US1643321A - Rail steel - Google Patents

Description

" ance to wear of rails,

Patented Sept. 27, 1927.

, U-NITED STA TES PATENT OFFICE.

JOSEPH KENT SMITH, OF DETROIT, MICHIGAN, ASBIGNOR TO 0. HAROLD WILLS, OF

MARYSVILLE, MICHIGAN.

nan. STEEL.

No Drawing.

This invention relates to rail steel, and steel of an analogous character.

The nature, objects, and advantages, of the invention will be best understood from the following: In the last few years, in railroad transportation, the average speed has greatly increased, as has also the average wheel load of cars and of locomotives, in addition to which the volume of trafiic has greatly increased. Thus, the life strength, and resisthave become increasingly important factors, and the rails now last so short a time that some railway engineers are contemplating heat treating rail steel in order to increase those physical properties such as resistance to shock, static strength, and resistance to wear.

However, heat treatment of such articles as steel rails involves a very heavy additional expense, especially in equipment, and will ordinarily decrease the tonnage out at of the rail mill. Mere increase in the slze of the rail certainly will not fulfill all the needs of the situation.

The primary object of the present invention is toprovide a rail steel which, among other things, will meet the conditions above specified, and which, although not heat treated, will have substantially the same properties as though heat treatment were resorted to. i

More specifically I propose to add certain alloying material which will give to the rail steel the desired physical properties at a much lower cost than would be involved in heat treatment, and this without restricting in any way mill production.

Other objects and advantages will be hereinafter more particularly set forth.

I accomplish the desired results by intensifying-and in extreme cases, perha s, reversingthe potential differential of t e ferrite and carbide constituents of the steel. To this end I add an alloying ingredient, such as copper, which will dissolve in the ferrite; and I also add another alloying ingredient, such as molybdenum, which will intensify the 2 :tion of the copper by the further solid solution of a little of the molybdenum. The molybdenum will, in addition, strengthen the carbides by the oo-formation in them of a molybdenum-complex carbide. I take every care to avoid the presence, in

Application filed June 22, 1826. Serial No. 117,829.

the carbide, of isolated spots of simple undissociated molybdenum carbide. I

In consequence, I produce a rail steel which will not deteriorate nearly as rapidly as standard rail steel. In "this connection, I have found beyond question that a strong contributory factor to the rate of wear of a rail in service is damp atmospheric attack, as it results in the continued presentation of fresh disintegrated surfaces, singly perhaps of extreme thinness, to the sweeping and abrasive action of the load. Such dis 'ntegration is counteracted largely by the presence of the copper in solid solution, the action of which is intensified by molybdenum. The increase in resistance to shock is primarily due to the employment of the copper and of. such mol bdenum as is in solid solution. The moly denum further adds to the general wearing properties, directly increasing the resistance to abrasion of the ferrite itself, and of the complex carbides finely distributed throughout the metal.

Thus, I am enabled to provide a rail steel of approximately normal weight per'yard which has the physical properties requisite to withstand the heavy service demands" of modern railroad practice, and, at the same time, has long life, without deviating from the usual mill practice of fabrication.

v Further, the correct molybdenum addition brings about the fine grain which is so desirable in metals which will most successfully resist wear and impact.

The rail steel'may be made according to.

standard mill practice with a number of further advanta es. Thus, for example, difliculties inrol ing, due to the nature of section, therefore the une ual rate of cooling, and consequently di ering structures of the thick-and thin parts, are minimized. The molybdenum makes the steel, in other words, less sensitive to local heat conditions, and greater uniformity of product is obtained. The allowable range within which the rollin temperatures must ordinarily be confined is substantially widened without detrimental results, the advantages of which will be obvious to those skilled in the art.

I prefer to employ a composition substantially as follows: carbon from about 35% to about .75%; manganese from about .5% to about 1.1%; copper from about 25% to was about 1.25%; molybdenum from about .07

to about 1.0%; and silicon, sulphur and phosphorus as per usual practice, that is to say, phosphorus not to exceed about .10%; silicon not to exceed about and sul hur not to exceed about .O6%.

s illustrative of the best practice that I am now aware of for a 120 lb. rail, I would make the steel of the following composition: carbon 58%; manganese .75.%; copper .45%; molybdenum .18%; and silicon, sulphur and phosphorus as usual.

It is to'be understood that my invention is not to be limited to the precise composition recited, nor to the precise alloying ingredients, as other ingredients may be employed to produce substantially the same results in giving an unheat-treated steel the properties above set forth, and such as would be obtained by heat treatment of an otherwise standard rail steel. For example, I may substitute nickel for some or all of the copper, and may utilize, in part, carbideforming elements like chromium, vanadium, etc.

I claim:-

1. A rail com osed of non-heat-treated steel of substantially the following composition: carbon from about .35% to .75%; manganese from about .5% to about 1.1%; copper from about to about 1.25%; molybdenum from about .07 to about 1%; and silicon, sulphur and phosphorus in about usual percentages.

2. A rail composed of non-heat-treated steel of approximately the following composition; carbon .58%; manganese .75%; copper. 45%; molybdenum .18 and silicon, sulphur and phosphorus n usual percentages.

In testimony whereof I have hereunto signed my name.

J. KENT SMITH.