US333748A - Eobeet hadfield - Google Patents

Description

' UNITED- STATES PATENT OFFICE.

ROBERT HADFIELD, OF SHEFFIELD, COUNTY OF YORK, ENGLAND.

SELF-HARDENING MANGANESE STEEL,

SPECIFICATION forming part of Letters Patent No. 333,748, dated January 5, 1886. Application filed May 7, 1885. Serial No. 164,678. (No specimers.) Patented in England December 6, 1884, No.16,049.

To all whom it may concern:

Be it known that I, ROBERT HADFIELD, a subject of the Queen of Great Britain, residing at Sheffield, in the county of York, England, have invented a certain new and useful Improvement in Self-Hardening Manganese Steel, (for which I have applied for Letters Patentin England, and which application has been accepted, and is numbered 16,049, and dated December 6, 1884;) and I do hereby declare that the following is a full, clear, and exact description of the invention, which will enable others skilled in the art to which it appertains to make and use the same.

To obtain a self-hardening steel, it has heretofore been considered absolutely necessary to use expensive foreign and other high class irons in conjunction with tungsten or its alloys. The great cost of the materials, its extreme stiffness, its liability to be spoiled in working, and its inability to be milled or machined have greatly limited its use and made it inapplicable for many purposes.

My improvement consists of a self-hardening steel containing from two and one-half to seven per cent. of manganese. By the use of this percentage of manganese I am enabled to dispense with the tungsten and the high-class expensive irons mentioned, and to use in place of the latter more inexpensive and common pig-iron, sufficiently refined or decarbonized, or iron or steel scrap, either separately or to gether, or steel produced by any steel-making process. The manufacture of prior self-hardening steel had to be conducted by the expensive crucible process, and it is one of the advantages of my improved steel that it can be made by any of the known steel processes. The manganese is added to the charge under treatment in the form of any of the alloys of ferro-manganese used in the manufacture and production of steel, such as ferro-manganese, silicon, or spiegel. I use such alloys either separately or together in such proportions as to obtain in the resultant product a percentage of manganese varying from two and onehalf (2%) per cent. up to about seven (7) per cent.,while, preferably, I keep the carbonlow. The exact proportions or quantities to be employed of such alloys are governed and regulated, first, by the percentage of manganese contained therein; secondly, by the character of the materials under treatment; and, thirdly, by the quality of the steel required to be produced, such quality being determined by the purpose or purposes to which it is to be applied; but I have found that where the maximum degree of hardness is essential in the resultant product such alloys may be beneficially used in proportions sufficient to obtain in such product a percentage of manganese varying from two and one-half per cent. up to about five per cent, while, where a lesser degree of hardness is required, I have found that it is beneficial to use such alloys in proportions sufficient to produce in the resultant product a percentage of manganese varying from about five per cent. up to about seven per cent.

The alloy or alloys employed are either melted with the materials under treatment or are added thereto when both are in a state of fusion, and the resultant product may either be run into molds and shapes as with ordinary steel and iron castings, or it may be run into ingots or other shapes and may be subsequently hammered, forged, rolled, or other wise reduced into bars, plates, or other forms, as desired.

By my invention I obtain a self-hardening steel, which, although extremely hard when cold, yet works quite mild, and which, when being reduced, allows of a much higher degree of heat being used than heretofore without deteriorating from its quality, thus facilitating working and effecting a considerable economy. It is also very free from impuritiessuch as dirt and slag-owing to the increased purifying properties of the manganese when used in the percentages hereinbefore indicated, and likewise from other defectssuch as honey-combs--while the presence of silicon does not interfere with its self-hardeni ng properties.

As an example of manufacture, I add to two thousand pounds of decarbonized and desiliconized iron eighty pounds of ferro-manganese containing eighty per cent. manganese.

Such improved self-hardening steel may be manufactured by any of the steel-manufacturing processes.

I preferably use an eighty-per-cent. ferro-manganese and produce a self-hardening steelviz., a hard steel which may be used for cutting-tools without. requiring the usual hardening and tempering operations of heating and quenching in water-containing at least two and one-half per cent. and less than seven per cent. of manganese, and preferably as little carbon as .40. In this it is totally different from the present practice, as all the se1f-hardening steels now in use contain a very large amount of carbon, averaging from one to one and a half per cent. I practically dispense with carbon, my steel containing, preferably, only about four-tenths per cent.

My improved steel possesses the important characteristic of being easily worked into sh ape when heated, whereas prior self-hardening steels were not only difficult to forge into form on account of stiffness, but also easily spoiled and rendered worthless, thus requiring more than ordinary care at the hands of the operator. Moreover, such prior steel cannot be shaped by machining, tooling, or filing, on ac- ROBERT HADFIELD. Vitnesses:

F. BOWDEN, S. Bowman.

count of its hardness, while by heating my improved steel to a dull red and then plunging it into cold water it is brought to a condition in which it can be finished to the required shape by machining, tooling, or filing. Its hardness may then be restored by heating it to a bright red and allowing it tocool in the air.

The plunging of this steel into water does not produce water-cracking, as would be the case with other self-hardening steels, or by my process of making manganese steel described in Patents Nos. 303,150 and 303,151.

- -What I claim, and desire to secure by Letters Patent of the United States, is

As a new article of manufacture, self-hardening steel containing from two and one-half up to but not including seven per cent. of manganese.