US1492973A - Steel alloy - Google Patents

Description

D No Drawing.

mas May 6, 1924.

UNITED STATES PATENT- OFFICE.

CHARLES 1*. Evans, or TITUSVILLE, rnnnsvnvnua, assrenoa T0 cYcLors s comm, or NEW max, N. Y.,

A conronn'rron on NEW YORK.

STEEL ALLOY.

Toiall whom it may Be it known that I, CHARLES T. Evans,

a citizenio'f the United States,residing at Titusville, county of Crawford, and State of Pennsylvania, have invented certain new and useful Improvements in Steel .Alloys, fully described and represented in the following specification.

This invention relates to improvements in steel alloys, and has for its object to produce a steel of the nickel-chromium type which possesses hardness, toughness, high resistance tOPiOOITQSiOII, and which further has the property of being hardened by the ordinary heat treatment, that is, b 'heating and quenching in a usual quenc ing medium, such as water or oil.

Many steels of the so-called nickel-chromium type possess great advantages for many purposes, but they are subject to marked limitations ,in use. Whenthe alloys have certain nickel, chromiuma'nd carbon contents typical of nickel-chromium steels, the. resulting steels are so hard that they cannot be machined. Articles-made from such ste'els, therefore, which require tobe .put

. resulting machined articles ,cannot be hardof the alloy 'ened by ordinary heat treatment, that is,

by sub ecting them to heat and hardening in a uenching medium, such as water or oil. -or instance, a typical chromiumnickel steel hasa nickel content'of about 3.5%, chromium, 1.5%, manganese, 0.45%, and carbon, 0.2. This steel can be machined, but the machined article cannot be hardened by the ordinary heat treatment. Case hardening can, of course, be resorted to, but this is objectionable in man instances. Again a-steel'having a nicke content of 3.5, chromium 1.25, carbon 0.4, manganese 0.4%, nickel 3.5%, exhibits a scleroscopic hardness of 76. Such a steel can scarcely be touched b a file, and, of course, cannot be machine In general, it may be said,'increasing the percentages either of carbon or of chro-. mium, or both, will increasethe hardness and thus render it diflicult, if not impossible to machine. Increasing the percentage of nickel in the alloy tends to reduce the scleroscopic hardness, but if the Application filed December 4., 1920. Serial 1T0. 428,205.

nickel is added in su-flicient quantity to effectsuch reduction in hardness as to bring the steel within machining limits, it cannot be hardened by ordinary heat treatment.

Steels which might be said to be of the nickel-chromium t 'p'e have been produced for certain specia purposes, such, for instance, as jewelers die work. Such steels are relativel hi hin carbon and relatively low in nicke and chromium, the nickel being about, say, 1.40%, and the chromium, say,

is not above normal, that is, about 0.15%

to 0.2%, steels can be produced in which the percentages of chromium, or chormium and nickel, are relatively high and yet the steel articles produced therefrom can be maund by the addition to steel al- I chined and subsequently hardened by the ordinary heat treatment, namely, heating and quenching in a usual medium, suc

as water or oi The amounts of refractory metal, .such as zirconium or titanium and silicon added,

will deepnd on varying conditions, such as the percenta I of the other constituents of the allo an the use to which the articles are to put. I have found that where the combined percentage of nickel and chromium amounts to about 15%, the nickel bein about 7% and the chromium 8%, satis acto results were obtained by adding 34% of sil con, zirconium and titanium. In the case referred to, the silicon added amounted to' about 25%, the zirconium 0.5%, and the titanium 0.25%. In the particular instance referred to, the siliconcontent .of the alloy, prior to the addition of the refractory metals, was. about normal, that is, about 0.15% to 0.2%. In this case, the scleroscopic hardness, after heat treatment and quenching was about 75 to-80.

In another instance, where the combined percenta of chromium and nickel was 12%, the nickel being 6%, and the chromium 6%, satisfactory results were obtained by adding 5.8% of the refractory metals, the silicon being 4%, zirconium 1.05% and the titanium 0. 5%. In this case, the silicon content of the alloy, before the 'addition of the silicon, was, as beforef wrmal. In this case, ;the scleroscopic hardness was slightly less than the case given before, that is, it was 65 to 70. Specific rules for the addition of the refractory metals of the carbon group cannot be given as the amounts be be added will, as before indicated, depend 1 on theiamount of hardness it is desired to produce and on the percentages of the other constituents of the alloy. :In general, it may be said that if the chromium content of the alloy lowered, the percentage of silicon added should be increased and vice versa, and if the nickel content of the alloy be lowered, the zirconium and titanium content should be increased, and vice versa. Of course, if the silicon content v of the alloy, prior to the addition of the that is, they are not attacked by vegetable acids and they are not suioject to atmos; phericacorrosion.

meagre What is claimed is: r T

1. A steel comprising carbon, manganese, nickel, chromium and iron, and also containing silicon above 0.2%, and ,at least one refractory metal of the'carbon group, the proportions of carbon, nickel, chromium, manganese, silicon and iron being such that the, steel, prior to the addition of the refractory metal, cannot be hardened by heat treatment and quenching, and the proportions of refractory metal added being such that the resulting steel can be hardened by heat treatment and quenching. 2. A steel comprlslng carbon, manganese, nickel, ChIOIl'llllIIl and iron, and also containing silicon above 0.2% and zirconium,

the proportions of carbon, nickel, chromium, manganese, SlllCOIl and iron being such that r the steel, prior to the addition of the silicon and zirconium, cannot be hardened by heat treatment and quenching, and the proportions of silicon and zirconium added being such that the resulting steel can be hardened by heat treatment and quenching.

3. A steel comprising carbon, manganese, nickel, chromium and iron, and also containing silicon above (3.2% and zirconium and titanium, the proportions of carbon, nickel, chromium, manganese, silicon and iron being such that the steel, prior to the addition of the silicon and zirconium, cannot be hardened by heat treatment and quenching, and the proportions of silicon,

zirconium and titanium, added being such that the resulting steel can be hardened by heat treatment and quenching.

In testimony whereof, I have hereunto set my hand .v

CHARLES T; EVANS.