Method of manufacturing an aluminium alloy rolled product
Described herein is a method of manufacturing an aluminium alloy rolled product of a heat-treatable aluminium alloy, comprising: semi-continuous casting a heat-treatable aluminium alloy into a rolling ingot; homogenizing of the rolling ingot to a peak metal temperature (PMT) and whereby said aluminium alloy has a specific energy associated with a DSC signal less than 2J/g in absolute value; hot rolling of the rolling ingot in multiple hot rolling steps into a hot rolled product having a final rolling gauge of at least 1 mm, whereby the hot rolled product during at least one of the last three rolling steps has a temperature less than 50° C. below PMT; quenching of the hot rolled product at final rolling gauge from hot-mill exit temperature to below 175° C.; optionally stress relieving and ageing of the quenched and optionally stress relieved hot rolled product.
1 . A method of manufacturing an aluminium alloy rolled product of a heat-treatable aluminium alloy having a thickness of at least 1 mm, comprising the steps of:
(a) semi-continuous casting a heat-treatable aluminium alloy into a rolling ingot having a thickness of at least 250 mm;
(b) preheating and/or homogenizing of the rolling ingot to a peak metal temperature (PMT) of less than 530°° C., wherein after said preheating and/or homogenizing the rolling ingot exhibits a specific energy associated with a Differential Scanning Calorimetry (DSC) signal less than 2 J/g in absolute value;
(c) hot rolling of the rolling ingot in multiple hot rolling steps into a hot rolled product having a final rolling gauge of at least 10 mm, wherein hot rolling occurs in at least three hot rolling steps whereby the hot rolled product during at least one of the last three rolling steps has a temperature less than 50° C. below PMT (° C.);
(d) quenching of the hot rolled product at final rolling gauge from hot-mill exit temperature to below 175° C.;
(e) optionally stress relieving of the quenched and hot rolled product at final rolling gauge; and
(f) ageing of the quenched and optionally stress relieved hot rolled product.
2 . The method according to claim 1 , wherein the method is free from any solution heat-treatment following the hot rolling to a final hot rolling gauge of step (c).
3 . The method according to claim 1 , wherein the quenching during step (d) is performed in-line with at least the last hot rolling step.
4 . The method according to claim 1 , wherein the aluminium alloy is selected from the group of 2XXX-, 6XXX, and 7XXX-series aluminium alloys.
5 . The method according to claim 1 , wherein after said preheating and/or homogenizing, the rolling ingot exhibits a specific energy associated with a DSC signal less than 1.0 J/g in absolute value.
6 . The method according to claim 1 , wherein for 2XXX-series aluminum alloy products the PMT for preheating and/or homogenizing is at a temperature of from 430° C. to 505° C., and wherein for 7XXX-series aluminium alloy products the PMT for preheating and/or homogenizing is at a temperature of from 430° C. to 490° C.
7 . The method according to claim 1 , wherein the hot-mill entry temperature is less than 40° C. below the PMT of the aluminium alloy.
8 . The method according to claim 1 , wherein the hot-mill exit temperature of the hot rolled product at final rolling gauge is less than 40° C. below the PMT of the aluminium alloy.
9 . The method according to claim 1 , wherein step (e) is performed and wherein during step (e) the stress relieving is by stretching in a range of 0.5% to 8% of its original length.
10 . The method according to claim 1 , wherein the hot rolled product at final hot rolling gauge is 25.4 mm or more.
11 . The method according to claim 1 , wherein during step (c) the rolling ingot is hot rolled in a first series of hot rolling steps to an intermediate hot rolled gauge, followed by an intermediate heating step and then in a second series of hot rolling steps hot rolled to final hot rolled gauge of at least 10 mm.
12 . The method according to claim 11 , wherein the intermediate heating step is to less than 40° C. below the PMT of the aluminium alloy.
13 . The method according to claim 1 , wherein the aluminium alloy is a 2XXX-series aluminium alloy having composition comprising, in wt. %:
Cu
1.9% to 7%,
Mg
0.3% to 2%,
Mn
up to 1.2%,
Si
up to 0.4%,
Fe
up to 0.4%,
Cr
up to 0.35%,
Zn
up to 0.4%,
Ti
up to 0.15%,
Zr
up to 0.25,
V
up to 0.25%, balance being aluminium and impurities.
14 . The method according to claim 1 , wherein the aluminium alloy is a 6XXX-series aluminium alloy having a composition comprising, in wt. %:
Si
0.2% to 1.7%,
Mg
0.1% to 1.5%,
Fe
up to 0.5%,
Cu
up to 1.0%,
Mn
up to 1.0%,
Cr
up to 0.3%,
Ti
up to 0.15%,
Zn
up to 1.0%, balance being aluminium and impurities.
15 . The method according to claim 1 , wherein the aluminium alloy is a 7XXX-series aluminium alloy having a composition comprising, in wt. %:
Zn
4% to 9.8%,
Mg
1% to 3%,
Cu
up to 2.5%,
and optionally one or more elements selected from the group consisting of:
Zr up to 0.3%, Cr up to 0.3%, Mn up to 0.45%,
Ti up to 0.15%, Sc up to 0.5%, and Ag up to 0.5%,
Fe
up to 0.3%,
Si
up to 0.3%, balance being aluminum and impurities.