracks which would tend to produce inequalities in the cooling.

4. For the same pieces to be treated and the same hardening bath, the heating of the said bath is more rapid as the initial temperature of the pieces is higher. This effect will compensate in a certain measure any differences of temperature between the pieces before the treatment and will permit forinstance to obtain substantially identical results by using the present process, without any reheating, for the treatment of bars leaving the rollsat temperatures above the critical point but differing among themselves by 25 to 50 centigrade.

It will be possible to determine in adtests whose results are checked by mechanical and micrographic tests. An example of I the use of the said process will be described in detail hereunder.

The said invention is applicable in a genoperating method employed and of an apparatus for the hardening of the rails by successive immersions and emersi-ons.

For a long time past, a thermic treatment of railway or tramway rails has been recommended which would have theeiiect of increasing the hardness of the rail to a considerablcdegree, thus increasing the resistance to the wear of the rail head to a depth of 15 or 20 millimetres below the rolling surface without appreciably modifying the other pro erties of the metal, and particularly wit out rendering it brittle. By the use of the present hardening process and apparatus as described hereunder, the desired treatmentcan be given with great facility to bars of all desired lengths which are operated upon directly after leaving the rolling mill.

The following description together with the accompanying drawings which are given by way of example show embodiments of this invention, wherein:

. Fig. 1 is an elevational view of of construction of the apparatus.

Fig. 2 is a cross-section of the same.

Figs. 3 and 4 show in like manner a moditied form of construction of the said apparatus.

Fig. 5 shows curves regarding the cooling of a rail in water, in open air and according to the process forming the subject matter of the present invention.

The apparatus comprises a horizontal beam at supporting by means of the brackets b the roller 0 whereuponare caused to bear the flanges or in the case of double-headed rails the bottom part of the rails under treatment. Below the beam (1 is disposed a small tank d containing a determined quantity of cold water which is calculated according to the one form section of the rail and which is renewed after the treatment of each bar. The 'rails leaving the rolls at a temperature of 800- 850 centigrade are suspended by the flange from the. beam (1 in such manner as to leave the head of the rail entirely free, as shown in Figs. 2 and 4. The headis then immersed in the water to a depth which varies with the section and is given a series of immersionsjwhich are determined by experiment according to the cross-section and the Weight per linear metre of the rail under treat ment. V

By-wa of' example, for a railway rail of the T-rail type weighing 45 kilograms per linear meter, the weight of the water employed will be 10 kilogrammes per meter -forth., The same results ma obtained for instance by pro ucin'g succesand the number or" immersions will be 15) per minute. After the requisite number of immersions, the rail is removed for the last time from the water, lifted out of the apparatus and placed upon a rack where it becomes slowly cooled olf in the open air.

'lVhen the hardening operation is completed, the water in the tank, which has reached a temperature of 90 to 95 centigrade is rapidly drawn off and is replaced by cold water, and the apparatus is now ready for the treatment of a new piece. In order that the hardening operation shall afford regular results throughout the whole length of the rail, it is essential that the beam or and the rails themselves shall remain in a perfectly horizontal position during the entire treatment. To this effect the beam a is calculated in such manner as to support without appreciable deflect-ion the weight of the heaviest rails under the treatment; the brackets Z) are also given a sufiicient length in order that the quantities of heat transmitted from the rails to the beam by conduction and by radiation shall not cause the deformation of the said beam. For the same purpose, heat insulating material is interposed between the rollers and the brackets, and also under the beam itself. If these precautions prove to be insufiicient for an active use of the apparatus, the said beam may be cooled by water circulation or by like means.

To obviate the deformation. of the rails themselves, which would tend to assume a curved shape under the action of the hardening operation, the apparatusmay be provided for instance with roller carrying brackets e disposed along the said beam for securing the rails in the horizontalposition after placing the same in the apparatus and for limiting the deformation to the very small deflection which may take place between one of the said rollers and the adjacent roller carrying bracket 6.

In the form of construction shown in Figs. 1 and 2, the beam (r is stationary and the tank 6 is movable in the vertical sense by means of a suitable mechanical device.

In the second form of construction shown in Figs. 3 and 4, the tank 5 is now stationary and the beam a is given an alternative vertical movement.

The invention is not limited to the two forms of construction as hereinbefore set in fact be sive variations in the level of the hardening liquid in the said tank, with the tank' and the rail both secured in the stationary position, and if desired the liquid will not be obliged to entirely leave contact with the bar to be treated.

Claims:

1. Process for the thermic treatment of &

objects having an elongated shape in steel or other alloys capable of being hardened, these objects being taken at a temperature ivhich is higher than the critical one and being partially hardened in a bath, consisting in eliecting the hardening through-several immersions and e'mersions of short duration of the object to be treated and this'in a bath of a determined volume. 2. Process for the thermic treatment of articles made of steel or other alloys capable of being hardened and having an elongated shape, consisting vin immersing several times in a" limited quantity of hardening liquid and for a short period at every operation and over their Whole length at each time the articles which have been previously heated above the critical point and in leaving these articles cool in the air for a few moments in the intervals between immersions, the duration of the immersions and emersions being such that the gradual lowering of the temperature ofthe articles will be in accordance, in proportion to the time, with a predetermined selected law.

3. 'A process for the treatment of rolled rails consisting in the act of taking the rail upon leaving the rolls, suspending the same withthe rail head downward above a tank containing, a hardening liquid, submitting the rail head to a succession of immersions in the said liquid, separated by emersions,

and finally removing the rail from the liquid and allowing-it to cool slowly in the open air.

4. An apparatus for the thermi'c treatment of steel rails comprising a horizontal beam, rollers suspended in pairs below the said beam, a tank containing a hardening liquid and means for alternately raising and lowering the said beam, the rollers being spaced apart 'in such manner that the rail under treatment with the head downward is enabled to pass between the said rollers and to rest thereupon by the rail flange.

5. In an apparatus for the thermic treatment of rails, the combination of a beam, rollers suspended therefrom andadapted to support the flanges of the rail under treatment, rollers suspended from the beam and located in the intervals between the first rollers, these second rollers being adapted for maintaining the railin a rigid position upon the first rollers, and a tank disposed below the said beam and containing a-hardening liquid.

In testimony, that we claim the foregoing as our invention, we have signed our names in presence of two subscribing witnesses.

LOUIS FRANCOIS JOSEPH CLAUDE ANTOINE THIBAUDIER.

HENRLVITEAUX. Witnesses:

JOHN F. Simone,

' MAURICE Roux.

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