US2127253A - Magnesium alloy - Google Patents

Description

uurrso STATE.

Patented Aug. 16, 1938 MAGNESIUM ALLOY No Drawing. Original application August l, 1035,

PATENT OFFICE Serial No. 35,128.

Divided and this application July 2, 1937. Serial No. 151,898

4 Claims.

This application is a divisional application of my copending Serial No. 35,126, filed August 7. 1935. The invention herein relates to wrought magnesium base alloys, and it is particularly 5 concerned with those alloys which contain from about 5 to per cent aluminum, 0.1 to 1 per cent manganese, 0.05 to 0.5 per cent calcium, and 0.1 to 115 per cent zinc.

Magnesium .base alloys containing aluminum lo and zinc have proved to be quite satisfactory for the production of castings. Manganese is frequently added to these alloys for the purpose of improving their corrosion resistance, but it does not aflect their casting quality to any substantial degree. Where attempts have been made to hot work these same alloys in the production of wrought articles, it has been found that the best workability is obtained by limiting the aluminum content to less than about 3 per cent. However, alloys containing 5 per cent or more aluminum have a higher strength and consequently are desired for many applications. Also. as the aluminum content of these alloys is increased, they become more dimcultto work, especially at elegs vated temperatures, because of the tendency of the billets to crack when pressed, rolled, or forged. In order to successfully fabricate the alloys containing more than 5. per cent aluminum it has been necessary to exercise rigid control 80 over the heating and working conditions. In other words, the attainment of high strength in alloys of the foregoing type is achieved at the expense of ease in hot working. In the production of wrought articles, the maas lor portion of the reduction or change in shape is accomplished at an elevated temperature where the metal is much more plastic than at ordinary temperatures. As a matter of practice the deformation of the metal is performed well above the temperature at which strains would be developed of the character found in the cold worked product. In the fabrication of magnesium base alloys hot working is usually done above about 600 Fahrenheit. At this and highit er temperatures the alloys are readily shaped without leaving deleterious residual strains. Although the alloy becomes suillciently plastic at these temperatures to be easily deformed, it may lose itscohesive quality to such an extent that I0 cracks or incipient fractures are created under pressure of the hammer, roll, or plunger, which prevent it from being utilized in the subsequent manufacture of wrought articlea' Some alloys are more prone to exhibit this behavior than 5 others. Magnes um base' alloys containing from about 5 to 10 per cent aluminum, 0.1 to 1 per cent manganese, 0.05 to 0.5 per cent calcium, and 0.1 to 1.5 per cent zinc belong to this group which in terms of the art are called hot short. Particular pains must therefore be taken to avoid I the formation of cracks with a consequent increase in cost of production.

My invention is directed toward overcoming the disadvantages enumerated hereinabove with respect to the hot working of magnesium-alumil0 num-manganese-zinc-calcium alloys. In particular, it is an object of my invention to improve the ductility of these alloys at elevated temperatures without detracting from their strength or other desirable properties. I have discovered II that magnesium-aluminum-manganese-zinc-calcium alloys can be rendered more ductile under the conditions imposed by working at high temperatures, such as have been referred to above, by the addition of a small amount of= lead 20 amounting to from 0.1 to 1 per cent or the total weight of the alloy. I have found, in addition. that thisalloying constituent does not substantially change or aifec't other desirable properties of the base alloy, but only elects a remarkable as and beneficial change in its working characterlstlcs at elevated temperatures. Further, I have determined that the hot working properties of magnesium-aluminum-manganese-sinccalcium alloys can be similarly improved by inso corporating in the alloy an amount of thallium and cadmium varying in amount from 0.1 to 1 per cent of the total weight of the alloy. My improved alloys containing the metals lead, thallium, and cadmium. individually or collectively as in combination, within the amounts set forth, show a pronounced beneficial effect during hot working, which is surprising in view of the small amount of the alloying constituent employed. If used in combination, the total amount should Q not exceed 2 per cent. The operation of hot working of this type of base alloy is simply and economically expedited by the use of these improved alloys.

The operation of my invention is well exem- (ii pliiled by the following test which has been found to indicate the relative capacity of different alloys for being hot worked. The test comprises heating test bars mounted in a fixture to a predetermined temperature, immediately fastening go the bar and fixture to a pendulum, and causing the pendulum to swing so that a cross member of the fixture encounters a stop on the frame of the machine with the resultant breaking of the bar in tension on impact. The elongation of the l having the greatest elongation under the impact being considered the most ductile and susceptible to hot working without exhibiting cracks. An exceptionally high correlation has been established between the results 01' this test and the actual behavior of alloys when rolled, extruded, pressed, or forged. The test has therefore come to be treated as a reliable guide in ascertaining the relative workability oi diflerent alloys at elevated temperatures.

The effect of lead, thallium, and cadmium is illustrated in alloys of the composition indicated below which were extruded and heated to a temperature oi 550 Fahrenheit, 600 Fahrenheit, the practicable minimum hot working temperature, 650 Fahrenheit, and 700 Fahrenheit, and broken in tension under impact. The temperature to which the particular bars were heated 2,127,258 broken test piece is then measured, the alloy manganese, 0.05 to 0.25 per cent calcium, 0.1 to 1.3 per cent zinc. and 0.2 to 0.75 per cent of at least one of the metals lead. thallium, and cadmium are particularly desirable in making wrought articles.

The alloy may be produced in any suitable manner. I prefer, however, to add the heavy low melting point metals to the melt in elemental form, stirring the liquid bath sufllciently to prevent segregation or settling of the added substance.

I claim:

I. A magnesium base alloy containing from 5 to 10 per cent aluminum, 0.1 to lper cent manganese, 0.1 to 1.5 per cent zinc, 0.05 to 0.5 per cent calcium. and 0.1 to l per cent thallium, and characterized by improved ductility and freedom from hot-shortness under mechanical deformation at elevated temperatures.

2. A magnesium base alloy composed of 6.5 per and the elongation of the broken test pieces are also shown in the table below. cent aluminum, 0.5 per cent zinc, 0.3 per cent Composition Percent elongation In 2" atu Zn Mn Cu Pb Tl d m" F. 000 r. can" 1. 100W.

0. s o. s n. a o. 1 21. a 21 s 10.0 as 0.5 as 0.1 0.: $4.0 41.1 as. 1 12.5 as 0.5 as o. 1 0.5 30.2 41. 1 15.8 10.0 5.5 0.5 0.3 0.1 0.7 32.0 31.8 mi 15.7 as 0.5 0.: at as an 40.2 30.5 222 as 0.5 0.3 0.1 0.11 am are set 12.4

From the i'oregoing data it is at once apparent that the elongation .o! the basic magnesium-aluminum-zlnc-manganese-calcium alloy decreases rapidly about 600 Fahrenheit, whereas the alloys containing lead, thallium, or cadmium show a much lower diminution in this property with a rise in temperature above 600 Fahrenheit. Furthermore, it is to be observed that the latter alloys show a better ductibillty at all the temperatures than does the normal product.

While magnesium base alloys composed of magnesium, from about 5 to per cent aluminum, 0.1 to 1 per cent manganese, 0.05 to 0.5 per cent calcium, 0.1 to 1.5 per cent zinc, and 0.1 to 1 per cent of at least one of the group of elements lead, thallium, and cadmium, may be satisfactorily hot worked; I have found that those alloys which are composed oi magnesium, from about 6 to 9 per cent aluminum, 0.2 to 0.8 per cent CERTIFICATE Patent No. 2,127,253.

EDWARD F. FISCHER.

It is hereby certified that error manganese, 0.1 per cent calcium, and 0.5 per cent thallium, the balance being magnesium.

3. A magnesium base alloy containing from 5 to 10 per cent aluminum, 0.1 to l per cent manganese, 0.1 to 1.5 per cent zinc, 0.05 to 0.5 per cent calcium, and 0.1 to 1 per cent each of lead and thallium, and characterized by improved ductility and freedom from hot-shortness under mechanical deformation at elevated temperatures.

4. A magnesium base alloy containing from 5 to 10 per cent aluminum, 0.1 to 1 per cent manganese, 0.1 to 1.5 per cent zinc, 0.05 to 0.5 per cent calcium, and 0.1 to 1 per cent each or lead, thallium and cadmium, and characterized by improved ductility and freedom from hot-shortness under mechanical deformation at elevated temperatures.

EDWARD F. FISCHER.

OF CORRECTIQN.

August 16, 1958.

appearsin the printed specification of the above numbered patent requiring correction as follows: Page 2, first column, line 56,",for "about" read above; andthat the said. Letters Patent should be read with this correction therein that the same may'coniorm to the record of the case in the PatentOffice.

Signed and sealed this 25th day of October, A. D. 1938.

(Seal) Henry v.Van Aredale Acting Commissioner of Patents.

having the greatest elongation under the impact being considered the most ductile and susceptible to hot working without exhibiting cracks. An exceptionally high correlation has been established between the results 01' this test and the actual behavior of alloys when rolled, extruded, pressed, or forged. The test has therefore come to be treated as a reliable guide in ascertaining the relative workability oi diflerent alloys at elevated temperatures.

The effect of lead, thallium, and cadmium is illustrated in alloys of the composition indicated below which were extruded and heated to a temperature oi 550 Fahrenheit, 600 Fahrenheit, the practicable minimum hot working temperature, 650 Fahrenheit, and 700 Fahrenheit, and broken in tension under impact. The temperature to which the particular bars were heated 2,127,258 broken test piece is then measured, the alloy manganese, 0.05 to 0.25 per cent calcium, 0.1 to 1.3 per cent zinc. and 0.2 to 0.75 per cent of at least one of the metals lead. thallium, and cadmium are particularly desirable in making wrought articles.

The alloy may be produced in any suitable manner. I prefer, however, to add the heavy low melting point metals to the melt in elemental form, stirring the liquid bath sufllciently to prevent segregation or settling of the added substance.

I claim:

I. A magnesium base alloy containing from 5 to 10 per cent aluminum, 0.1 to lper cent manganese, 0.1 to 1.5 per cent zinc, 0.05 to 0.5 per cent calcium. and 0.1 to l per cent thallium, and characterized by improved ductility and freedom from hot-shortness under mechanical deformation at elevated temperatures.

2. A magnesium base alloy composed of 6.5 per and the elongation of the broken test pieces are also shown in the table below. cent aluminum, 0.5 per cent zinc, 0.3 per cent Composition Percent elongation In 2" atu Zn Mn Cu Pb Tl d m" F. 000 r. can" 1. 100W.

0. s o. s n. a o. 1 21. a 21 s 10.0 as 0.5 as 0.1 0.: $4.0 41.1 as. 1 12.5 as 0.5 as o. 1 0.5 30.2 41. 1 15.8 10.0 5.5 0.5 0.3 0.1 0.7 32.0 31.8 mi 15.7 as 0.5 0.: at as an 40.2 30.5 222 as 0.5 0.3 0.1 0.11 am are set 12.4

From the i'oregoing data it is at once apparent that the elongation .o! the basic magnesium-aluminum-zlnc-manganese-calcium alloy decreases rapidly about 600 Fahrenheit, whereas the alloys containing lead, thallium, or cadmium show a much lower diminution in this property with a rise in temperature above 600 Fahrenheit. Furthermore, it is to be observed that the latter alloys show a better ductibillty at all the temperatures than does the normal product.

While magnesium base alloys composed of magnesium, from about 5 to per cent aluminum, 0.1 to 1 per cent manganese, 0.05 to 0.5 per cent calcium, 0.1 to 1.5 per cent zinc, and 0.1 to 1 per cent of at least one of the group of elements lead, thallium, and cadmium, may be satisfactorily hot worked; I have found that those alloys which are composed oi magnesium, from about 6 to 9 per cent aluminum, 0.2 to 0.8 per cent CERTIFICATE Patent No. 2,127,253.

EDWARD F. FISCHER.

It is hereby certified that error manganese, 0.1 per cent calcium, and 0.5 per cent thallium, the balance being magnesium.

3. A magnesium base alloy containing from 5 to 10 per cent aluminum, 0.1 to l per cent manganese, 0.1 to 1.5 per cent zinc, 0.05 to 0.5 per cent calcium, and 0.1 to 1 per cent each of lead and thallium, and characterized by improved ductility and freedom from hot-shortness under mechanical deformation at elevated temperatures.

4. A magnesium base alloy containing from 5 to 10 per cent aluminum, 0.1 to 1 per cent manganese, 0.1 to 1.5 per cent zinc, 0.05 to 0.5 per cent calcium, and 0.1 to 1 per cent each or lead, thallium and cadmium, and characterized by improved ductility and freedom from hot-shortness under mechanical deformation at elevated temperatures.

EDWARD F. FISCHER.

OF CORRECTIQN.

August 16, 1958.

appearsin the printed specification of the above numbered patent requiring correction as follows: Page 2, first column, line 56,",for "about" read above; andthat the said. Letters Patent should be read with this correction therein that the same may'coniorm to the record of the case in the PatentOffice.

Signed and sealed this 25th day of October, A. D. 1938.

(Seal) Henry v.Van Aredale Acting Commissioner of Patents.