US2378993A - Cold rolled manganese steels - Google Patents

Description

Patented June 26, 1945 UNITED STATES PATENT orrlce COLD ROLLED MANGANESE STEELE Russell Franks, Niagara Falls, N. Y., assign to Electro Metallurgical Company, a corporation of West Virginia No Drawing. Original application July 22, 1942, Serial No. 451,893. Divided and this application April 28, 1944. Serial No. 533,241

4 Claims. (Cl. 148-31) advantage gained by a high ratio of strength to weight.

Austenitic-type chromium-nickel stainless steels, cold-rolled to a high tensile strength, have also gained considerable favor for the manufacture of airplanes, railway cars, and other structures. These steels are very tough and ductile, and offer the advantage not only of a high ratio of strength to weight but also of a high ratio of strength to volume. They are, moreover, very resistant to corrosion and ordinarily do not require surface-protection against the weather.

Several special alloy steels, containing but a few per cent of alloying ingredients, and submitted to strengthening heat treatments, have been used for a limited number of wrposes, for instance, airplane tubing and railway trucks, wherein a high ratio of strength to weight. is important; but such steels when welded and not specially annealed have not had enough toughness and ductility at very high strength levels to adapt them to all uses in the field of highstrength, light-weight structures.

An object of this invention is to provide a new material havinga very high strength per unit of weight and per unit 01' volume, and great toughness and ductility. This application is a division of my application Ser. No. 451,893, flied July 22, 1942.

Another object is to provide a new steel for" use in cold drawing, cold rolling, and other cold forming operations.

Another object is to provide novel cold drawn, cold rolled, and otherwise cold formed steel articles; and a further object is to provide such steels and articles which are also resistant to progressive rusting.

In a search for steels which would achieve the objects of the invention, the so-called Hadfleld manganese steels containin 10% to 14% manganese were investigated. The results were dia- 50 highstrength while retaining improvement in certain appointing throughout the composition range, because the material cracked alter relatively light cold rolling. Raising the manganese content to 16%, 17.5%. and 18% did not obviate this difnculty. when the manganese content rose to 20% or 30%, the material'was ("limit to hot roll.

I have discovered, however, that a manganese steel which is readily hot rolled, and is readily cold rolled or otherwise cold worked, and which has when sufllciently cold worked a very high strength and excellent ductility and toughness.

can be obtained it the manganese content is maintained within certain narrow, critical limits. and if nickel and chromium are added in certain 1 small, critical proportions. I have also diseov-q ered that these steels have a substantial-moist n ance to progressive rusting.

The invention comprises steels for '7 I ing, cold rolling, and other cold forming opera tions, and articles composed of such steels, containing manganese between-15.5% and 20%, Preferably between 16% and 18%, and nickel and chromium, remainder substantially iron.

In a preferred embodiment of the invention, the steel contains in, addition to manganese, nickel between 0.25% and 4.5%,.preferably 1% to 2.5%. 0.25% and 7%, preferably 1% to 5%.

By "remainder iron and "remainder substantially iron as used herein and in the appended claims, I mean to include not only chemically pure iron but also iron ordinary steels. For instance, carbon may be present in a proportion from'0.01% to 1% or somewhat higher without greatly altering the characteristics of the steel, although it is preferred that the carbon content be less than 0.35%. Nitrogen in a proportion up to about 0.15%. phosphorus-up to about 0.2%, sulfur up to about 0.05%, silicon up to about 1%, and residual deoxidizers, scavengers, and grain refiners, such as calcium, may also be present.

The steels of the invention, described above, rolled readily, with-1; out checking, cracking, or tearing, and can vbecold worked, withoutintermediate-or subsequent. to obtain a very can be hot forged and hot annealing at high, temperatur great toughness and high ductility.

Although the steels of the present invention are suitable for lightweight high strength membersinthecoldrolledccnditimatlll'mrther physical Pr perties may and chromium in a proportion between containing the common' lngredientsi'ound in be eil'ected by subjecting the cold rolled steel articles, resistant to progressive rusting, comto a low temperature heat treatment between posed substantially of manganese between 15.5% 100 C. and 250' C. A suitable treatment is at 200 n 20%, i k l bet een 0,25% and 45%, C. for 24 hours. At the lower end of the'temmium between 0.25% and 7%, remainderiron. perature range a Som wh t longer time is re- 2.-Colddrawn or otherwise cold worked steel w r to effect deliled e as th articles, resistant "to progressive rusting, comtime may e l fl e a the 11 temperature! posed substantially of manganese between 16% of the range. At the higher temperaturesoi. 18%, nickel between 0.5% and 2%, chrothe range, some benefit may be derived from mium between 1% and 5%,remainder iron. heating for as short a period as 30 minutes. In '3. Cold drawn or otherwise cold worked steel other instances, particularly at the lower ttemarticles, resistant to progressive rusting having pcratures of the range, it may be desirable ,to approximately the composition: 16% manganese. heat for as long as 100 hours. 2% nickel, 3% chromium, remainder iron.

The materials oi this invention may be welded 4. A cold formed, high strength article comy e common we ns m t including the It posed of a steel containing manganese between various "spot" electrical resistance welding 15.5% and 20%, nickel between 0.25% and 4.5%, methods, electric arc welding, and oxyacetylene chromiunri'between 0.25% and 7%, remainder torch welding. This characteristic is of ;parttcsirbstan'tidlly iron, said article being in the com ular value, because weldingis'nsuallyfasterand resulting from heating within the range cheaper than riveting. The material need not 90 (it-100' 6. to 250 C. for a time between 30 minbe annealed .after welding. utes and 100 hours.

I 0mm: 7 RUSSELL THANKS.

1. Cold drawn or Otherwise cold worked steel