US2124555A

US2124555A - Magnesium base alloy

Info

Publication number: US2124555A
Application number: US156942A
Authority: US
Inventors: John A Gann
Original assignee: Dow Chemical Co
Current assignee: Dow Chemical Co
Priority date: 1937-08-02
Filing date: 1937-08-02
Publication date: 1938-07-26
Anticipated expiration: 1955-07-26

Description

Patented July 26, 1938 i v 4 UNITED, STATES PATENT OFFICE MAGNESIUM miss ALLOY John A. Gann, Midland, Mien, assignor to The Dow Chemical Company, Midland, Mich., a corporation of Michigan No Drawing. Application August 2, 1937, Serial 3 Claims. (Cl. 75168) The present invention relates to magnesium 9.1- Solution heat treated alloys loys and more particularly to those in which magnesium is the predominant constituent. Nominal composition in perjcent Most of the present commercial uses for mag- (MFmmainde') 'fg gg Yield strength nesium alloys are due to their high strength and lhlsq. in.

high strength-weight ratio. If these character M ed istics could be further improved, the field of application of these light weight alloys would be 0 2 0.2 32,000 10,000 greatly extended. g 81% i The principal object of this invention is to produce magnesium alloys having improved physical 3 3 81% 3;;33 3:383 properties. A more specific object is to produce 2 s 0.2 e 34,000 12,200 magnesium alloys that are amenable to heat treatment. Other objects and advantages will appear Solution heat treated and aged u as the description proceeds.

This invention is based on the discovery that the 6 Q 2 32, 900 10 200 properties of magnesium-aluminum-cadmium- 0 2 0 2 37,500 14,900 manganese alloys as described in United States 3 3 3% g 33% $1288 Patent No. 1,959,913 may be improved to a very d marked extent by the addition of relatively small 3 g 8:; g:% I ,25% amounts of zinc, without appreciably increasing 2 8 6 37,000 19,200 the specific gravity of the alloy. I have discoved a maximum p ty improvement is I have likewise discovered that the addition tained when these alloys are subjected to the well of zinc t magnesjm-aluminum-cadjum-manga..

known methods of solution heat treatment and nese alloys has resulted in a marked improvement solution heat treatment plus aging. I have also 'in corrosion resistance. This beneficial effect oi.' found that the advantages occurring from the ad- Z c s Particularly PrOhOlmCed in the s Of the dition of zinc are present when approximately cast and the solution heat treated and aged y 0,5 t 3 per cent 1 zinc are added to magnesium although it is evident in some of the solution heat alloys containing from about 1 to 12 per cent of treated alloysh following table illustrates aluminum, f about 0 to 10 per cent of this improvement as obtained from alternate immium, and from about 0.1 to 05. per cent of mersion tests conducted for one week in a 3 per mangane-Se 7 cent salt solution.

Specific examples of the property improvements that result in the production of my new alloy by Nmniml in am. Loi it .da

adding zinc to the well known magnesium-aim" 825 8 mm as nwegh mg/cm y minum-cadmium-manganese alloys'are shown in thefollowing tables where illustrations are given M e Mn Zn cast i S P H TI of cast, solution heat treated, and solution heat treated and aged alloys. 6 2 M L94 n1 2 i at: 2'? 2;: cast e 2 012 0 0:50 8:0 24.7

Nominal composition in percent 1 S. H. 'l.=8olution heat treated. i (Mg=remainder) l a'tlensgitlie1 Yied strength I S. P. H. T.-=Solutlon heat treated and aged.

ran 1 I -l q- I have furthermore discovered that if my im- M ed M- proved alloy likewise contains approximately 0.5

I to 10 per cent oi! lead, or, in other words, if the g g 3:; 2 33 $133 improved alloy-is obtainedby adding both lead 2 8 o 2 25 200 and zinc to the magnesium-aluminum cadmi-um- 2 s 012 4 281700 manganese alloy, that the resultant composition 2 8 6 10,200 is superior to that obtained when only one of the v metals, lead or zinc, is added to the known mairnesium aluminum cadmium manganese alloy. 1 This is illustrated, for example, by the yield strength and hardness data in the following table:

Nominal composltion in per cent (Mg= remam- Yield Brine] der) Condition strength, hardlb./sq. in. ness Al Cd Mn Pb Zn 1 S. H. T.=Solution heat treated. l S. P. H. T.=Solution heat treated and aged.

When the alloy is to be used for the production of castings, I normally prefer to use compositions containing approximately 85 to 92 per cent of magnesium, from 4 to 10 per cent of aluminum, 3 from 1 to 6 per cent of cadmium, from 0.1 to 0.3 percent of manganese, and from 2 to 6 per cent of zinc. Where lead is likewise required, it should be present in amounts ranging from about 1 to 6 per cent. When the alloy is to be used in plastic deformation operations it should, in general, contain 90 to 96 per cent of magnesium, and the various alloying elements in the following proportions: 1 to 8 per cent of aluminum, 0.5 to 3- per cent of cadmium, 0.1 to 0.5 per cent 'of manganese, 0.5 to 2 per cent of lead, and 0.5 to 2 per cent of zinc.

My new polynary alloys may be prepared by the methods usually employed for melting and alloying metals with magnesium, such as adding the respective alloying metals singly or jointly to a bath of molten magnesium protected from oxidation by a cover of fluid flux. The solution heat treatment for the zinc-free alloys may consist in heating the material for 20 hours at 430 (3., followed byair cooling, or, when zinc is present in the alloy, 12 hours at 320 C. plus 16 hours at 420 C., followed by air cooling. The aging treatment consists of approximately 16 hours heating at 175 C., subsequent to the above solution heat treatment. Plastic deformation operations, such as extruding, forging, and rolling are best conducted at temperatures between 300 and 5 I Other modes of applying the principle of my invention may be employed instead of those explained, change being made as regards the ingredients and the steps herein disclosed, pro- 20 vided those stated by any of the following claims or their equivalent be employed.

I particularly point out and distinctly claim as my. invention I 1. A magnesium-base alloy containing from ap- 'ance being magnesium.

2. A magnesium-base alloy consisting of approximately 4 to 10'per cent of aluminum, and from about 1 to 6 per cent of cadmium, and from about 0.1 to 0.3 per cent of manganese, and from about 2 to 6 per cent of zinc, the balance being' magnesium.

3. A magnesium-base alloy consisting of approximately 6 per cent of aluminum, and 2 per cent of cadmium, and 0.2 per cent of manganese, and 2 per cent of zinc, the balance being 40 magnesium.

JOHN A. GANN.