US919544A - Tool-steel. - Google Patents

Description

JESSE ii. DARKE, or LYNN,

MASSACHUSETTS, ASSIGNOR TO GENERAL ELECTRIC COMPANY,

A CORPORATION OF NEW YORK.

TOOL-STEEL.

To all whom it'may concern:

3e it, known that 1, Jesse M. DARKE, a citizen of the United States, residing at Lynn,

county of Essex, State of Massachusetts,

ence of manganese in relatively high percenta e, by the low carbon content, and by the re ativelyflow chromium content. For certain purpq'ses vanadium may be present in small percentage.

The process whereby this improved product is roduced differs from prior practice and is ereinafter set forth in 'suflicient detail to enable persons skilled in the art to compound the steel.

Asa basis for the steel, I prefer to use Swedish muck-bar, ferro-tungsten and ferrochromium. The ferro-tungsten may be of the variety now being produced by the electric furnace process and may contain about 67% tungsten and little or no carbon. The ferro-chromium may also be of the electric furnace variety, lowin carbon and containing say 68% chromium. I prefer to use sufficient ferro-tungsten to give the finished steel about 13.5 per cent. tungsten, though the percentage oftungsten may bevaried somewhat above or below this value as in the chrome-tungsten steels now commonly designated as high-speed steels. "lhe ferrochromium is used in relatively small quantity, and the percentage ofchromium in the steel is kept lower than one-half of one per cent. As previously stated, the carbon content is loW, preferably less than one-half of one per cent. in the finished steel.

The components above mentioned may be melted in a crucible in the usual way. Or dinarily these materials, during fusion, yield a slag which floats on the top and protects the. steel. If for any reason the (011i ponents are too dry to produce slag. I add a certain amount of slag to the crucible according to common practice. When the steel is Specification of Letters Patent.

Application filed April 27, 1907.

Patented April 27, 1909.

Serial No. 370,575.

nearly ready for pouring, I introduce sufficient manganese to yield a finished steel having approximately 3% manganese. Some variation in the manganese content is permissible, but the quantity should not be greater than 3.25% nor less than 2%. 1 prefer to introduce this manganese as ure metal, or at least in a form substantial y or entirely free from carbon. The manganese now commercially produced by the Goldschmidt Thermit process is substantially free from carbon and is quite suitable for use accordin to my invention.

Ast he protective layer of slag in the crucible has a great chemical affinity for manganese, special means must be resorted to for introducing the manganese into the steel. 1 find that this step can be successfully effected by introducing a tube of iron, steel'or other suitable material through the top' of the furnace and into the crucible until the end of the tube is well below the layer of slag, and then introducing the manganese through the tube. The manganese may be in lumps the size of a walnut and will pass through the tube into the steel with very little loss by slagging. After the manganese is introduced, the crucible may remain in the fire for about five minutes and may then be poured in the usual way.

The steel resulting from, the above described process may be hardened like other air hardening steels and is suitable for cutting tools. Like the alloy steels relatively high in chromium, it may be used for heavy cuts at high speed. The tools retain their cutting edge at high temperatures much better than carbon steels, and are in other ways well suited for heavy duty.

For certain purposes I may introduce a certain quantity of vanadium into the steel, say in the proportion of about one-fourth of one er cent. This vanadium increases the re hardness and enables the tool to stand u better when taking a heavy cut or chip; w at is more important, it prevents the chi p from sticking to the point of the tool. Jhe vanadium may be introduced'in any suitable form, as by including ferrovanadium with the Swedish mucker and other components of the original charge,

The novel features of the process of manufacture are not herein claimed as these form the subject-matter'of a divisional application Serial No. 424,054, filed March 30, 1908.

What I claim as'new and desire to secure inately 13.5% tungsten and approximately 15 3% manganese.

5. At0ol steel containing approximately 13.5% tungsten, less than one-half of 1% chromium, approximately 3% manganese, and approximately one-fourth of 1% vana- 20 dium. In witness whereof, I have hereunto setmy hand this 25th day of April, 1907.

JESSE DARKE.

Witnesses:

BENJAMIN B. HULL, HELEN ORFORD.