US1942173A - Method of treating steel - Google Patents

Description

- result.

Patented Jan. 2, 1934 METHOD OF TREATING STEEL.

Clarence I. Justheim, Salt Lake City, Utah No Drawing. Application: May 31, 1932 Serial No. 614,630

3 Claims. (01. 75 27) My invention relates to "the treating of steel and has forits object to provide a new and efficient'method of tr'eating 'steel"to produce a better quality steelth'an has heretofore'been accomplished,' producing -a steel 'of greater tensile strength considering the low point of carbon content A 'further "object is' to' provide a method of producing steel using a flux of carbonaceous deposit; carrying ahigh content-of silica.

A still further object is to produce a steel having greater ductility and producing such steel at less cost than by the known methods.

A still further object is to produce a steel having a better structure than the present day standard methods of making steel as revealed by the microscope.

A still further object is to provide a method of treating steel when in the molten state, which consists of introducing a flux forming a complete covering for the molten steel in the furnace or crucible, thereby prohibiting the entrance of gases or atmosphere.

These objects I accomplish with the following methods:

The steel producing mixture is introduced into the furnace or crucible and treated in the usual manner. Silica sand is used in all cases for the first slag to eliminate the first impurities, sufficient heat being used to produce the necessary The oxidized slag is then removed and a new slag formed, which in my case would consist of a carbonaceous shale deposit carrying a hgh percentage of silica. Then a quantity of ferromanganese is added. The resulting slag is removed and the metal poured as desired.

In some cases the use of the deoxidizing agent, such as ferromanganese, may be eliminated and the flux used in varying quantities either one or more times during the time of the melt, depending upon the type of steel desired.

The deoxidizing agent used may be ferromanganese, spiegeleisen, ferrosilicon, or any other suitable agent used in the present-day methods of making steel, depending upon the type of steel desired.

Ferromanganese, spiegeleisen, and ferrosilicon, are all deoxidzing agents of the type which must be prepared or manufactured for use, as they are alloys made by treating the materials of which they are composed, in a suitable manner to make them combine into the finished alloy for use in the process of making steel. In my process the manufactured alloy is introduced into the melt as before stated, by adding the ferromanganese 'or other alloy to the melt after the carbonaceous shale has been added, but in some cases the melt is made with the usual silica sand, slag formed, deslagged, and then the ferromanganese or manufactured deoxidizing agent is introduced and later the cleaning and finishing slag is formed by the addition of my carbonaceous shale. This latter may be added to the melt after it is in theladle, if desired.-

The following tests were run in an electric nace to prove the above specification. 'Five heats were'inade, of which number 1 was a present} day*meth'od. The steel making mixture used analyzed carbon 0.20 to 0.25%; manganese 0.60 to 0.75%; silicon 0.30 to 0.40% phosphorus and sulphur 0.05% maximum. Silica sand was used in all cases for the first slag. This oxidizing slag was then removed and a new slag formed under the following conditions:

Heat No. 1 Silica sand, sufficient for steady arc Heat No. 2 0.25 lb. of fiux Heat No. 3 0.12 lb. of flux Heat No. 4" 0.60 lb. of flux Heat No. 5 1.001b. of flux Just prior to tapping the following additions of 80% ferromanganese were added (no other de- The metal was then poured into test bars. The bars had the machining qualities typical to those having similar analysis and heat treatment.

Results m' w :l V321. 1:! .0 ,9 3m 3 s s a 5 z e 2 2 a 5 953 =2 3 5 a 2 a .2 3 2016s 5 e m a a o a 5 D m m m nascent oxygen contained in the metallic bath.'

The nascent oxygen comes from two sources, metallic oxides, and the atmosphere. If there is not sufficient nascent silicon or other deoxidizing agents as ferromanganese present to react with the nascent oxygen, it will remain in the steel in the form of metallic oxides or blow holes with the entrapped oxygen therein, either event weakening the steel.

The nascent silicon is the free atom or active atom liberated from the flux in the heat, and it is the state of the silicon in the flux which is responsible for the resulting metal.

An analysis of one portion of the flux showed the following, being an average of several analyses:

Uranium a No trace Having thus described my invention I desire to secure by Letters Patent and claim:

1. A method of making steel in which carbonaceous shale is used as a natural deoxidizing agent in combination with a manufactured deoxidizing agent to form the slag and produce steel having greater tensile strength, greater Brinell hardness, and greater elongation at less cost.

.2. In a process for making steel the steps of melting a steel producing charge in the presence of a siliceous slag, removing the slag, and placing upon the metal a carbonaceous shale rangingfrom 40 to '70 percent silica and heating the same to form a second clearing slag and to precipitate nascent silicon into the steel and thendeoxidizing the melt.

3. In a process for making steel the steps of melting a steel producing charge: in the pres-" ence of a siliceous slag, removing the -slag,-and

placing upon the metal a carbonaceousshale,

ranging from 40 to 70 percent silica, and heat ing the-same to liberate nascent silicon and form a clearing slag. 1 CLARENCE I.:JUSTI-IEIM.