US2013137A - Alloy steel - Google Patents

Description

Patented Sept. s, 1935 awor PATENT OFFICE STEEL- Walter Grafts, New York, N.- 1., assignor to a...

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This invention relates to sulfur-bearing steels, more especially referring to improvements in such steels, and the immediate object of my invention is to produce a superior free-machining 81111111 steel.

The presence of sulfur in amounts appreciably greater than those considered desirable in structural and engineering steels is known to be advantageous from the standpoint of ease of me.- 10 chining. Screw stock for example is cus produced with a sulfur content of about 0.10%, as contrasted with the upper limit of about 0.050% usually specified for engineering'steels. Despite their desirable machining characteristics however, the high sulfur steels are strictly limited in their application, for when made by methods heretofore known they are not suitable for general engineering uses. 1 A superior freemachining high sulfur steel is not only of value in the present field of application, since it pro-' vides a uniform and reliable-engineering ma terial, but also extends that field to many other uses where its desirable machining characteristics lead to savings in fabrication and finishing costs.

I have discovered that asuperior high sulfur steel may be produced by the alloyed addition of proper amounts of vanadium. According to the preferred embodiment of my invention, from about 0.05% to about 1% of vanadium is added to a steel containing from about 0.075% to about- 0.5% of sulfur to produce steel of superior machining and physical properties. The presence of vanadium in these amounts improves the maworking characteristics, and decreases the size- ,and effects a more uniform distribution of the sulfide inclusions in the steel without decreasing the ductility or shock resistance, as is shownby physical tests-and microscopic examination.

The addition of vanadium in amountsother than those within the preferred range are of some benefit to the properties of sulfur'steels, but less than 0.05% has only a slight effect, while the use of more than about 0.5% is inadvisable chiefly because the added'expense of the vanadium ofi'sets the advantages to be gained by the use of a greater amount. Furthermore, al-' though the addition of vanadium appears to benefit the sulfide distribution in all sulfur steels, the free-machining sulfur steels as a class come within the range of sulfur content given above, and therefore m'yainvention is most profitably to be applied to steels within this range. 1 Taste which I have made demonstrate clearly the improvement effected by the addition of.

chining properties, improves the hot and cold Company, a corporation of October 17. 1931, 589,548

(01. 15-1) vanadium. For example, typical high sulfur 1 steels containing about 0.11% of sulfur, 1.2% of manganese and 0.15% of carbon were compared with similar-steels containing as an alloyed aodition from about 0.05% to about 0.35% of 5 vanadium. It was found that the presence of vanadium effected a marked improvement in sulfide-inclusion size and distribution, and improved the' machining characteristics remarkably. Further tests on these samples demon- 10 I 0.30% of-carbon, about 1.5% of chromium, al- 20.

loyed additions of vanadium up to about 0.5%, and the remainder chiefly iron, has remarkably good machining properties in addition to excellent and valuable physical properties which render it valuable for engineering uses. The steels of the present invention contain the small amounts of carbon, silicon, phosphorus. etc. usually contained as incidental impurities in Although I have described the preferred form 30 of my invention, and have mentioned certain specific typical embodiments, it will be understood that my invention pertains to alloy sulfur steels generally.

' 1. An alloy steel characterized by propertie of free-machinability and high strength, and which contains sulphur, vanadium, manganese, and carbon, the sulphur content being from about 0.075% to about 0.5%. the vanadium con- 40 tent being'from about 0.05% to about 1.0%, the, manganese content being not over about 1.25%, thecarbon content being not over 0.5%, and the remainder, except for incidental impurities, being iron.

2. An alloy steel characterized by properties of free-machinability and high strength, and which contains sulphur, vanadium, manganese. and carbon, the sulphur content being from free-machining sulphur steels.

' about 0.075% to about 0.5%, the vanadium content being from about 0.05% to about 0.50%, the manganese content being not 'over about 1.25%, the carbon content being not over 0.5%, and the remainder, except for incidental impuri-