JPWO2021130636A5 - - Google Patents

Description

On an industrial scale, a process or method for producing rolled sheet, sheet and plate articles of aluminum alloys, particularly heat treated aluminum alloy articles of the 2XXX series, 6XXX series and 7XXX series aluminum alloys, comprises:
(i) a process step of preferably degassing and filtering the aluminum melt prior to casting and then casting an aluminum alloy rolling ingot;
(ii) a process step of preheating and/or homogenizing the rolling ingot;
(iii) hot rolling the ingot to an intermediate or final thickness rolling product, coiled or cut to length, and cooled to ambient temperature; ,
(iv) optionally cold working, e.g. cold rolling, the hot rolled product to final rolled thickness;
(v) for the solution heat treatment ("SHT") of the rolled product, heating from ambient temperature to a target solution heat treatment temperature to remove as much or as little of the soluble elements as zinc, magnesium, manganese and copper; a process step to substantially all solid solution;
(vi) quenching the SHT rolled product to a temperature below 175°C, preferably ambient temperature, for example by one of injection quenching and immersion quenching in water or other suitable quenching agent; a process step (which may also use air and air jets) that prevents or minimizes uncontrolled precipitation of subphases in the aluminum alloy;
(vii) optionally stretching or compressing the SHT and its cooled rolled product to relieve stress and improve flatness of the rolled product;
(viii) Aging, i.e. natural aging or artificial aging, on the rolled product, depending on the heat treatable aluminum alloy and conditions desired, for example to conditions of T3, T4, T6, T7 or T8. , or a process step of performing aging treatment combined with these,
in that order.

Described herein is a method of producing an aluminum alloy rolled product made of a heat treatable aluminum alloy having a thickness of at least 1 mm, comprising: semi-continuously casting the heat treatable aluminum alloy; making a rolling ingot having a thickness of at least 250 mm and homogenizing the rolling ingot to a maximum plate temperature (PMT), whereby in said aluminum alloy, the ratio associated with the DSC signal a step where the energy is less than 2 J/g in absolute value, and hot rolling the rolling ingot in multiple hot rolling steps to a hot rolled product having a final rolled thickness of at least 1 mm; Thereby, the temperature of the hot-rolled product in at least one of the last three times of the rolling process does not fall below the PMT by more than 50 ° C., and the hot-rolled product at the final thickness is quenching from the mill exit temperature to less than 175°C; optionally stress relieving the quenched hot rolled product at final rolled thickness; optionally stress relieved quenched and aging the hot rolled product.

1 shows a schematic flow chart of a prior art method for producing plate articles, for example of 7XXX series aluminum alloys. In a first step 20, a raw material for rolling of a 7XXX series aluminum alloy is cast by a semi-continuous casting method or a continuous casting method. In step 30, the rolling ingot is homogenized and/or preheated, preferably at a temperature in the range of 400°C to 480°C. In step 40, the rolling ingot is hot rolled to thin sheet, and upon exit from the final hot rolling stand is coiled (for thin sheet) and slowly cooled to ambient temperature, or or for thicker rolled products, slow cool to ambient temperature, cut to length, optionally further cold rolled to final thickness in step 50 and then cut to length. . At step 60, at final thickness, the rolled product is subjected to a solution heat treatment, typically at a temperature in the range of 400°C to 480°C, and quenched at step 70. The drawing operation 80 relieves the stress in the rolled product and improves the flatness of the rolled product before an aging operation 90 is performed, for example, by artificially aging to T7651 conditions. 1 shows a schematic flow chart of a method according to the invention for producing plate articles, for example of 7XXX series aluminum alloys. In a first step 20, a rolling stock of a 7XXX series aluminum alloy having a thickness of at least 250 mm is cast by semi-continuous casting, preferably by DC casting. At step 30, the rolling ingot is homogenized. In step 40, the rolling ingot is hot rolled into a hot rolled product having a final hot rolled thickness of at least 1 mm, and upon exit from the hot rolling stand, in step 45, below 175°C, It is preferably quenched to less than 60°C. The hot rolled product is not subsequently annealed or solution heat treated. Optionally, the drawing operation 80 relieves the hot-rolled product of its final hot-roll thickness and improves the flatness of the rolled product before, for example, aging treatment practices common in the art. Aging operation 90 is performed by performing artificial aging treatment to the condition of T7651 using .

Described herein is an alternative method of manufacturing aluminum alloy rolled plate articles. The present invention provides a method for producing aluminum alloy rolled products made from heat treatable aluminum alloys, i.e. sheets, sheats or plates having a thickness as described herein (e.g. , meeting or exceeding the above and other objectives and further advantages, the method comprising:
(a) semi-continuously casting a rolling ingot having a thickness of at least 250 mm;
(b) preheating and/or homogenizing the rolling ingot at a peak metal temperature (“PMT”), whereby said aluminum after said preheating and/or homogenization the specific energy associated with the differential scanning calorimetry (“DSC”) signal in the alloy is less than 2 J/g in absolute value;
(c) hot rolling the rolling ingot, preferably in a plurality of hot rolling steps, to a hot rolled product having a final rolled thickness of at least 1 mm, whereby the rolling step or pass; the temperature of the hot-rolled product in at least one of the last three times of the step does not fall below the PMT by more than 50 ° C.;
(d) quenching the hot rolled product at final hot roll thickness from the hot mill exit temperature to less than 175°C, preferably less than 100°C, most preferably less than 60°C;
(e) optionally relieving the stress of the quenched hot-rolled product of final hot-rolled thickness;
(f) aging, i.e., natural aging or artificial aging, of the optionally stress- relieved and quenched hot-rolled product;
in that order.

Aluminum alloys are provided as ingots or slabs for processing into rolled products by semi-continuous casting methods such as direct chill (DC) casting, electromagnetic casting (EMC) casting and electromagnetic stirring (EMS) casting. In a preferred embodiment, the semi-continuous casting is by DC casting of rolling ingots. The semi-continuously cast rolling ingot has a thickness of at least 250 mm, preferably greater than about 350 mm. Its maximum thickness is about 800 mm, preferably about 600 mm. Start with semi-continuously cast rolling ingots that are at least 250 mm thick compared to using continuously cast ingots that are much thinner (e.g. up to about 40 mm). As a result, the degree of deformation of the rolled product is increased, for example, the constituent grains are refined, and when aging treatment is performed to the final temper, the strength is increased and the damage tolerance is improved. Also, the increased degree of deformation results in good destruction of any oxides in the as-cast structure, if they still exist after the degassing and filtering operations, and reduces their size. becomes significantly smaller. Grain refiners such as those containing titanium and boron or titanium and carbon, as known in the art, may also be used. The Ti content in the aluminum alloy is at most 0.15%, eg in the range 0.01% to 0.1%. Optionally, particularly for high alloying degree 2XXX series aluminum alloys and 7XXX series aluminum alloys, the ingot for rolling by semi-continuous casting is subjected to a temperature in the range of, for example, about 275°C to 450°C, for example, about 300°C to 400°C. C. for up to about 24 hours, eg, 10-20 hours, preferably followed by slow cooling to ambient temperature to relieve stress in the ingot. After the semi-continuous casting of the rolling ingot, the rolling ingot is generally chamfered to remove segregation near the casting surface of the ingot to improve the flatness and surface quality of the rolling ingot. .

In one embodiment, particularly in 2XXX and 7XXX series aluminum alloys, hot-rolled and quenched rolled material at final thickness may be stress relieved . Stress relief can be achieved by cold rolling, stretching, leveling or compression.

In one embodiment, the stress relief and flatness improvement of the rolled product in step (e) is achieved by reducing the cold rolling rate to less than 5% of the original thickness before the cold rolling operation. It is preferably carried out by cold rolling at ambient temperature. Preferably, the cold rolling reduction is less than 3%, more preferably less than 1% of its original thickness. Other than for this purpose in the method according to the invention, no further cold rolling steps or cold rolling operations are performed on the aluminum alloy rolled product.

In another embodiment, the stress relief in step (e) is by leveling in the range of about 0.1% to 5% of the original length to remove the residual stress and reduce the Improve flatness. Preferably, leveling ranges from about 0.1% to 2%, more preferably from about 0.1% to 1.5%. Preferably, the leveling operation is performed at ambient temperature.

In a preferred embodiment, stress relief in step (e) is performed by stretching in the range of about 0.5% to 8% of its original length to relieve its residual stress and improve the flatness of the Preferably, the stretch ranges from about 0.5% to 6%, more preferably from about 1% to 3%. Preferably, the stretching operation is carried out at ambient temperature.

The cast ingot was stress relieved by soaking at 350° C. for about 12 hours and then cooling to ambient temperature.

DSC measurements of stress- relieved specimens in the as-cast condition were performed on a TA Instruments 910 DSC instrument from room temperature at a standard heating rate of 20°C/min until the specimen finally melted. rice field. This measurement yielded a eutectic phase melting peak of 18.7 J/g at 482°C, an S-phase melting peak of 0.3 J/g at 488°C, and a Mg _Si phase melting peak of 0.5 J/g at 542°C, total was shown to be 19.5 J/g.

EXAMPLE Example 1 is a method of producing an aluminum alloy rolled product made of a heat treatable aluminum alloy having a thickness of at least 1 mm, comprising: (a) semi-continuously casting the heat treatable aluminum alloy to a thickness of (b) preheating and/or homogenizing the rolling ingot to a maximum plate temperature (PMT), whereby differential scanning is performed on the aluminum alloy; a specific energy associated with a calorimetric (DSC) signal of less than 2 J/g in absolute value; The hot-rolled product has a final rolled thickness of at least 1 mm, whereby the temperature of the hot-rolled product in at least one of the last three rolling steps is 50°C or more below the PMT (°C). (d) quenching the hot-rolled product at final rolled gauge to less than 175°C from the hot mill exit temperature; and (e) optionally, quenching the hot-rolled product at final rolled gauge and (f) optionally aging the stress-relieved and quenched hot rolled product.

Example 9 shows that in step (e) the stress relief is in the range of about 0.5% to 8% of its original length, preferably about 0.5% to 6% of its original length. A method according to any preceding or hereinafter illustrated example wherein the stretching is by stretching in the range of .

Claims (15)

1. A method for producing an aluminum alloy rolled product made of a heat treatable aluminum alloy having a thickness of at least 1 mm, comprising:
(a) semi-continuously casting a heat treatable aluminum alloy into a rolling ingot having a thickness of at least 250 mm;
(b) preheating and/or homogenizing the rolling ingot to a maximum plate temperature (PMT), such that the specific energy associated with the differential scanning calorimetry (DSC) signal in the aluminum alloy is , an absolute value of less than 2 J/g;
(c) hot rolling said rolling ingot in a plurality of hot rolling steps to a hot rolled product having a final rolled thickness of at least 1 mm, whereby the last three steps of said rolling step A step in which the temperature of the hot-rolled product in at least one of the steps is between PMT (° C.) and [PMT (° C.)-50° C.],
subjecting the aluminum alloy to a temperature in the range used for solution heat treating aluminum alloys while allowing all or at least a substantial portion of the hot rolling to occur;
(d) quenching the hot-rolled product of final thickness from the hot-roller exit temperature to less than 175°C;
(e) optionally relieving the stresses of said hot rolled product which has been quenched to final thickness;
(f) aging the optionally stress-relieved quenched hot-rolled product;
The above method comprising 2. The method of claim 1, wherein the hot rolling in step (c) to final hot rolled thickness does not include any solution heat treatment. 3. A method according to claim 1 or 2, wherein said quenching in step (d) is performed in-line with at least said last hot rolling step. A method according to any one of the preceding claims, wherein the aluminum alloy is selected from the group of aluminum alloys of the 2XXX, 6XXX and 7XXX series. 5. The method of any one of claims 1-4, wherein the specific energy associated with the DSC signal in the aluminum alloy is less than 1.0 J/g in absolute value. A method according to any one of claims 1 to 5, wherein for 2XXX series and 7XXX series aluminum alloy articles, the PMT is no more than 15°C below the initial melting temperature of the given aluminum alloy. . The method according to any one of claims 1 to 6, wherein the hot rolling mill entry temperature is in a temperature range of no more than 40°C below the PMT of the aluminum alloy. The hot-rolling mill delivery temperature of the hot-rolled product of the final rolled plate thickness is a temperature range not lower than the PMT of the aluminum alloy by 40 ° C. or more, according to any one of claims 1 to 7. Method. A method according to any preceding claim , wherein in step (e) stress relief is by stretching in the range of 0.5% to 8% of its original length. The method according to any one of claims 1 to 9, wherein the hot rolled product has a final hot rolled thickness of 5 mm or more. In the step (c), the ingot for rolling is hot-rolled in a first set of hot rolling steps to obtain an intermediate hot-rolled plate thickness, and after performing an intermediate heating step, a second A method according to any one of the preceding claims, wherein the hot rolling is performed in a set of hot rolling steps to a final hot rolled thickness of at least 1 mm. 12. The method of claim 11, wherein said intermediate heating step is to a temperature no more than 40[deg.]C below said PMT of said aluminum alloy. The aluminum alloy, in weight percent,
Cu: 1.9% to 7% ,
Mg: 0.3% to 2%,
Mn: maximum 1.2%,
Si: maximum 0.4%,
Fe: maximum 0.4%,
Cr: maximum 0.35%,
Zn: maximum 0.4%,
Ti: maximum 0.15%,
Zr: maximum 0.25,
V: maximum 0.25%,
balance: aluminum and impurities,
The method according to any one of claims 1 to 12, which is a 2XXX series aluminum alloy having a composition comprising The aluminum alloy, in weight percent,
Si: 0.2% to 1.7% ,
Mg: 0.1% to 1.5% ,
Fe: maximum 0.5%,
Cu: maximum 1.0% ,
Mn: maximum 1.0%,
Cr: maximum 0.3%,
Ti: maximum 0.15%,
Zn: maximum 1.0%,
balance: aluminum and impurities,
The method according to any one of claims 1 to 12, which is a 6XXX series aluminum alloy having a composition comprising The aluminum alloy, in weight percent,
Zn: 4% to 9.8% ,
Mg: 1% to 3%,
Cu: maximum 2.5% ,
Optionally, Zr: max 0.3%, Cr: max 0.3%, Mn: max 0.45%, Ti: max 0.15%, Sc: max 0.5%, Ag: one or more elements selected from the group consisting of up to 0.5%;
Fe: maximum 0.3%,
Si: maximum 0.3%,
impurities and residual aluminum,
The method according to any one of claims 1 to 12, which is a 7XXX series aluminum alloy having a composition comprising