US2064150A - Low-carbon ferro-titanium-silicon alloy - Google Patents

Description

Patented Dec. 15, 1936 UNITED STATES PATENT OFFICE George F. Comstock, Niagara Falls, N. Y., assignor to The Titanium 'Alloy Manufacturing Company, New York, N. Y., a corporation of Maine No Drawing. Application July 23, 1936,

Serial No. 92,149

3 Claims. (01. 75-124) My invention relates to a new and improved type of ferro-titanium alloy for use in treating molten steel for the purposes of incorporating titanium therein for carbide control and "assist- 5 ing the removal of gaseous and other objectionable impurities.

Low-carbon ferro-titanium is generally made by an aluminothermic or thermit reaction process in one of two grades, containing respec- 1 tively 20 to 25%, or 38 to 42% titanium. Both of these grades as ordinarily made in the past have contained about to 8% aluminum which is not desired, but is unavoidably retained by the alloy from the fine-grained aluminum used as the reducing agent and source of heat in the process of manufacture. Other impurities commonly found'in low-carbon ferro-titanium are 2 to 5% silicon and about 0.1% carbon.

When true titanium alloy steel is made, it' is often desirable for various reasons to add the titanium in the form of a ferro-alloy with as small an amount of aluminum, accompanying the titanium, as possible. Up to this time the best way to attain this objective has been the use of a low-grade ferro-titanium produced in the electric .fumace, where the aluminum content can be reduced to about 3%. That process has not been applied commercially to the production of the high-grade, or 40% ferro-titanium, so far as I am aware, and attempts to produce this high-grade alloy with less than about 7 or 8% aluminum by the thermit process have generally failed commercially (although theoretically possible) because of low yield of metallic product per pound of charge, or difiicult maintenance of the crucible used for the reaction, on account of super-heating.

Both of these results increase the cost of the alloy so much that its production becomes unprofitable. This fact presents an unfortunate 1 situation for steel-makers because the high-grade alloy containing 38 to 42% titanium would be a more desirable alloyfor their use, since less weight of addition is required when it is used for a given titanium content in the steel, if its aluminum content could be reduced as low as that of the 25% grade. 1

I have now discovered that by using granular aluminum made with cryolite and rutile as described in the co-pending patent application Serial No. 73,640, filed April 10, 1936, by V. V. Efimoff and myself, and by using sodium, magnesium, calcium silicide, and ferro-silicon as auxiliary reducing agents, a low-carbon ferro-titanium may be made containing from 38 to 42% titanium, 7 to 15% silicon, 0.01 to 0.12% carbon,

2 to 5% aluminum, with the balance substantially iron. A preferred ferro-titanium alloy was found to contain over 38%. titanium, less than 4% aluminum, and less than 0.1% carbon, but 5 with about 11% silicon and the balance substantially iron. Furthermore this new ferro-titanium alloy is practical to produce at moderate cost, giving as high yield of clean metallic product as the ordinary grade of 40% low-carbon ferro- 1 titanium with 7 or 8% aluminum, and not involving any super-heating of the crucible or other unusual practice which would decrease its useful life.

My new high-grade ferro-titanium-silicon al- 15 loy is especially useful for ladle additionsto steel made in a basic furnace, sincesuch alloy is high in titanium, thus requiring the smallest practical ladle addition for a given titanium content in the steel; also on account of its silicon content 20 and low-carbon, it dissolves very rapidly in the ladle and no other addition of ferro-silicon is required.

Its aluminum content is as low as occurs in the low-aluminum grade of 25% ferro-titanium 25 used by those who demand the, lowest possible aluminum content in their ferro-titanium, and yet the titanium content is practically as high as in the highest grade low-carbon ferro-titanium commercially produced up to the present 30 time.

As examples of the production of my new alloy, six thermit reactions will now be described. The charge used, weight of alloy produced and the results of, all the analyses made are given in 35 the following table:-

Reaction No.: 1 2 3 4 5 6 Granular ilmenite (lbs.) 195 195 195 195 195 195 40 Milled rutile (lbs.). 35 35 35 38 35 38 Granular aluminum (lbs.) 115 115 115 115 115 115 Magnesium (lbs.) l0 10 10 10 l0 10 Calcium silicide (lbs.) 15 5 7 6 6 6 Sodium chlorate (lbs.) 30 30 30 30 30 30 Cryolite (lbs.). 15 10 10 l0 10 10 45 Ferrosilicon (lbs.) 0 8 l0 9 9 9 Sodium (lbs.) 2 2 2 2 2 2 Weight of alloy produced Obs.) 81 102 64 102 104 Titanium content 39. 3 40. 3 39. 1 39. 5 Silicon content 8. 74 9. 36 13. 32 11.75

50 The ilmenite used contained 61.8% TiO2, 9.65% FeO, 26.4% F6203, with the balance silica, magnesia, etc. The rutile contained 75.8% TiOz, 10.96% F6203, 5.02% S102, 4% A1203, 1% MnOz, with the balance lime, magnesia, phosphates. 5s

etc. The granular aluminum was made to contain about aluminum and 12.5% each of the same milled rutile and of cryolite (sodium aluminum fluoride). 'I'he-ferro-silicon was the regular grade.

The charge (except the sodium) was mixed in a ball mill for about half an hour, then placed in a crucible with 2 lbs. of regular 40% ferro titanium fines (through 20 mesh) on the bottom, and 2 lbs. of sodium on top, and ignited with a little magnesium and sodium chlorate. The reactions lasted between 85 and seconds. The product was not removed from the crucibleuntil cold.

The six alloy products were separated from the slag, crushed, mixed together, and sampled, and 528 lbs. of alloy coarser than 8 mesh were obtained. Its analysis showed 39.36% titanium, 10.77% silicon, 3.32% aluminum, 0.06% carbon, with the balance substantially iron.

I claim as my invention:-

1. A ferro-titanium-silicon alloy containing from 38 to 42% titanium, from 8 to 12% silicon, not to exceed 5% aluminum, from 0.01 to 0.12% carbon, and balance substantially iron.

2. A low-carbon silicon-bearing term-titanium alloy containing about 40% titanium, not to exceed 0.12% carbon, about 3.5% aluminum, about 11% silicon, and balance substantially iron.

3. A ferro-titanium-silicon alloy containing 38 to 42% titanium, 7 to 15% silicon, 0.01 to 0.12% carbon, 2 to 5% aluminum, and balance substantially iron.

GEORGE F. COMSTOCK.