US2120894A

US2120894A - Method of producing free cutting steel

Info

Publication number: US2120894A
Application number: US86889A
Authority: US
Inventors: Haag Johannes
Original assignee: Individual
Current assignee: Individual
Priority date: 1935-06-24
Filing date: 1936-06-23
Publication date: 1938-06-14
Anticipated expiration: 1955-06-14

Description

Patented June 14, 1938 UNITED STATES PATENT OFFICE METHOD OF PRODUCING FREE CUTTING STEEL Johannes Haag, Neunkirchen, Germany No Drawing. Applicati No. 86,889. In Germany 8 Claims. 75-58) amorphous sulphur or even of iron sulphide. This method of adding the sulphur, however, is accompanied by quite a number-of disadvantages, and in particular the sulphur cannot be mixed sufli- ;ciently intimately with the molten metal, this being attributable, among other things, to the dif ferences in specific gravity.

It is the object of the invention to eliminatethese disadvantages, and for this purpose the invention is based on the fact that, after tapping, de-oxidizing metal; generally manganese or some other metal which is to be alloyed with the molten metal is generally added to the molten steel. According to the invention, the said metal, for example manganese, and the sulphur are not added separately, but together in the form of a mixture in the necessary mixing proportion. This mixture is made for example by stirring manganese metal or ferromanganese in the finely ground state, or even so-called manganese dust, into the molten, thinly-fluid sulphur. Upon cooling, this mixture assumes peculiarly a metallic character, and may be cast conveniently into slabs or pieces of any desired shape. These pieces are added to the steel bath.

The peculiar metallic character of the solidi fied mixtureis apparently not produced by-chemical combination between the sulphur and the manganese, but the manganese in the form of dust is suspended in the sulphur. Since this suspension is also adequate even in the thinly-fluid state, the mixture may also be added fluid to the steel bath, the same advantages being attained. These consist on the one hand in that the mixture has a higher specific gravity than has pure sulphur, and therefore mixes better with the molten steel or penetrates the latter more rapidly. On the other hand, due to the manganese particles being suspended in the sulphur, the ignition temperature of the sulphur is also raised, or at least its rate of combustion is diminished, whereby the disadvantages residing in the difficulty of proportioning the necessary quantities of sulphur due to its rapid combustion, and in the effect of the burnt sulphur in acting as a carrier of oxygen to the iron and manganese in the bath, are also eliminated.

According to the invention, however, it is preferred to add the mixture in the solidified lump on June 23, 1936, Serial June 24, 1935 form to the bath, since it is thereby possible to apply a further step for preventing the combustion of the sulphur by surrounding the lumps or pieces with an envelope protecting them from oxidation. A solution of water glass for example, into .which the pieces are dipped, is suitable for such an envelope. Preferably, however, an

envelope of a reducing substance, such as for:

example paper, will be employed.

The principal advantage of the invention con-' sists in anextraordinarily uniform distribution of the sulphur in the solidified steel ingot. Whereas, in the usual process for the production of free-cutting steel, differences in the sulphur content of the head and base of the ingot of about 0.10 per cent for a mean content of 0.23 per cent are normal, these differences are reduced to half by the application of a sulphur-manganese mixture according to the invention, and are practicallyentirely eliminated by the further application of an anti-oxidizing envelope. This advantage is all the more remarkable since the differences in the sulphur content in the usual freecutting steels cannot be attributed to segregation" in the usual sense, so that therefore it has not been possible heretofore to preventthese differences by steps capable of producing the socalled re-segregated steels.

The invention is described herein with reference to the example of the mixture of sulphur and manganese, because this is an excellent form of application. Of course, the idea of the invention may also be utilized by stirring with the sulphur any other metal to' be alloyed with the steel bath,

even iron itself, in place of manganese. 7 Example A free-cutting steel of the following contents is to be produced:

C=0.08 per cent.

Mn=0.'70 per cent.

P==0.07 per cent. I v

s=0.200 per cent.

The molten steel which was to be sulphurized has in the finished cast sample an analysis with a manganese content of 0.72% and a sulphur content of 0.206%. I

180 kilograms of pieces consisting of a mixture of 22% sulphur and 78% manganese and coated with paper, were employed as addition. This mixture was produced by melting crystalline sul- 1 phur in a pan until it was thinly fluid; and stirring into the latter finely-ground IS-per cent ferr 01119118311886.

I claim:

1. Method of producing free cutting steel containing sulphur and alloy metal as ingredients which method comprises mixing molten sulphur and a finely divided alloy metal to form a uniform mixture, shaping the same into solid bodies by solidification and introducing the same into the molten steel.

2. A new product for the manufacture of free cutting steels containing sulphur and a deoxidizing alloy metal as ingredients consisting of a solid body produced by solidification of a mixture of molten sulphur and deoxidizing alloy metal particles.

3. A new product for the manufacture of free cutting steels containing sulphur and deoxidizing alloy metal as ingredients consisting of a solid body produced by solidification of a mixture of molten sulphur and pulverized manganese.

4. Method of producing free cutting steel containing sulphur and alloy metal as ingredients which method comprises forming a mixture of sulphur and alloy metal by solidifying a melt of sulphur containing substances with alloy metal particles distributed therein and adding said mixture to the molten steel.

5. Method of producing free cutting steel containing sulphur and alloy metal as ingredients which method comprises forming a mixture of sulphur and deoxidizing alloy metal by solidifying a melt of sulphur containing substances with alloy metal particles distributed therein and adding said mixture to the molten steel.

6. Method of producing free cutting steel con-' taining sulphur and alloy metal as ingredients which method comprises forming a mixture of sulphur and manganese by solidifying a melt of sulphur containing substances with manganese particles distributed therein and adding said mixture to the molten steel.

7. Method of producing free cutting steel containing sulphur and alloy metal as ingredients which method comprises forming a mixture of sulphur and term-manganese by solidifying a melt of sulphur containing substances with ferromanganese particles distributed therein and adding said mixture to the molten steel.

8. A new product for the manufacture of free cutting steels containing sulphur and deoxldizing metal as ingredients consisting of a solid body produced by solidification of a mixture of molten sulphur and deoxidizing alloy metal particles said body being covered by a protecting envelope.

JOHANNES HAAG.