US1515794A - And samuel peacock - Google Patents

Description

Patented or. 11

ISAAC M. scorr, or WHEELING, WEST VIRGINIA, AND SAMUEL PEACOCK, or

PHILADELPHIA,

PENNSYLVANIA.

PRQCESS OF MAKING STEEL INGOTS- FREE FROM BLOWHOLES.

No Drawing. Application filed May 8,-

To all whom it may concern:

Be it known that we, ISAAC M. Soo'r'r and SAMUEL PEACOCK, both citizens of the United States, respectively residing at Wheeling, in the county of Ohio and State of West Virginia, and Philadelphia, in the county of Philadelphia and State of Pennsylvania, have invented certain new and useful Improvements in Processes of Making Steel Ingots Free from Blowholes; and we do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use'the' same.-

This invention relates to a process of making purified cast steel ingots and has for its ob]ect to improve the procedures heretofore proposed.

With these and other objects in view, the invention consists in the novel steps and combinations of steps constituting-the process, all as will be more fully hereinafter disclosed and particularly pointed out in the claim.

In order that the precise invention may i be more clearly understood, it is said: It is well known that it is common to purify molten steel by adding ferro-silicon thereto, but it is also well known that in carrying out such practice it is found impossible to prevent the silicon from being absorbed to a greater or less degree by the molten metal, and thus often raising its silicon content to an objectionable degree. This absoprtion of the added silicon is particularly objectionable in those cases where the silicon content must be low, or when it must be constant, for there is no way to govern with exactness the amount of silicon absorbed, and there is no satisfactory way to eliminate the silicon after it is absorbed. In fact, even when there is provided in the bath a great excess of iron oxide, it is found impossible to oxidize. all the silicon added and to thus prevent some of it from being absorbed into the final product, owing to the principles involved in the well known phase rule of Gibbs.

When it comes to ferro-manganese as a cleansing agent, it is also well known that while it is highly satisfactory under most conditions yet it does sometimes leave manganese sulphide in the steel. This said sulphide has a melting point of about 1600 de- 1923. Serial No. 637,569.

degrees (3., it does not readily separate out of the molten mass, and therefore in many cases it'is left in the steel and later gives trouble.

Metallic aluminum'is also frequently used 6 as a cleansing agent, but like other agents it has its good and bad points which are well known. And it can be safely said that, however well ferro-silicon, ferro-manganese aluminum, or other cleansing agent may perform its function, in so far as we are aware, none of them except ferro-sodium,

the one made-the subject of this invention, have any efiiclency in removing any hydrogen, or nitrogen, that may be occluded in the metal.

In carrying out this invention, we prefer to proceed as follows: We take pig iron concarbides and compounds of silicon carried by the original pig iron will react with the iron oxide of the ore to form metallic iron, carbon monoxide, and silica. It, however, is not possible by this procedure to remove all the combined carbon and silicon present in the'pi by this method, because if the ore is in su cient excess to oxidize all the carbon and silicon, it is found that a considerable proportion of iron oxide from the ore enters the molten mass, which is undesirable. If,

on the other hand, a less quantity of ore is used some of the original carbon and silicon remain in the molten bath, We next subject the bath to the reducing action of hot gases in the open hearth process or otherwise refine the molten metal according to the established practice. But instead of using. a cleansing agent such as ferro-silicon, ferromanganese, aluminum, etc, we add ferrosodium to the ladle, or we place it in the ingot molds. The advantagev of ferro-sodium over. other cleansing agents for the molten mixture above disclosed resides in the following: Y

There is always a greater or less quantity of occluded hydrogen or nitrogen or both in a bath of molten iron as is 'well known, which injures the casting, and when these gases collect at particular points in the mass, they form blow holes. The sodium in the ferro-sodium on the other hand, at the tempig iron and admix 75 perature" of the molten iron, forms sodium If any excess of iron oxide is present in the bath, asis frequently the case, or in fact if any iron oxide is present which is almost always the case, the sodium of the ferrosodium readily reduces the same to form sodium oxide, and the same is true of any y other oxygen compound. In the same way, the said sodium will unit with any. silicon present to form a sodium silicide, or with any silica present to form a sodium silicate, and it will similarly unite with any other contaminating impurity usually found in bathsof molten iron to cleanse the same. In all cases the melting points of the sodium compounds formed are far below that of the iron, and therefore all these. sodium compounds readily rise to the top of the bath in the form of a slag or of a gas and are readily separated out in the usual manner.

Another important advantage of ferrosodium over other cleansing agents is found in the 'fact that it may be freel added in excess without injury to the pr not, for in such cases the sodium will not alloy with the metal to any appreciable extent, but will simply boil ofi as a vapor. In the case of ferromanganese, ferrosilicon, or. aluminum,

on .the other hand, an excess contaminates the product.

Again, the sodium present in ferrosodium will unite with any carbon monoxide oceluded in the metal to form sodium carbonate which rises to the top in the form of a slag in accordance with the following equations:

(b' 2FeO+Na C :Fe+2Na-{2CO. It will thus be seen that one molecule of carbon monoxideis used up, or eliminated,

for each molecule of sodium carbonate formed. In the case of a silicon compound on the other hand, the silicon combines with the oxygen of the CO, and precipitates the carbon in the metal which is undesirable. Ferromanganese and aluminum does not re move occluded CO at all.

What is claimed is:

The process of producing steel ingots free from blow holes and contaminating oxides which consists in mixing iron oxide with molten pig iron to eliminate a portion of the carbides and any compounds of silicon pres-v ent; refining the molten metal thus produced by subjecting. it to the action of reducing gases; and adding ferrosodium to the refined product in a quantity sufiicient to remove all oxides and occluded gases present;

In testimony whereof we afiix our signatures. ISAAC M. SCOTT.

SAMUEL PEACOCK.