US1968344A - Malleable aluminium alloy - Google Patents

Description

Patented July 31, 1934 UNITED STATES PATENT OFFICE one-half to the firm Diirener Metallwcrke Aktiengesellschatt, Duren, Germany, a jointstock company of Germany No Drawing.

No. 631,301. In 1931 3 Claims.

This invention relates to malleable and agehardenable aluminum alloys. In the employment of aluminum alloys, above all for vehicular construction, and especially in aircraft construction, the constant endeavour,

5 since the invention of the age-hardenable aluminum alloys, has been to improve still further the mechanical properties of these alloys, with a view to lowering the dead weight of the structures. In so doing, importance has been attached, not only to increasing the tensile strength, but also, in particular, to increasing the elastic limit and yield point, which constitutes a factor of almost greater importance. Although it was possible without difliculty to raise the yield point and tensile strength of the aluminum alloys known in the art, by cold working, this treatment could be only applied to a certain extent, since otherwise, other valuable properties such as elongation and capacity for cold working would be too adversely affected thereby. On this account it became necessary to discover alloys endowed, from the outset, with greater strength coupled with satisfactory values with respect to elongation and capacity for cold working.

Exhaustive experiments have now shown that specially high qualities are possessed by aluminum alloys of the following composition:-

Per cent Copper 3 to 5 Magnesium 0.7 to 1.2 Silicon 0.4to 0.7 Manganese 0.6 to 1.4

Remainder aluminum.

Alloys of this composition are still suitably mal- 3 leable, both in the. hot and in the cold states.

For example, an alloy containing 4.0% of cop alloy attains mechanical properties hitherto un- Application August 31, 1932, Serial Germany September 12,

obtainable, namely, .yield points of about 31 to 33 kgs. per sq. mm. and tensile strengths of 48 to 50 kgs. per sq. the elongation receding to about 18 to 20 per cent. 7

Another alloy, containing 4.0% of copper, 1.2% of magnesium, 0.7% of silicon and 1.2% of manganese, exhibits, immediately after quenching from the high temperature treatment, tensile values regarded as normal in the case of the previously known alloys when in the fully age-hardened state. The tensile strength of this alloy is already 37 to 39 kgs. per sq. mm., and the elongation about 20 to 21%. At the same time, however, the yield point of about 19 to 20 kgs. per I sq. mm., is still lower than that of the hitherto known alloys after aging. After being kept for several. days at room temperature, this alloy also attains a yield point of about 31 to 33 kgs. per sq.

cess of either free magnesium or free silicon.

I claim 1. A malleable aluminum alloy which consists of about 4% of copper, about 1% of magnesium, about 0.58% of silicon, and about 1.2% of manganese, the remainder being aluminum.

2. A malleable aluminum alloy which consists of about 4% copper, about 1.2% of magnesium, 1 about 0.7% of silicon, and about 1.2% of manganese, the remainder being aluminum.

3. A malleable aluminum alloy which consists of aluminum with 3 to 5% of copper, 0.6'to 1.4% of manganese, 0.7 to 1.2% of magnesium, and 0.4

-to 0.7% of silicon, the latter two components being so proportioned that they are present almost wholly in the form of the compound magnesium silicide without leaving either free m nesium or silicon.