High strength cast aluminium alloy for high pressure die casting

Abstract

A high strength cast aluminium alloy for high pressure die casting comprising magnesium silicide 6 to 12 wt. %, magnesium 4 to 10 wt. %, X element from copper (Cu), zinc (Zn), silver (Ag), gold (Au) and Lithium (Li) at 3 to 10 wt. %, manganese 0.1 to 1.2 wt. %, iron max. 1.5 wt. %, titanium or the other grain refining elements from Cr, Nb, and Sc with 0.02 to 0.4 wt. %, and impurity and minor alloying elements at a level of maximum 0.3 wt. % and totally <0.5% of at least one element selected from scandium (Sc), zirconium (Zr), Nickel (Ni), chromium (Cr), niobium (Nb), gadolinium (Gd), calcium (Ca), yttrium (Y), antinomy (Sb), bismuth (Bi), neodymium (Nd), ytterbium (Yb), vanadium (V), chromium (Cr), beryllium (Be) and boron (B) and the remainder aluminium.

Claims

1. An aluminium alloy comprising: magnesium silicide from 5 to 14 wt %, excess magnesium from 4 to 12 wt %, from 2 to 12 wt % element X, wherein element X is selected from the group consisting of copper (Cu), zinc (Zn), silver (Ag), gold (Au), lithium (Li), and combinations thereof, manganese from 0.1 to 1.2 wt %, titanium from 0.02 to 0.4 wt %, not more than 1.5 wt % iron, and impurity elements at a level of maximum 0.3 wt % for any one element and in total not more than 0.3 wt %, and the remainder of the alloy is aluminium.

2. An aluminium alloy comprising: magnesium silicide from 6 to 10 wt %, excess magnesium from 4 to 9 wt %, from 3 to 8 wt % of element X, wherein element X is selected from the group consisting of copper (Cu), zinc (Zn), silver (Ag), gold (Au), lithium (Li), and combinations thereof, manganese from 0.3 to 0.8 wt %, titanium from 0.08 to 0.3 wt %, not more than 0.7 wt % iron, and impurity elements at a level of maximum 0.2 wt % for any one element and in total not more than 0.25 wt %, and the remainder of the alloy is aluminium.

Description

EXAMPLE A

(1) An alloy that has the following composition: magnesium silicide from 5 to 14 wt. %, magnesium from 3 to 12 wt. %, X element from copper (Cu), zinc (Zn), silver (Ag), gold (Au) and Lithium (Li) from 2 to 12 wt. %, Manganese from 0.1 to 1.2 wt. %, iron maximum 1.5 wt. %, titanium or the other grain refining elements from Cr, Nb, and Sc with 0.02 to 0.4 wt. %, and impurity and minor alloying elements at a level of maximum 0.3 wt. % and totally <0.5% of at least one element selected from zirconium (Zr), niobium (Nb), gadolinium (Gd), calcium (Ca), yttrium (Y), antinomy (Sb), bismuth (Bi), neodymium (Nd), ytterbium (Yb), vanadium (V), chromium (Cr), beryllium (Be) and boron (B). and the remainder aluminium.

EXAMPLE B

(2) An alloy that has the following composition: magnesium silicide from 6 to 10 wt. %, magnesium from 4 to 9 wt. %, X element from copper (Cu), zinc (Zn), silver (Ag), gold (Au) and Lithium (Li) from 3 to 8 wt. %, manganese from 0.3 to 0.8 wt. %, titanium or the other grain refining elements from Cr, Nb, and Sc with 0.08 to 0.3 wt. %, iron maximum 0.7 wt. %, impurity and minor alloying elements at a level of maximum of 0.2 wt. % and totally <0.4% of at least one element selected from zirconium (Zr), niobium (Nb), gadolinium (Gd), calcium (Ca), yttrium (Y), antinomy (Sb), bismuth (Bi), neodymium (Nd), ytterbium (Yb), vanadium (V), chromium (Cr), beryllium (Be) and boron (B). and the remainder aluminium.

EXAMPLE C

(3) An alloy that has the following composition: magnesium silicide from 6 to 9 wt. %, magnesium from 5 to 7 wt. %, X element from copper (Cu), zinc (Zn), silver (Ag), gold (Au) and Lithium (Li) from 3 to 6 wt. %, manganese from 0.4 to 0.7 wt. %, titanium or the other grain refining elements from Cr, Nb, and Sc with 0.10 to 0.25 wt. %, iron maximum 0.3 wt. %, impurity and minor alloying elements at a level of maximum of 0.2 wt. % and totally <0.25% of at least one element selected from zirconium (Zr), niobium (Nb), gadolinium (Gd), calcium (Ca), yttrium (Y), antinomy (Sb), bismuth (Bi), neodymium (Nd), ytterbium (Yb), vanadium (V), chromium (Cr), beryllium (Be) and boron (B). and the remainder aluminium.

(4) The results of the tensile tests carried out are listed in Table 1. In the case of the alloys listed therein the alloys of tests 1 to 8 are in accordance with the invention; the reference alloy represents an alloy the composition of which corresponds to an alloy in accordance with the invention, but does not contain any grain refiner.

(5) TABLE-US-00001 TABLE 1 Tensile Yield Breaking strength strength elongation (MPa) (MPa) (%) 1 Al8Mg.sub.2Si6Mg4.5X0.6Mn0.2Ti 350 250 2.8 2 Al6Mg.sub.2Si6Mg4X0.6Mn0.2Ti 330 230 3.5 3 Al8Mg.sub.2Si6Mg4.3X0.6Mn0.3Cr 345 234 3.6 4 Al8Mg.sub.2Si6Mg3.5X0.6Mn 350 245 2.1 5 Al10Mg.sub.2Si4Mg3.5X0.6Mn 330 230 2.5 6 Al8Mg.sub.2Si6Mg4.5X 340 235 4.0 7 Al8Mg.sub.2Si6Mg4X0.6Mn0.3Fe 325 175 6.1 8 Al8Mg.sub.2Si6Mg0.6Mn 340 180 7.0 9 Al8Mg.sub.2Si6Mg 330 170 7.5

(6) As it can be seen from the table, the adding of X element can result in a significant increase of the yield strength and UTS with accepted elongation. The alloys under as-cast condition can offer a high yield strength and ultimate tensile strength with reasonable ductility. The mechanical properties can be further improved with a quick T6 treatment. It is also seen that the grain refinement is useful in this alloy to improve mechanical properties.

(7) In an embodiment the alloy is subjected to a quick heat treatment for further improvement of mechanical properties. The quick heat treatment consists of two stages: a short time of solution treatment and a short time of ageing treatment. The results of the tensile tests carried out for the mechanical properties after solution and/or ageing treatment are listed in Table 2, in which the high temperature over 450 C. is for solution treatment and the low temperature below 200 C. is for ageing treatment. The process only with high temperature treatment indicates that the alloy is treated by solution only and no ageing is applied to the alloy. Similarly, the process only with low temperature treatment indicates that the alloy is treated by ageing only and no solution is applied to the alloy. In the case of the alloys listed therein the alloys of tests 1 to 8 are in accordance with the invention.

(8) TABLE-US-00002 TABLE 2 Tensile Yield strength strength Elongation (MPa) (MPa) (%) 1 Al8Mg.sub.2Si6Mg4.5X0.6Mn0.2Ti 440 350 4 15 mins@490 C. and 90 mins@180 C. 2 Al8Mg.sub.2Si6Mg4.5X0.6Mn0.2Ti 336 200 7 15 mins@490 C. 3 Al8Mg.sub.2Si6Mg4.5X0.6Mn0.2Ti0.3Cr 440 350 3 15 mins@490 C. and 90 mins@180 C. 4 Al8Mg.sub.2Si6Mg4.5X0.6Mn0.2Ti0.3Cr 380 260 5 15 mins@490 C. 5 Al7Mg.sub.2Si5Mg5X0.6Mn0.2Ti 460 390 3 15 mins@490 C. and 90 mins@180 C. 6 Al7Mg.sub.2Si5Mg5X0.6Mn0.2Ti 445 380 3 10 mins@490 C. and 60 mins@180 C. 7 Al7Mg.sub.2Si5Mg4X0.6Mn0.2Ti 420 340 3 15 mins@490 C. and 90 mins@180 C. 8 Al8Mg.sub.2Si6Mg4.5X0.6Mn 410 330 2.5 15 mins@490 C. and 90 mins@180 C.

(9) As it can be seen from the table, the short term solution can increase the elongation and short time of ageing can improve the strength. The best combination is provided by the quick solution and subsequent ageing heat treatment. Therefore, it is a preferred heat treatment in this invention.

(10) All optional and preferred features and modifications of the described embodiments and dependent claims are usable in all aspects of the invention taught herein. Furthermore, the individual features of the dependent claims, as well as all optional and preferred features and modifications of the described embodiments are combinable and interchangeable with one another.

(11) The disclosures in UK patent application number 1402323.8, from which this application claims priority, and in the abstract accompanying this application are incorporated herein by reference.