US1158318A - Ingot-mold. - Google Patents

Description

H. E. SHELDON.

INGOT MOLD. APPLICATION FILED M'AR130 1912.

Patentel Oct. 26, 1915.

FIG. 1

- INVENTOR Lfdbum WITNESSES.

' cast metal appears as free carbon, not being I UNITED STATES PATENT OFFICE- HARRY E. SHELDON, OF PITTSBURGH, PENNSYLVANIA.

INGOT-MOLD.

To all whom it may concern Be it known that I, HARRY E. SHELDON, a citizen of the United States, and resident of Pittsburgh, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Ingot- Molds; and I do hereby declare the following to be a full, clear, and exact description thereof.

a My invention relates to an ingot mold for casting steel ingots, its object being to provide an ingot'mold of longer life than the cast iron molds now in universal use.

It is well known that cast iron ingot molds are short lived by reason of the recesses or cavities which appear in the inner surfaces, particularly in the lower portion thereof, and more particularly within two feet of the bottom of the mold. The molten metal supplied to the mold during the casting of the ingot enters within these recesses or cavities and upon solidification locks the ingot in the mold so that it, cannot be stripped therefrom thereby necessitating the destruction of the mold, these'ingot molds'having an average life of only about sixty heats. I have discovered vthat these cavities in the molds'are not,'to any appreciable extent, due to the abrasion produced by the stripping of the ingots from the molds, but are due to a phenomenon akin to osmotic action. This action can be described as follows: The cast iron ingot molds are relatively high in carbon, and may be higher in manganese sulfur phosphorus and other impurities than the molten steel; and a large portion of the carbon in' such chemically united with the iron. The molten steel cast therein is of course much purer than this cast iron, having only a relatively small proportion of ,,carbon or other impurities chemically united with the iron of the steel body. \Vhen this steel in a highly mol'ten'condition is poured within the cold cast iron mold, the latter does not melt and so mix with the molten steel or dissolve gradually from the face of the mold, but the molten steel which is composed of a more dilute alloy, infuses itself or immigrates into the higher alloy and causes, or tends to cause, an increase in the size and dilution of the higher alloy until both alloys are. of the same composition, there being a sharp separation between the higher alley, or cast iron, and the lower i Specification of Letters Patent.

Patented Oct. 26, 1915.

Application filed March 30, 1912. Serial No. 687 ,366.

' alloy,-or molten steel, which envelops it.

During this infusion or immigration of the steel 1nto the 'cast iron, globules or fragments of the cast iron separate therefrom and continue to be acted on by the molten steel or lower alloy in the same fashion as is above described with reference to the parent mass of the cast iron or higher alloy, and in this way the globules or fragments are, as it were, dissolved within the molten steel or lower alloy. If the infusion or immigration of the molten steel into the cast iron be checked, as by the solidification of the metal, at any stage previous to complete merger of the [two metals or alloys, the remaining globules or fragments, if any, of the cast iron or higher alloy separated from the mold body, will remain as hard spots in the mass of the steel or lower alloy. I have found that such infusion or immigration of the molten steel acts upon the Walls of the cast iron molds and is responsible for the attack of the former upon the latter, causing the recesses or cavities in the inner mold faces hereinbefore referred to, and the appearance of the hardspots in the sheets,

plates or. other products :made from the ingots. r

I have discovered that, if the'mold wall is of approximately the same composition as the metal poured into the mold, osmotic infusion or immigration of the poured metal in themold Wall does not take place, and consequently the formation ofcavities within the mold walls andhard spots in the ingots are practically overcome, and the life of the mold is prolonged and the quality of the metal cast is greatly improved.

My invention therefore consists, generally stated, in an integral mold for casting steel sectional View of the sam The ingot molds embodying the invention are formed of cast steel,-f9r examplajoither Bessemer steel or open hearth steel, lind are' metal can bepoured-into the ingot-mold.

. either through 'tlie' openingijf thereing of the steel ingot mac 1 of or fromf, below, the runner 5 which has 3 ingv to dilferent ingot nicating with the base the 'Inthe form.-

faetory results have been secured where the steel in the mold contains-fromffzll to .30

percent. of carbon, theamonnt pf manga-v nese, phosphorus and sulfur pr'eiqmt being within reasonable commercial limits,-

To adapt the steel ingot molds for the casting of all characters-of steel, however, they should not have aca'rbon co r rt of over two per cent. when there is no difference in proportion of impurity or al in the metalthan is found between-the o; nary molten steel cast: in ingots and a steel mold having this proportion,such so called osmotic action'is practically overcome. in

like manner theother impurities generally resent in steel should be within .the same practical working limit, the percentage of manganese 'not. bein over-twoper cent. and the percentage of so for and phosphorus not being higher than in steel containing such Within such roportions of impurities. Imits I practically prevent such osmotic in fusion. or immi ation of the poured steel .into'the walls 0 the mo ld,-and' thereby pre 1 vent the formation of cavities in the mold walls, and the appearance in the ingot of the hard spots formed from portions of the mold walls d'etachedas a result of such incomposed of iron alloyed with carbon, mlfltganese, sulfur and phosphorus, the content lofi of one of the main-alloying elements of the fusion or immigratioi i, as above described. I alwa s refer,'however, to employ a mold forme o steel within, say, 10 or 20 points of carbon content of the actual steel to oe cast ,in'the mold, so that alltendency to this osmotic action. between the steel and the mold body shall be eliminated.

. Another advantage obtained from the inventionis that in 'the use of the cast steel :mold's in casting the steel ingots, the body I ofithe mold'is never raised to an thingapproximating the meltin point 0 the metal 9 v of which it is compose For example, the

illustrated the ingot mold a ming "onrthefl bottom plate or casting stands and the.

lemnrougri runnersgolead' ids and iCOiiImuthe most satis- J melting point of. cast iron is approximately ofth'e molten metal is quickly taken up by the mold which is raised to a temperature of 68 from 1200 to 1400, about two-thirds of the melting' in: of the mold 'metal. This hming up 0 the mold close to its melting point;

naturally-leads to disintegration and aids fin the gradual. cutting out of particles or'70 ,portions-ofthe mold body.v In use of, the

steel molds, however, while they may absorb about the same-heat from the bo%of thinxetahthe mold is only raised to a lit one-half of its melting temperature, and 76 such disintegration is therefore naturallyre sistpdzi-f-Practical use of molds made in accordance with the present invention proves that theyoutlast thecast iron molds many times, the limit'of wear not having yet. been 80 full ascertained. p v

'6- inner faces of the molds remain smooth and practically solid without any substantial indication of the formation of recesses or cavities which when solidified 8 6 would-lock the integral taperin cast steel molds upon the steel ingots. ile' the molds are made integral and are lifted longitudinally ofl' the soldified ingots, as the so-called osmotic infusion doesv not take place betweenthe steel'of the mold and the steel of the in 0t cast therein all dangerof the locking 0 the ingot mold to the ingot v is overcome.

I claim: '1. An ingot mold for casting steel com posed of cast steel having approximately the same carbon content as that ofthe steel '0 be cast 'therein.

2'. An integral ingot mold for casting steel composed of steel containing a carbon content of not over two per cent.

3. 'A steel ingot mold for casting steel,

mold being not more than two per cent.

above the content'of the same elemdnt of the steel to be poured into the mold.

, In testimony whereof, I the saillHamllO

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