US1762098A

US1762098A - Ingot mold

Info

Publication number: US1762098A
Application number: US379580A
Authority: US
Inventors: Kauffman Edmund Jamison
Original assignee: Valley Mould & Iron Corp
Current assignee: Valley Mould & Iron Corp
Priority date: 1929-07-19
Filing date: 1929-07-19
Publication date: 1930-06-03
Anticipated expiration: 1947-06-03

Description

Patented June 3, 1930 PATENT; OFFICE EDMUND JAMISON KA'UFF'MZAN, OF

GIRARD, OHIO, ASSIGNOR TO VALLEY MOULD IBON CORPORATION, OF HUBBARD, OHIO, A CORPORATION OF NEW YORK INGOT MOLD Ho Drawing.

vThe present invention relates to metallurgy and more specially to ingot molds.

Ingot molds heretofore in the art have, and now are, generally made from molton iron, usually direct from the blast furnace, but in some cases from the cupola. Blast furnace iron or direct metal, does not possess the physical characteristics of refined iron, and it sometimes happens that direct metal ingot molds in use will develop cracks. Such cracks occur early in the use of the mold and are referred to in the art as premature cracks. This type of crack may be caused by the wall of the ingot mold being too thin in proportion to the size of the matrix of the mold, or it may be due to insuflicient annealing, or bad iron, or other causes which result in a crack starting at the outside of the mold and gradually enlarging until it reaches the matrix of the mold, at which time the mold is usually ruined and not adaptable for further use. Direct metal molds or other molds unduly high in raphitic carbon sometimes tend to burn or recrack, which usually arises because the graphitic carbon often forms in relatively large plates or flakes, the edges of which may extend to the matrix of the mold. When the mold is in use and molten steel comes in contact with the carbon flakes, the flakes burn out and the iron starts to oxidize in the flake cavities. The oxides form in these cavities when the mold is very hot. When the mold cools these oxides are subjected to enormous stresses and consequently the extraneous material in each of these carbon cavities acts as a wedge tending to open up a small insipient crack. In view of the, fact that the entire surface of the matrix of such a mold is composed of metal high in graphitic carbon, these cracks during use of the mold, extend in diflerent directions over the matrix face of the mold so that the matrix face may take on the appearance of burned or old leather. This weakens the surface of the matrix so that erosion occurs and this is referred to as burning. when a crack starts from a carbon pocket it is called in the art a burnout crack. Such a crack will start as a Application filed July 19, 1929. Serial N0. 879,580.

small incipient crack at the matrix of the mold and gradually extend through to the outside of themold.

To obviate the foregoing difficulties, molds have been made from steel. Steel molds, however, are unsatisfactory for the reason that steel molds invariably warp due to the heat of molten steel poured into the molds. When a mold warps the ingot connot be stripped from the mold. Furthermore, if in pouring the stream of molten steel strikes the side of a steel mold so as to heat the same up to substantially the heat of the molten steel, the steel ingot will weld to the side wall of the steel mold in view of the fact that the steel mold is of substantially the same metal as the molten metal from .which the ingot is made.

The present invention overcomes the difli culties of the prior art, and resides in mixing direct metal from a blast furnace (containing usually from 3.75% to higher per cents of carbon) or metal from a cupola (which usually contains from 3.0% to higher percentages of carbon) with steel containing from .10% to .40% of carbon. The molten steel and the direct metal are, according to the present invention mixed after the molten metals have left the fur naces. These mixed metals result in a product which is different from the mixture. formed by introducing scrap steel into a cupola or air furnace, iron, and melting the metals therein. Where steel scrap is introduced into 9. cu-' pola, or air furnace, both the pig iron and the steel scrap are materially injured through contamination with the impurities in the fuel or'fuels used for melting. Further, the melting processes used are oxidizing in character, thus tending to introduce oxidation products and other refractory dirt particles picked up from the furnace linings. In. addition, it is extremely difficult to obtain and reproduce the exact chemical compositions and physical characteristics required due to variations of the raw materials, and melting variations of the difl'erenantiypes of furnaces used, or even been together with pig erent furnaces of the same type.

On the other hand, pig iron used in the molten state direct from the blast furnace,

known in the art as direct metal is a product made from virgin raw materials and by a combination of powerful reducing chemical reactions within the blast furnace. More exact mixtures from the standpoint of chemical compositions and physical characteristics may be made, as the composition of the direct pig iron and molten steel may be pre-checked and then mixed in such relative proportions as will yield a resultant mixture with the exact chemical and physical characteristics desired. As a result of the factors as outlined above, the mixed metals produce a novel alloy of direct metal and steel peculiarly adapted to' resist premature cracking of ingot molds, or other heat resistant castings, due not only to the better control of the amount of graphite carbon, but also to the better conformation, distribution and flake size of the graphite embedded in the metallic matrix, which matrix has been materially strengthened by the steel addition. The present metal, therefore, does not substantially lose the desirable characteristics of direct metal, but does gain very materially in physical strength from the steel addition due to the improved eutectic. This obviates erosion, burning out and cracking which, as above explained, are liable to occur in direct metal molds.

The mixture of steel and iron according to the present invention, may vary from 5% of molten steel in the total mass, to large per cents of steel, dependent somewhat upon the amount of carbon in the direct metal and also upon the use to which the mold is to be ut.

ccording to the present invention, it is desirable to obtain the molten steel from the same source as directmetal is obtained. In other words, preferably, part of the direct metal from the blast furnace is converted into steel in a Bessemer converter, an

. open hearth,'an electrical furnace, or other known means in the art to produce steel. This converted portion of the run of the blast furnace is then mixed directly with the remaining portion of the direct metal from the blast furnace or cupola, thereby producing the molten metal to be used to cast ingot molds in accordance with the present invention.

Molds made in accordance with the present invention retain all the advantages of molds cast from direct metal or cupola metal plus the addition of added physical strength and consequently such molds do not tend to warp as do the steel molds referred to and they do not tend to "weld to the steel ingot, as is one of the diificulties of a steel mold; neither do, they crack as readily as direct metal molds. y 4 v The. present method maybe carried out in such manner as to only very slightly increase the cost of production while at the same time greatly increasing the life of the mold so that in the end molds in accordance with the present invention are much more economical than direct metal molds. In other words, the slight additional cost of production is more than exceeded by the economy due to the increased life of the novel mold.

As a further development of the present invention, it may be desirable to cast the molds in such manner that the steel content adjacent the matrix wall of the mold will be higher than the steel content on the outside of the mold. This mold construction increases the stren h of the mold over that portion which is su j ected to the most severe strains and at the same time the metal which supports the inner wall has the advantages of heat absorption and slow radiation which is desirable in ingot molds.

One method by which the steel content adjacent the matrix wall may be increased is to rapidly rotate the set-up for casting the ingot mold, after the practice known in the art as centrifugal casting, and during which time the direct metal is poured into the setup. This causes the cast iron or direct metal to be thrown outwardly to form the outside portion of the mold. After a sufficient amount of direct metal has been introduced into the set-up to makea substantial mold wall portion, the molten steel is poured around the core bar, which steel will unite with the direct metal forming the outside of the mold and will mingle with the same so as to form a continuous body comprisingthe walls of the mold. This body will have a large proportion of direct metal' on the outside and with a large proportion of steel onthe inside adjacent the matrix. Such molds are very' useful in the metallurgy art, and particularly for use in casting ironferrous ingots.

Having described my invention, I claim:

1. An ingot mold with the walls thereof comprising direct metal cast iron and steel.

2. An ingot mold with the body thereof comprising an alloy of direct metal high in carbon combined with a small proportion of steel low in carbon.

3'. An ingot mold with the walls thereof comprising an alloy of cast iron containing not less than three per centum of carbon and steel containing not more than four tenths of a per centum of carbon.

4. An ingot mold having mold walls comprising a physical mixture of cast iron and steel.

5. An ingot mold having mold walls comprising an iron alloy of a large proportion of direct cast iron and a small proportion of steel.

6. ingot mold having mold walls comprising direct cast iron, and steel with the proportion of steel being higher adjacent the matrix of the mold than adjacent the outer surfaces ofthe mold.

7. An ingot mold having-mold walls comprising cast iron and steel with the proportion of steel being highest adjacent the matrix and with the proportion of cast iron being highest adjacent the outer surfaces of the mold.

8. An ingot mold having body walls comprising substantially steel adjacent the faces of the matrix walls and substantially cast iron adjacent the faces of the outside walls.

9. As an article of manufacture, an ingot mold member having a portion adapted to contact with molten steel when said member is in use, said member comprising an alloy of cast iron and steel.

EDMUND JAMISON KAUFFMAN.