ARMOUR COMPONENT PRODUCED FROM A 7XXX-SERIES ALUMINIUM ALLOY
Described herein are armour components for civil or military vehicles made of high-strength 7XXX-series aluminium alloys requiring ballistic protection. For example, described herein are armour components used for manufacturing armour hulls and add-on appliqués, which are removable panels to be mounted on the external faces of the military vehicles.
1 . An armour component produced from a 7XXX-series aluminium alloy, wherein the aluminium alloy comprises:
Zn 7.1% to 7.5%,
Mg 1.90% to 2.25%,
Cu 1.3% to 1.8%,
at least 0.05-0.4% of a dispersoid forming element selected from the group consisting of Zr, Sc, V, Hf, Ti, Cr, and Mn,
Ti 0.01% to 0.06%,
Si up to 0.15%,
Fe up to 0.15%,
balance unavoidable impurities and aluminium,
wherein the 7XXX-series aluminium alloy is in the form of a plate having a thickness of 12.7 mm to 76.2 mm;
wherein the 7XXX-series aluminium alloy is over-aged to achieve a combination of:
(i) tensile yield strength in LT-direction >497 MPa,
(ii) ultimate tensile strength in LT-direction >538 MPa,
(iii) elongation in LT-direction >9%, and
(iv) an armour piercing V50 ballistic limit such that meets the requirements of US military spec MIL DTL-32375B (MR) (2021).
2 . The armour component according to claim 1 , wherein the Zn content is in a range of 7.20% to 7.5%.
3 . The armour component according to claim 1 , wherein the Zn content is in a range of 7.30% to 7.5%.
4 . The armour component according to claim 1 , wherein the Zn/Mg ratio is less than 4.
5 . The armour component according to claim 1 , wherein the Zn/Mg ratio is less than 3.9.
6 . The armour component according to claim 1 , wherein the dispersoid forming element comprises Zr in a range of 0.06% to 0.15%.
7 . The armour component according to claim 6 , wherein the Zr content is in a range of 0.08% to 0.14%.
8 . The armour component according to claim 7 , wherein the Zr content is in a range of 0.09% to 0.13%.
9 . The armour component according to claim 1 , wherein the Mg content is in a range of 1.9% to 2.25%.
10 . The armour component according to claim 1 , wherein the Mg content is in a range of 1.95% to 2.20%.
11 . The armour component according to claim 1 , wherein the over-ageing treatment comprises the following 2-step treatment: 4-12 hours at 110° C.-130° C. followed by 4-20 hours at 140° C.-160° C.
12 . The armour component according to claim 1 , wherein the over-ageing treatment comprises the following 2-step treatment: 4-12 hours at 110° C.-130° C. followed by 12-20 hours at 140° C.-160° C.
13 . The armour component according to claim 1 , wherein the over-ageing treatment comprises the following 2-step treatment: 4-12 hours at 110° C.-130° C. followed by 12-18 hours at 140° C.-160° C.
14 . The armour component according to claim 1 , wherein the 7XXX-series aluminium alloy is manufactured with the following steps:
a. casting said alloy into an ingot form;
b. homogenizing said ingot;
c. hot working said ingot to obtain a plate;
d. solution heat treating;
e. quenching;
f. stretching to obtain a permanent elongation from 1% to 3%; and
g. over-ageing at least in two steps, the over-ageing treatment corresponding to the following 2-step treatment: 4-12 hours at 110° C.-130° C. followed by 12-20 hours at 140° C.-160° C.
15 . The armour component according to claim 1 , wherein the 7XXX-series alloy comprises, in wt. %:
Zn 7.1% to 7.5%,
Mg 1.90% to 2.25%,
Cu 1.3% to 1.8%,
Zr 0.06% to 0.15%,
Ti 0.01% to 0.06%,
Si up to 0.15%
Fe up to 0.15%,
balance unavoidable impurities and aluminium.
16 . The armour component according to claim 15 , wherein the Si or the Fe content is up to 0.10 wt. %.
17 . The armour component according to claim 1 , wherein the elongation in LT-direction is >9%.
18 . A method of producing an armour component according to claim 1 , comprising:
a. casting said alloy into an ingot form;
b. homogenizing said ingot;
c. hot working said ingot to obtain a plate;
d. solution heat treating;
e. quenching;
f. stretching to obtain a permanent elongation from 1% to 3%; and
g. over-ageing at least in two steps, the over-ageing heat treatment corresponding to the following two-step heat treatment: 4-12 hours at 110° C.-130° C. followed by 12-20 hours at 140° C.-160° C.
19 . The method according to claim 18 , wherein the over-ageing treatment comprises the following 2-step treatment: 4-12 hours at 110° C.-130° C. followed by 12-20 hours at 140° C.-160° C.
20 . The method according to claim 18 , wherein the over-ageing treatment comprises the following 2-step treatment: 4-12 hours at 110° C.-130° C. followed by 12-18 hours at 140° C.-160° C.