US2221254A - Magnesium base alloy - Google Patents

Description

Patented Nov. 12, 1940 i 2,221,254

UNITED STATES PATENT OFFICE I I 2,221,254 MAGNESIUM BASE ALLOY Joseph D. Hanawalt and John C. McDonald, Midland, Mich assignors to The Dow Chemical Company, Midland, Mlch., a corporation of Michigan v No Drawing. Application November 13, 1939,

Serial No. 304,131 I 3 Claims. (Cl. 75-168) .This invention relates to magnesium base alhigh degree 01' ductility, do have exceptionally loys. It more particularly concerns alloys of this high tensile and yield properties, thus making nature having improved physical properties, such them very suitable for use in castin operations. I as high tensile and yield strengths associated with The f l win table, which lists some 9 the n a sufficient degree of ductility or formabillty to- P p s S et metal e from 0111' new permit relatively sharp bends to be made wlthternary alloy. as we s t p o e of the out the article developing external cracks. related paren i y magnesium 9 having Magnesium alloys are being widely used in a similar composition, illustrates theimproveous structural and mechanical arts, where a light ment in strength characteristics of the new a weight metal is highly desirable, such as for use 3:22 g fi gi g s fi fi g g z the fifigfg g i ure of the ductility or iormability oi the alloys.

to make sheet metal articles requiring forming "I'able Nominal composition in percen Annealed v Oold rolled (remainder-magnesium) Y Yield Tensile n Percent Yield Tensile Percent I Mn Sr strength in strength in elongatiolr strength in strength in elongation 2 lbsJsq. in. lbs/sq. in. in 2 inches lbsJsq. in. lbeJeq. in. in 2 inches z -i 10,000 33,000 4 23,000 31,000 2 0. 6 16, 000 so, 000 9 24, 000 31, 000 8 3 0.5 23,000 35,000 9 27,000 34,000 5 25 operations, such as bending, drawing, and the The properties listed in the above table under like, has not progressedtas rapidly, due to the the section headed by the term annealed were fact that, in genera-1, alloys of good formability obtained by first rolling the alloys at a temperado not possess the most desirable characteristics tur b t b t 00 t 300 F" and t as regards their yield and tensile strengths. fter annealing them at various temperatures 80 It s ac rd y t e vp nc p l ject of e through a temperature range of from 400 to inv nti o p v d a a iu s a y \800 F. The properties selected for the table which y be rolled into Sheet the like, 9 were those of the annealed specimens which ex- SeSSing a sufficient deg e of ductility hibited the maximum elongation. The properties 3 ability be bent drawn, othfamrise shaped listed under the section headed cold rolled were and still possess high tensile and yield strengths. obtained by subjecting specimens of t alloys Other objects and advantages of the invention which had b hot rolled a temperature be apparent as h dasmptim the invenfrom 600-to 800 F. to additional rolling in the proceeds cold state, to bring about a total reduction in 40 Our invention resides in the discovery that a thickness of from 2 to 10 per cent. The prone 4o magnesmm base alloy composed f 0' to 3 ties selected for the table were those of the cold per cent of manganese and from to 1 per cent rolled specimens which showed the greatest terlof strontium, the balance being substantially all I slle and yield strengths, whlle having at least a magnesium, is endowed with the afore-mentioned liper cent elongation in 2 inches. I

5 properties. While the properties of high tensile a and yield strengths, together with a sufilclent By cmpaflsn the Pmperties listed degree of formability, are manifest over the enw above it will be served that t tire range of composition indicated, we have bmed Pmpertles of our new ternary l found that, in general, the preferred combinato the P s n binary "l tion of properties, such as high tensile and yield mm alloys havmg comparable Percentales 50 strengths coupled withgood ductility, is found Y ingredientsxa it Wm be 7 in alloys containing from 1 to 3 er cent of mannoted hat in th a n a st the p im ganese and from 0.1 to 0.6 per cent of strontium. Showed a marked improvement in yi d n h Alloys containing the higher percentages of alover that of the related binary alloys without 1 loying ingredients, while not possessing such a any loss in per cent elongation. Similarly the rolled state where the new ternary alloy shows improvement in yield and tensile properties, as

- well as in elongation. Similarly in other portions of the composition range improvement in these properties will also be observed. Further, the new alloy has highly desirable characteristics as regards resistance to corrosive conditions.

While the alloy is most useful in wrought form, such as sheets due to its formability characteristics it may also be suitably used in making castings, iorgings, extruded forms and the like:

The new alloy may be compounded in any of the ways known to the art, such as by adding the alloying ingredients to the molten magnesium under a suitable flux. The flux should be tree from magnesium chloflde if the strontium content of the alloy is to be above about 0.4 per cent. In thwe instances where an alloy is to be compounded containing less than 0.4 per cent oi strontium, magnesium chloride may. be present in the flux, without exerting deleterious eirect. but in this case it is usually preferable to add the strontium last and without too much stirring in order that the loss of strontium into the flux will be substantially prevented.

We claim:

1. A magnesium base alloy containing from 0.1 to 3 percent of maganese and from 0.05 to l per cent or strontium,,the balance being magnesium.

2. A magnesium base alloy containing i'rom l to 3 per cent or manganese and from 0.1 to 0.6 per cent ot strontium, the balance being magnesium.

3. A magnesium base alloy containing from 1 to 2 per cent of manganese and 0.5 per cent of strontium, the balance being magnesium.

7 JOSEPH D. HANAWALT.

JOHN C. McDONALD.