CN118497642A - Method for improving high-temperature mechanical properties of 2000 series aluminum alloy - Google Patents
Method for improving high-temperature mechanical properties of 2000 series aluminum alloy Download PDFInfo
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Abstract
The invention discloses a method for improving the high-temperature mechanical property of 2000 series aluminum alloy, which comprises the following steps: determining a recrystallization temperature interval and an alloy correlation coefficient of the aluminum alloy according to actual production conditions; determining an annealing temperature T A according to the determined recrystallization temperature interval and the alloy correlation coefficient; carrying out recrystallization annealing treatment on the aluminum alloy according to the confirmed annealing temperature T A; carrying out solution treatment on the annealed aluminum alloy; and aging the aluminum alloy subjected to solution treatment, and air cooling to obtain the aluminum alloy with high-temperature mechanical properties. According to the method, under the same solid solution aging condition, the recrystallization annealing treatment can improve the stress relaxation stability of the alloy by 20-60%; under the same solid solution aging condition, the recrystallization annealing treatment can ensure that the high-temperature tensile property is improved by 10 to 25 percent while the alloy keeps good room-temperature mechanical property; is suitable for large-scale industrial production of heat-resistant aluminum alloy.
Description
Technical Field
The invention belongs to the technical field of heat treatment of metal materials, and particularly provides a method for regulating and controlling the grain size and precipitated phase of a 2000 series aluminum alloy, so as to improve the high-temperature strength and the heat stability of the alloy and improve the high-temperature mechanical property of the 2000 series aluminum alloy.
Background
The 2000 series aluminum alloy has a precipitated phase with better thermal stability, such as an S phase (Al 2 CuMg), a theta' phase (Al 2 Cu), an omega phase (Al 2 Cu) and the like, can be stably used for a long time in an environment of 150-250 ℃ and is widely applied to the fields of aerospace, rail transit and the like. With the development of spacecrafts, airplanes, high-speed trains and the like in the direction of light weight, ultra-high speed and low cost, further improvement of the high-temperature strength and the thermal stability of 2000-series aluminum alloys has become a hot spot for research in the field.
At present, the main method for improving the high-temperature strength and the thermal stability of the 2000 series aluminum alloy is to regulate and control the types and the distribution of precipitated phases. For example, two-stage homogenization, multi-stage solution treatment, or elevated solution temperatures are employed to obtain more fine precipitated phases to increase the strength and thermal stability of the alloy [ Wang Peng; liu Guanhua; liu Zhiyi influence of the solution temperature on microstructure and mechanical properties of Al-Cu-Mg-Ag alloys [ J ]. Mining and metallurgy engineering, 2019, 39 (6): 115-119.]. The intermittent aging is adopted to refine the precipitated phases in the crystal and the grain boundary, and the distribution of the precipitated phases at the precipitation zone without precipitation is changed, so that the thermal stability and the elongation of the alloy are improved [ Zhang Jianbo; zhang Yongan; zhu Baohong; effect of multistage intermittent aging on Al-Cu-Mg-Ag-Zr alloy structure and properties [ J ]. Rare metals, 2011, 35 (2): 170-175.]. Incomplete precipitation is formed by adopting underaging treatment, so that supersaturated solute atoms are reserved in a matrix, and solute atoms interact with dislocation during high-temperature deformation to prevent the growth of a precipitated phase, thereby improving the thermal stability [ Xia Qingkun ] of the alloy; liu Zhiyi; li Yuntao; heat resistance of an underaged state of Al-Cu-Mg-Ag alloy [ J ]. Rare metal material and engineering, 2007, (S3): 608-611.].
In addition to the precipitated phases, the grain size also has a great influence on the high temperature strength and thermal stability of the polycrystalline alloy. In a polycrystalline alloy, the enhancement of the grain boundary diffusion effect at high temperature can enable stress relaxation to occur more easily [Naveed A,Alexander H.Mechanisms of grain boundarysoftening and strain-rate sensitivity in deformation ofultrafine-grained metals at high temperatures[J].ActaMaterialia,2011,59:4323-4334.]., the grain boundary density is reduced (large-size grains are obtained), the high-temperature strength and the thermal stability of the alloy are improved, but the blocking effect of the grain boundary on dislocation slip is reduced, and the room-temperature strength of the alloy is reduced.
Therefore, how to improve the high-temperature mechanical properties without obviously reducing the room-temperature mechanical properties is one of the challenges faced by the research of heat-resistant aluminum alloy. The conventional processing path of 2000 series aluminium alloy is casting-homogenizing-deforming-solid solution-aging, in order to effectively regulate and control the grain size of alloy while guaranteeing the precipitation strengthening effect of alloy, the application proposes to add a recrystallization annealing procedure before solid solution treatment on the premise of not changing the solid solution and aging system. The grain size of the alloy is regulated and controlled through recrystallization annealing treatment, and the types and distribution of precipitated phases in the alloy are regulated and controlled through subsequent solution aging treatment, so that the reasonable matching of the grain size and the morphology distribution characteristics of the precipitated phases is realized, and the purposes of improving the high-temperature strength and the thermal stability of the alloy are achieved. However, the experimental method for determining the proper recrystallization annealing temperature and annealing time is large in workload, and high in experimental period and experimental cost. How to quickly determine the recrystallization annealing temperature that makes the grain size larger is the key to the annealing process described above.
Disclosure of Invention
In view of the above, the present invention discloses a method for improving the high-temperature mechanical properties of 2000-series aluminum alloys, so as to solve any one of the above and other potential problems in the prior art.
In order to solve the technical problems, the technical scheme of the invention is as follows: the method for improving the high-temperature mechanical property of the 2000 series aluminum alloy specifically comprises the following steps:
S1) determining recrystallization temperature interval and alloy related recrystallization kinetic parameters of the aluminum alloy to be treated according to actual production conditions;
S2) determining the value range of the annealing temperature T A of the treated aluminum alloy according to the recrystallization temperature interval and the alloy related recrystallization kinetic parameters obtained in the S1);
S3) carrying out recrystallization annealing treatment on the aluminum alloy to be treated according to the annealing temperature T A obtained in the S2);
S4) carrying out solution treatment on the aluminum alloy treated in the step S3);
S5) aging the aluminum alloy treated in the step S4), and obtaining the aluminum alloy with high-temperature mechanical property after air cooling.
Further, the specific steps of S1) are as follows:
S1.1) determining the heat preservation time t A and the heating rate epsilon A of the aluminum alloy to be treated according to actual production conditions, and obtaining a recrystallization curve A of the alloy with the heating rate epsilon A;
S1.2) confirming a recrystallization temperature interval range delta T with the temperature rise rate epsilon A according to a recrystallization curve A, namely, the temperature range which can be selected as the annealing temperature;
s1.3) then increasing or decreasing the temperature rise rate epsilon A to obtain a recrystallization curve B with the temperature rise rate epsilon B and epsilon B, and determining the recrystallization kinetic parameters related to the material according to the temperature characteristic points on the recrystallization curve A and the recrystallization curve AB.
The method for obtaining the recrystallization curve is a hardness method or a three-point bending stress relaxation method;
The temperature characteristic points are a recrystallization starting temperature T Start and a recrystallization finishing temperature T Finish; obtained by a tangential method.
Further, the parameters in S1.3) include a time index n, a recrystallization activation energy value Q r of the alloy, and a constant B, which are respectively calculated by the following formulas, the specific formulas are as follows:
Wherein R is a gas constant, T Finish-A is a temperature value when the alloy is recrystallized under the condition of the temperature rising rate epsilon A, and T Finish-B is a temperature value when the alloy is recrystallized under the condition of the temperature rising rate epsilon B;
Wherein n is a time index, n > 0; t Start-A and T Finish-A represent temperature values that produce a recrystallized volume fraction of X Start-A and X Finish-A, respectively, at a given temperature increase rate ε A;
Wherein: t Finish-A represents the temperature value at which the volume fraction X Finish-A of the recrystallization is produced at a given temperature increase rate ε A.
Further, the annealing temperature T A in S2) is determined by the following formula:
Where X A1 is the volume fraction of recrystallization from the temperature increase to T A at a given temperature increase rate ε A, and X F is the volume fraction at the time of T A isothermal annealing T A, and X F ≡1.
Further, the specific steps of S3) are as follows:
S3.1) firstly heating the aluminum alloy to be treated from room temperature to T A along with a furnace at a heating rate epsilon A,
S3.2) at the temperature of T A, after the temperature is kept for T A time, the recrystallization annealing is finished, and the materials are discharged and cooled to the room temperature.
Further, the solid solution treatment in S4) is a single-stage solid solution treatment.
Further, the temperature of the single-stage solid solution treatment is 480-520 ℃, and the heat preservation time is 1-6h.
Further, the aging treatment in S5) specifically includes: the aging treatment temperature is 180-200 ℃, and the heat preservation time is 2-14h.
Further, the stress relaxation stability of the aluminum alloy treated by the method is improved by 20-60% under the test condition of 250 ℃, and the tensile strength is improved by at least 10.0% -25.0%.
An aluminum alloy with high-temperature mechanical properties is obtained by adopting the method.
The application provides a concept of improving high-temperature strength and thermal stability of 2000 series aluminum alloy by recrystallization annealing and solution aging treatment, and simultaneously provides a method for rapidly determining proper recrystallization annealing temperature according to annealing time requirements, which aims to greatly improve high-temperature mechanical properties of the alloy on the premise of not obviously reducing room-temperature strength of the alloy.
The technical principle is as follows:
Depending on the recrystallization kinetics, the soak temperature T B and soak time T B of the recrystallization isothermal anneal can be represented by the following formulas:
{-ln(1-XV)}1/n＝BtBexp(-Qr/RTB) (A)
Wherein R is a gas constant; b is a constant greater than 0; x V is the recrystallized volume percent; q r is the recrystallization activation energy; n is a time index. For continuous, rapid heating recrystallization kinetics, assuming a ramp rate ε A =dT/dT, finishing of formula (A) is available:
Wherein the volume percent of recrystallization X A depends on the rate of temperature increase ε A and the final temperature T A.
From equations (a) and (B), a relationship can be established in which the alloy is isothermally annealed by increasing the temperature of the alloy to a temperature T A at a temperature increase rate epsilon A:
Where T A is the soak time, ε A is the ramp rate, X A1 is the volume fraction of recrystallized product from a ramp to T A at a given ramp rate ε A, X F is the volume fraction at T A of isothermal annealing of T A, and typically X F ≡1.
In the formulae (A) to (C), the material-dependent recrystallization kinetics n, Q r and B are independent of temperature changes and can be determined by isothermal or non-isothermal experiments.
For a given recrystallization volume percent X A, the following expression for the recrystallization activation energy Q r can be obtained with formula (B):
Wherein Q r is the recrystallization activation energy of the alloy, T Finish-A is the temperature value when the alloy finishes recrystallization under the condition of the temperature rising rate epsilon A, and T Finish-B is the temperature value when the alloy finishes recrystallization under the condition of the temperature rising rate epsilon B;
Similarly, for a given ramp rate ε, the following expression for the time index n can be obtained using equation (B):
Wherein n is a constant greater than 0; t Start-A and T Finish-A represent temperature values that produce a recrystallized volume fraction of X Start-A and X Finish-A, respectively, at a given temperature increase rate ε A;
for the constant B, the following expression can be obtained with the expression (B):
Wherein: t Finish-A represents the temperature value at which the volume fraction X Finish-A of the recrystallization is produced at a given temperature increase rate ε A, R being a gas constant.
In summary, the material-dependent recrystallization kinetics parameters n, Q r and B were calculated by combining the formulas (1) to (3). And determining the heat preservation time T A and the heating rate epsilon A of the aluminum alloy to be treated according to actual production conditions, and carrying the parameters into formula (C) to determine the corresponding annealing temperature T A.
The beneficial effects of the invention are as follows: by adopting the technical scheme, the recrystallization annealing treatment can improve the stress relaxation stability of the alloy by 20-60% under the same solid solution aging condition;
Under the same solid solution aging condition, the recrystallization annealing treatment can ensure that the high-temperature tensile property is improved by 10 to 25 percent while the alloy keeps good room-temperature mechanical property;
The recrystallization annealing and solid solution aging heat treatment process provided by the invention can be carried out in a solid solution heating furnace without additionally adding equipment, and is suitable for large-scale industrial production of heat-resistant aluminum alloys.
Drawings
FIG. 1 is a schematic diagram of the process route of the recrystallization annealing and solid solution aging method according to the present invention.
FIG. 2 is a graph showing the load-temperature profile of example 1 at a heating rate of 10℃per minute and 15℃per minute with an initial load of 3N.
FIG. 3 is a graph showing the stress relaxation curve of example 1at a holding temperature of 250℃and an initial load of 8N.
FIG. 4 is a graph showing the load-temperature profile of example 2 at a heating rate of 5℃per minute and 15℃per minute with an initial load of 4N.
FIG. 5 is a graph showing the stress relaxation curve of example 2 at a soak temperature of 250℃and an initial load of 8N.
FIG. 6 is a graph showing the load-temperature profile of example 3 at a heating rate of 20℃per minute and 5℃per minute with an initial load of 4N.
FIG. 7 is a graph showing the stress relaxation curve of example 3 at a holding temperature of 250℃and an initial load of 8N.
Detailed Description
The technical scheme of the invention is further described below by referring to examples. The recrystallization curve obtaining method in the examples is a three-point bending stress relaxation method. According to the method, by utilizing the characteristic that stress relaxation occurs in the heating recovery and recrystallization processes of deformed metal, load (Load) change data of a three-point bending sample under the continuous temperature rising condition is collected, and an obtained Load-temperature curve is a recrystallization curve.
The core idea of the invention is as follows: firstly, adopting recrystallization annealing to the deformed metal to obtain large-size grains, and then regulating and controlling the types and distribution of precipitated phases through solid solution-aging treatment.
The process flow of the heat treatment method of recrystallization annealing and solid solution aging provided by the invention is shown in figure 1, and mainly comprises the following steps:
(1) After the heat preservation time t A and the heating rate epsilon A of the aluminum alloy to be treated are determined according to actual production conditions, a recrystallization curve A of the alloy with the heating rate epsilon A is obtained through experiments (including a hardness method, an internal friction method, a three-point bending stress relaxation method and the like). The measured temperature interval range deltat is an optional temperature range for the annealing temperature. The rate of temperature rise is then increased (or decreased) to obtain a recrystallization curve B having a rate of temperature rise of epsilon B. Temperature characteristic points (recrystallization start temperature T Start and end temperature T Finish) on the two curves measured according to the tangential method are substituted into formulas (1) to (3) to determine recrystallization kinetic parameters n, Q r and B related to the material.
The recrystallization starting temperature T Start and the end temperature T Finish are respectively tangential to the non-recrystallization region, the recrystallization region and the recrystallization completion region according to the slope change of the curve, and the intersection temperature value of the tangential is the recrystallization starting temperature T Start and the end temperature T Finish;
Further, the solving process for the recrystallization kinetic parameters n, Q r and B described in step (1) is: after confirming the recrystallization start temperature T Start and the end temperature T Finish of the two recrystallization curves A and B, respectively. For the recrystallization activation energy Q r, the recrystallization activation energy Q r of the alloy can be calculated by substituting the temperature rise rates ε A and ε B of the two curves, and the recrystallization end temperature values T Finish-A and T Finish-B of the two curves into formula (1).
For the recrystallization kinetic constant n, the time index n can be calculated by substituting the temperature increase rate ε A, the recrystallization start temperature T Start-A, the end temperature T Finish-A, and the obtained Q r into formula (2).
For the recrystallization kinetic constant B, the constant B can be calculated by substituting epsilon A, the final temperature T Finish-A, and Q r and n obtained in the equation (3).
(2) Substituting the heating rate epsilon A, the holding time T A and the test results n, Q r and B in (1) into the formula (C) to determine the corresponding annealing temperature T A (the aluminum alloy just completes recrystallization when the temperature is held at T A and T A).
(3) And (3) recrystallizing and annealing: and heating the deformed aluminum alloy from room temperature to T A along with a furnace at a heating rate epsilon A, keeping the temperature for T A, discharging the aluminum alloy, and cooling the aluminum alloy to room temperature.
(4) Solution treatment: carrying out single-stage solution treatment on the annealed alloy obtained in the step (3);
Further, for the steps (3) and (4), the steps may be completed in one heat treatment process: the aluminum alloy with the changed morphology is heated from room temperature to T A along with a furnace at a heating rate epsilon A, is subjected to recrystallization annealing treatment for heat preservation T A time, and is then heated to a solution treatment temperature along with the furnace to carry out solution treatment.
(5) Aging treatment: and (3) performing single-stage aging treatment on the alloy obtained in the step (4) after solution treatment.
The solution treatment temperature is 500-520 ℃, the heat preservation time is 1-6h, and then water quenching is carried out at room temperature;
the aging treatment temperature is 180-200 ℃, the heat preservation time is 2-14h, and then air cooling is carried out to room temperature.
Example 1:
For a 75% cold deformed Al-Cu-Mg-Ag alloy (Cu content 4.45wt.%, mg content 0.37wt.%, ag content 0.41wt.%, mn content 0.25wt.%, zr content 0.09wt.%, balance Al).
The method comprises the following specific steps:
After the heat preservation time t A and the heating rate epsilon A of the aluminum alloy to be treated are determined according to actual production conditions, a three-point bending continuous heating load-temperature curve of the heating rate epsilon A and the other heating rate epsilon B is obtained through a three-point bending stress relaxation experimental device, as shown in fig. 2. The values of the recrystallization start temperature T Start and the end temperature T Finish on the load-temperature curve were measured according to the tangential method. The recrystallization temperature interval range deltat (T Start-A～TFinish-A) with the temperature rising rate epsilon A is the optional temperature range of the annealing temperature. And (3) determining the recrystallization kinetic parameters n, Q r and B of the alloy by combining the formulas (1) to (3). The annealing temperature T A is determined by substituting the annealing temperature T A and the temperature rise rate ε A into the formula (C). And (3) carrying out recrystallization annealing treatment under the conditions of heating rate epsilon A, annealing temperature T A and heat preservation time T A on the aluminum alloy to be treated, and then carrying out subsequent solid solution and aging treatment. The specific scheme is as follows:
And (3) determining a recrystallization temperature interval and an alloy correlation coefficient: when the actual production conditions are that the temperature rise rate epsilon A =10 ℃/min and the heat preservation time t A =6 h. From the test results, it was determined that the recrystallization temperature ranges under the conditions of a heating rate of 10℃per minute and 15℃per minute were 295℃to 370℃and 313℃to 378℃respectively, as shown in FIGS. 2 (a) and (b). The recrystallization kinetics values of the alloy were n=0.5, q r＝165.6KJ/mol,B＝2.1×1012s-1, respectively.
Annealing temperature T A determines: according to the tangential method measurement result in the attached figure 2, the annealing temperature T A is determined to be 325 ℃ under the conditions of the heating rate of 10 ℃/min and the heat preservation time of 6 hours.
And (3) recrystallizing and annealing: heating the cold rolled aluminum alloy from room temperature to 325 ℃ along with a furnace, wherein the heating rate is 10 ℃/min, preserving heat for 6 hours, and then performing water quenching at room temperature;
solution treatment: the annealed alloy is kept at 520 ℃ for 1h and then quenched in water at room temperature;
Aging treatment: the alloy after solution treatment is kept at 185 ℃ for 2 hours, and experimental alloy is obtained after air cooling.
The mechanical properties of the alloy prepared by the heat treatment of the invention and the conventional T6 treated alloy are shown in the accompanying figure 3 and the table 1. The results show that the proposed annealing+t6 treatment can improve the stress relaxation stability of the alloy by 54% at 250 ℃ under test conditions, the tensile strength by 10%, and maintain similar room temperature strength as compared to the conventional T6 treatment, as shown in fig. 3.
TABLE 1 mechanical Property test results of example 1
Example 2:
for an Al-Cu-Mg-Ag alloy with a forging deformation of 60% (Cu content of 5.20wt.%, mg content of 0.26wt.%, ag content of 0.78wt.%, mn content of 0.32wt.%, zr content of 0.2wt.%, balance Al.)
After the heat preservation time t A and the heating rate epsilon A of the aluminum alloy to be treated are determined according to actual production conditions, a three-point bending continuous heating load-temperature curve of the heating rate epsilon A and the other heating rate epsilon B is obtained through a three-point bending stress relaxation experimental device, as shown in fig. 4. The values of the recrystallization start temperature T Start and the end temperature T Finish on the load-temperature curve in FIG. 4 were measured according to the tangential method. The recrystallization temperature interval range deltat (T Start-A～TFinish-A) with the temperature rising rate epsilon A is the optional temperature range of the annealing temperature. And (3) determining the recrystallization kinetic parameters n, Q r and B of the alloy by combining the formulas (1) to (3). The annealing temperature T A is determined by substituting the annealing temperature T A and the temperature rise rate ε A into the formula (C). And (3) carrying out recrystallization annealing treatment under the conditions of heating rate epsilon A, annealing temperature T A and heat preservation time T A on the aluminum alloy to be treated, and then carrying out subsequent solid solution and aging treatment. The specific scheme is as follows:
And (3) determining a recrystallization temperature interval and an alloy correlation coefficient: when the actual production conditions are that the temperature rise rate epsilon A ℃ per minute and the heat preservation time t A are 8 hours. According to the tangential method measurement result, the recrystallization temperature ranges under the conditions of the temperature rising rate of 5 ℃ per minute and 15 ℃ per minute are determined to be 300 ℃ to 425 ℃ and 353 ℃ to 470 ℃ respectively, as shown in (a) and (b) of fig. 4. The recrystallization kinetics values of the alloy were n=0.55 and q r＝93.3KJ/mol,B＝1.4×105s-1, respectively.
Annealing temperature T A determines: according to the test result in fig. 4, it is determined that the annealing temperature T A is 350 ℃ under the conditions of a heating rate of 5 ℃/min and a holding time of 8 hours.
And (3) recrystallizing and annealing: heating the cold rolled aluminum alloy from room temperature to 350 ℃ along with a furnace, keeping the temperature for 8 hours at a heating rate of 5 ℃/min, and then performing water quenching at room temperature;
Solution treatment: the annealed alloy is kept at 520 ℃ for 6 hours and then quenched in water at room temperature;
Aging treatment: the alloy after solution treatment is kept at 185 ℃ for 5 hours, and experimental alloy is obtained after air cooling.
The mechanical properties of the alloy prepared by the heat treatment of the invention compared with those of the conventional T6 treated alloy are shown in FIG. 5 and Table 2. The results show that the proposed annealing+t6 treatment can increase the stress relaxation stability of the alloy by 38.5% at 250 ℃ test conditions, increase the tensile strength by 21.5%, and maintain similar room temperature strength as compared to the conventional T6 treatment, as shown in fig. 5.
TABLE 2 mechanical Property test results of example 2
Example 3:
2014 alloy for 50% press deformation (Cu content 4.04wt.%, mg content 0.65wt.%, si content 0.96wt.%, mn content 0.63wt.%, fe content 0.24wt.%, zn content 0.08wt.%, cr content 0.02wt.%, balance Al.)
After the heat preservation time t A and the heating rate epsilon A of the aluminum alloy to be treated are determined according to actual production conditions, a three-point bending continuous heating load-temperature curve of the heating rate epsilon A and the other heating rate epsilon B is obtained through a three-point bending stress relaxation experimental device, as shown in fig. 6. The values of the recrystallization start temperature T Start and the end temperature T Finish on the load-temperature curve were measured according to the tangential method. The recrystallization temperature interval range deltat (T Start-A～TFinish-A) with the temperature rising rate epsilon A is the optional temperature range of the annealing temperature. And (3) determining the recrystallization kinetic parameters n, Q r and B of the alloy by combining the formulas (1) to (3). The annealing temperature T A is determined by substituting the annealing temperature T A and the temperature rise rate ε A into the formula (C). And (3) carrying out recrystallization annealing treatment under the conditions of heating rate epsilon A, annealing temperature T A and heat preservation time T A on the aluminum alloy to be treated, and then carrying out subsequent solid solution and aging treatment. The specific scheme is as follows:
(1) And (3) determining a recrystallization temperature interval and an alloy correlation coefficient: when the actual production conditions are that the temperature rise rate epsilon A =20 ℃/min and the heat preservation time t A =10 h. According to the tangential method measurement result, the recrystallization temperature ranges under the conditions of 20 ℃ per minute and 5 ℃ per minute are determined to be 317 ℃ to 462 ℃ and 290 ℃ to 425 ℃ respectively, as shown in (a) and (b) in fig. 6. The recrystallization kinetics values of the alloy were n=0.52 and q r＝147.9KJ/mol,B＝2.9×109s-1, respectively.
(2) Annealing temperature T A determines: according to the test result in fig. 6, it is determined that the annealing temperature T A is 360 ℃ under the conditions of a heating rate of 20 ℃/min and a holding time of 10 hours.
(3) Recrystallization annealing + solution treatment: heating the cold rolled aluminum alloy from room temperature to 360 ℃ along with a furnace at a heating speed of 20 ℃/min, carrying out recrystallization annealing treatment for 10h, heating to 500 ℃ along with the furnace, carrying out solution treatment for 4h, and then carrying out water quenching at room temperature;
(4) Aging treatment: the alloy after solution treatment is kept at 185 ℃ for 10 hours, and experimental alloy is obtained after air cooling.
The mechanical properties of the alloy prepared by the heat treatment of the invention and the conventional T6 treated alloy are shown in the accompanying figure 7 and the table 3. The results show that the proposed annealing+t6 treatment can increase the stress relaxation stability of the alloy by 22% at 250 ℃ under test conditions, increase the tensile strength by 14.8%, and maintain similar room temperature strength as compared to the conventional T6 treatment, as shown in fig. 7.
TABLE 3 mechanical test results of example 3
The method for improving the high-temperature mechanical properties of the 2000 series aluminum alloy provided by the embodiment of the application is described in detail. The above description of embodiments is only for aiding in the understanding of the method of the present application and its core ideas; meanwhile, as those skilled in the art will have variations in the specific embodiments and application scope in accordance with the ideas of the present application, the present description should not be construed as limiting the present application in view of the above.
Certain terms are used throughout the description and claims to refer to particular components. Those of skill in the art will appreciate that a hardware manufacturer may refer to the same component by different names. The description and claims do not take the form of an element differentiated by name, but rather by functionality. As referred to throughout the specification and claims, the terms "comprising," including, "and" includes "are intended to be interpreted as" including/comprising, but not limited to. By "substantially" is meant that within an acceptable error range, a person skilled in the art is able to solve the technical problem within a certain error range, substantially achieving the technical effect. The description hereinafter sets forth a preferred embodiment for practicing the application, but is not intended to limit the scope of the application, as the description is given for the purpose of illustrating the general principles of the application. The scope of the application is defined by the appended claims.
It should also be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a product or system that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such product or system. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a commodity or system comprising such elements.
It should be understood that the term "and/or" as used herein is merely one relationship describing the association of the associated objects, meaning that there may be three relationships, e.g., a and/or B, may represent: a exists alone, A and B exist together, and B exists alone. In addition, the character "/" herein generally indicates that the front and rear associated objects are an "or" relationship.
While the foregoing description illustrates and describes the preferred embodiments of the present application, it is to be understood that the application is not limited to the forms disclosed herein, but is not to be construed as limited to other embodiments, and is capable of numerous other combinations, modifications and environments and is capable of changes or modifications within the scope of the inventive concept as expressed herein, either as a result of the foregoing teachings or as a result of the knowledge or technology of the relevant art. And that modifications and variations which do not depart from the spirit and scope of the application are intended to be within the scope of the appended claims.
Claims (10)
1. The method for improving the high-temperature mechanical properties of the 2000 series aluminum alloy is characterized by comprising the following steps of:
S1) determining recrystallization temperature interval and alloy related recrystallization kinetic parameters of the aluminum alloy to be treated according to actual production conditions;
S2) determining the value range of the annealing temperature T A of the treated aluminum alloy according to the recrystallization temperature interval and the alloy related recrystallization kinetic parameters obtained in the S1);
S3) carrying out recrystallization annealing treatment on the aluminum alloy to be treated according to the annealing temperature T A obtained in the S2);
S4) carrying out solution treatment on the aluminum alloy treated in the step S3);
S5) aging the aluminum alloy treated in the step S4), and obtaining the aluminum alloy with high-temperature mechanical property after air cooling.
2. The method according to claim 1, wherein the specific steps of S1) are:
S1.1) determining the heat preservation time t A and the heating rate epsilon A of the aluminum alloy to be treated according to actual production conditions, and obtaining a recrystallization curve A of the alloy with the heating rate epsilon A;
S1.2) confirming a recrystallization temperature interval range delta T with the temperature rise rate epsilon A according to a recrystallization curve A, namely, the temperature range which can be selected as the annealing temperature;
S1.3) then increasing or decreasing the temperature rise rate epsilon A to obtain a recrystallization curve B with the temperature rise rate epsilon B and epsilon B, and determining the recrystallization kinetic parameters related to the material according to the temperature characteristic points on the recrystallization curve A and the recrystallization curve B.
3. The method according to claim 2, wherein the parameters in S1.3) include a time index n, a recrystallization activation energy value Q r of the alloy, and a constant B, which are respectively found by the following formulas:
wherein R is a gas constant, T Finish-A is a temperature value when the aluminum alloy is recrystallized under the condition of the temperature rising rate epsilon A, and T Finish-B is a temperature value when the aluminum alloy is recrystallized under the condition of the temperature rising rate epsilon B;
Wherein n is a time index, n > 0; t Start-A and T Finish-A represent temperature values that produce a recrystallized volume fraction of X Start-A and X Finish-A, respectively, at a given temperature increase rate ε A;
Wherein: t Finish-A represents the temperature value at which the volume fraction X Finish-A of the recrystallization is produced at a given temperature increase rate ε A.
4. A method according to claim 3, characterized in that the annealing temperature T A in S2) is determined by the following formula:
Where X A1 is the volume fraction of recrystallization from the temperature increase to T A at a given temperature increase rate ε A, and X F is the volume fraction at the time of T A isothermal annealing T A, and X F ≡1.
5. The method according to claim 4, wherein the specific step of S3) is:
S3.1) firstly heating the aluminum alloy to be treated from room temperature to T A along with a furnace at a heating rate epsilon A,
S3.2) at the temperature of T A, after the temperature is kept for T A time, the recrystallization annealing is finished, and the materials are discharged and cooled to the room temperature.
6. The method according to claim 5, wherein the solution treatment in S4) is a single-stage solution treatment.
7. The method according to claim 6, wherein the single-stage solution treatment is performed at a temperature of 480 to 520 ℃ for a holding time of 1 to 6 hours.
8. The method according to claim 5, wherein the aging treatment in S5) is specifically: the aging treatment temperature is 180-200 ℃, and the heat preservation time is 2-14h.
9. The method of claim 1, wherein the aluminum alloy treated by the method has a stress relaxation stability of 20-60% and a tensile strength of at least 10.0% -25.0% at 250 ℃ under test conditions.
10. An aluminium alloy with high temperature mechanical properties, characterized in that it is obtained by the method according to any one of claims 1-9.
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