US714139A - High-tungsten steel. - Google Patents

Description

UNITED STATES PATEN OFFICE.

GEORGE B. BROWN, OF READING, PENNSYLVANIA, ASSIGNOR TO CARPEN- TER STEEL COMPANY, A CORPORATION OF NEW JERSEY.

HlGH-TUNGSTEN STEEL.

SPECIFICATION forming part of Letters Patent N 0. 714,139, dated November 25, 1902. Application filed July 1,1902. Serial No. 113,994. (No specimens.)

To all whom it may concern:

Be it known that I, GEORGE B. BROWN, a citizen of the United States of America, and a resident of Reading,'in the county of Berks and State of Pennsylvania, have invented certain new and useful Improvements in High- Tungsten Steel, of which the following is a specification.

My invention relates to the manufacture of IO high-grade steel; and it consists, essentially,

in the admixture of a large proportion of tungsten, as hereinafter specified, with iron or steel, whereby I produce a new description of steel possessing valuable qualities not here- I5 tofore attained and remarkably well adapted to certain nsessuch, for instance, as the manufacture of projectiles.

The invention further consists in the admixture with this tungsten steel of a suitable 2o proportion ofchromium, whereby its qualities are changed as desired to meet somewhat different requirements, while retaining the essential characteristics imparted by the tungstem.

The invention is fully described below and is specifically pointed out in the subjoined claims.

The limited use of tungsten in the manufacture of steel has been heretofore practiced in the production of what is known as self hardeningorair-hardeningsteelsintended particularly for making metal cutting tools, the purpose of such steels being l0 se cure increased working capacity by avoiding the injurious effects upon the tool which ordinarily result from We hi h temperatures produced by continued hard service. Heretofore, however, the percentage of tungsten employed in the manufacture ot'steel has been 0 confined within comparatively narrow limits and generallyin connection with another element or elements considered essential to securingdesirable results. Theexperimentson which the practice heretofore has been based 5 have been found to demonstrate that as low as one per cent. of tungsten produced marked effects and that no materially-improved results were to be obtained by increasing the proportion of tungsten used to above six per cent. though I am aware that as high as eleven per cent. of tungsten has been used, though without admittedly-improved results. This practically negative effect of percentages of tungsten running above about six per cent., especially in view of the greater cost of the product resulting therefrom due to the comparatively high price of tungsten, has naturally deterred experimenting with much larger percentages; but I have been led to go into such experiments particularly by the desire to produce a steel product especially adapted to the production of projectiles of greater penetrative capacity than those heretofore produced, and by appreciation of the fact that the great atomic weight and specific gravity of tungsten, aside from its known efiect when used in small proportions upon the hardness and fusibility of the steel product in which it is used, might be of great value if it could be successfully incorporated in large propor- 7o tions, because of the resulting increase in the weight of a given size of projectile and the corresponding increase in force of ballistic impact and penetrative efficiency obtainable at given velocities. I have discovered as the result of such experiments, extending from the use of twelve and one-half to thirty-five percent. of tungsten, that not only has the desired result been secured by incorporating such large percentages of tungsten, so far as producing a steel body of greatly-increased spi-t'lfiu graviiy is concerned, but that the character of the steel is otherwise very markedly and beneficially changed by such increase of the tungsten element beyond the 8 proportions heretofore found effective of good results. As an example of the results secured, I have found thata projectile of standard size formed of my improved high-tungsten steel containing twenty-four per cent of tung- 9o sten Was increased in weight about fifteen per cent. over a similar projectile formed of the best quality of steel heretofore used for the purpose, so far as I am aware. It will be readily'understood that this increased weight 5 of a given size of projectile carries with it a corresponding increase in its penetrative capacity, assuming that the penetrative characteristics of the metal itself are not deteriorated thereby. Instead of' there being any such deterioration, however, I have discovered that the quality of the metal is greatly improved and that its distinguishing characteristics are remarkably in accord with the requirements. These are, mainly, first, its high specific gravity, as stated, and its extreme density, both natural resultants of the incorporation of a large proportion of the tungsten element, which has an atomic weight over three times as great as iron (one hundred and eighty-four to fifty-six) and a specific gravity nearly two and a half times as great, (19.26 to eight;) second, its very high fusing or melting pdint, which insures themaintenance of its form under the high temperatures developed in the case under consideration by the ballistic impact and penetration; third, its high cohesion or tenacity, notwithstanding the great hardening eifect resulting from the use of small percentages of the tungsten and which would seem to presage excessive brittleness as the result of using it in the present large proportions.

While I have described my improved steel product, particularly in connection with its adaptability to the manufacture of projectiles, it will be understood that its use is not restricted to any special field, but that it has a wide range of usefulness in the arts. equally well adapted for metal-cutting toolsfor instance, for forging and forming dies, &c.

It is It is unnecessary to describe particularly the manner of carrying my invention into effect, inasmuch as there need be no departure from the general procedure in well-known steel-making processes. The ordinary ferrotungsten of commerce may be employed; but I prefer that it should be especially rich in tungsten and free from carbon or other foreign elements, or metallic tungsten may be used. In each case it may either be melted separately and then poured into the molten iron or steel, or they may be melted together, the chromium or other element being similarly admixed, if desired, in the resulting product. The proportionate amount of tungsten used may vary, so that the product shall contain anywhere between fifteen and thirty per cent. and in all cases present, essentially, the same characteristics; but I consider that about twenty-five per cent. is generally preferable. If chromium be added, the percentage employed is practically between one and three per cent., the usual proportion employed being about two per cent., which produces substantially the beneficial effect desired in introducing it.

What I claim is- 1. As a new article of manufacture, hightungsten steel, containing from fifteen to thirty per cent. of tungsten substantially as described.

2. As a new article of manufacture, a hightungsten steel containing from one to three per cent. of chromium and from fifteen to thirty per cent. of tungsten substantially as described;

Signed at Reading, Pennsylvania, this 30th day of June, 1902.

GEORGE E. BROWN.