US397476A - Robert - Google Patents

Description

- poses statml.

UniTn STATES aTnT Tricia,

ROBERT J. TILFORD AND HENRY MY. REDEMANN, OF LOUISVILL l, KEN'lllCKY,

ASSIGNORS TO THE REDEMANN- PLACE.

TILFORD STEEL COMPANY, OF SAME MANUFACTURE OF STEEL.

SPECIFICATION forming part of Letters Patent No. 897,476, dated February 5, 188 9.

Application filed July 25, 1888.

To all whom it may concern:

Be it known that we, Roenn'r J. TILFORD and HFNRY M. REDEMANN, citizens of the United States, residing at Iamisville, Kentucky, have invented new and useful Improvements in the Process of. Hardening S1 eel, of which the :t'ollowing' is a specification.

()ur invention relates to certain new and useful improvements in the treatment of crude or low-grade steel to produce a refined or high-grade steel.

The most successful method of producing low-grade steel that known as the Bessemer process, described in his patent of 1855; but this product, as is well known,is suitable chiefly for railways, axles, and like uses, and is totally unsuited for structures, machinery, and tool purposes unless 'repuddlcd, hammered, and rolled, tor the reason that in its normal state it is too soft, and when hardened itbecomcs too hard and brittletm' thepur- It was the recognition of these i nherent dcl'ccts in the Bessemer and low and medium grade steel which led us totheinvcstication of the subject which has developed our present invention, the object oi which is the production at slight cost and a minimum degree of labm'ot' t igher grz-tde and more rcfined steel by trcatin 5,1" the Bessemer and other low-grade steel in such manner as to produce a molecular change from a coarse grain to a .tine grain and silky fracture, to increase the tensile strength, elasticity, toughness, and ductility, and to greatly increase the carbon. \Ve have found from experience that uniform results in all instances flow from the trcatmen t of metals having like properties.

\Vith these ends in view our invention con sists in heatin low-grade steel to a degree of heat re ilrcscntml by white heat, and then subjecting' the metal so heated to a previouslypreparcd liquid bath of such character that the contzict ot' the lunttwl metal and liquid bath will gmierate hydrocarlmn gases, which will be a'bsliirbcd or taken up by the metal, and allowing, the metal to remain in the bath until it has become substantially cool, in contradistinction to what is known as the cementation or dry process, as will be hereinafter more fully set forth.

Serial No. 231,018. (Specimens) As an illustration of one of the baths employed in the practice of our invention, we would state that we employ glycerinc andwater in the proportion otf th ree ounces of glye crinetio one-half (1}) gallon ot water, and all0w---55 the' change is ellectel'l, which should be until the metal substantially cool, or until such reduction in heat in the metal is made that it will no longer take up the gases generated by contact with the bath. \\'e have also found that by addin to the bath of glycerine and water spirits of .niter, aqua-ammonia, chloride of ammonium, sulphate of zinc, sulphate of alumina, and ammonia the results and effects obtained by a bath of 'cerine and water alone are improved, althou h good results are oliitaincd by the latter.

In practicing" our invention by the last named bath we employ the several chemical bodies in about the .t'ollowin proportions, to wit: spirits of niter,onc and ahalt' (l ounce; aqna-ammonia, one and a half (14-) ounce; chloride of annnonium, two ounces; sulphate of zinc, one and a halt (111,) ounce; sulphate ot alumina and ammonia, one and a half (1%) ounce; glyccrinc, three (53) ounces; water, one-halt gallon.

\Ve desire to state herein, however, that we lay no specific claim to eitherof the baths 8o dcscri bed above by which we practice our inventi on, as the one first described forms the subject-matter of a divisional application of this case filed on 13th day of November, 1888, Serial No. 990,737, while the second bath described forms the subject-matter of a second divisional application filed on the same day and bearing Serial No. 200,738, to which divisional applications reference is made for a more full. and complete description of the manner of carrying out the generic idea which the present application is intended to cover.

As further explanatory, however, of the advantages gained by the present invention, we would state that by the practice of our proccss (which should be understood as being distinguished from processes for tempering steel in oil) the nature, the physical construction, and the molecular construction of the metal are completely changed, whereas the the heated metal to remain submerged until tempering of steel in oil, as practiced by some processes, simply tempers the steel more slowly than is done by tempering in water and other properties, leaving the metal less hard, but som ewhat tougher than water-tempered matcrial. The changes caused by the oil-tempering process are merely temporary, and do not change the physical or granular construction of the metal, and such changes as are caused thereby can be readily neutralized by reheatin and allowing the metal to cool. The changes caused by treatment by our process are permanent, and cannot be removed by any known treatment or process without entirely destroying the steel properties of the metal by l'nu'ning.

\Ve have of course been unable to analyze the gases resulting from the contact of the hot-metal body with the bath, but are led to believe that they constitute a hydrocarbon gas which has a strong allinity for the metal, and that the. latter, being in a heated state, is in such a physical condition as to readily take up or absorb such gas; but as to the fact that the metal is highly improved we have no doubt whatever, as has been demonstrated by all the well-known scientific and m(-cht1nieal tests.

It will be understood, of course, that when the treatment is applied adjacent to the furnaces where the low-grade steel is manufactured. the ingots may be treated without reheating, and thus the expense of such reheating is avoid ed. After the metal has been subjected to the treatment it is allowed to cool in the ordinary manner, and it may atterwanl be subjected to any culinary hardening or tempering process, and the temper may, if necessary, be drawn and again restored without at all atli'ecting the other properties acquired from the bath.

\\e are of course aware that the quality of Bessemer and other low and medium grade steel may be improved by what is known as the dry or cementation process, which requires a large expenditure of skilled labor and great length of time, and that, too, without always securing uniform and satisfactory results.

*0 desire itto be distinctly understood that we lay no claim to the broad idea of in.- creasing the quality of steel by subsequent treatment, as that has been heretofore done, especially by what is known as the cementation process, which may be termed a dry process, our invention differing from such process in the particular that it requires a period of time amounting to a small percentage of the time required in the cementation or dry process, and is in eol'itradistinction to such process essentially a liquid or wet process, the former requiring many days, while the latter involves only a few minutes.

By our invention we greatly increase the tensile strength and elasticity, and yet do not destroy the per cent. of reduction or ductility, while with ordinary tempering the tensile strength and elasticity are greatly increased, but the per eent. of reduction and ductility is very much impaired.

Having thus described our invention, what we claim as new, and desire to secure by Lettei s Patent, is

The process of converting low-grade steel into refined or high-grade steel, which consists in first heating the metal to be treated to a degree of heatrepresented by white heat,