US1016560A

US1016560A - Armor-plate and other steel article.

Info

Publication number: US1016560A
Application number: US396864A
Authority: US
Inventors: Federico Giolitti
Original assignee: Anonima Italiano Gio Ansaldo Armstrong & Co Soc
Current assignee: Anonima Italiano Gio Ansaldo Armstrong & Co Soc
Priority date: 1906-09-06
Filing date: 1907-10-10
Publication date: 1912-02-06
Anticipated expiration: 1929-02-06

Description

F. GIOLITTI. ARMOR PLATE AND OTHER STEEL ART IOLE.

APPLIOATION FILED 0C1.10 1907.

Patented Feb. 6, 1912.

minesses:

%& W

UNITED STATES PATENT onrion.

FEDERIG O GIOLTTTI, OEROME, ITALY, ASSIGNOB, TO SOCIETA ANONIMA ITALIANO GIO ANSALDO ARMSTRONG 80 (30., OF GENOA, ITALY, A COMPAN T INCORPORATED IN ITALY.

ARMOR-PLATE AND OTHER STEEL ARTICLE.

Specification of Letters Patent.

Patented Feb. 6, 1912.

Originaliapplication filed September 6, 1906, Serial No. 333,408. Divided and this application filed October To all whom it may concern Be it known that I, FEDERICO GIoLrrrI, a subject of the King of Italy, residing in Rome, Italy, have invented certain new and useful. Improvements in Armor-Plates and other Steel Articles, of which the following is a specification.

This application is a division out of an application filed in the United States Patent Ofiice Sept. 6, 1906, Serial No. 333,408.

This invention relates to armor plates or other objects made of steel, composed of either superficial or deep successive zones in steels of different composition, not only as regards the proportion of carbon contained but also as regards the presence in some of them of foreign metals and as regards the proportions in which these metals enter into the composition. This latter varies gradually in passing from one zone to another. The accompanying drawing illustrates diagrammatically a steel plate after treatment according to the present invention.

The result in question is obtained by submitting the mass of homogeneous steel (either ordinary carbon steel or a special ternary, quaternary or like steel) to the action of suitable granular mixtures contain.- ing the metal it is desired to introduce into the steel, such for instance, as chromium,

nickel, tungsten, molybdenum, manganese,

Vanadium and sometimes silicon and uranium in a free state or in a state readily dis-' associated under certain conditions, which, as hereinafter set forth, varies from one preparation to the other as well as from one phase to the other of the same preparation. These granular mixtures are strongly pressed against one or both surfaces of the plate or other article that is treated.

For each given composition of the homogeneous steel which forms the mass under manipulation, as well as for one or more of the given metals contained in the mixture employed, there exists a determined range of temperature, which depends strictly on the range of the critical points of the homogeneous steel itself, and on the nature of the metals employed. It is in this range that occurs the diffusion of the metal or metals contained in the mixture pressed against the surfaces of the mass of steel, toward the interior of the mass. The range of temper- 10, 1907. Serial No. 396,864.

comprised between the temperature of the first critical point of the steel employed and a temperature below its point of fusion. The depth to which the metal contained in the granular mixture-extends into the homogeneous mass of steel submitted to such an operation, depends primarily on the duration of the operation; but even by considerably prolonging this duration, a very deep or gradual diffusion would not be obtained in the'greater number of cases if the temper ature were always maintained constant from thebeginning of the operation until the end.

The constancy 6f the temperature-a condition which would be very useful if a certain concentration as regards the, foreign metal introduced had not been surpassed,

and if a great homogeneousness of cOncentration for a given zone of the plate had to be obtained, prevents a very definite given limit of concentration being surpassed, because if this latter is increased there is produced a displacement of the critical points and consequently of the interval of temperature in which the diffusion can be effected. It results that at a certain moment the temperature maintained constant is no longer comprised in this interval and consequently the passage of the metal of the mixture to the mass under treatment is no longer effected and the difi'usionis effected only at the interior of the mass until the concentration is suitably lowered owing to the interior diffusion referred to. It will then generally be advisable to suitably alternate the reduction and the increases of temperature in limits which can easily be determined for each. case and which generally ought to determine the critical points.

The product of the treatment referred to above will consist of a heterogeneous mass of steel, the composition of which varies in the various zones or layers according to the composition of the micro-construction of the homogeneous steel at the beginning, the

composition of the granular mixture em have (as well as the ternary zone) the same end. As example a steel carbon plate initial proportion of carbon, or a different proportion according as the granular mass did or did not containactive substances or was more or less rich in carbon or metazllic 0.1 to 0.2 per cent. of'carbon) may be taken, maintained in cont-act with a mixture of wolframic acid and of substances suitably carbonaceous, or nitrogenous, compressed against one of its surfaces at a temperature near that of fusion. As an example of such steel and Wolfram nitrogenous substances may be mentioned: charcoal 50% barium 25%, and ferrocyanid of potassium 5%. In this case the preceding operation must be followed by a'superficial de-carbonization, obtained by means of heating in contact with mixtures of metallic oxids. On the contrary, ifa start is made with a ternary homogeneous steel ingot (for example, a chrome steel with two to four per cent. of chromium) the final product will have a structure similar to that of the former ingot, but the layer of ternary steel would be substituted by a layer of quaternary steel, while the rest of the body would still be ternary steel. In the case just mentioned, by employing a mixture of the preceding case, the quaternary layer will consist of chrome steel. The procedure is followed in a similar manner for the more complex steels.

Similar considerations will apply in the case where the treatment by diffusion is effected on two surfaces or on all the surface of the steel objects, in one, two, or more times; these operations alternating with thermic treatment (temperings and the like) or suitable mechanical operations which may vary for each case according to the nature of the steel employed and of the steel desired to be obtained. The operation just referred to may be applied directly to the mass of homogeneous steel as cast, or to the mass when brought to the desired shape by the mechanical manipulations, such as hammering, rolling, pressing and the like. In every instance, however, it would almost always be necessary to follow the chemical treatment described by a suitable thermic treatment. But it is in the temper of the metallic bodies where the greatest advantages of this method of manufacture and the superiority of the bodies produced in this manner,

elasticity and bone black 20%, carbonate of are evident as compared With those obtained by other methods. As a matter of fact, by employing this method, any desired composition for the various zones of the body of steel, can be obtained, and consequently various parts of the object may be given the most suitable composition by means of a homogeneous tempering applied to the whole whereby each part acquires physical, chemical or mechanical properties (such as magnetic properties, resistance to chemical agents, hardness, plasticity, the like) the most suit able for the purposes for which the bodies are to be employed. By this method, armor plates for example, can be obtained which, after one or more omogeneous temperings efl'ected under the desired conditions of temperature and the like, possess mechanical properties (hardness, tenacity, and the like differing in the various layers so that they can be most suitably adapted to the mostvaried uses.

Let us suppose for example to have to do with a special nickel steel showing'the following composition: Nickel 2.20%, carbon 0.10%, manganese 0.42%, silicon 0.30%, sulfur 0.04% phosphorus 0.02%, and that it be intended to obtain a zone of 3 mm. thickness, in which the percentage of carbon should vary from 0.9% (on the outer face) down to 0.4% at 3 mm. depth, while the percentage of manganese, namely of the metal to be introduced by diffusion according to the present invention should vary between 3% (on the outer face) and 0.7% at 3 mm. depth. In order to obtain this result it will be suflicient to heat the steel piece in contact with a granular mixture consisting of three parts of charcoal, one of finely pulverized manganese dioxid and one of barium carbonate. A temperature of 1150 degrees C. is to be kept up during about half an hour; whereupon the same is to be allowed to gradually drop down to 700 degrees C. at the end of three hours. In making these statements, as to the duration of the heating, it has been assumed that the time begins to run since the full heat has been laid on the steel pieces; the additional time necessary for reaching the aforesaid temperatures as well for cooling after each treatment, of course depends upon the size of the pieces and the arrangement of the heating furnaces.

Having described my invent-ion I claim:

1. A steel plate or other article having on one or more surfaces a zone of considerable thickness throughout which is diffused a characteristic metallic steel component not contained in the other part of the article, the said metallic component being graded from a maximum inwardly to a minimum, such zone having a less p'ro ortion of carbon than in the other portion of the article.

2. A ternary steel plate or other article less proportion of carbon than in the other having on one or more surfaces a quaternary portion of the article. 10 zone of considerable thickness throughout Signed at Nos. 9-15 Murray street, New which is diffused a characteristic metallic York, N. Y., this first day of October, 1907.

5 steel component not contained in the other FEDERICO GIOLITTI.

part of the article, the said metallic com- Witnesses: ponent being graded from a maximum in- WILLIAM H. REID,

wardly to a minimum, such zone having a FRED. J (DOLE.-