US2250470A - Manganese alloy - Google Patents

Description

Patented: m .2 1941 UNITED STATE (PATENT err-Ice moms]: ALLOY Reginald 8. Dean and Clarence T. Anderson, Salt Lake City. Uta aaaignors to Chicago, Development Company, Illinois No Drawing. Application September 23, 1940,

Chicago, 111., a corporation of semi No. 857,922

6 Claims.

This invention relates to non-ferrous alloys having a high degree of corrosion resistance, es-

pecially with respect to brines and dilute acids. It relates particularly to such alloys wherein manganese is present asa major constituent and. is especially concerned with alloys manganese, copper, nickel and chromium which may be hardened by heat treatment.

The alloys of the present invention tall within the range oi manganese from 30% to 90%, nickel from 1% to 35%, chromium from 1% to 20%,

and the balance substantially all copper, the copper comprising at least 5%. A particularly preerred range is about 40% to about 50% man- .ganese, about 33% to about 40% copper, about period of about 12 hours. It will be understood,

or course, that the amount of hardening produced will depend upon the particular composition of the alloy as well as upon the exact mode 01' heat treatment.

For example, it the composition oi the alloys, with the exception 01 the chromium content, in other words, the proportions of manganese, copper and nickel, fall within the range disclosed in our copending application, Serial No. 300,798, filed October 23, 1939, then the hardening will not be greatly affected by the addition oi up to about of chromium. with higher percentages of chromium in this group of alloys, there is atendency tor the alloy to become brittle. The

addition of chromium to alloys within this range increases their corrosion resistance.

The addition oi chromium to alloys oi manganese, copper and nickel within the broader composition range specified hereinabove, but outside the'range oi hardenable alloys described in our aforementioned application, Serial No. 800,- 798, makes such alloys readily susceptible to hardening by heat treatment. The hardness which is obtainable by heat treatment varies, among other things. with the chromium content, being relatively slight with 1% chromium, reach- The-iollowing examples are illustrative of alloys railing within the scope of the present ining a substantially maximum hardness at approximately 10% to 12% chromium, and

showing brittleness at about 20% chromium.

vention. It will be understood that these are merely representative and that the full scope of the invention is not in any wise to be limited to the examples given, but is to be construed in accordance with the claims.

Example I An alloy was prepared by melting together 45 parts by weight of electrolytic manganese, 36 parts by weight of electrolytic copper, 9 parts by weight of electrolytic nickel and 10 parts by weight of electrolytic chromium. The resulting.

alloy may be fabricated hot or cold. Its tensile strength, after quenching from 1000 degrees C., was approximately 75,000 pounds per square inch and it had a hardness of zero as measured on the Rockwell C scale. After heating at 425 degrees C. for 12 hours, the hardness on the Rockwell C scale was 49. In the hardened condition, the alloy was exceptionally tough. It was highly corrosion resistant to salt water and dilute acids in both the soft and hardened condition.

Example II tensile strength of 60,000 pounds per square inch and a hardness of -14 as measured on the Rockwell C scale. On reheating the alloy at a temperature of 425 degrees C; for 12 hours, its hardness, on the Rockwell C scale, increased to 42 and its tensile strength increased to 180,000 pounds per square inch. In both the hard and soft states, the alloy was corrosion resistant.

Example Ill An alloy was made by melting together 50 parts by weight of electrolytic manganese, 40 parts by weight of electrolytic copper, 9 parts by weight of electrolytic nickel, and 1 part by weight of .electrolytic chromium. The resulting alloy, as quenched from degrees 0., had a tensile strength oi 59,000 pounds per square inch and a Rockwell C hardness 0! --15. On heating the alloy at 425 degrees C. for 12 hours, its tensile strength increased to 85,000 pounds per square inch and its hardness to Rockwell C 4. In addition to the mechanical and corrosion resistant properties 01' the alloys 01' the present coefllcient of expansion of these alloys is also relatively high, varying from about to about 25. The higher coeflicients to expansion are found in those of the alloys which contain the minimum amount of chromium and whose composition, except tor the chromium content, falls closely within the range of manganese, copper and nickel set forth in our copending application Serial No. 303,006, filed November 6, 1939.

In the preparation of the alloys of the present invention, we have found it to be particularly advantageous to employ substantially pure metals. In the case of manganese, we prefer particularly to employ electrolytic manganese having a purity of 99.9+%. Manganese derived from other sources but of substantially equal purity can also be used withgood results. When the amount of chromium is relatively small, the so-called pure chromium of commerce may be utilized. However, when chromium approaches the maximum percentage as specified in accordance with the present invention, we find it distinctly advantageous to use electrolytic chromium.

It will be understood that the invention encompasses alloys of the type described hereinabove wherein minor percentages of other elements are added but where the fundamental characteristics and properties of our alloys are not adversely affected.

What we claim as new and desire to protect by Letters Patent of the United States is:

-1. A hardenable alloy, having good corrosion resistant characteristics, containing manganese from 30% to 90%, nickel irom 1% to chromium from 1% to 20%, and the balance substantially all copper, the copper comprising at least 5%.

2. An alloy containing from 1% to 20% chromium, from 5% to 56.5% copper, from 30% to 90% manganese, and the balance, to total substantially 100%, being from 7% to 22.5% nickel, the manganese being present in amounts of at least about four times that of the nickel.

3. A quenched and reheated alloy, having high hardness and good corrosion resistant properties, containing manganese from 30% to 90%, nickel from 1% to 35%, chromium from 1% to 20%, and the balance substantially all copper, the copper comprising at least 5%.

4. An alloy containing about 40% to about 50% manganese, about 33% to about 40% copper, about 5% to about, 15% nickel, and the balance comprising about 5% to about 15% chromium.

5. An alloy containing approximately manganese, approximately 36% copper, approximately 9% nickel, and the balance chromium.

6. A quenched and reheated alloy, having high hardness and good corrosion resistant characteristics, containing the following elements in substantially the stated proportions:

Per cent Manganese 40 to Copper 33 to 40 Nickel 5 to 15 Chromium 5 to 15 REGINALD S. DEAN. I CLARENCE T. ANDERSON.