US2234428A - Manganese alloy - Google Patents

Description

Patented Mar. 11, 1941 UNITED STATES- PATENT OFFICE MANGANESE ALLOY No Drawing.

Application September 16, 1938,,

Serial No. 230,209 3 Claims. (01. 75-134) This invention relates to manganese alloys and is a continuation-in-part of my prior application, Serial No. 199,329, filed April 1, 1938.

The object of the invention is the productio 5 of improved alloys of manganese having very valuable properties over the entire range orwithin certain portions of the range to' which the present invention relates, some of these alloys possessing unusual combinations of properties making them very desirable for certain purposes, as will be described. Detailed objects and present application is directed in the main, to

high manganese alloys containing at least 60% manganese, but the proportion of manganese may run as high as 97% or even slightly above. The principal alloying constituents are copper and nickel employed together or alone with the manganese, with or without proportions of other metals having the efi'ect of modifying in certain respects the characteristics of the alloy such, for example, as tin, aluminum or chromium. The manganese employed is prefer'ably a high purity manganese such as that made by the electrolytic method and containing not more than about 0.3% of impurities, and having the general composition disclosed in my application above referred to. Although some of the alloys of my in-' vention may be made with manganese of a commercial grade having a somewhat greater proportion of impurities, in general to obtain uniform and maximum properties desired the high purity o electrolytic manganese should be employed. This is particularly true of alloys containing a very high percentage of manganese such as above 85%.

or 90% manganese, for example, as I have found that it is impossible to produce a ductile alloy such as produced in accordance with my present invention unless the high purity electrolytic mananese is used.

A typical electrolytic manganese suitable for use in my invention throughout the range of alloying constitutents disclosed herein, contains in excess of 99.7% of pure manganese, approximately 0.27% to 0.28% sulfur (of which slightly less than half is present as sulfide) and approximately .015% of other impurities. The total pro- 5| portion of silicon is in the neighborhood of lithium, including carbide, c'yanamid, nitride or .001%, while the carbon content is so small as to be non-detectable by ordinary methods of analysis. For best results in the practice of my invention, it is desirable that the total of carbon and silicon be less than .05%. Other impurities such 5 as aluminum should preferably be kept to a minimum, it having been found that substantial proportions of aluminum as an impurity prevents obtaining suitable ductility in certain alloys, although in some cases, someslight proportions of aluminum may be added to the alloy with advantageous results. While for some purposes the electrolytic manganese may be employed as it is obtained from the cells, for the most part it is preferable to de- 15 sulfurize it by suitable methods. I have found that the sulfur may be reduced to .005% by appropriate treatment, such as by the use of easily reducible compounds of calcium, magnesium and 20 hydride, or alloys of calcium with other metals which are relatively volatile, such as magnesium,

' as great as that of the above mentioned compounds and alloys. The amount of desulfurizing material used depends on the sulfur content.

By treatment to remove sulfur, the purity of the manganese may be brought to above 99.9%. Such a raw material may be used to produce excellent alloys which cannot be successfully produced by the use of so-called commercial grades of manganese.

Among the properties obtainable in the alloys 10 of my present invention are high modulus of elasticity, the property of being hardenedby'cold work and by heat treatment, the property of having a high co-eflicient of expansion, the property of high electrical resistance, in many in- 45 stances with extremely low temperature co-emcient, and remarkable vibration damping capacities. 1 While the maximum value of these various properties does not lie in identically specific ranges throughout the range to which-the pres- 50 cut invention relates, some of the properties do lie in the same range or have their peaks within the same range whereby unusually desirable combinations of properties are obtainable. In. general, however, the properties referred to are 'present over the entire range of alloys described in the present application so that the quantities illustrated my invention in this regard in the following table:

Taste 2 Composition Cold Worked Annealed Tensile Yield Tensile Yield Mn Cu Ni Qther strength point Elongation strength 7 point Elongation 92 05, 000 40, 000 2 68, 500 None 90 115,000 52,000 1.5 ,000 None 25 80 85, 000 41, 000 2 62, 000 None 26 so 105, 000 46, 000 l. 8 74, 000 None 42 75 85, 600 40, 000 2 63, 000 None 25 70 106, 000 44, 000 2 72, 000 None 31 70 95, 800 38, 000 2 67, 000 None 33 75 82, 000 37, 000 2 62, 000 None 35 60 78, 000 35, 000 2 51, 000 000 21 54 02, 000 38, 000 2 59, 000 24, 000 26 47 109, 000 43, 500 2 73, 000 32, 000 38 30 81. 600 36, 500 2 63, 000 19, 000 24 30 118,000 51,000 2 73,000 24,000 29 I of various characteristics may be so combined as to produce unusual combinations of properties in making it possible to employ the alloys of the present invention to very great advantage for a relatively large number of uses.

For convenience, I shall describe the invention by reference to the various properties discussed and show in general the ranges in which these properties are obtainable.

I have found, for example, that certain manganese alloys possess a modulus of elasticity higher than any of the common non-ferrous metals or alloys. As is the case with iron, I find that this modulus is an intrinsic property of the metal itself and is high in all manganese alloys of the present invention, but 'is particularly pronounced in alloys containing 70% or more manganese. I interpret this to mean that alloys containing more than this percentage of manganese contain a substantial proportion of a constituent which is either gamma manganese or a solid solution of some other n' ietal or metals in gamma manganese. The following illustrates the modulus of elasticity of several alloys to illustrate my invention.

TABLE 1 Modulus of elasticity of ductile manganese alloys V made witnhigh. purity manganese 'I'he uses of a manganese alloy having the high modulus of elasticity will be apparent when the other properties of these alloys ,are disclosed.

I have found, for example, that these manganese alloys may be obtained with varying tensile strength, elongations and yield points by suitable cold work and heat treatment. I have An examination of the data in this table in comparison with that in Table 1 shows that-the alloys which possess a modulus of 20,000,000 or more are those which have no definite yield point in the annealed state.

This further confirms my main classification of alloys containing more than 60% manganese as having a substantial proportion of a constituent having new and useful properties. The very con- TABLE 3 COeificient of expansion of ductile manganese alloys made unth hzgh purity manganese Mn Cu N 1 Other ig; Annealed v 97 1s. 0X10" 24. 7x10- cm./cm./ c.- 92 19.1 25. a as 20. a 21. 4 90 18.0 21. s so 25. 5 27. 9 76 28.3 26. 4 70 26.5 26. 0 so 23. a 23.6 54 21.4 21.8 so 19.8 19. 0 v5 27. 2 26.6 41 19.0 23. s 70 23.1 23. e 0 1e. 5 18.2 30 19.0 18.3

From this table, it will be seen that the hard drawn alloys show co-efilcients of expansion as high as 28.3x10 centimeters per 0'. m. per de'- for the 60 to 80% manganese alloys are known:

for the soft metals like zinc and lead, they have not heretofore been observed in alloys having at the same time a modulus of more than 20,000,000 and a yield point of more than 20,000 pounds per square inch. The usefulness of such com-' bination properties will be evident but I may illustrate it by the construction of bi-metal strips,

for thermostats. Such strips haveheretofore been commonly made of such materials as brass I have also found that the electrical proper-.,

ties of alloys made in accordance with my invention are new. In the following table, I have illustrated the specific electrical resistance of the alloys in the hard drawn and annealed state and their temperature coefficient for the annealed state.

TABLE 4 I Specific resistance Cu Other Temp. coefi.

Annealed ohms/100 C.

It will be seen that the specific resistance has 'values of more than 200 for certain alloys which also have a substantially negligible temperature coefficient. The-composition range having this useful'coinbination of properties is from 60 to 80% manganese, that is, the same range having a high temperature coefficient of expansion. It would be predicted that alloys within this range made in accordance with the known art would not possess this desirable combination of properties but would have a specific resistance below 140 and a very much greater temperature coefiicient. c

I have foun d that several of the alloys studied show an increase in resistance on annealing the electric current is used to bring about expansion and make or break a connection.

I have also found that certain alloys made in accordance with my invention possess a higher vibration damping capacity than heretofore found in alloys having relatively high strength, yield point and modulus. This property is indicated by the lack of metallic ring in alloys containing substantially more than 60% manganese.

. In order to generally quantify this effect, I have measured vibration damping capacity according to the resonance method and have recorded the results in the following table:

TABLE 5 Damping capacity of manganese alloys Composition h l- Loss in ergs per cycle per unit volume per Mn Cu Ni Other 7 unit strain squared 85 10 200 80 20 92 75 16.7 32. 2 70 20 12.2 60 40 99. 6 90 '10 182 91. 9 4. 8 3. 3 212 54. 3 37. 2 8. 5 10.04 47. 2 42. 1 Zn 10.4 10.18 %.2 55. 9 Zn 15.9 7. 39 31. 6 48. 4 4. 9 Zn 15.1 7. 82

For purposes of comparison, I have found that the damping capacity of steel is 15-20. I have observed that hardening by either cold work or heat treatment is substantially without effect on the vibration damping capacity of my novel alloys. Alloys having a. high damping capacity together with the modulus, strength and yield point of these alloys may be used to form gears, cams andother machinery elements where noise is objectionable.

In my copending application, I disclose the hardening of alloys composed essentially of gamma manganese by heat treatment. I postulated that this hardening was due to the transformation of part of the gamma manganese into a lower temperature stable form so that very fine hard particles of this form of manganese were dispersed through a matrix of gamma solid solution. This hardening may take place in any manganese alloys which may be maintained inthe ductile state by quenching and which contain insufficient alloying element to render the gamma form stable at room temperature. As I also disclosed in my copending application, the hardening may be so great in some of these alloys as to produce a brittle and useless alloy. I have found V 'obvious that with so many variables I can only indicate by a few examples the direction in which changes in these conditions affect the final properties of the alloys. It is interesting to note that the dimension change in hardening is very small,

being of the order of 2.8 10 cm./cm.

Table 6, which follows, indicates in general the effect of composition on the hardening with a fixed quenching temperature of ldegrees C., a

water quench, reheating for two hours at 700 de- .Tsnus copper or nickel, is exposed so that the attack does not proceed iurther. This layer of more Hardening of ductile manganese alloils quenched Hardened 700' O.- Annealed 800 C.

n. T. s. Mod. Er. Res. 11. 'r. s Y. r. Mod. Ex. Res. 11. '12s. Mod. Ex. Res.

2 b 66 .l87 78 27 b 90 68 27 25 112 3 b 70 20s 88 2e 5 72 H 4 b 80 70 None b 80 '63 6 b 80 71 None 20 b 80 62 2O 7 b 88 66 NOIJO 29 H 182 86 66 26 182 (The yield point for the quenched and annealed sam les given above was very low (substantially none) in each instance).

left of the above table stand for u 1 Ni 3 Ni The numbers at the 97 Mn 2 92 Mn 95 Mn 90 Mn 85 Mn 6 Ni 80 Mn 75 Mn 9 Ni In reading the table, the abbreviations are a) be interpreted as follows: H. stands for hardness on the Rockwell scale; T. 8." stands for tensile strength; Mod. stands for modulus in The density of these alloys is substantially less ness. Cold work between the quenching and reheating step greatly accelerates hardening and in some instances produces much greater hardness. This is to be expected because the hardening temperature is not sufllcient to remove the hardening by cold work. Y

In general, a temperature of 800 degrees is required to bring about definite softening of the hardened alloy and a higher temperature is required for full anneal. As an example of theeffect of reheating temperature on hardness I give the following results:

than that of steel being from-7.0 to "l.2.

In the above table, Rb stands for hardness on the Rockwell B scale, and "Re" stands for hardness on the Rockwell 0 scale.

In my copending application, I have disclosed the formation of a tenacious hard case alloys high in manganese by heating in ammonia at 500 C. I have found that the alloys which are capable of hardening by heat treatment can be successfully case hardened in this way.

In my copending application, I have disclosed the chemical properties of 'certaln manganese alloys. The alloys of my present invention behave in general like solid solutions in which the parting limit occurs at an unusually low percentage of-the added element; that is, the surface atoms oi manganese are attacked by the etchant and a continuous layer of the more noble metal, erg.

'- nealed states.

0y samples as iollows:

noble metal is extraordinarily continuous and remains intact with further rolling or drawing operations on the alloy. The advantages of such copper, nickel or zinc clad alloys will be evident.

The proportion of alloying constituents for alloys of manganese hardenable by heat treatment varies somewhat, and in general the following tabulation is a guide to at least the proportion of elements which are required to produce a dellnite pronounced hardening under heat treatment:

Alloying elements Composition Percent I Cu 2-40. Ni 1- 5 Cu [H0 Al 1- 3 Cu 5-10 Zn l- 3 This table is not in any sense complete, particularly as to ternary and quaternary alloys, nor.

does it include all possible factors, it being obvious that constituents of ternary alloys cannot be plotted along a straight line. In the case of nickel alone, for example, some hardening occurs when as much as 20% nickel is used, but the The characteristics 01' the alloys of the present invention are further evidenced by their remarkable ductility in both the quenched and fully anpure grades 01' commercial manganese, which show considerable ductility (at least some of them) in the quenched state, develop brittleness when subjected to heat treatments which iully anneal and soften similar alloys when made. in accordance with my invention.

For the most part, the preceding description I have found that alloys of high manganese content produced from relatively immost pronounced hardening occurs in the neighborhood oi the range indicated.

is concerned at any given point with only a single property of the alloysoi my invention, but by the use of the tables the ranges in which desirable combinations 0! properties may be obtained will be made clear. There is a definite range, however, within which all of these properti s m be found in some cases to quite a pronounced degree in a single alloy. Most of the alloys of my present invention contain at least of manganese, at least one of the elements copper,

nickel and zinc, and in some cases one or more of the elements tin. aluminum and chromium. Either copper or nickel may be used alone in proportions as high as 40%; zine, preferably employed with one or both of the elements copper and nickel, may be used in proportions as high as 30%; while aluminum and chromium, generally, should not be present in proportions greater than about 5% and it more than one of the latter group of metals is present, the total .amormt of such group should not be appreciably greater than 5%. The ranges in which the properties discussed above are for the most part present are those ranges in which at least 70% oi' e is employed, except in the in stances, as pointed out, where the proportion of manganese may be as low as 60% or somewhat below.

' There are a very large number 01 uses for the alloys of my present invention where the unusual properties or combinations of properties discussed can be taken advantage of. They'include all uses where high tensile strength. vibration damping properties, machinability, high temperature co-eiiicient and other properties dis:

cussed are desired alone or in combination. Examples are thermostatic elements, electrical resistances, heating elements for lowtemperature sealed units, spring material, fabricated parts subjected to strain.- gears, sprockets, chains,

ratchets, pawls, and other transmission elements where vibration is objectionable,"artillery t m where sound deadening is required, supporting members for punching dies and similar purposes to deaden solmd, non-magnetic machine parts or adequate-mength, Poppet valves and'seats in sasandotheruses.

In connection with the vibration damping capacity, it may be noted that this capacity begins to fall oiirather sharplyabove temperatures of I about 100 degrees C. There are many instances where the vibration damping capacity for these alloys maybe used where it would be substantially at room temperature, however, such as in the production of organ pipes and musical instruments where wood and lead are commonly used, and for such uses as acoustic filters made, for example, by periorating'plates oi the alloy .and arranging them'in the form of a filter. The low thermal conductivity and high reflection together with the ability to roll thin sheets makes value, and in the cases where my alloys would replace non-ferrous alloys they have properties not ordinarily found in non-ferrous alloys.

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

1. An alloy having high vibration damping. capacity comprising at least 1% nickel, at least 2% copper, and the balance being submantially all manganese, the manganese constituting at least 95% of the alloy.

2.'An alloy having high vibration damping capacity comprising about 1% nickeL'about 2% copper, and about 97% manganese.

3. An alloy comprising from 1% to 10% nickel, from 2% to 20% copper, and the balance being substantially all manganese, the manganese constituting from to 97% of the alloy.

woman: s. mum.