US1424782A - Alloy - Google Patents

Description

UNHTEID STATES PATENT @FFEWEE.

WILLIAM E. SMITH, 0F CLEVELAND, OHIO, ASSIGNOR TO THE CLEVELAND BS8 MANUFACTURING COMPANY, OF CLEVELAND, OHID, A CORPORATION OF OHM.

Patented Aug. 8, 1922.

ALLOY.

1,424,782. Specification of Letters Patent.

No Drawing. Application filed III-arch 23, 1918.

T0 all'whom it may concern Be it known that I, WILLIAM H. SMITH, a citizen of the United States, residing at Cleveland in the county'of Cuyahoga and State of Ohio, have invented a certain new and useful Improvement in Alloys, of which the following is a full, clear, and exact description.

This invention relates to an alloy having many desirable inherent properties, perhaps the most important of which is its resistance to corrosion and surface flaking incident to repeated heating in the presence of gases either oxidizing or reducing in character. Another important property of the alloy is its freedom from warping, cracking and breaking. And a still further advantageous property is the fact that the alloy has an exceedingl mits it to e subjected to high temperature.

A very important use for an alloy having the characterlstics described is in the making of containers, sometimes known as saggars, which serve to hold articles which are to be in some manner subjected to a heat treatment.

Containers or boxes of this character have heretofore for the most part been made either from cast iron or steel. Such boxes in use are frequently subjected to temperatures varying from 1650 Fahrenheit to temperatures in excess of 2000 Fahrenheit, and in the course of this treatment are contacted by hot gases which may be of an oxidizing or reducing nature.

Experience has taught that boxes made of the material specified, are subject to rapid deterioration due to the action of the hot gases causing the formation of scale which is loosely adherent and drops off.

Another defect which develops from the use of cast iron or steel boxes is that they are exceedinly prone to warp, particularly on repeated use, andin an effort to overcome this deficiency, boxes having very thick walls have been tried, and while perchance some improvement with regard to warping has been made, the difficulty has not been overcome, and the boxes so made are exceedingly heavy, making them difiicult to handle and expensive to make. I

An alloy such as disclosed in thislcase,

when fabricated to form a heat treating box or container, is free from the objectionable flaking or warping characteristics of the cast high melting point which per- Serial No. 224,113.

iron or steel boxes and permits a container to be made having thin walls thereby reducing the weight of the container, and furthermore, the ingredients are such that the cost of manufacture of the alloy is very much lower than the chromium-nickel-iron alloy to which reference has been made.

The alloy of my invention comprises. a combination of iron, chromium, nickel, silicon and manganese as its principal elements, with carbon present in any quantity which. may result from the source of material used. The alloy may contain 15 to 40 per cent of chromium, 1 to 3 per cent of silicon, to 3 per cent of manganese, 1 to 10 per cent of m nickel, the balanceconsisting mainly of iron carbon. As before stated, the amount of carbon present in the final alloy is a matter of no consequence and will vary in accordance with the quantity of carbon present in the initial raw materials, but usually it varies from 1% to 3 per cent.

There may also appear in the final alloy,

traces of titanium for reasons which will later appear, and if the'source of ferrochrome employedin the making of the alloy is the product of the thermite process of producing ferro-chrome, aluminum will be found in the final alloy.

An alloy which I have found to give very good results is of the following composition:

18 per cent chromium.

2% per cent nickel.

' 2 per cent silicon.

1 per cent manganese.

Balance, iron and carbon.

The alloy is produced in the electric furg nace by melting commercial ferro-chrome in its unrefined state, that is to say, ferro chrome which is directly produced by the electric furnace process or the thermite process. Ferro-chrome in this condition contains quite a high percentage of carbon, but I have discovered that the presence of this carbon is not at all deleterious to' the subloo 'se uent usage of the alloy.

tals of carbon which might otherwise form,

thereby assisting in causing the formation of carbides of iron and chromium in the ultimate. alloy.

Silicon is added to the alloy just before the furnace charge is poured. The silicon makes are added to the charge at about the same time as the silicon is added, the purpose of the addition of titanium being to act as a.

scavenger to free the metal charge from occluded gases, particularly nitrogen. The quantity of titanium added is very small and is intended to be only in such quantities as will flux out and not appear in the final alloy.

However, traces of titanium may be found in the final alloy, but the presence of titanium is not disadvantageous.

The flux which is used is the usual and well known calcium flux, which as before stated, takes up the titanium as well as part of the silicon.

In making the alloy it is only necessary to bring the temperature of the furnace to a sufficient degree to insure a thorough meltihg and incorporation of the various elementsof the alloy. No refining of the alloy need be employed, for as before stated, the presence of carbon in any quantities is not disadvantageous.

The final alloy obtained is a metal which is very easily handled and can be poured and cast in exactly the same manner as molten cast iron, and by methods usual and ordinary in cast iron foundry practice.

The alloy has a high tensile strength, and on fracture shows a fine compact gra n. The alloy is tough and resistant to breakage.

The melting point of the alloy is high, being in the neighborhood of 2600 Fahrenheit.

A container cast from the alloy specified may be subject to oxidizing or reducing conditions in gas furnaces, and heated to such temperatures as are usually employed in such furnaces without in any substantial manner deteriorating. Apparently as soon as the boxes are heated, a protective covering of oxides of SlllCOIl, 1ron, chromium and possibly manganese is formed which protective covering is permanently adhesive to the surface of the box, and so protects against further deterioration. Furthermore,

the boxes or containers are non-warping even though the walls of the containers are. comparatively thin with respect to the thickness dients, iron, chromium and nickel, the iron '1 to 10 per cent of nickel, 1 to 2 of walls of similar containers which have heretofore been usd. Containers of the alloy herein described. may be heated repeatedly without cracking, and are 'not at all fragile. They withstand the rough usage towhich they are subjected in handling while in use, which is animportant element from the commercial standpoint.

In thissp'ecificationI have laid consider able stress upon 'ithe useof the alloy in the making of heat treating boxes or saggars. However, the alloy has other uses than this, and may be employed very usefully whereever a metallic surface or part is designed to withstand repeated heatings under oxidizing or reducing conditions, where the properties heretofore described are necessary or desirable, such as furnace parts, crucibles, glass moulds, metal foundry moulds, zinc retorts, etc.

Having described my invention, I claim 1. An alloy containing as principal ingrepresent being not less than 50% nor greater than 85%, the nickel present being not less than 1% nor greater than 10%, together with silicon from approximately 1 to 3%.

2. An alloy containing as principal ingredients, iron, chromium and nickel, the iron present being not less than 50% nor greater than 85%, the nickel present being not less than 1% nor greater than 10%, together with silicon substantially 1 to 3% and manganese substantially l to 3%.

3. An alloy containing as ingredients sub stantially 15 to 40 per cent of chromium, l to 10 per cent of nickel, 1 to 2 per cent of manganese, the balance being of iron, silicon and carbon.

4. An alloy containing as ingredients, substantially 15 to 40 per cent of chromium,

per cent of manganese, 1 to 3 per cent of SillCOIl, the balance being iron and carbon.

5.- An alloy containing as ingredients, substantially 18 per cent of chromium, 2%,- per cent of nickel, 2 per cent of silicon, 1% per cent of manganese, with the balance iron and carbon. I

In testimony whereof, I hereunto afiix my signature.

- WILLIAM H. SMITH.