US1018000A - Heat treatment and rolling of manganese steel. - Google Patents

Description

r I do hereby dynamic value (i.'e.,

the production of railroad rails of stand-1 ard length and section for -whose.produc- 'winrrnnn s. POTTE'RHOI NEW 'Ym,'-1t.l y

HEAT TEEA'JfllllEIwl'T AND Drawing.

I Spacification of Letters Patent. Application filed' 3unuary-'27, 1911. Serial No. 604,995

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-Be it known that I, WINFIELD S, Forum, a citizen of the United States, residing at New York city, county of New York, State of' New York, have invented certain new and useful Improvements in Heat Treat ment and Rolling'of Manganese Steel; and declare the following to be a full, clear, and exact description of the in- ?vention, such' as will enable others skilled in the. art to which it appertains to make and use'the same' i My invention relates to certain new and useful improvements in the heattreatment of manganese steel during the operation of" frolling. the ingot to the finiShed for-m.

The purpose of the invention is to increase the hardness, the elastic limit and the resistance to failure by. exhaustion) of'the steel, partict larly in tionthe invention is especially designed.

In carrying out the invention, the ingot- ,ofmanganese steel, from which the rail is to-be made is raised to such a temperature as. will bring about the absorption and redistribution throughout' the mass of any carbide of iron and manganese which may have separated out during and after the freezingof the metal in the ingot mold and so that the metal, in a soft and plastic condition shall have recrystallized throughout into a substantially homogeneous austenitestru'cture. One of' the methods of obtaining this condition is described in United States Patent No. 975,371 granted to me under dat 'of November 8th, 1910.

The ingot, in this condition, is .withdrawn from'the furnace and subjected to the action 'of the rolls of a rail-forming mill, and

when ithas progressed through the mill to. a point of; delivery represented, for instance, by its issuance from the roughing tion which rolls and is at an average temperature of about 1125 C., the-average temperature is temperature final product finishing pass,

' erably applied temperature may Ifatented Feb. so; 1912;

tions oftheblooml-aseries of jets of w-ater,'-

as, 'for' instance, by directinglthese jets against the lower surface of the head ofthe partially formedrail along the line of jl1l10 ture 9f the head'withthe-web portion, or, by directing a like series of jets of water against the top of the head of the partially formed rail, or by similarly cooling other portions of the bloom which may be hotter than is desired. By this expedient, the tem- "perature of the bloom is lowered to an average of say 1190 C. before the bloom enters the succeeding passes, wherein the temperature of the bloom is still'further lows ered, as it progresses, to an average final offrom .1075 Cflto 800 C. the stiifness required in the As the rail issues from the it is immediately quenched, or otherwise so rapidly cooled as to make permanent the condition which the steel according to 'has'at thattime. The water jets are prefas. the bloomleaves the passes in the rolls so that a suitable .intermay flow outward and equalize with the lowered exterior temperature, avoiding too great an inequality of temperature in the bloom while it is being worked in the following pass.

Instead of employing the cooling jets of water for lowering the temperature of the blank as it. passes throughv the rolls, the 4 blank may be transferred to a heating furnace of a temperature lower than that of therebyv .val is afforded in. which the internal heat- I the thicker and hotter portions of the blank,

in which furnace the temperature of the blank is equalized throughout to the lower' temperature required for the completion of the rolling operation. As, above noted, this conveniently be 1100 C. or even somewhat lowerdepending upon the number of passes,v the character of the work involved in completing the rolling operation and the intended finishing temperature; that is to say,

issues from the final finishing pass to as low a temperature as say 800 (1., and if accordingly, a greater number of'passes in the finishing rolls is employed, the temperature for the reheating will be lower than if it is desired to finish the rail "at say ,1075 C. I:

It is broadlycharacteristic of the invention that the ingot after it enters the rolls if the completion of the operation is to brlng the rail as it seen: 1

as to increase the elastic limit of the finished product, the finishing operation being conductedatsuch a temperature and in such a manner that the product may nevertheless issue from the-finishing pass of the mill in a condition of uniformity of distribution of its constituents, which condition may thereupon be fixed by rapid cooling. The rolling operation may begin with a temperature ranging from 1125 C. to 1225' 0., and that portion of the operation prior to-cooling may terminate with an average temperature in the bloom ranging say from 1075 C. to 117 5 C. The cooling may be done'fractionally, i e., in part as it leaves each of two or more passes of the mill, the important fea' ture beingthat the bloom during the finishing operation is worked at such a temperature below a certain limit thatall parts of the section are thoroughly worked and compressed, so that a uniform very fine-grained and stiif'condition of the steel shall exist throughout all portions of the finished prod uct. The limit below which the metal should be cooled before the final working is a temperature usually of about 1075 C. and so far removed from the melting point of the eutectic at about 1125 C. that the eutectic ation to the desired degree upon the mill table as the bloom issues from a pass or passes of the mill and before it is subjected to the final working and compression at a temperature below the fixation point. In most instances, however, as hereinbefore de scribed, I prefer to employ the water jets for more nearly equalizing the temperature of the thicker portions ofthe section, such- .as the head and center line of the base of the rail with the temperatureof the cooler portions of the base rather than to rely upon the cooling due to air radiation, which has the tendeno to accentuate the constantly increasing di erences in temperature bet-ween the thicker and the thinner parts of the' bloom already initiated as soon'as it begins to take on its molded form, v I

' While I have here' before referred to the production of railroad rails, as an exemplification of the practice of my invention, I desire it to be understood that it is likewise applicable to the production of other similar rolled shapes and bars.

Having thus described my invention, what I claim is:

1. The method of producing rolled shapes of manganese steel, which consists in first heating a manganese steel ingot or blank to a point above the melting point of the eutectic until it is ina condition of substantial uniformity of distribution of its constituents, rolling it in that condition until the shape is partially formed, then rolling and intermittently cooling and equalizing the temperatures of the different portions of the bar, until the bar is finally finished and worked throughout at temperatures below the fixation point; substantially as described.

2. The method of producing rolled shapes of manganese steel, which consists in first heating a manganese steel ingot or blank to a-point above the melting point of the eutectic, rolling to a bloom, and cooling and working to finished shape at temperatures .below 1075" (1, substantially as described.

3.. Themethod of producing rolled shapes of manganese steel, which consists in first heating a manganese steel'ingot or blank to a point above the melting point of the eutectic, rolling to a bloom, cooling to the fixation point, and thoroughly working the bloom, by rolling, to finished shape at temperatures below the fixationpoint, to produce a uniform fine-grained structure throughout; sub stantially as described.

4. The method of producing rolled shapes of manganese steel, which consists in first heating a manganese steel ingot or blank to apoint above the melting point of the eutectic, rolling 'to a bloom, and cooling and working to finished shape at temperatures below 1075" C., and thereupon immediately quenching; substantially as described.

5. In the production of wrought shapes of manganese steel from metal-which has been heated to a temperature above the melting point of the eutectic until in a condition of substantial uniformity of distribution of its and rapidly cooling; substantially as .described;

In testimony whereof I affix my signal-- ture, in presence of two witnesses..

WI FIE D sJP T-TER,

Witnesses: WILLIA H.- DAVIS,

'Jonn YCLPENNIEJ.