US1545705A - Alloy and method of making and casting same - Google Patents

Description

July 14, 1925. I H 1,545,705

w. H. SMITH ET AL- ALLOY AND METHOD OF MAKING AND CASTING SAME Filed Augf22, 1921 INVENTORS.

William H.5m'urh Patented July 14, 1925.

UNIT ST TES PATENT OFFICE.

WILLIAM E. SMITH, OF EAST CLEVELAND, AND CHARLES CAMPBELL,- O l' CLEVE- LAND, OHIO, ASSIGNORS 1'0 THE PIONEER LAND, OHIO, A CORPORATION 01 DELAW ALLOY IiRODUCTS COMPANY, 01' CLEVE- ALLOY, nun man or mxme AND oasrme sum Application filed August 22, 1921. Serial No. 484,055.

To all whom it may concern: Y

Be it known that we, WILLIAM H. SMITH- Thls invention relates to apparatus for technical chemical operations such as are encountered in acid works, alkali works, oil refineries, dye works, steel works, general chemical manufacturing, electrolytic, works and numerousother places in the arts where valves, cocks, pipes, fittings, pumps, containers, evaporators, condensers, concentrators, mixing machines and other devices are employed. The ultimate object of the invention is the provision of an intrinsically inexpensive metal or alloy for these purposes which shall be sufficiently resistant to corrosion to exhibit a long life, which shall be sufiiciently strong mechanically to withstand the ordinary usage to which such devices are subjected, and which shall be easily machined, forged, or otherwise fabricated. No material having all these qualities has ever come into commercial use, although materials possessing some of these qualities have long been known. For example, platinum is nearly perfect excepting vfor its cost: glass and porcelain having the necessary chemical resistivity but are mechanically fragile and also difficult to Work. Numberless alloys exist having the necessary strength and workability but deficient in chemical resistivity.

It has long been suspected that some alloy containing essentially chromium and one or more iron group metals could be employed for this purpose, but no one has heretofore produced either a composition or a mode of handling it which resulted in a product of the highest utility from the chemical standpoint, the chief difficulty being that an admixture of any material amount of carbon renders such an alloy unworkably hard, physically brittle, and'j chemically non-resist- I operation to be conducted away from it.

ant. However, ods of producing such alloys have always resulted, at'least when performedon a commercial scale, in the abso tion of such an amount of carbon asto ren er the product of verysmall value for chemical apparatusregardless of whether an open hearth furnace, crucible furnace, or electric furnace be employed. A bath containing any material amount of molten chromium will dissolve solid carbon from fuel or crucible, carbon gas such as hydrocarbon or monoxide from combustion products, or volatilized carbon from an electric arc with equal avidity. Heretofore alloys containing more than about of chromium have been considered practically unmanageable.

The immediate objects of this invention are the provision of a furnace charge and a mode of mani ulation which shall result in a useful, low-car on, alloy, containing essentially the ingredients named, with or without other ingredients; the provision of a furnace charge containing the essential substances in their chea able forms; the provision of a furnace charge and mode of manipulation such as shall facilitate the fusion and enable the at the lowest possible temperature; the provision of a new and improved slag for alloys of this nature; while further objects and advantages of the invention will appear as the description proceeds.

In the drawings, Fig. 1, is a View showing the charge prior to melting, and Fig. 2 shows the same charge melted; Fig. 3 illustrates the mold, and Fig. 4 certain apparatus made of alloy.

It is necessary to employ an electric furnace and this of a type wherein all the electric terminals are located above the surface of the metal bath. The hearth of the furnace is preferably made of magnesite and all carbon or carbonaceous matter is kept We preferably mix it with st and most avail' between this previous niethhydrochloric acid instead of the usual mo-' I lasses, and mold the mixture into the desired form, afterwards sintering the hearth in any mode customary in electric furnace practlce, This operation serves to contaminate the ma esite with a certain 'amount of carbon which must now beremoved and this we effect as by introducing a small amount of low carbon iron scraptogether with lime and enough fluorspar to thin the slag. The furnace interior is thoroughly washed as man times as is necessary to cure chemical resistivity.

Ferrochrome (.40% O.) 35. lbs.

Cr 24.86 C 0.14

Iron (.14% C.) 25. lbs.

Nickel (free from carbon) 30. lbs.

Ferro-molybdenum (1.% C.) 10. lbs.

Fe 4.9 Mo 5. C 0.1

100. lbs.

In terms of totals this charge contains approximately: chromium 25, iron 40, nickel 30, molybdenum 5, carbon .28.

Inasmuch as the iron content of ferrochrome and ferro-molybdenum is quite variable it is impossible to predict a charge with accuracy in terms of these ingredients, although considerable latitude in ultimate composition is permissible. In general we preferably adjust the proportions of these ingredients in accordance with their comosition so as to secure a charge lying substantially within the range indicated by the following:

A B C D E F G H Chromium 2o 20 25 25 30 30 35 Nickel (or 00- balt) 35 40 30 40 25 30 30 40 Iron 40 35 40 30 40 35 30 22 Molybdenum. 5 5 5 5 5 5 5 8 Carbon below about .3 .3 .3 .3 3 .25 .25 .2

The hi her the chromium and the lower the nickel the less the carbon content must be in order to avoid brittleness and low chemical resistivity.

We do not restrict ourselves to the charge s ecified as we may omit the nickel entirely, replacing it with either cobalt or iron, and may vary the chromium content through a wide range. Indeed in the absence of nickel (or cobalt) an increased amount of chromium is necessary to se- We have used Silica and its compounds are excluded with success a charge containing approxi- A mately:

Chromium 50 Iron 44-% Molybdenum 5 resulting in an alloy of approximately: Chromium 45-47 Iron -48 Molybdenum 5 This alloy is extremely diflicult to make owlngto its great avidity for carbon, and to the necessity for keeping the carbon below .2% and preferably even lower. This requirement necessitates the use of a purer grade of ferrochrome which increases its expense disproportionately, and the melting point is inconveniently high. The use of nickel avoids all these drawbacks, yet the termary alloy just mentioned is very satisfactory in use and can be made successfully by the process herein described.

The iron is thrown or piled in the center of the hearth as shown at Ain Fig. 1, the

nickel (when used) around it, as shown at at with the electrodes and covered with a mixture of lime and uorspar D, some three or four inches dee This lime and fluorspar must be of goo quality, mixed thoroughly together in the proportion of about 80% to of lime and the balance fluorspar, the two being preferably ound together to a condition of insepara le interminglig;

t because of the danger of reduction by chromium and the certainty that the meltin point of the slag would be unduly decrease The molybdenum is not added until the last. Indeed it is possible' and highly satisfactory to add on y the iron at first and follow with the other ingredients but the the ferrochrome around that, ,as' shown mode described is quicker and more con venient.

The furnace is" then startedin the usual manner, and as soon as the iron has melted the heat thereof slowly causes the ferrochrome to dissolve therein and the slag to soften and flow thereover, so that the arc' the same will absorb carbon from the arc,

but the iron and nickel will not do so. When the entire charge has been melted and incorporated thorou hly together, a suitable deoxidizer is adde and the molybdenum or ferro-molybdenum or other added substance is incorporated, after which the alloy is This covering of the C, that last being kept out of contact llt)

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