US1704385A - Manufacture of steel products - Google Patents

Description

f, steel from the central portion of. the ingot in an outward direction consequent upon the Patented Mar. 5, 1929. V

UNITED STATES PATENT OFFICE.

nonmrrnnno'rr HADFIELD, or wEs'rMINsrEanNoLAnn.

iitanu'mo'runn or STEEL raonoors.

No Drawing. a ncaami'mea July 7, 1926, Serial No. 121,059, and in Great Britain April 29, 1926.

This invention has reference to the manuj tacture, 1n a regular and economical manner,

of steel products sound in character as regards freedom from blow holes, rocks, pipes,

segregations or other like defects. As the invention is specially applicable to the production of rolled steel rails of a sound, and

reliable character, the manner of carrying it into effect will now be described with ref ronce to such steel products without any intention however of limiting'it to such rolled products.

In the manufacture of rolled steel rails,

the usual procedure adopted is to produce a heat of normally finished steel of the desired composition by some approved process in an open hearth furnace or other suitable furnace or apparatus, as for instance a Bessemer converter, to tap or deliver theheat of fin ished steel into a ladle, the composition of' the steel being, if necessary, adjusted to'suit requirement, either before or after tapping or delivering the steel into the ladle, to afterwards run oil the niolten steel from the ladle into ingot moulds and afterwards to roll theingots into rails of the desired weight and section. With this method of procedure, there is no certainty that the steel run" off from the ladle into the ingot moulds will produce sound steel ingots. In a large proportion of cases it will not. The ingots,

on the contrary, are frequently ot' a porous or honeycomb nature, particularly towards their upper portions, due to gas evolved from the steel during cooling, so that. in order to obtain from such ingots a portion of steel approximately sound, a considerable percentage of the upper portion of the in-- gots has to be cut off and discarded. Often,

almost complete ingots have to be discarded, owing to their unsound condition. This adds considerably to the cost-of manufacture. During cooling of a cast steel ingot, piping thereof will, aslwell understood, also occur if the steel be of what is called aset- -tling nature, due to the contraction of the chilling etlectof the metal-ingot mould used. When a cast steel ingot pipeswell, it is commonly considered that the steel of. which it isiformed is of sound quality. To determine, before casting, whether a heat of normally finished steel is of a good settling nature, a sample of the steel is usually tested by castin .it into a small. metal mould by which it is quickly chilled, and if it settles 'Welltherein, that is to say, if a cavity is which are afterwards rolledinto rails, As

a matter of fact however, although the steel may appear to be ofa good settling nature, it'niay nevertheless be and often is, of unsound nature.

,Cllllltest in a small metal mould is, to some I have found that the extent, an'illusive'one, so far as determining.

the real soundness of the steel is concerned. Asa result, large quantities ofrolled steel rails are made, and passed into railroad service, that are whol y cause ser ous railway accidents, as the statistics pnblished ffrom time to time by the authorities concerned, am ly prove.

The pipin thatoccurs n steel ingots also assists in t e roduction' of faulty *rails,

because, althoug it is supposed that the pipe will be closed up and the metal around the same caused to become welded: up during the rolling of the ingots into rails, this will not actually take place, or notrin an' effective manner. In every case however a considerable proportionfof the piped upper end of unreliable and oftenthe ingot has to be discarded before rolling.

the. remainder, intoa rail. The formation -of a pipe in an ingot of good settling steel can however be avoidedby feeding molten metal to the top of the ingot, during the cooling of the lower portion of the ingot. This can be done "in various ways, as for example'by the method-and apparatus described in the specification of my former Letters Patent No. 933,731, No. 954,183, No.

,.1,172,279 and No; 1,301,072, :according to which the ingot mould is formed with a head of refractory non-conducting material, for

track structures, as'well as other rolled or forged steel articles, as for instance, steel plates and sheets, to be made with cert ainty, of steel of a thoroughly sound and reliable character throughout, in a regular and economical manner.. It also has for its object to enable not only steel made by the open hearth method but also steel made by the Bessemer method, which is now usually re garded as unsuitable for the manufacture of steel rails, to be used with confidence in.

the manufacture of steel rails.

test sample but will, on the contrary, allowit to 0061 only comparatively slowly, that if the sample of steel contains such an amount of gas as would result in the production of an unsound ingot, if the heat of steel were at once cast into an ingot, this fact would be indicated by the evolution of from the'sample of steel in the mould causing the steel to rise, that is to say, to extend,

more or less above the top of the mould. If; on the other hand, the sample of steel be of a sound and settling nature, a cavity will be formed in the top of the small ingot formed in the test mould, indicating that,

the-heat of steel is of a sound and settling -nature and can therefore, without further treatment, becast into an lngot from which a sound rail can be produced.

A mould of the character referred to, can advantageouslybe formed. of green sand. Such a mould may, for example he internally about six to eight inches in height and about one inch in diameter or width and be of cylindrical or prismatic shape. ()1' it may internally be of an inverted conical or pyramidal shape so that it will be of gradually increasing cross'sectional area from bottom to top. Or a test mould of oblong shape and of'abo'ut one and a half to two square inches in section may be used. If the sample of steel tested in a mould of the kind referred to, rises, thus giving an indication that the steel is of an'unsound nature, then there is thoroughly incorporated with the heat of normally finished steel, whilst the same is in the furnace, or in a ladle into which it has been transferred,- a sutlicient quantity of a deorridant, as for example aluminium or ferro-silicon, as will remove the gas absorbed therein, or rcduce'it to so small a degree as to convey th st l i t a sound and settling steel. This result may be ascertained 'by testing a. sample of the treated steel inthe same way as the untreated steel. The heat of treated steel, when a sample thereof shows that it of a settling nature, isthen run off from the ladle into one or more ingot moulds provided with a refractory non-conducting head suchas hereinbefore referred to. A test mould made of dry sand has not so far been found satisfactory for the purposementioned.

During the cooling of the ingot, or each ingot, molten steel is fed into the top of the ingot, in the way hereinbcfore described, to prevent the formation of a pipe therein on cooling. In this way, an ingot of thoroughly sound and reliable steel can be produced. The ingot is afterwards rolled into a rail of any desired weight and section which willbe found to be of a thoroughly sound and reliable character.

The invention can advantageously be applied in connection with the manufacture of low, medium and high carbon steel rails.

Although-the invention has more particularly been described in connection with the manufacture of steel rails, it can, as hereinbefore indicated, advantageously be used in the manufacture of sound steel ingots for conversion into other rolled or forged articles of any desired weight or section. It can also be used in the production of castings of various kinds of sound steel.

1. In the manufacture of steel products, the method of ensuring that a normally finished heat of molten steel shall be of a settling nature before casting it into a mould, which consists in transferring a sample of the normally finished steel to a test mould of green sand and allowing it to cool therein and adding to the bath of molten steel, a sufiicient quantity of a dcoxidizing agent to convcrt'it into steel of a sound and settling nature, if the tested sample shows that the bath of molten steel is of a rising nature, substantially as described. 7

Z. In the manufacture of sound steel ingots, the method of ensuring that a normally finished heat of molten steel shall be of a settling nature before casting it into an ingot mould, which consists in transferring a sample of the normall finished steel to a test mould of green san and allowing it to cool therein and adding to the bath of molten. steel, a sufficient quantity of a deoxidizing agent to convert it into steel of a sound and settling nature, if the tested sample shows that the bath of molten steel is of a rising nature, substantially as described.

Signed at the city of Westminster. London, England, this twenty-fourth day of dune, L926.

RQBERT ABBOTT HADFIELD.