US1671484A - Method of treating alloys - Google Patents

Description

- {Patented May 29, 1928. i

UNITED. STATES PATENT OFFICE.

NORMAN B. IPILLING, OF WILKINSBURG, TENNSYILVANIA, ASSIGNOR TO WESTING- HOUSE ELECTRIC & MANUFACTURING VANIA.

No Drawing.

My invention relates .to ferrous alloys, such as silicon and similar steels, more especially to a "method of treating such alloys to make them readily workable mechanically.

It is among the objects of this invention to provide a metliod of treating ferrousalloys which shall render them readily workable by mechanical operations, such as bend ing, stamping, drawing, shearing or the like.

It is a further object of-this invention to provide a'method of treating ferrous 'alloys which shall be simple, inexpensive and practical for use in the commercial adaptation of such ferrous alloys. I

It is generally known that silicon imparts to iron or steel hardness and brittleness that render silicon-iron-or steel alloys of more than about 4% silicon difficult to work and of little value except in castings. However,

- silicon-iron or steel alloys have low hysteres'is and eddy-current losses and, therefore, are specially advantageous for utiliza tion in the manufacture of transformer cores and armature and stator structures in electrical machines, in which the steel is utilized in thin-sheet form. a

I have found: that certain grades of silicon steel, such as are used in electro-magnet're devices, exhibit excessive brittleness when an attempt is made to work them. This is made manifest by the inability of the metal sheets to withstand such operations as cut- 'ting,shearing, stamping, drawing or similar operations in which a certain amount of,

. formation at arslightly elevated temperature.

Thus, in a particular case in which the silicon steel had a composition S'i4.69% Mn-0.32%, a 14 mil thick sheet was so brittle that a strip bent with the fin ers through an ang1e'o f 90 cracked in two w on METHOD OF TREATING ALLOYS.

COMPANY, A CORPORATION OF PENNSYL- Application filed September 2, 1922. Serial No. 585,856..

heated to 100 C. the same sheet could not only be bent, but the bend flattened with a hammer blow without fracture.

It appears that the brittleness which has been noted in silicon steel is a modification .of the brittleness which even iron of the highest purity (electrolytic, vacuum fused) develops at sufliciently low temperatures, ap-

proximately 110 C. The action of alloyed silicon is'to raise the temperature at 4 which brittleness is appreciable, slowly for the first 2% silicon, thereafterat a more rapid rate, until it reaches atmospheric temperatures at about 4% Si. For higher percentages of silicon, an elevation of the temperature at which deformation is attem ted, proportioned to the silicon content, ylelds temporary ductility.

From the discovery that. the brittleness is not a peculiar property of iron-silicon alloys, but that it is a'modification of the low-temperature brittleness of iron, I have concluded that ductility may be produced in other. ferrous alloys in which the alloying elements are in solid solution by increasing the temperature at which mechanical deformations are conducted. I have found that an iron-aluminum alloy, containing about 7% aluminum, which was so brittle when cold as to be unworkable cguld be hammered and otherwise deformed at a temperature of 150 C. without difficulty.

Generally, the temperature of treatment of ferrous alloys to give temporary ductility ranges from about 30 to about 200 C.

It will be evident from the above descrip};

tion ofmy invention that, by treatingsilicon and other steels 'in accordance therewith, a larger amount of silicon may be used in commercial electrical steels, since'it is. possible to readily work the same'in the above-described manner. Another advantage of my method of treating ferrous alloys, such as silicon steel, is that the treated metals are not as destructive on 'dies' and other machine tools, resulting in a considerable increase of life which reduces the expense of manufacture.

. Although I have described a specific em bodiment of this invention, itwill be obvious to those skilled in the art that various modifications may be made in the details of.

the process herein set forthwithout departing from the principles thereof. For inheat and then subjecting'them to mechanistance, the working temperatures at which cal alterations while within this temperathe physical properties of alloys are altered ture range, the temperature of working beto obtain greater temporary ductility may ing proportionallto the amount of alloying 5 vary from a temperature somewhat above metal insaid' alloys.

atmospheric to a temperature below a vis- 3. The method of working iron-silicon alible heat. The amount of silicon or other loys containing from 4 to 8% silicon which substance permissible in such alloys maybe comprises heating said alloys to temperavaried to obtain an alloy having desired tures above 30 C. and below a visible heat 10 characteristics. The alloys may contain and subjecting them to mechanical alteraother ingredients, such as manganese, phostions while within this temperature range.

phorus and carbon, which are present as im-' 4. The method of working iron-silicon alpurities or are added to modify the characloys containing from I to 8% silicon which teristics of the alloy. comprises heating "said alloys to tempera- I claim as my invention: tures above 30 and below 200 C. and tlien 1. The method of working iron-silicon alsubjecting them to mechanical alterations ,loys containing about 4 to 8% silicon which while within this temperature range, the

comprises heating said alloys to a temperatemperature of working being proportional ture above 30 and below 200 C. and subto the amount of alloying metal in said jecting them to mechanical alterations While alloys. v

within this temperature range. In testimony whereof, I have hereunto 2. The method of working iron-silicon subscribed nay name this 17th day of Aualloys containing from 4 to 8% silicon gust,1922.

which comprises heating said alloy s to tem- I peratures above C; and below'a visible NORMAN B. FILLING.