阅读说明：本技术 一种高效6000系铝合金中厚板热轧方法 (High-efficiency 6000-series aluminum alloy medium plate hot rolling method ) 是由 郑忱奕 陈秋林 闫焱 周志乐 孙钊 韦勇敏 于 2020-12-29 设计创作，主要内容包括：本发明公开了一种高效6000系铝合金中厚板热轧方法,包括以下步骤：对6000系铝合金铸锭进行均热预热一体化热处理；将铸锭轧制到中间坯厚度；将中间坯剪成3段以上,分别记为中间坯1至中间坯N；分别将中间坯1至中间坯N轧制到成品厚度,相应获得批次1板材至批次N板材。本发明可以实现在完成铸锭均热预热一体化热处理之后直接进行轧制,避免了单独进行均匀化热处理而导致生产效率下降的问题,同时还可以确保铸锭与板材不发生过烧现象；此外,在热轧过程中可以实现单块铸锭被轧制到3个及以上的目标厚度,而不会因温度过低发生轧制失败,从而在保证6000系铝合金中厚板性能达标的同时提高了热轧过程的生产效率。(The invention discloses a high-efficiency 6000 series aluminum alloy medium plate hot rolling method, which comprises the following steps: carrying out soaking and preheating integrated heat treatment on the 6000 series aluminum alloy cast ingot; rolling the cast ingot to the thickness of the intermediate blank; cutting the intermediate blank into more than 3 sections, and respectively marking as an intermediate blank 1 to an intermediate blank N; and respectively rolling the intermediate blanks 1 to N to the thickness of a finished product, and correspondingly obtaining the plates of the batches 1 to N. The invention can realize direct rolling after finishing the integrated heat treatment of soaking and preheating of the cast ingot, avoids the problem of reduction of production efficiency caused by single homogenization heat treatment, and simultaneously can ensure that the cast ingot and the plate are not over-burnt; in addition, in the hot rolling process, the single ingot can be rolled to the target thickness of 3 or more, and rolling failure caused by too low temperature can be avoided, so that the performance of the 6000 series aluminum alloy medium plate can reach the standard, and the production efficiency in the hot rolling process is improved.)

1. A high-efficiency 6000 series aluminum alloy medium plate hot rolling method is characterized by comprising the following steps:

s1, carrying out soaking and preheating integrated heat treatment on the 6000 series aluminum alloy cast ingot;

s2, rolling the cast ingot to the thickness of the intermediate blank;

s3, cutting the intermediate blank into more than 3 sections, and respectively marking as an intermediate blank 1, an intermediate blank 2, an intermediate blank … … and an intermediate blank N, wherein N is more than or equal to 3;

and S4, respectively rolling the intermediate billets 1, 2 and … … and the intermediate billets N to the thickness of a finished product, and correspondingly obtaining the batch 1 plates, the batch 2 plates, … … and the batch N plates.

2. The high-efficiency 6000 series aluminum alloy medium plate hot rolling method as claimed in claim 1,

and S1, keeping the temperature of the cast ingot at 530-545 ℃ in the soaking and preheating integrated heat treatment, and keeping the temperature for 6-10 h.

3. The high-efficiency 6000 series aluminum alloy medium plate hot rolling method as claimed in claim 1,

step S2, rolling the cast ingot to the cogging temperature of the thickness of the intermediate billet which is 500-530 ℃.

4. The high-efficiency 6000 series aluminum alloy medium plate hot rolling method as claimed in claim 1,

step S2 is to roll the ingot to an intermediate thickness with a reduction ratio of less than 7% for the first 5 passes before cogging.

5. The high-efficiency 6000 series aluminum alloy medium plate hot rolling method as claimed in claim 1,

and S4, when the intermediate billet N is rolled to the thickness of a finished product, the finishing temperature of the intermediate billet N is more than or equal to 420 ℃.

6. The high-efficiency 6000 series aluminum alloy medium plate hot rolling method as claimed in claim 1,

the 6000 series aluminum alloy comprises the following components in percentage by mass:

si: 1.10-1.25%, Fe: 0-0.30%, Cu: 0-0.09%, Mn: 0.70-0.90%, Mg: 0.80-1.00%, Cr: 0.18 to 0.22%, Zn: 0-0.18%, Ti: 0 to 0.10% by weight, and the balance of Al and inevitable impurities.

7. The high-efficiency 6000 series aluminum alloy medium plate hot rolling method as claimed in claim 1,

the 6000 series aluminum alloy comprises the following components in percentage by mass:

si: 0.56-0.70%, Fe: 0.40 to 0.50%, Cu: 0.20 to 0.35%, Mn: 0.10-0.15%, Mg: 0.90-1.20%, Cr: 0.30-0.35%, Zn: 0-0.15%, Ti: 0 to 0.10% by weight, and the balance of Al and inevitable impurities.

8. The high-efficiency 6000 series aluminum alloy medium plate hot rolling method as claimed in claim 1,

in step S3, the number of segments into which the intermediate slab is cut is 3, and these segments are respectively denoted as intermediate slab 1, intermediate slab 2, and intermediate slab 3.

9. A method for preparing a 6000 series aluminum alloy medium plate comprises the following steps: batching, casting, hot rolling, solution quenching, pre-stretching and aging strengthening, and is characterized in that the hot rolling adopts the high-efficiency 6000 series aluminum alloy medium plate hot rolling method of any one of claims 1 to 8.

Technical Field

The invention relates to the technical field of aluminum alloy preparation, in particular to a high-efficiency 6000-series aluminum alloy medium plate hot rolling method.

Background

The aluminum alloy medium plate is a plate with the thickness of more than or equal to 12mm obtained by hot rough rolling, and the 6000 series aluminum alloy has the characteristics of good formability, good corrosion resistance, higher strength and the like, and is widely applied to the fields of aerospace, transportation, interior decoration and the like. Along with the increase of the demand of the market for 6000 series aluminum alloy medium and heavy plates with different thicknesses, the existing 6000 series aluminum alloy plate hot rolling process has low production efficiency due to high energy consumption and long consumed time, and can only roll a single ingot to 1 or 2 target thicknesses, so that the increasing demand of the market can not be met.

In the existing hot rolling process of 6000 series aluminum alloy plates, ingot casting is firstly subjected to homogenization heat treatment under a heat treatment schedule of 530-540 ℃/10-14 h, which is mainly used for eliminating dendrite segregation and promoting dissolution of non-equilibrium phases, and after the homogenization heat treatment is finished, the ingot casting needs to spend 1-2 days for waiting for cooling; after the cast ingot is cooled, the cast ingot can be rolled only after being heated by the preheating process of 430-470 ℃/2-4 h, because the 6000 series aluminum alloy has good plasticity at 430-470 ℃, the rolling requirement can be met, if the heating temperature is increased, the heating cost is increased, and meanwhile, the overburning phenomenon is possibly caused. However, in the existing process, after the ingot is subjected to homogenization heat treatment, the ingot needs to wait for 1-2 days for cooling and transferring, so that the production period is prolonged; in addition, the ingot needs to be preheated again before hot rolling, which further increases energy consumption; and because the temperature of the preheating process is relatively low at 430-470 ℃/2-4 h, the temperature of the intermediate billet can be too low to cause rolling failure in the final rolling stage of hot rolling, so that the single ingot can only be rolled to 1 or 2 target thicknesses.

In conclusion, the existing hot rolling process for 6000 series aluminum alloy plates has the following defects: (1) after the ingot is subjected to homogenization heat treatment, the ingot can be transported only after being cooled, and the period is long; (2) the ingot needs to be preheated again before hot rolling, so that the energy consumption is further increased; (3) the relative temperature of the preheating process is low, and the temperature of the intermediate billet may be too low to cause rolling failure in the final rolling stage of hot rolling, so that only a single ingot can be rolled to 1 or 2 target thicknesses, and if the heating temperature is increased, not only the heating cost is increased, but also the overburning phenomenon is highly likely to occur.

Disclosure of Invention

Aiming at the defects, the invention provides the high-efficiency 6000 series aluminum alloy medium plate hot rolling method which is short in period and low in energy consumption.

In order to achieve the purpose, the invention adopts the following technical scheme:

a high-efficiency 6000 series aluminum alloy medium plate hot rolling method comprises the following steps:

s1, carrying out soaking and preheating integrated heat treatment on the 6000 series aluminum alloy cast ingot;

s2, rolling the cast ingot to the thickness of the intermediate blank;

s3, cutting the intermediate blank into more than 3 sections, and respectively marking as an intermediate blank 1, an intermediate blank 2, an intermediate blank … … and an intermediate blank N, wherein N is more than or equal to 3;

and S4, respectively rolling the intermediate billets 1, 2 and … … and the intermediate billets N to the thickness of a finished product, and correspondingly obtaining the batch 1 plates, the batch 2 plates, … … and the batch N plates.

Further, in the step S1, the heat preservation temperature of the ingot in the soaking and preheating integrated heat treatment is 530-545 ℃, and the heat preservation time is 6-10 hours, so that the homogenization effect is good.

Further, step S2 is to roll the ingot to the cogging temperature of the thickness of the intermediate billet which is 500-530 ℃ so as to ensure that the ingot and the intermediate billet are in a high-temperature state in the hot rolling process.

Further, the processing rate of 5 passes before cogging of rolling the ingot to the thickness of the intermediate billet in the step S2 is lower than 7%, so that the phenomenon of overburning caused by overhigh temperature of the ingot due to overhigh processing rate is prevented.

Further, when the intermediate billet N is rolled to the thickness of a finished product in the step S4, the finish rolling temperature of the intermediate billet N is more than or equal to 420 ℃, so that the rolling failure caused by too low temperature can be avoided in the process of rolling the intermediate billet N finished product plate.

Further, the 6000 series aluminum alloy comprises the following components in percentage by mass:

si: 1.10-1.25%, Fe: 0-0.30%, Cu: 0-0.09%, Mn: 0.70-0.90%, Mg: 0.80-1.00%, Cr: 0.18 to 0.22%, Zn: 0-0.18%, Ti: 0 to 0.10% by weight, and the balance of Al and inevitable impurities.

Further, the 6000 series aluminum alloy comprises the following components in percentage by mass:

si: 0.56-0.70%, Fe: 0.40 to 0.50%, Cu: 0.20 to 0.35%, Mn: 0.10-0.15%, Mg: 0.90-1.20%, Cr: 0.30-0.35%, Zn: 0-0.15%, Ti: 0 to 0.10% by weight, and the balance of Al and inevitable impurities.

Further, the number of segments into which the intermediate slab is cut in step S3 is 3, and these segments are denoted as intermediate slab 1, intermediate slab 2, and intermediate slab 3, respectively.

The invention can simultaneously complete the homogenization heat treatment and the preheating process through the soaking and preheating integrated heat treatment of the 6000-series aluminum alloy ingot, not only shortens the production period, but also avoids the energy consumption increase caused by secondary heating, and simultaneously can ensure that the ingot and the plate are not overburnt through formulating a reasonable soaking and preheating integrated process, and in addition, can ensure that a single ingot is rolled to more than 3 target thicknesses at higher cogging temperature and finishing temperature, and cannot cause rolling failure due to over low temperature.

The invention also provides a preparation method of the 6000 series aluminum alloy medium plate, which comprises the following steps: batching, casting, hot rolling, solution quenching, pre-stretching and aging strengthening, wherein the hot rolling adopts the high-efficiency 6000 series aluminum alloy medium plate hot rolling method.

Compared with the prior art, the invention has the beneficial effects that: the invention can realize direct rolling after finishing the integrated heat treatment of soaking and preheating of the cast ingot, avoids the problem of reduction of production efficiency caused by single homogenization heat treatment, and simultaneously can ensure that the cast ingot and the plate are not over-burnt; in addition, in the hot rolling process, the single ingot can be rolled to 3 or more than 3 target thicknesses, rolling failure caused by too low temperature can be avoided, and therefore the production efficiency in the hot rolling process is improved while the performance of the 6000 series aluminum alloy medium plate is ensured to reach the standard.

According to the method for preparing the 6000 series aluminum alloy medium plate, which is provided by the invention, by using the high-efficiency 6000 series aluminum alloy medium plate hot rolling method, the production period can be shortened, the energy consumption is saved, a single ingot can be rolled to more than 3 target thicknesses, rolling failure caused by too low temperature is avoided, and the overall production efficiency is improved.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below.

FIG. 1 is a schematic flow chart of an embodiment of the present invention;

FIG. 2 is a scanning curve of differential scanning calorimetry of a 6082 aluminum alloy ingot used in the present invention;

FIG. 3 is a metallographic diagram of a 6082 aluminum alloy ingot before soaking and preheating integrated heat treatment;

FIG. 4 is a diagram of a gold phase of a 6082 aluminum alloy ingot after soaking and preheating integrated heat treatment;

FIG. 5 is a gold phase diagram of an aluminum alloy intermediate billet 1 in the cross section in example 1;

FIG. 6 is a scanning curve of differential scanning calorimetry of a 6061 aluminum alloy ingot used in the present invention;

FIG. 7 is a gold phase diagram of a 6061 aluminum alloy ingot before soaking and preheating integrated heat treatment;

FIG. 8 is a gold phase diagram of a 6061 aluminum alloy ingot after soaking and preheating integrated heat treatment;

FIG. 9 is a gold phase diagram in cross section of an intermediate billet 1 of an aluminum alloy in example 2;

FIG. 10 is a gold phase diagram in cross section of an intermediate billet 1 of an aluminum alloy in example 3;

FIG. 11 is a schematic flow chart of a comparative example of the present invention;

fig. 12 is a photograph showing the occurrence of plate thickness unevenness in the event of rolling failure of the intermediate slab 2 of the comparative example.

Detailed Description

The technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

Referring to fig. 1, the present embodiment provides a high-efficiency hot rolling method for 6000 series aluminum alloy medium plates, which includes the following steps:

and S1, carrying out soaking and preheating integrated heat treatment on the 6000 series aluminum alloy cast ingot.

The 6000 series aluminum alloy of the embodiment comprises the following components in percentage by mass: si: 1.20%, Fe: 0.26%, Cu: 0.08%, Mn: 0.77%, Mg: 0.92%, Cr: 0.20%, Zn: 0.06%, Ti: 0.02 percent, and the balance of Al and inevitable impurities, which substantially belongs to 6082 aluminum alloy. The ingredients are refined, slag removed and filtered, then the casting is carried out, after the casting is finished, the symmetrical surface milling is carried out on the ingot, and finally the ingot specification is obtained: 570, 1700, 5700mm, wherein the refining, slagging-off, filtering, casting, symmetrical surface milling and other processes adopt the conventional 6000 series aluminum alloy medium and heavy plate preparation process parameters.

Carrying out soaking and preheating integrated heat treatment on the aluminum alloy cast ingot, wherein the heat preservation temperature is 545 ℃ and the heat preservation time is 6.2h, so as to ensure good homogenization effect.

Fig. 2 shows the differential scanning calorimetry results of the 6082 aluminum alloy ingot used in the present invention, wherein the lowest overburning temperature is 555-557 ℃ in the range of the 6082 aluminum alloy composition of the present invention, which indicates that the present embodiment has a reasonable insulation temperature and no overburning occurs.

Referring to fig. 3 and 4, fig. 3 is a gold phase diagram of a 6082 aluminum alloy ingot used in the present invention before soaking and preheating integrated heat treatment, and it can be seen that a large amount of non-equilibrium phases exist at grain boundary positions in the ingot. Fig. 4 is a gold phase diagram of the 6082 aluminum alloy ingot used in the present invention after the soaking and preheating integrated heat treatment, and it can be seen from the figure that most of the nonequilibrium phase at the grain boundary position in the ingot is dissolved or spheroidized after the soaking and preheating integrated heat treatment, and no overburning occurs, and the soaking effect is good.

And S2, rolling the cast ingot to the thickness of the intermediate billet.

The ingot is rolled to the thickness of the intermediate billet by the roughing mill, the cogging temperature of the ingot is 521 ℃, the machining rate of the first 5 passes is lower than 7%, and the overburning phenomenon that the temperature of the ingot is increased due to the overlarge machining rate can be prevented.

And S3, cutting the intermediate blank into 3 sections, and respectively marking as an intermediate blank 1, an intermediate blank 2 and an intermediate blank 3.

The intermediate billet is divided into 3 sections by heavy hydraulic shears, namely an intermediate billet 1, an intermediate billet 2 and an intermediate billet 3.

And S4, rolling the intermediate billets 1, 2 and 3 to the thickness of a finished product respectively to obtain the plates of batch 1, the plates of batch 2 and the plates of batch 3 correspondingly.

Rolling the intermediate blank 1 to a finished product thickness of 1 through a roughing mill to obtain a batch of 1 plates; rolling the intermediate blank 2 to a finished product thickness of 2 through a roughing mill to obtain a batch of 2 plates; the intermediate billet 3 is rolled to a finished thickness 3 by a roughing mill to obtain a batch 3 of plate material.

FIG. 5 is a cross-sectional metallographic view of the intermediate billet 1 of the aluminum alloy of the present example, in which no overburnt structure was observed.

Table 1 shows the rolling pass distribution and the billet surface temperature variation of the hot rolling process in example 1, wherein the billet surface temperature was maintained at a higher temperature at all times and did not exceed the overburn temperature of the 6082 aluminum alloy used in the present invention. Meanwhile, as can be seen from table 1, when the step S4 is performed, the temperature of the intermediate billet 3 is 470-471 ℃, and the 6082 aluminum alloy still has good plasticity at the temperature, so that rolling failure due to too low temperature is avoided when the intermediate billet 3 is rolled.

TABLE 1 Rolling pass distribution and billet surface temperature variation in Hot Rolling Process in example 1

After hot rolling, the present embodiment performs subsequent processing on each batch of aluminum alloy plates, and performs heat treatment strengthening and plate finishing on each batch of aluminum alloy plates after hot rolling, mainly including: the 6082/T651 aluminum alloy medium and thick plate product is prepared by solid solution quenching, pre-stretching and aging strengthening, and finally carrying out finishing procedures such as sawing, surface brushing and the like, wherein the processes of solid solution quenching, pre-stretching, aging strengthening, sawing, surface brushing and the like adopt the conventional 6000 series aluminum alloy medium and thick plate preparation process parameters.

Table 2 shows the properties of the 6082/T651 aluminum alloy medium and thick plate product of each batch in example 1, wherein all the mechanical properties meet the national standard requirements.

TABLE 2 Performance index for each batch of 6082/T651 aluminum alloy medium plate product in example 1

Status of state	Thickness/mm	Rp0.2/MPa	Rm/MPa	A/％
					6082/T651-national standard	＞60.0～100.0	≥240	≥295	≥7.0
Batch 1	93.1	307	334	12.0
					Batch 2	82.9	310	335	12.0
Batch 3	72.4	302	331	12.5

Example 2

Referring to fig. 1, the present embodiment provides a high-efficiency hot rolling method for 6000 series aluminum alloy medium plates, which includes the following steps:

and S1, carrying out soaking and preheating integrated heat treatment on the 6000 series aluminum alloy cast ingot.

The 6000 series aluminum alloy of the embodiment comprises the following components in percentage by mass: si: 0.62%, Fe: 0.43%, Cu: 0.28%, Mn: 0.12%, Mg: 1.03%, Cr: 0.32%, Zn: 0.11%, Ti: 0.03 percent, and the balance of Al and inevitable impurities, which substantially belongs to 6061 aluminum alloy. The ingredients are refined, slag removed and filtered, then the casting is carried out, after the casting is finished, the symmetrical surface milling is carried out on the ingot, and finally the ingot specification is obtained: 568 1640 7700mm, wherein the refining, slagging-off, filtering, casting, symmetrical surface milling and other processes adopt the conventional 6000 series aluminum alloy medium and heavy plate preparation process parameters.

Carrying out soaking and preheating integrated heat treatment on the aluminum alloy cast ingot, wherein the heat preservation temperature is 530 ℃, and the heat preservation time is 9.5 hours, so as to ensure good homogenization effect.

FIG. 6 shows the results of differential scanning calorimetry of 6061 aluminum alloy ingots used in the present invention, wherein the lowest overburning temperature is 583-586 ℃ in the range of 6061 aluminum alloy compositions of the present invention, which indicates that the insulation temperature in this example is reasonable and no overburning occurs.

Referring to fig. 7 and 8, fig. 7 is a gold phase diagram of a 6061 aluminum alloy ingot used in the present invention before soaking and preheating integrated heat treatment, and it can be seen that a large amount of non-equilibrium phases exist at grain boundary positions in the ingot. Fig. 8 is a gold phase diagram of the 6061 aluminum alloy ingot used in the present invention after the soaking and preheating integrated heat treatment, and it is understood from the figure that most of the nonequilibrium phase at the grain boundary position in the ingot is dissolved or spheroidized after the soaking and preheating integrated heat treatment, and the soaking effect is good without the overburning phenomenon.

And S2, rolling the cast ingot to the thickness of the intermediate billet.

The ingot is rolled to the thickness of the intermediate billet by the roughing mill, the cogging temperature of the ingot is 501 ℃, the machining rate of the first 5 passes is lower than 7 percent, and the overburning phenomenon that the temperature of the ingot is increased due to the overlarge machining rate can be prevented.

And S3, cutting the intermediate blank into 3 sections, and respectively marking as an intermediate blank 1, an intermediate blank 2 and an intermediate blank 3.

The intermediate billet is divided into 3 sections by heavy hydraulic shears, namely an intermediate billet 1, an intermediate billet 2 and an intermediate billet 3.

And S4, rolling the intermediate billets 1, 2 and 3 to the thickness of a finished product respectively to obtain the plates of batch 1, the plates of batch 2 and the plates of batch 3 correspondingly.

Rolling the intermediate blank 1 to a finished product thickness of 1 through a roughing mill to obtain a batch of 1 plates; rolling the intermediate blank 2 to a finished product thickness of 2 through a roughing mill to obtain a batch of 2 plates; the intermediate billet 3 is rolled to a finished thickness 3 by a roughing mill to obtain a batch 3 of plate material.

FIG. 9 is a cross-sectional metallographic view of the intermediate billet 1 of the aluminum alloy of the present example, in which no overburnt structure was observed.

Table 3 shows the rolling pass distribution and the billet surface temperature variation of the hot rolling process of example 2, wherein the billet surface temperature is always maintained at a higher temperature and does not exceed the over-firing temperature of the 6061 aluminum alloy. Meanwhile, as can be seen from table 3, when the step S4 is performed, the temperature of the intermediate billet 3 is 459 to 460 ℃, and the 6061 aluminum alloy still has good plasticity at the temperature, so that rolling failure due to too low temperature is avoided when the intermediate billet 3 is rolled.

TABLE 3 Rolling pass distribution and billet surface temperature variation in the Hot Rolling Process in example 2

After hot rolling, the present embodiment performs subsequent processing on each batch of aluminum alloy plates, and performs heat treatment strengthening and plate finishing on each batch of aluminum alloy plates after hot rolling, mainly including: the 6061/T651 aluminum alloy medium and thick plate product is prepared by solid solution quenching, pre-stretching and aging strengthening, and finally carrying out finishing procedures such as saw cutting and surface brushing, wherein the processes of solid solution quenching, pre-stretching, aging strengthening, saw cutting, surface brushing and the like adopt the conventional 6000 series aluminum alloy medium and thick plate preparation process parameters.

Table 4 shows the properties of the 6061/T651 aluminum alloy medium and thick plate product of each batch in example 2, wherein all the mechanical properties meet the national standard requirements.

TABLE 4 Performance index for each batch of 6061/T651 aluminum alloy medium plate product of example 2

Status of state	Thickness/mm	Rp0.2/MPa	Rm/MPa	A/％
					6061/T651-national standard	＞50.0～100.0	≥240	≥290	≥5
Batch 1	99.1	289	329	13.0
					Batch 2	87.8	291	326	12.8
Batch 3	78.4	292	329	13.7

Example 3

Referring to fig. 1, the present embodiment provides a high-efficiency hot rolling method for 6000 series aluminum alloy medium plates, which includes the following steps:

and S1, carrying out soaking and preheating integrated heat treatment on the 6000 series aluminum alloy cast ingot.

The 6000 series aluminum alloy of the embodiment comprises the following components in percentage by mass: si: 0.64%, Fe: 0.40%, Cu: 0.26%, Mn: 0.15%, Mg: 1.08%, Cr: 0.30%, Zn: 0.10%, Ti: 0.02 percent, and the balance of Al and inevitable impurities, which substantially belongs to 6061 aluminum alloy. The ingredients are refined, slag removed and filtered, then the casting is carried out, after the casting is finished, the symmetrical surface milling is carried out on the ingot, and finally the ingot specification is obtained: 609, 2100, 5500mm, wherein the refining, slag skimming, filtering, casting, symmetrical surface milling and other processes adopt the conventional 6000 series aluminum alloy medium and heavy plate preparation process parameters.

Carrying out soaking and preheating integrated heat treatment on the aluminum alloy cast ingot, wherein the heat preservation temperature is 540 ℃, and the heat preservation time is 8.1h, so as to ensure good homogenization effect.

FIG. 6 shows the results of differential scanning calorimetry of 6061 aluminum alloy ingots used in the present invention, wherein the lowest overburning temperature is 583-586 ℃ in the range of 6061 aluminum alloy compositions of the present invention, which indicates that the insulation temperature in this example is reasonable and no overburning occurs.

And S2, rolling the cast ingot to the thickness of the intermediate billet.

The ingot is rolled to the thickness of the intermediate billet by the roughing mill, the cogging temperature of the ingot is 510 ℃, the machining rate of the first 5 passes is lower than 7%, and the overburning phenomenon that the temperature of the ingot is increased due to the overlarge machining rate can be prevented.

And S3, cutting the intermediate blank into 3 sections, and respectively marking as an intermediate blank 1, an intermediate blank 2 and an intermediate blank 3.

The intermediate billet is divided into 3 sections by heavy hydraulic shears, namely an intermediate billet 1, an intermediate billet 2 and an intermediate billet 3.

And S4, rolling the intermediate billets 1, 2 and 3 to the thickness of a finished product respectively to obtain the plates of batch 1, the plates of batch 2 and the plates of batch 3 correspondingly.

Rolling the intermediate blank 1 to a finished product thickness of 1 through a roughing mill to obtain a batch of 1 plates; rolling the intermediate blank 2 to a finished product thickness of 2 through a roughing mill to obtain a batch of 2 plates; the intermediate billet 3 is rolled to a finished thickness 3 by a roughing mill to obtain a batch 3 of plate material.

In fig. 10, the cross section of the intermediate billet 1 of the aluminum alloy of the present example is a metallographic view in which no overburnt structure is observed.

Table 5 shows the rolling pass distribution and the billet surface temperature variation for the hot rolling process of example 3, wherein the billet surface temperature was maintained at an elevated temperature and did not exceed the over-firing temperature of the 6061 aluminum alloy. Meanwhile, as can be seen from table 5, when the step S4 is performed, the temperature of the intermediate billet 3 is 465 to 468 ℃, and the 6061 aluminum alloy still has good plasticity at the temperature, so that rolling failure due to too low temperature is avoided when the intermediate billet 3 is rolled.

TABLE 5 Rolling pass distribution and billet surface temperature variation for hot rolling in example 3

After hot rolling, the present embodiment performs subsequent processing on each batch of aluminum alloy plates, and performs heat treatment strengthening and plate finishing on each batch of aluminum alloy plates after hot rolling, mainly including: the 6061/T651 aluminum alloy medium and thick plate product is prepared by solid solution quenching, pre-stretching and aging strengthening, and finally carrying out finishing procedures such as saw cutting and surface brushing, wherein the processes of solid solution quenching, pre-stretching, aging strengthening, saw cutting, surface brushing and the like adopt the conventional 6000 series aluminum alloy medium and thick plate preparation process parameters.

Table 6 shows the properties of the 6061/T651 aluminum alloy medium and thick plate product of each batch in example 3, wherein all the mechanical properties meet the national standard requirements.

TABLE 6 Performance index for each batch of 6061/T651 aluminum alloy medium plate product of example 3

Status of state	Thickness/mm	Rp0.2/MPa	Rm/MPa	A/％
					6061/T651-national standard	＞25.0～50.0	≥240	≥290	≥5
6061/T651-national standard	＞50.0～100.0	≥240	≥290	≥7
					Batch 1	78.4	279	315	15.0
Batch 2	56.8	283	319	14.8
					Batch 3	46.2	281	323	14.3

Comparative example 1

Referring to fig. 11, the present comparative example provides a hot rolling method of a 6000 series aluminum alloy medium plate of the prior art, comprising the steps of:

s1, carrying out homogenization heat treatment on the 6000 series aluminum alloy ingot.

The 6000 series aluminum alloy of the embodiment comprises the following components in percentage by mass: si: 1.12%, Fe: 0.23%, Cu: 0.03%, Mn: 0.70%, Mg: 0.81%, Cr: 0.21%, Zn: 0.02%, Ti: 0.02 percent, and the balance of Al and inevitable impurities, which substantially belongs to 6082 aluminum alloy. The ingredients are refined, subjected to slag skimming, filtered and then cast, wherein the refining, slag skimming, filtering, casting and other processes adopt the conventional 6000 series aluminum alloy medium plate preparation process parameters.

Carrying out homogenization heat treatment on the prepared 6082 aluminum alloy ingot, wherein the heat preservation temperature is 535 ℃, and the heat preservation time is 10.8 hours, so as to eliminate dendrite segregation; promoting dissolution of the non-equilibrium phase.

And S2, waiting for the ingot to cool.

Waiting for the heated ingot to cool to room temperature, wherein the time consumption is about 1.5 days, then symmetrically milling the ingot to obtain the ingot with the specification: 510 x 1600 x 5600 mm.

S3, preheating the 6000 series aluminum alloy cast ingot.

Preheating the cast ingot, heating the cooled cast ingot to 440 ℃, and preserving heat for 3 hours to ensure that the cast ingot has certain plasticity for rolling.

And S4, rolling the cast ingot to the thickness of the intermediate billet.

And rolling the ingot by a roughing mill to obtain an intermediate billet with the ingot cogging temperature of 432 ℃.

And S5, cutting the intermediate blank into 2 sections, and respectively marking as the intermediate blank 1 and the intermediate blank 2.

The intermediate billet is divided into 2 sections by heavy hydraulic shears, namely an intermediate billet 1 and an intermediate billet 2.

And S6, respectively rolling the intermediate blank 1 and the intermediate blank 2 to the thickness of a finished product, and correspondingly obtaining the plate of batch 1 and the plate of batch 2.

Rolling the intermediate blank 1 to a finished product thickness of 1 through a roughing mill to obtain a batch of 1 plates; the intermediate slab 2 was rolled to a finished thickness of 2 by a roughing mill to obtain a batch 2 of plate material.

Table 7 shows the rolling pass distribution and the slab surface temperature change in the hot rolling process of comparative example 1, in the rolling process of intermediate slab 2, the temperature of intermediate slab 2 was already low, and the temperature was only 388 ℃ in the last rolling pass, which resulted in rolling failure and product rejection.

Table 7 rolling pass distribution and billet surface temperature change in hot rolling process in comparative example 1

Fig. 12 is a photograph showing the occurrence of thickness unevenness of the sheet when rolling failure occurred in the intermediate slab 2 of comparative example 1.

As can be seen from examples 1 to 3, according to the high-efficiency hot rolling method for the 6000 series aluminum alloy medium plate of the present invention, compared with the conventional hot rolling method for the 6000 series aluminum alloy medium plate in the comparative example, the time for waiting for cooling the ingot after the homogenization process is shortened, the ingot is prevented from being heated again before hot rolling, and the ingot or the intermediate billet is maintained at a high temperature during the hot rolling process, so that it is ensured that a single ingot can be rolled to a target thickness of 3 or more than 3.

In conclusion, the high-efficiency 6000 series aluminum alloy medium plate hot rolling method can realize direct rolling after finishing the ingot casting soaking preheating integrated heat treatment, can also ensure that the ingot casting and plates are not over-burnt, can also ensure that a single ingot casting is rolled to 3 or more than 3 target thicknesses at higher hot rolling temperature, and cannot cause rolling failure due to too low temperature, obtains a process route capable of greatly improving the hot rolling efficiency of 6000 series aluminum alloy, and overcomes the defects of high energy consumption and long time consumption of the existing 6000 series aluminum alloy medium plate hot rolling process. Meanwhile, the invention and the embodiment thereof also substantially provide a method for preparing the 6000 series aluminum alloy medium plate, and by using the high-efficiency 6000 series aluminum alloy medium plate hot rolling method, the production period can be shortened, the energy consumption can be saved, a single ingot can be rolled to 3 or more than 3 target thicknesses, rolling failure caused by too low temperature can be avoided, and the overall production efficiency can be improved.

The above description is only for the specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.