Method for regulating and controlling desolventizing phase of large-size aluminum alloy extruded plate

Abstract

The invention belongs to the technical field of heat treatment of high-performance aluminum alloy materials for space flight and aviation, and particularly discloses a method for regulating and controlling a desolventizing phase of a large-size aluminum alloy extruded plate. The problems that a traditional spraying mode is low in quenching cooling speed and long in quenching transfer time are solved. Comprising the following steps that (1) after being extruded, an aluminum alloy extruded plate is loaded into a roller hearth type quenching furnace for solid solution, then discharged from the furnace and settled in a quenching water well to be soaked for 15 min or above, and a quenched plate is obtained; (2) the quenched plate is placed for 42-45 h; and (3) aging treatment is conducted, specifically, the quenched plate subjected to standing treatment is subjected to artificial aging. The quenching transfer time is shortened, the cooling strength is enhanced, desolventizing phase precipitation in the quenching cooling process of the extruded plate is reduced, and the strength, toughness and stress corrosion performance of the aluminum alloy extruded plate with the thickness larger than 80 mm are effectively improved.

Description

Technical Field

[0001] The invention belongs to the technical field of heat treatment of high-performance aluminum alloy materials for aerospace, and in particular relates to a method for regulating and controlling the desolvation phase of a large-size aluminum alloy extruded plate. Background Art

[0002] 7000 series aluminum alloys have the characteristics of high strength, high toughness and corrosion resistance, and are widely used in the aerospace field. Aluminum alloy extruded sheets can obtain supersaturated solid solution through solid solution quenching and adopt a sufficiently fast cooling rate, thereby improving the comprehensive performance of the material.

[0003] However, the traditional horizontal furnace roller hearth quenching method is: the extruded plate is quenched by spraying after it comes out of the horizontal furnace. This method has the following problems: the quenching cooling speed is slow, the quenching transfer time is long, which reduces the concentration of supersaturated solid solution and seriously affects the performance of large-size (i.e., thickness over 80mm) aluminum alloy extruded plates. Summary of the invention

[0004] The purpose of the present invention is to provide a method for regulating the desolvation phase of large-size aluminum alloy extruded plates, which effectively solves the problems of slow quenching cooling speed and long quenching transfer time in traditional spray quenching.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0006] A method for regulating and controlling the desolvation phase of a large-size aluminum alloy extruded plate comprises the following steps: S1, solution heat treatment: after extrusion, the aluminum alloy extruded plate is placed in a roller bottom quenching furnace for solution treatment at a solution temperature of 469°C to 479°C for 8 to 10 hours, then taken out of the furnace and settled in a quenching water well for soaking for more than 15 minutes to obtain a quenched plate.

[0007] S2. Parking treatment: park the quenched plate for 42h to 45h.

[0008] S3. Aging treatment: artificial aging is performed on the quenched plate after the parking treatment, and the insulation temperature is 130℃~140℃, and the insulation time is 24h~30h.

[0009] Furthermore, in step S1, the thickness of the aluminum alloy extruded sheet is greater than 80 mm.

[0010] Furthermore, in step S1, the soaking time is 20 minutes.

[0011] Furthermore, in step S2, the parking time is 45 hours.

[0012] Compared with the prior art, the beneficial technical effects of the present invention are:

[0013] (1) In the present invention, after the solid solution treatment of large-size ultra-high-strength aluminum alloy (thickness>80mm) extruded plates is completed, they are directly settled in a quenching water well, thereby shortening the quenching transfer time, enhancing the cooling intensity, reducing the precipitation of the dissolution phase during the quenching cooling process of the extruded plates, ensuring the quenching effect, and effectively improving the strength of the extruded plates with a thickness of more than 80mm, while also improving their toughness and stress corrosion resistance.

[0014] (2) The present invention reasonably controls the storage time of the quenched plate before aging treatment, so that the precipitated dissolution phase of the quenched plate after aging treatment is small in size and evenly distributed, the artificial aging nucleation rate is increased, and the strengthening phase is increased, thereby effectively improving the tensile strength, yield strength and elongation after fracture of large-size ultra-high strength aluminum alloy extruded plates. DETAILED DESCRIPTION

[0015] Example 1: The product of this example is a rectangular bar of 7075 aluminum alloy extruded sheet, the width of the rectangular bar is 150 mm, and the thickness is 115 mm. The specific process of the desolvation phase control method of the product is as follows.

[0016] (1) Solution heat treatment: After extrusion, the product is placed in a roller-type quenching furnace for solution treatment at a temperature of 474°C for 9 hours, and then taken out of the furnace and placed in a quenching water well for soaking. Soak in the quenching water well for 20 minutes to obtain a quenched plate.

[0017] (2) Parking treatment: The quenched plate is parked for 45 hours.

[0018] (3) Aging treatment: The quenched plate after the parking treatment is artificially aged at a holding temperature of 135°C for 27 hours.

[0019] Comparative Example 1: The product of this comparative example is a rectangular bar of 7075 aluminum alloy extruded sheet, the width of the rectangular bar is 150 mm, and the thickness is 115 mm. The specific process of the desolvation phase control method for the product is as follows.

[0020] (1) Solution heat treatment: After extrusion, the product is placed in a roller hearth quenching furnace for solution treatment at a temperature of 474°C for 9 hours, and then taken out of the furnace for spray quenching.

[0021] (2) Parking treatment: The quenched product is parked for 45 hours.

[0022] (3) Aging treatment: The products after the parking treatment are artificially aged at a holding temperature of 135°C for 27 hours.

[0023] Comparative Example 2: The product of this comparative example is a rectangular bar of 7075 aluminum alloy extruded sheet, the width of the rectangular bar is 150 mm, and the thickness is 115 mm. The specific process of the desolvation phase control method for the product is as follows.

[0024] (1) Solution heat treatment: After extrusion, the product is placed in a roller-type quenching furnace for solution treatment at a temperature of 474°C for 9 hours, and then taken out of the furnace and placed in a quenching water well for soaking. Soak in the quenching water well for 20 minutes to obtain a quenched plate.

[0025] (2) Parking treatment: The quenched plate is parked for 35 hours.

[0026] (3) Aging treatment: The quenched plate after the parking treatment is artificially aged at a holding temperature of 135°C for 27 hours.

[0027] The performance indicators (tensile strength, yield strength and elongation after fracture) of the products after aging treatment in Example 1, Comparative Example 1 and Comparative Example 2 were tested respectively according to ASTM B557. The test results are shown in Table 1.

[0028] Table 1 Performance indicators of products after aging treatment

[0029] serial number Tensile strength / MPa Yield strength / MPa Elongation after break / % Example 1 606 543 10.3 Comparative Example 1 554 503 9.7 Comparative Example 2 574 516 9.7

[0030] Combined with Table 1, by comparing Example 1 and Comparative Example 1, it can be seen that Example 1 shortens the quenching transfer time, enhances the cooling intensity, reduces the precipitation of the desolvated phase during the quenching cooling process of the extruded plate, ensures the quenching effect, and effectively improves the strength of the extruded plate with a thickness of more than 80 mm.

[0031] Compared with Comparative Example 2, the parking time of Example 1 before aging treatment is 45 hours, which is longer than the parking time of Comparative Example 2 before aging treatment. Therefore, the tensile strength, yield strength and elongation after fracture of the product obtained in Example 1 after aging treatment are better than those of the product obtained in Comparative Example 2 after aging treatment. The applicant has shown through a large number of studies that when large-size ultra-high strength aluminum alloy is parked for 42h to 45h, the precipitated dissolution phase is small in size and evenly distributed, the artificial aging nucleation rate increases, and the strengthening phase increases; if the parking time is short (less than 42h), the precipitated dissolution phase is unstable and re-dissolves into the matrix, the artificial aging nucleation rate decreases, and the strengthening phase decreases; if the parking time is long (more than 45h), the precipitated dissolution phase is larger in size and the performance of the aluminum alloy is unstable.

[0032] Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by technicians in this technical field within the essential scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. A method for regulating the desolvation phase of a large-size aluminum alloy extruded sheet, characterized in that: The following steps are involved: S1. Solution heat treatment: After extrusion, the aluminum alloy extruded plate is placed in a roller-type quenching furnace for solution treatment at a solution temperature of 469°C to 479°C for 8 to 10 hours. The plate is then taken out of the furnace and placed in a quenching water well for soaking for more than 15 minutes to obtain a quenched plate. S2. Parking treatment: park the quenched plate for 42h to 45h; S3. Aging treatment: artificial aging is performed on the quenched plate after the parking treatment, and the insulation temperature is 130℃~140℃, and the insulation time is 24h~30h.

2. The method for controlling the desolvation phase of large-size aluminum alloy extruded sheet according to claim 1, characterized in that: In step S1, the thickness of the aluminum alloy extruded sheet is greater than 80 mm.

3. The method for controlling the desolvation phase of large-size aluminum alloy extruded sheet according to claim 2, characterized in that: In step S1, the soaking time is 20 minutes.

4. The method for controlling the desolvation phase of large-size aluminum alloy extruded sheet according to claim 3, characterized in that: In step S2, the parking time is 45 hours.