US1055832A - Steel shape. - Google Patents

Description

B. TALBOT.

STEEL SHAPE.

APPLICATION rum) NOV. 6, 1912.

1,055,832, Patented Mar. 11,1913.

INVENTOR 7 British subject, residing at 'Woodburn,

internal shrinkage, liberation of gas after 'nated in great measure and large cavities or pipes are formed in the center of the up collecting in excess in the central part of UNITED STATES BENJAMIN TALBOT, OF WOODBURN, DARLINGTON, ENGLAND.

STEEL SHAPE.

Specification of Letters Patent. Patented Mar. 11, 1913.

duplication filed November 6,1912. Serial No. 729,765;

To all whom it may conc 'em:

Be it known that I, BENJAMIN TALBOT, a-

Darlington, Durham county, England, have invented new and useful Improvements in Steel Shapes, of which the following is a specification.

My invention relates more particularly to railway rails and has as its primary object to improve the structure of the metal of the usual steel rail so that it shall be free from flaws and defects andpossessed of a uni formly'tough interior lower in carbon than the outer strata. Y i Steel rails frequently contain hidden flaws and structural defects due to blow holes, cavities and segregates, which have resulted 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 condi tions arising in the process of manufacture in which the ingot is formed by pouring the molten steel into a mold and allowing it to solidify without provision compensating for the outer strata have hardened, and segregation within the upper part 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, either scattered through the mass, or where a powerful deoxidizer has been added to the molten steel, the smaller blow holes are elimiper third of the ingot. In the process of cooling, carbon, sulfur and phosphorus segregate and move, as the metal cools, from the outer to the inner parts of the ingots,

the upper third as a segregate, frequently in seriously objectionable degree. When such ingots are heated to the requisite tempera ture androlled, 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 which the excessive segregationhas takenplace produce sections more or less of the metal in such sections being brittle and treacherous.-

I have found that if an ingot be stripped I as soon as practicable after casting, placed in a heating furnace or soaking pit until the solidified envelop has increased in thickness and become sufliciently 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 itscrosssectional area to compensate for shrinkage and eliminate cavitiesdue to confined gas and unequal cooling, it'will be found that the interior of the ingot is (due to't-he condensing lateral pressure) solid in texture and free from blow holes, cavities or pipes except in a limited end portion; that the mass of the central portion of the ingot is 7 lower in carbon than the outer'strata; that there is a slight but unobjectionable indication of segregation approximately parallel to and at a short distance from the surface of the ingot; and that there 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 the upper part of the ingot is partially formed and the metal. between the solidified but ductile outer strata and fluid central mass has little coherence 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 forced outwardly, passing through or being absorbed by the enveloping metal, while carbon, phosphorus and sulfur dilfused through the congealing metal are. retained, tests in the finished products which are defective,

In carrying out my invention, I prefer to" tion take place in the upper third of the ingot, I may confine. the squeezing operation for the purpose of eliminating the cavities and disseminating the segregates to such upper third or only the upper part of the ingot.

In steel which has been treated by an electrical refining process, the amount of segregation 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 defects resulting from such cavities,

While it is not essential to do so in all cases, the ingots will generally, after having been subjected to the squeezing operation, be returned tothe heating furnace or soaking pit, to effect a more nearly equal and desirable temperature and condition throughout the mass of the metal prior to rolling or finally forming the desired-shape.

In the accompanying drawings, Figure 1 is a longitudinal sectional View of a steel 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 af-.

ter it has been heated in -a soaking pit for such time and at such temperature that the envelop has become sulficiently thick and sufiiciently soft to work without rupturing; Fig: 3' is a longitudinal sectional view representing an ingot or bloom that has resulted from squeezing the-ingot shown in Fig. 2 by the application of lateral pressure thereto so as to reduce its cross-sectional area; Fig. 4 is. a. transverse sectional view of a rail produced 'by rolling the ingot or bloom shown in Fig. 3; Fig. 5 is a transverse sectional view of an I-beam rolled from an ingot or bloom like that shown in Fig. 3; and Fig. 6 'isa longitudinal sectional view representing an ingot having'the cross section of only its upper. part reduced to eliminate cavities and force the segregates ontwardlyl The ingot A, shown in Fig. 1, is 'say 2 wide at the bottom and has an envelop a which may be 1 thick, such envelop being too thin and hard for satisfactory contraction by rolling or squeezing to reduce the cross section of the ingot while its central part a is still fluid. a

The ingot B, shown in Fig. 2,'results from heating the ingot A until there is produced the comparatively soft or ductile and thick envelop 1) containing the fluid central mass I) at the top of which the cavity 19* will have 7 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 otherwisev squeezing it so as to reduce its cross sectional area, eliminate the cavities or confine themto a restricted part of the top, and provide the comparatively pure central part c surrounded by the strata 0' of some- I going parts an average of .80% carbon, 04%

phosphorus and .O6% sulfur.

It will beunderstood that there is no distinct or aburpt line of demarcation between the strata, which term is used here with reference to zones containing different amounts of the elements, the change in the amounts of the elements throughthe several strata being gradual.

The rail D, shown in Fig. 4', is the product produced by rolling the ingot or bloom C, the rail having the comparativel pure and softer central part d and the bar er exterior d providing a tough center combined with a hard wearing surface. The I-bea-m E, shown in- Fig. 5, is likewise provided with the comparatively pure and softer central or body part c with a" slightly harder surface e.

' The ingot F, shown in Fig. 6., has its upper part onlyreduced in cross section, with resulting elimination of cavitie's and diffusion of the 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 parts thereof adjacent to the central art It will be understood that while 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. Y v

Having described my invention, I claim:

1. A steel shapehaving a purified central part lower in carbon and phosphorus than outer strata thereof.

2. A steel shape having the segregate removed from the central part and distributed substantially parallel to a surface or surfaces thereof.

3. A steel rail having a head with apurified central part lower in carbon than the outer strata, and the segregate distributed between said central part and outer surfaces thereof.

4. A steel rail having a purified central part, an enveloping part, and a stratum of maximum carbon between the central part and the enveloping part.

5. A steel rail having a purified central part, an enveloping part higher in carbon than said central part, and strata between said central and enveloping parts in which impurities removed from said central part are deposited.

6. A steel rail having a purified central part, an outer stratum higher in carbon than said central part, and a stratum between said central part and said outer stratum higher in carbon than said outer stratum.

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:

Jos. G. DENNY, Jr., GEO. A. CUNNEY.

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