It is routine to use vanadium to increase strength of steel. Many vanadium containing addition agents have been developed and used for this purpose. For example, U.S. Pat. No. 1,715,867 describes a ferrovanadium addition agent containing 85 to 95% vanadium for use in steel making. U.S. Pat. No. 3,334,992 describes an addition agent comprising about 80% vanadium, 10 to 12% carbon, and 2 to 10% iron and less than 2% oxygen. The addition agent of this patent has an average density of 2.8 to 3.4. U.S. Pat. No. 3,982,924 describes a process for producing ferrovanadium carbide addition agents at atmospheric pressure and without the need for use of vacuum furnaces.
The steel making art, of course, desires addition agents which provide the greatest level of vanadium on a weight basis as is possible. It is also desirable that a vanadium containing addition agent contain minimum levels of other elements or impurities which could adversely affect properties of the treated steel. Also, it is important that the addition agent have physical characteristics which will foster dissolution of vanadium when it is added to molten steel. Indeed, most vanadium-carbon containing addition agents known and used prior to this invention are characterized by low density, a factor which limits the level of recovery of vanadium added to steel when slag is present. High density vanadium addition agents, that is, agents having a density of greater than 5 have been known in the art, however, these addition agents contain elements other than vanadium such as manganese and silicon which are often undesirable.
It is an object of this invention to provide a high density, high vanadium content addition agent which is low in oxygen content and which will readily combine with molten steel to produce high strength alloys.
USPTO Backgrounds
USPTO Backgrounds