US1055833A - Manufacture of steel shapes. - Google Patents

Description

ENJAMIN TALBOT, 0F WOODBURN, DARLINGTON, ENGLAND.

MANUFACTURE OF STEEL SHAIES.

Specification of Letters Patent.

Patented Mar. 11, 1913,

Application filed November 6, 1912. Serial No. 729,766.

To al whom it may concern:

Be it known that I, BENJAMIN TALBOT, a British subject, residing at Woodburn, Dar lington, Durham county, England, have in vented new and useful Improvements in the Manufacture of Steel Shapes, of which the following is a specification.

My invention relates more particularly to the manufacture of railway rails and it has as its primary object to improve the structure of the metal of the usual steel rail sothat it shall be free from flaws and defects and possessed of a uniformly tough interior lower in carbon' than the outer strata.

Steel rails frequently contain hidden flaws and structural defects, due to blow holes, cavities and segregates, which have result-ed in many serious accidents. Usually the carbon in the central part of the upper third of the ingot is higher than in the outer strata, which produces a rail or rails having harder interior sections than the exteriors subject to wear, which is the reverse of the desired conditions. These defects are due to conditions arising in the vprocess of manufacture in which t-he ingot is formed by pouring the molten steel into a mold and allowing 1t to solidify'` without provision compensating for internal shrinkage and the presence of gas confined within the hardened outer strata, and segregation within the upper Apart of the mass. If usual cold ingots` be divided longitudinally, they will be found to contain blow holes or cavities,

particularly in the upper third part, eithery scattered through the mass or, where a powerful deoxidizer has been added to the molten steel, the smaller blow holes are eliminated in great measure and large cavities or pipes are formed in the center of the upper third of the ingot. In the rocess of cooling, carbon, sulfurY and p osphorus segregate and move,as the metall cools, from the outer to the inner parts of the ingots, collecting in excessin the central part of the upper third as a segregate, frequently in se-v riously objectionable degree. When such ingots are heated to the requisite temperature and rolled, the blow holes and cavities or pipes are found in the finished products as cracks or flaws, since the metal surrounding them cannot be heated to a fluid condition, and the sections` in whichthe excessive segre ation has taken place produce sections 1n the finished products which are defective, more or less of the metal in such sections being brittle and treacherous.

I have found that if an ingot be stripped as soon as practicable after casting, placed in 'a heating furnace or soakin pit until the solidified envelop has increased 1n thickness and become sufficiently ductile or plastic to work without cracking or rupturing, and

then squeezed while its interior is still in a fluid condition so as to contract its cross sectional area to compensate for shrinkage and eliminate cavitesdue to confined gas and unequal cooling, it will be found thatthe interior of the ingot is, due to the condensing lateral pressure, solid in texture, free from blow holes, cavities or pipes except in a limited end portion; that the mass of the central portion of the ingot is lower in carbon than the outer strata; that there is a slight but unobjectionable indication of segregation approximately parallel 4to and Aat a short distance from the surface of the ingot; and thatthere is no segregation within the central mass of the ingot and no objectionable segregation elsewhere.

At the end of the treatment in the soaking pit, the pipe in t-he upper part of the ingot is partially formed and themetal be- -tween the solidified but ductil outer strata and fluid central mass has little colference, so that when the ingot in this condition is subjected to lateral pressure, as by passing it through a cogging mill, the liquid metal fills'the pipe and the contained gases are Aforced outwardly, passing throughor being absorbed bythe enveloping metal, `while carbon, phosphorusv and sulfur diffused through the congealing metal are retained, tests showing these elements in, higher degree and distributed in a comparatively uni form manner through the envelop, with a slightly increased amount at a short distance from the surface Where a segregate, if substantial in character, would be least objectionable. An ingot of this character, when rolled or drawn, will produce'rails, beams and other shapes or products having comparatively pure and tough interiors combined with --comparatively hard exteriors, without the usual defects and with substantial economy of material, since there is required to be removed but a small crop or discard as practically the whole ingot is solid.

In carrying` out my invention, I prefer to treat the moltensteel,Vv either before or af- Fig.` 3 1s a longitudinal sectional view repreter it is poured' into the. ingot mold, with metallic aluminum, or other deoxidizerLsuch as silicon, ferro-sllicon, sillco-manganese or ferro-titanium, for the purpose, prlmarily, of effecting initially the elimination of small blow holes disseminated throughout the envelop of the upper portion of the ingot and to hasten the stitening ofthe metal.

As the objectionable cavities and segregation take place in the upper third of the ingot, I may confinethe squeezing operation `gation observed is usually very small, but -the cavities form in the same way as in steel made by the Bessemer or Siemens processes, and it is my. purpose to produce ingots and the products thereof without the efects resulting from such cavities.

While it is not essential to do so in all cases, the ingots will generally, after having been su'bJected to the squeezing operation, be returned to the heating furnace or soaking pit, to effect a more nearly equal andV` desirable temperature and condition throughout the mass of the metal rior to rolling or finally formi the desire shape.

In the accompanyi rawing's, Figure 1 is a longitudinal sectlonal view of a st eel ingot after stripping when it has a comparatively thin envelop of solid metal surrounding a fluid body; Fig. 2 is a longitudinal sectional view of the same after it has been heated in a soaking pit for such time and at such temperature that the envelop has become suticiently thick and sufcient-ly Soft to work without rupturing;

senting an ingot or bloom that has resu ted fro'm squeezing the ingot shown in Fig. 2 by t-he application of lateral pressure thereto so .asto reduce its cross-sectional area;

Figy is #transverse sectional view of a rail producedbyxrolling the ingot or bloom 'shown in 3,; Fig. 5'is a transverse sectional view 'of an I-beam rolled from an ingot orbloo'ln like that shown in Fig-3; and 1g. 6 is @longitudinal sectional view representing anv ingot having the cross section of Ionly its upper part reduced to eliminate cavities and force the segregates outwardly.

The ingot A, shown in Fig. 1, is say 20 wide at the bottom and has an envelop a which may be 1v thick, such envelop being too thin .and hargfor satisfactory contraction by neezang to reduce the *crossQ vsection ofthe `ingot while its central part av lis still tluid.-

XThe ot B,`:s'hown .in "Fig."2, results from'heatlng the ingot A until there is producedthe comparatively soft VAor ductile and-v thick envelop b containing the fluid central mass b', at the top of which the cavity b2 will have formed, the envelop being, say, 3 thick.

The ingot or bloom C, shown in Fig. 3, is the product resulting from giving the ingot B several passes in a cogging mill or otherwise squeezing-it so as to reduce its cross sectional area, eliminate t-he cavities or confine them to a restricted part' of the top, and provide the comparatively pure central part c surrounded by the Strata o' of somewhat higher carbon, together with phosphorus and sulfur (if any), there being generally a noticeable but unobjectionable stratum of segregation along the inner part c2 ofthe strata c. That is to say, as shown by averaging sections of a typical ingot,

where the central part c contained an average of .50% carbon, .02% vphosphorus and .03% sulfur, an outer stratum c" near the edge ofthe ingot contained lan average of .70% carbon, .03% phosphorus and .04%.

'soft central part d and the harder exterior d providing a tough body combined with a hard Wearing surface.

' The I-beam- E, shown in Fig. 5, is likewise provided with the comparatively pure and soft central or body part e with a slightly harder surface e.

The ingot F, shown in Fig. 6, has its upper art only reduced in cross section, with resu ting elimination of cavities and diffusion ofthe matter which would otherwise form a segregate in the center of such upper part. The lower part of the ingot will be found to be in the-usual condition, the center f of the upper part will be found comparatively pure, and the outer strata f will be found to have the segregates diffused therethrough, particularly through the part-s thereof adJacent to the central part f.

It will be understood that vwhile I have given specific illustrations of dimensions and conditions, in order to explain my invention by example, such illustrations are merely by way of example and not limiting features of my invention.

Having described my invention, I claim:

1. The process which comprises .subject-V ing a steel ingot having la fluid center to a f heating operation at vtf'ax'n'pe'rature and for such time as to so soften and increase the thickness of the envelop that it can be Worked Without rupturing; then subjecting said ingot to lateral pressure so as to reduce its cross-sectional area, eliminate cavities, and diffuse the segregates; and finally rolling said ingot into a rail.

2. The process which comprises subjecting an ingot composed of steel that has been treated with a deoxidizer to a heating operation While its center is still fluid, at such temperature and for such time to soften the envelop and increase its thickness so that it can be Worked without rupturing; then subjecting the ingot to lateral pressure so as to eliminate cavities therein and di'use carbon from the center thereof through the strata exterior to the fluid center; and finally drawing said ingot into a shape having a refined central part lower in carbon than the outer part.

3. The process Which comprises subjecting an ingot composed of steel that has been treated with a deoxidizer to a heating operation while its center is still fluid, at such temperature and for such time as to soften the envelop and increase its thickness so that it can be Worked without rupturing, subjecting the ingot to lateral pressure so as to eliminate cavities therein, and inally rolling the ingot into a rail.

4. The process which comprises subjecting an ingot composed of steel to a heating operation While its center is still fluid, at such temperature and for such time as to soften t-he envelop and increase its thickness so that it can be worked without rupturing; then subjecting such ingot to lateral pressure so as to eliminate cavities therein; reheating said ingot for such time and at such temperature as may be required to it it for rolling into a shape, and finally rolling said ingot into a shape.

In Witness whereof I have hereunto set my name this 4th day of November, 1912, in the presence of the subscribing Witnesses.

BENJAMIN TALBOT.

Witnesses: j

Jos. G. .DENNY, Jr., j GEO. A. CRENNEY.

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