7XX aluminum casting alloys, and methods for making the same
New shape-cast 7xx aluminum alloys products are disclosed. The new shape-cast products may include from 3.0 to 8.0 wt. % Zn, from 1.0 to 3.0 wt. % Mg, where the wt. % Zn exceeds the wt. % Mg, from 0.35 to 1.0 wt. % Cu, where the wt. % Mg exceeds the wt. % Cu, from 0.05 to 0.30 wt. % V, from 0.01 to 1.0 wt. % of at least one secondary element (Mn, Cr, Zr, Ti, B, and combinations thereof), up to 0.50 wt. % Fe, and up to 0.25 wt. % Si, the balance being aluminum and other elements, wherein the aluminum casting alloy include not greater than 0.05 wt. % each of the other elements, and wherein the aluminum casting alloy includes not greater than 0.15 wt. % in total of the other elements.
1. A method comprising:
(a) shape casting a 7xx aluminum casting alloy into a shape-cast part, wherein the 7xx casting alloy consists of:
(i) from 3.0 to 8.0 wt. % Zn;
(ii) from 1.0 to 3.0 wt. % Mg;
wherein the wt. % Zn exceeds the wt. % Mg;
(iii) from 0.35 to 1.0 wt. % Cu;
wherein the wt. % Mg exceeds the wt. % Cu;
(iv) from 0.05 to 0.30 wt. % V;
(v) from 0.01 to 1.0 wt. % of at least one secondary element, wherein the at least one secondary element is selected from the group consisting of Mn, Cr, Zr, Ti, B, and combinations thereof;
wherein, when present, the aluminum casting alloy includes not greater than 0.50 wt. % Mn as a secondary element;
wherein, when present, the aluminum casting alloy includes not greater than 0.40 wt. % Cr as a secondary element;
wherein, when present, the aluminum casting alloy includes not greater than 0.25 wt. % Zr as a secondary element;
wherein, when present, the aluminum casting alloy includes not greater than 0.25 wt. % Ti as a secondary element;
wherein, when present, the aluminum casting alloy includes not greater than 0.05 wt. % B as a secondary element;
(vi) up to 0.50 wt. % Fe
(vii) up to 0.25 wt. % Si; and
(viii) the balance being aluminum and other elements, wherein the aluminum casting alloy includes not greater than 0.05 wt. % each of the other elements, and wherein the aluminum casting alloy includes not greater than 0.15 wt. % in total of the other elements;
wherein the shape casting process is selected from the group consisting of low pressure die casting, gravity permanent mold casting, semi-permanent mold casting, sand mold casting and centrifugal casting;
(b) solution heat treating and then quenching the shape-cast part; and
(c) artificially aging the shape-cast part to a T6 or T7 temper:
wherein the shape-cast part is stress corrosion cracking (SCC) resistant being capable of passing SCC testing in accordance with ASTM G109-97(2011), wherein the SCC testing is conducted at a net stress of 240 MPa for 14 days, wherein 5 specimens are tested, and wherein all 5 specimens do not fail during the 14 days of testing.
2. The method of claim 1 , wherein the shape casting process is low pressure die casting.
3. The method of claim 1 , wherein the 7xx casting alloy includes not greater than 0.20 wt. % V.
4. The method of claim 1 , wherein the 7xx casting alloy includes not greater than 0.18 wt. % V.
5. The method of claim 1 , wherein the 7xx casting alloy includes not greater than 0.16 wt. % V.
6. The method of claim 1 , wherein the 7xx casting alloy includes not greater than 0.14 wt. % V.
7. The method of claim 1 , wherein the 7xx casting alloy includes at least 0.07 wt. % V.
8. The method of claim 1 , wherein the 7xx casting alloy includes at least 0.09 wt. % V.
9. The method of claim 1 , wherein the shape-cast part is an automobile part.
10. The method of claim 9 , wherein the automotive part is a body-in-white (BIW) part or a suspension part.