US2399747A

US2399747A - Metallurgy

Info

Publication number: US2399747A
Application number: US505842A
Authority: US
Inventors: Linz Arthur
Original assignee: Climax Molybdenum Co
Current assignee: Climax Molybdenum Co
Priority date: 1943-10-11
Filing date: 1943-10-11
Publication date: 1946-05-07
Anticipated expiration: 1963-05-07

Description

Patented May 7, 1946 METALLURGY Arthur Linz, New York, N. Y., assignor to Climax Molybdenum Company, New York, N. Y., a corporatlon of Delaware No Drawing. Application October 11, 1943, Serial No. 505,842

1 Claim. '(Cl. 75122) The present invention relates to a new, useful and improved process for the addition of boron to metals and particularly to molten ferrous metals. I

Objects and advantages of the invention will be set forth in part hereinafter and in part will be obvious herefrom, or may be learned by practice with the invention, the same being realized and attained by means of the. processes, steps and combinations pointed out in the appended claim.

The invention consists in the novel steps, methods, procedures, combinations and improvements herein described.

Heretofore it has been proposed to add boron to molten metals the result of this addition being additional advantageous properties and particularly an increase in the hardenability oi the resultventlon, boron is added to a molten mass of metal in the form of a mixture with a molybdenum silicide. r

In my prior Patent No. 2,290,194 I have dis- 0 closed a process for producing molybdenum sili-' cide for admixture with a molten mass of metal and the present invention particularly relates to the formation of a boron-molybdenum silicide mixture or complex which can be added to a molten metal. By this means not only will the advantages disclosed in said prior patent be obtained in making a quick solution in the molten mass-of ant alloy and relatively small quantities of boron have been "effectively utilized for this purpose. As is well known, however, boron is an element characterized by'a high afllnity for oxygen, nitrogen, and oxygen containing gases and therefore one of the difllculties of introduction of boron into a molten metal mass has been the oxidization of part 01 the boron, at least. Furthermore, since only a small quantity oi! boron has been found desirable for such use, another problem is thenecessity or providing rapid and uniform dispersion of the boron throughout the molten mass. v

In the prior proposals the boron has been introduced into the molten mass for example in the form of term-boron or as an admixture with other metals such as aluminum, calcium, titanium and term-silicon.

The object of the present invention is to pro-.

. vide a novel and improved process for 'the addition of boron into molten metal such as iron or steel while preventing oxidization of the boron;

A further object of the invention is to provide for incorporating boron into molten iron or steel or like metals while obtaining a rapid dispersion throughout the molten mass of the boron, thus reducing the opportunity for oxidization of the boron. Itis also an object of thepresent invention .to provide a novel and improved process by which a definite ratio of boron can be accurately added tothe molten metals such as iron or steel.

The invention further provides the process of producing alboron-containing compound which is adapted to .be added to a molten bath of metal molybdenum and silicon, but also. the boron carried by the molybdenum silicide will be dispersed quickly in the molten mass and dissolved therein without substantial exposure'to .oxidization by virtue of this fact and also by virtue of the fact that the silicon in the silicide will help prevent oxidization of the boron.

Various processes may be used for the preparation of the molybdenum-silicon-boron' addition agent which may be used in the alloying process oi! the present invention. I preferably mix a molybdenum oxide such as roasted molybdenite concentrates or pure molybdenum trioxide with ferro-silicon and a fluxing agent such as fluorspar, with aluminum, together with either boric acid, sodium tetra borate, or other compound forming a source of boron. This mixture is' then ignited in a suitable crucible and after the slag has been tapped of! the desired proportion of molybdenum and silicon, together with boron is present in the form of a molybdenum-siliconpending upon the desired composition of the resultant product and particularly how much boron is to be introduced into the final alloy.

It is desired, preferably, to produce a final addition product which will be molybdenum silicide containing from 1% to 1% to 2.50% of boron. A

I typical analysis of the addition product produced to provide ready and rapid dispersion of the boron therethrough while avoiding losses by oxidization.

According to the process of the present inby the reaction of such a mixture is:

' Per cent Mo Si 30 B 1.5 A1 .2 AlzOa- 4.7 09.0 1.5 $102 2.1

If desired an excess of silicon may be added to the mixture so as to introduce a larger proportion of silicon into the final alloy and also present an adequate surplus of silicon for the prevention of oxidization of the boron.

After the mixture has been ignited and the slag tapped off, the resultant mass of molybdenum silicide plus boron can be crushed to form smaller lumps which can be weighed out into convenient amounts for addition to the molten metal in any desired manner.

In use the molybdenum silicide boron complex is employed in substantially the same manner as is customary with ferro-alloys whereby the addition agent is added directly to the molten material as for instance in the ladle, although the molybdenum silicide boron complex has a different range of usefulness from that of ferro-molybdenum due to its exothermic nature and by reason of the fact that there is accomplished the simultaneous addition of molybdenum silicon and boronwith a rapid dispersion of the boron through the mix. These properties combine to make the process of the present invention su- 'hereinbefore-mentioned specific example, then the amount of the complex which is added to the molten batch will be such as to include 10 points of molybdenum in the final cast alloy which will result in the cast alloy containing .0025% of bo- -ron. Other compositions of the molybdenum silicide boron complex addition agent may be obtained by varying thev quantity of the boron and of the molybdenum and silicon in the reaction mixture in order to obtain the desired amount of all three of these materials in the final cast alloy.

It is thus obvious that the present invention provides a distinct advantageous process in that not only is the quantity of molybdenum and silicon controllable with respect to the final alloy but also the quantity of boron can be controlled to suit the desired result.

If desired, the molybdenum silicide boron complex may be added with the other ingredients of a ferrous alloy prior to introduction into a, blast furnace or electric furnace and in this case the molybdenum silicide' boron complex is dissolved in the ferrous material as this is melted, the silicon thus generated being capable of preventing the oxidization of the boron so that the boron will ultimately be dispersed through the molten mass. Alternatively, the molybdenum silicide boron complex may be used to replace a portion of the now commonly used ferro-molybdenum whereby a smaller proportion of silicon will be obtained in the final alloy and the advantages of the boron will result in a final alloy with increased properties such as hardenability.

While the process of this invention has been described principally in connection with the-production of ferrous alloys having a molybdenum and silicon content to which it is desired to add boron, the process may also be applied to the production of non-ferrous alloys such as aluminum and magnesium alloys where it is desired to introduce a, small quantity of boron into the alloy.

The invention i'n its broader aspects is not limited to the specific steps and procedures described but departures may be made therefrom within the scope of the accompanying claim without departing from the principles of the invention and lybdenum silicide complex containing approximately molybdenum} approximately 30% silicon, approximately 1.5% boron, and the remainder impurities, the addition being made at a temperature suflicient to dissolve the boroncontaining complex in the'molten metal.

ARTHUR .LINZ.