US2069717A - Mixture for the production of malleable iron - Google Patents

Description

Patented Feb. 2, 1937 PATIENT OFFICE MIXTURE FOR THE PRODUCTION OF MALLEABLE IRON Rex A. Edmunds, Detroit. Mich., assignor to National Malleable & Steel Castings Company, Cleveland, Ohio, a corporationof Ohio No Drawing. Application March 2, 1935, Serial No. 9,014. In Canada February 4, 1935 14 Claims. (Cl. 75-123) This invention relates to improvements in mixture and method for the production of malleable iron, and it consists of the matters hereinafter described and more particularly pointed out in the appended claims.

It is an object of my present invention to provide a mixture for usein the production of malleable iron, which will produce a malleable metal having high tensile strength and yield point and which will machine easily and be of a uniform quality throughout. 7

In general, the invention is directed primarily to a particular relationship of carbon and silicon, the other ingredients being present to give particular characteristics for particular purposes or merely as impurities. In this respect, the particular range of manganese recited is not essential to the invention in its broadest sense, but said range is the preferable one and could be varied or altered without departing from the spirit of the invention.

The object of my invention is attained by proportioning the various ingredients charged into the furnace, or by varying the melting practice 5 employed in fusing, or both, to obtain a ferrous metal with ingredients as follows:

I Per cent Carbon 1 -1.8 Silicon .9 -2

Manganese '.05-1.4

Phosphorus .01- .20

Sulphur 011- .35

Per cent Carbon 1.35 Silicon 1.60

Manganese .30 Phosphorus .04 Sulphur .03

The mixture will pro-vide, when annealed, a black, easily machined structure, a yield point at approximately 55,000 lbs. per square inch, an

. bylowering the carbon and silicon proportions and raising the manganese. This is:

Per cent 5 Carbon 1.15 Silicon 1.25 Manganese up .85 Phosphorus .08 Sulphur .05 20 This mixture anneals to a gray pearlitic structure not as dark as ordinary malleable iron, and though the Brinell reading is approximately at 300 kilograms, the metal machines more easily than this reading would indicate due to the ex- 25 ceptionally even distribution of the nodular .carbon, said distribution provided by the combined action of the constituents of the balance.

It is found that in malleable metal made in accordance with my invention, the carbides resulting from the use of carbon in the foregoing relative proportions are evenly distributed throughout the entire mass of metal. A most important characteristic of a metal made in accordance with my invention is that it may be poured in the ordinary green sand mould, the same as ordinary malleable iron without causing an undesirable precipitation of the carbides contained in the metal. Such precipitation as is obtained is in the form of a nodular or spheroidal carbon, or both, (when the carbon content is below 1.7%)

I have found that a variation of the carbon and silicon content to the extent of disturbing the foregoing relative balance between the two ingredients, results in undesirable changes in the physical properties of the resulting malleable metal.

Bythe use of the proportions embodying my 50 invention, I have found that the resulting malleable metal is relatively free from shrinks and blow holes, and with proper handling makes a smooth, well-run casting. Likewise, the resulting malleable metal in a hard or unannealed frac- 55 and closing of the proportions as a primary graphite retarder, grain refiner, and '70 We shows a fine, dense, nondendrltic'structure.

' In theuse of the foregoing proportions of ingre- 110,000 lbs. per square inch, and has an elongation uponspecial annealing of as high as 22% and an average elongation with ordinary annealing of from 5% to 14%.

' Its yield point is approximately 14,000 to 24,000 lbs. below its ultimate tensile strength as above given. It is to be understood that these figures will vary if a special treatment is given the metal to secure added elongation.

It machines like ordinary malleable iron except where given special heattreatment to increase its tensile properties, in which case it machines slightly harder than gray iron. In addition, this metal can be worked hot either in its hard or annealed state. Likewise, it can be hammered, forged, rolled or punched while hot,

in temperatures lower than those required in the working of steel by these methods. It has been found that hot working of the metal serves to increase its physical strength due to a refining grain by such working, and the ability to be hot worked is one of the significant and valuable features of this metal.

In hardness it shows a Brinellreading of from to 300 depending again on the heat treatment used on the ironf Its annealed appearance is substantially the same as ordinary malleable iron except where oxidation throws the proportion out or balance, in which case the resulting iron has'a mottled appearance which, however, may be remedied by additional heat treatment. When hard fractured the malleable metal using my invention shows few similarities either to ordinary malleable iron or to steel, and is characterized by being very close grained and non-dendritic in its formation. malleable metal using my invention anneals at lower temperatures and more quickly than ordinary malleable iron and thus effectsa considerable saving in the annealing process.

From the foregoing it will be apparent that malleable metal produced using my invention is a different metal from the ordinary malleable iron produced by ordinary methods. The mixture most generally used in the production of ordinary malleable iron is as follows:

, Percent Carbon i. 2.20-2.60 Silicon .75-l.05 Manganese ..22- .3! Phosphorus .09.- .20

In using a mixture made up in the foregoing proportions for ordinary malleable iron, the manganese acts as a sulphur neutraliz'er and dizer, and the silicon provides a carbon precipitator and a deoxidizer and provides additional fluidity to the mass.

In the mixture made in accordance with my invention. the fusing of the elements in these shows-that the manganese acts also carbondistributor, while the silicon adds to its reactions by checking the dendrites, raising the yield, and acting with the manganese to form a fine carbon flake or grain, which is evenly distributed and easily annealed.

The use of the ordinary mixtures in the pros,oea',v1r

duction of dead limits of both known.

" 37,000 lbs. per

mercial ferrous metals. Also, under -cial melting practice deoximalleable iron having an ultimate tensile strength of from 45,000 to 55,000 lbs..per square inch. as compared to the greatly incre ultimate tensile strengthwhich malleable metal 11 1 my invention shows. yield point of iron made in the ordinary method is from 80,000 to square inch. as compared to the yield point ,of from 50.000'to 108,000 lbs. per square inchusingmyihvention.

It is to'be understood that the phosphorus conv tent is to be" held to as low a percentage as is possible in maintaining fluidity in order to avoid the objectionable features of this element when alloyed to excess in iron. It is also to be under-v stood that although sulphur has not been mentioned in the specification'heretofore, it is assumed that this element is presented inali' comconcan' be so balanced as to ditions, this element increase the ductility and mschineabili'ty'. In

suchcaseaitissometimesexpedientto sddthis element in an advantageous form to the metal. Ltherefore, wish to avail myself of the scope as listed in the disclosure.

I have found that under range is from .4%-1.4%, since its addition in these percentages'expedltes and increases the tensile properties. However, under favorable conditions the use of thiselement inpercentages lower than .4% is sometimes of value since manganese Y has a tendency to retardthe annealing or heat treating process, and also tends in appreciable was. iron and melting conditions, a preferable consistent commeramount to decrease the machineability of the metal, particularly when out of balance with the silicon and carbon proportions.

Itisalsotobeunderstood-thatduetothe nature of my invention large quantities of scrap. metal can be included in the furnace charge and in this scrap,

various elements other than those above enumerated maybe found which will be considered as impurities to the iron.

' While I have given a range of percentages, and the percentages of ingredients which I have found to be the most satisfactory for general use, I do not desire .to limit the scope of my invention, but I desire to avail myself of all changes within the scope of the appended claims.

This application is a continuation inp art of 0 my earlier applications-Serial No. 000,670,111-

December 8,. 1900, and 678,190, filed June 29, 1933. 7

I claim as my invention:

:1.- A malleablised cast ferrous alloy comprising 1% to 1.8% carbon. 1.0%.to less than 2% silicon. eirective amounts up to not over 1.4% manganese and the balance substantially all iron.

2. A-malleabliaed castferrous alloy comprising'1%-l.'l% carbon, silicon less'than 2% and more than 1%, effective amounts up to not over 1.4% manganese and the balance substantially alliron.

3. As a new article of'manufacture, a high strength, hot workable, easily m'achineable, malleablized iron containing as-essential elements,

carbon about 1.35%. silicon about-1.00%, efiective amounts uptto not over 1.4% manganese.

phosphorus about 94%. sulphur about 93%, and the balance substantially iron. 0 4. An alloy for the production of malleable not less than 1% ormore than 1.8%, silicon not less than 9% or more than 2%,1-1 smeme iron comprising a given quantity of iron, carbon i combined amount of carbon and silicon in substantially equal proportions not less than 1.9% by weight of the mixture; effective amounts up to not over 1.4% manganese, by weight of the mixture; phosphorus not less than .01% or more than .27% by weight of the mixture; and suf-' ficient commercial iron and its characteristic impurities and contaminations to constitute the balance of 5. An alloy containing as essential elements, carbon 1% to 1.80%, silicon .90% to 1.95%, manganese .4% to 1.4%, phosphorus .01% to .l5%, sulphur .01% to .35%, the carbon and silicon being in approximately equal proportions and the remainder substantially iron.

6. A malleablized alloy containing as essential elements: carbon 1% to 1.80%, silicon .90% to 1.95%, manganese .4% to 1.4%, phosphorus .0l% to .14%, sulphur .01% to 35%, the carbon and silicon being in approximately equal proportions and the remainder substantially iron.

7. A ferrous alloy comprising 1.2% to 1.6% carbon, .46% to .5% manganese, 1.5% to 2% silicon, and the balance substantially all iron.

8. A malleablized ferrous alloy casting comprising 1.2% to 1.6% carbon, -,46% to .5% manganese, 1.5% to 2% silicon, and the balance substantially all iron.

9. As a new article of manufacture, a high strength, hot workable, easily machineable, malleablized iron containing as essential elements: carbon about 1.5%, silicon about 1.38%, manganese about phosphorus about .17%, and the balance substantially iron.

10. An alloy for the production of malleable iron comprising a given quantity of iron, carbon not less than 1% or more than 1.8%, silicon not less than .9% or more than 2%, the aggregate combined amount of carbon and silicon in substantially equal proportions not less than 1.9%

nor more than 3.8% by weight of the mixture:

manganese not less than .4% and not more than 1.4% by weight of the mixture; phosphorus not less than .15% or more than 27% by weight of the mixture; and sufficient commercial iron and its characteristic impurities and contaminations to constitute the balance of 100%.

11. A ferrous alloy graphitizable to increase its malleability and capable upon cooling to normal temperatures in an ordinary green sand mold of forming an alloy substantially free from primary cementite and which, upon annealing, will give an alloy having a Brinell hardness of about to 300, said alloy comprising 1 to 1.7% carbon, .9 to 2% silicon, efiective amounts up to not over 1.4% manganese, and the remainder mainly iron.

12. A ferrous alloy as defined in claim 11 including .4 to 1.4% manganese.

13. A malleablized cast ferrous alloy as defined in claim 1 including .4 to 1.4% manganese.

14. A malleablized cast ferrous alloyas defined in claim 1 which is hot workable and contains