US1520033A - Alloy - Google Patents

Description

Patented Dec. 23, 1924..

UNITE? STATES PATENT OFFICE.

ALLOY.

No Drawing.

To all whom it may concern:

Be it known that I, STUART EVAN MAC- Garcon, a subject of the King of England, residing at Windsor, in the county of Essex, Province of Ontario, Canada, have invented certain new and useful Improvements in Alloys, of which the following is a specification.

This invention relates to alloys and it comprises as a new and useful composition of matter, an alloy containing nickel, cobalt, chromium, tungsten and carbon.

The primary use of this alloy is for cutting tools for the machining of cast iron and soft steel at a high rate of speed. It has alsobeen found to beef great value. in turning alloy steels containing nickel, molybdenum, and other hardening'ingredients. It is especially valuable for use with cast iron and steel articles where the surface is very hard.

The alloy is non-magnetic, non-corrosive and is not readily attacked by any single acid. It will .not stain or tarnish under any conditions so far observed. It will take a razor edge and maintain it better than any other similar alloy now known.

The preferred composition of the alloy will consist of nickel about 14 per cent, cobalt about 27 per cent, tungsten about 28 per cent, chromium about'31 per cent, and carbon about 1.25 per cent. An excellent modification of this alloy has the following composition: Nickel about 16 per cent, cobalt about 20 per cent, tungsten about 32 per cent, chromium about 32 per cent, and carbon about .98 per cent.

It will be obvious that the percentages of amounts of ingredients set forth in these examples may be varied within reasonable ranges while maintaining the same general characteristics of the alloys obtained in employing such variations as obtained through the use of the percentages presented in these examples.

The function of the nickel appears to be to produce a quality of toughness highly de-. sirable in a cutting tool.

The cobalt has asimilar function to that of the nickel in producing the quality of toughness and it also seems to impart the quality of resistance to heat so that the tool will maintain its cutting quality even when at a red heat.

Applicationfiled December 28, 1921. Serial N0. 525,521;

The nickel and cobalt may vary jointly any increase in the amount of cobalt, being accompanied by a corresponding decrease in the amount of nickel. The total ercentage of the nickel and cobalt jointly wi 1 not vary greatly from 0 per cent of the total amount.

The chromium has the function of imparting great hardness to the alloy and it is also an important factor in resistance to cor- IOSlOIl.

The tungsten has the function of increasing the resistance to heat and probably also increasing the hardness of the alloy.

The carbon should not vary greatly from 1 per cent, except for certain special uses referred to later.

It is thought that the nickel, chromium and carbon unite to form a double carbide of nickel and chromium which gives to the alloy its extreme hardness as well as its fine grain and resistance to shock. The alloy is thus probably composed of a solid solution in cobalt and tungsten of a carbide of nickel and chromium.

The alloy is made by melting the ingredients in a crucible in an electric or oil furnace at a temperature of approximately 3600 F. The carbon is included by the addition of boron carbide. The nickel and cobalt are placed in the bottom of the crucible and the chromium placed in a layer over them. The tungsten mixed thoroughly with the requisite amount of boron carbide is then placed upon the chromium and covered with a layer of broken glass.

Upon heating, the glass quickly melts and forms a protecting layer of slag which prevents any loss of carbon and which also protects the hot metal from the oxidizing effect of the air. Any oxides which may be in the mix are removed by the boron. In practice very little, if any, of the boron remains in the finished alloy:

Certain types of arc furnaces may also be used for melting, but those types which are directly to the path must beavoided. This alloy is very sensitive. to carbon and therefore anything that tends to make the carbon content hard to control must be avoided.

The alloy should be poured at a heat of about 8600 F. or 200 F. above the melting point. It is very important that the heat of pouring be controlled closely. The alloy should be poured as soon as possible after melting because upon standing the tungsten tends to separate and to form a semi-fluid mass at the bottom of the crucible.

The alloy should be poured into graphite molds. A small percentage of carbon is taken up by the metal from the graphite so that a casting is obtained with an extremely hard outer or cutting edge and yet with a center sufficiently tough to withstand severe shocks.

For certain purposes, such as valves for acid-proof pumps, where an extremely hard outer edge is not of paramount importance, the melt may be poured into sand molds. In such cases, however, the amount of carbon in the alloy may be increased as much as 75 per cent. With close supervision, an alloy is obtained which is uniform in composition and properties, and which is entirely free from blowholes which in other cutting alloys cause so much trouble.

It will be of course understood that the ingredients as obtained upon the market will contain small percentages of other metals or non-metals, but the addition of these to the alloy in small percentages will not the total greatly afi'ect the qualities of the alloy and for certain uses these additional ingredients may even be beneficial.

I claim i 1. An alloy containing nickel and halt, not varying, jointly, widely from 40 per cent of the total, each being present in substantial amount; chromium and tungsten, each not varying widely from 30 per cent of and carbon, in appreciable amount.

2. An alloy containing'nickel about 14 per cent, cobalt about 27 per cent, chromium about 31 per cent, tungsten about 28 per cent, and carbon about 1.25' er cent.

3. An alloy in which. nickel and cobalt constitute about 40 per cent, chromium and tungsten each about 30 per cent, and carbon about 1 per cent.

In testimony whereof I afiix my signature in presence of two witnesses.

STUART EVAN MACGREGOR. Witnesses:

ARTHUR MINNICK, CHARLES W. STAUFFIGER.