Homogenizing heat treatment process for Zr-containing aluminum alloy

Abstract

The invention relates to the field of alloy heat treatment, in particular to a homogenizing heat treatment process for a Zr-containing aluminum alloy. The invention provides a homogenization heat treatment process of Zr-containing aluminum alloy. The homogenization heat treatment process comprises two stages of homogenization treatment, the temperature of the first-stage homogenizing heat treatment mainly aims at the uniformity distribution of zirconium-containing precipitates, if the first-stage temperature is not within the range, the uniformity distribution of the zirconium precipitates can be influenced, and if the second-stage temperature is lower than the range, the uniformity distribution of copper and lithium elements can be influenced. The homogenization degree of copper and lithium elements can be influenced, and over-burning can be generated if the homogenization degree is higher than the range. And a thermocouple is arranged in the cast ingot for monitoring, so that the precise temperature control of the homogenizing heat treatment is realized. Experiments show that according to the process provided by the invention, accurate homogenization heat treatment of the 2A55 aluminum alloy ingot can be carried out, serious element segregation of the 2A55 alloy is avoided, and sufficient homogenization of chemical components of the alloy is ensured.

Description

Technical Field

[0001] The invention relates to the field of alloy heat treatment, in particular to a homogenization heat treatment process of a Zr-containing aluminum alloy. Background Art

[0002] Homogenization heat treatment is an extremely important process in the material processing process. However, there is currently no suitable homogenization heat treatment process for 2A55 alloy ingots. The main purpose of homogenization heat treatment is to reduce or eliminate microsegregation as much as possible, which generally requires higher temperatures for treatment. For alloys containing transition elements, it is also necessary to consider the precipitation of dispersed phases containing transition elements, which is generally treated at lower temperatures. Therefore, a two-stage homogenization process needs to be developed. Currently, there is no identical or similar homogenization heat treatment process for 2A55 alloy. In addition, the existing technology is not accurate enough in controlling the temperature and holding time during the homogenization heat treatment of the ingot, resulting in the actual effect being less than expected. Summary of the invention

[0003] In view of this, the technical problem to be solved by the present invention is to provide a homogenization heat treatment process for Zr-containing aluminum alloys. The homogenization heat treatment process provided by the present invention can perform precise homogenization heat treatment, and for Zr-containing aluminum alloys, especially 2A55 aluminum alloys, can ensure that their processing performance and use performance are improved without overburning.

[0004] The present invention provides a homogenization heat treatment process for a Zr-containing aluminum alloy, comprising the following steps:

[0005] The Zr-containing aluminum alloy ingot is subjected to a first-stage heat preservation and a second-stage heat preservation in sequence;

[0006] The temperature of the first stage of insulation is 465°C to 475°C, and the time of the first stage of insulation is 15 h to 17 h;

[0007] The temperature of the second stage insulation is 515° C. to 525° C., and the time of the second stage insulation is 27 h to 29 h.

[0008] The homogenization heat treatment process provided by the present invention is for a Zr-containing aluminum alloy. Specifically, the Zr-containing aluminum alloy includes: Si: ≤0.10 wt%; Fe: ≤0.15 wt%; Cu: 3.7~4.1 wt%; Mn: 0.20~0.40 wt%; Mg: 0.20~0.60wt%; Cr: ≤0.05 wt%; Zn: 0.20~0.60 wt%; Ti: 0.02~0.10 wt%; Zr: 0.09~0.14 wt%; Li: 1.15~1.35 wt%; Ag: 0.20~0.55 wt%; the balance is Al and impurities. More preferably, the Zr-containing aluminum alloy provided by the present invention is 2A55 aluminum alloy.

[0009] The inventors of the present application creatively discovered that through a two-stage homogenization treatment, a lower first-stage equalization temperature is firstly adopted to increase the dispersion of the Zr-containing second phase, and then a higher second-stage equalization temperature is adopted. Under the premise of not overburning, the microsegregation of alloy elements can be weakened as much as possible, and ultimately the alloy products can obtain better processing performance and use performance.

[0010] The first-stage insulation of the present invention is also called the first-stage heat treatment, and the temperature of the first-stage insulation is preferably 465°C~475°C, and the time of the first-stage insulation is preferably 15 h~17 h; the second-stage insulation is also called the second-stage heat treatment, and the temperature of the second-stage insulation is preferably 515°C~525°C, and the time of the second-stage insulation is preferably 27 h~29 h.

[0011] Preferably, the temperature of the first stage insulation is 467°C~474°C, and the time of the first stage insulation is 15 h~17 h; the temperature of the second stage insulation is 516°C~523°C, and the time of the second stage insulation is 27 h~29 h.

[0012] More preferably, the temperature of the first insulation stage is 467°C to 474°C, and the time of the first insulation stage is 16 hours; the temperature of the second insulation stage is 516°C to 523°C, and the time of the second insulation stage is 28 hours.

[0013] In some embodiments of the present invention, the temperature of the first stage of insulation is 467° C., and the time of the first stage of insulation is 16 h; the temperature of the second stage of insulation is 516° C., and the time of the second stage of insulation is 28 h.

[0014] In some other embodiments of the present invention, the temperature of the first-stage insulation is 471° C., and the time of the first-stage insulation is 16 h; the temperature of the second-stage insulation is 520° C., and the time of the second-stage insulation is 28 h.

[0015] In some other embodiments of the present invention, the temperature of the first-stage insulation is 474° C., and the time of the first-stage insulation is 16 h; the temperature of the second-stage insulation is 523° C., and the time of the second-stage insulation is 28 h.

[0016] Before the Zr-containing aluminum alloy ingot is subjected to the first stage of thermal insulation and the second stage of thermal insulation in sequence, the alloy ingot must first be loaded into a furnace, specifically, the Zr-containing aluminum alloy ingot is placed in a soaking furnace and subjected to the first stage of thermal insulation and the second stage of thermal insulation in sequence; before the Zr-containing aluminum alloy ingot is placed in the soaking furnace, the temperature of the soaking furnace is below 300°C.

[0017] In the present invention, when the number of the Zr-containing aluminum alloy ingots exceeds one, the spacing between the Zr-containing aluminum alloy ingots is greater than 100 mm. Specifically, when multiple ingots are placed in one furnace, spacers of ≥ 100 mm should be placed between the ingots to facilitate lifting and hot air circulation.

[0018] The Zr-containing aluminum alloy ingot of the present invention is provided with a thermocouple, and the temperature is monitored by the thermocouple; the time of the first-level insulation is calculated only when the thermocouples all reach the temperature of the first-level insulation; the time of the second-level insulation is calculated only when the thermocouples all reach the temperature of the second-level insulation. Specifically, the thermocouples are arranged at the hot end and the cold end of the Zr-containing aluminum alloy ingot, and the time of the first-level insulation is calculated only when all the thermocouples reach the temperature of the first-level insulation; the time of the second-level insulation is calculated only when all the thermocouples reach the temperature of the second-level insulation. The hot end of the Zr-containing aluminum alloy ingot of the present invention refers to the end of the ingot close to the heat source in the soaking furnace, and the cold end refers to the end of the ingot far away from the heat source in the soaking furnace. The depth of the thermocouple arranged in the Zr-containing aluminum alloy ingot of the present invention is 25~35 mm. The present invention arranges a thermocouple in the ingot, and monitors the temperature and time of the soaking treatment of the ingot by the thermocouple, so as to achieve accurate control of the temperature and the soaking time during the homogenization heat treatment.

[0019] In the present invention, after the Zr-containing aluminum alloy ingot is subjected to the first-stage heat preservation and the second-stage heat preservation in sequence, the Zr-containing aluminum alloy ingot is immediately cooled.

[0020] The present invention provides a homogenization heat treatment process for a Zr-containing aluminum alloy. The homogenization heat treatment process for a Zr-containing aluminum alloy provided by the present invention includes two-stage homogenization treatment; the temperature of the first-stage homogenization heat treatment is mainly aimed at the uniform distribution of zirconium-containing precipitates. If the first-stage temperature is not within this range, it will affect the uniform distribution of zirconium precipitates. The temperature of the second-stage homogenization heat treatment is mainly aimed at the uniform distribution of copper and lithium elements. If the second-stage temperature is lower than this range, it will affect the homogenization degree of copper and lithium elements. If it is higher than this range, overburning may occur. The present invention also realizes precise temperature control during homogenization heat treatment by arranging a thermocouple in the ingot for monitoring. Experiments show that according to the process provided by the present invention, precise homogenization heat treatment of 2A55 aluminum alloy ingots can be carried out, which avoids serious element segregation of 2A55 alloy and ensures that the chemical composition of the alloy is fully homogenized. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a 50x SEM image of the 2A55 alloy obtained in Example 1 of the present invention;

[0022] Figure 2 This is a 50x SEM image of the 2A55 alloy obtained in Example 2 of the present invention;

[0023] Figure 3 This is a 50x SEM image of the 2A55 alloy obtained in Example 3 of the present invention;

[0024] Figure 4 This is a 50x SEM image of the 2A55 alloy obtained in Comparative Example 1 of the present invention. DETAILED DESCRIPTION

[0025] The present invention discloses a homogenization heat treatment process for a Zr-containing aluminum alloy. Those skilled in the art can refer to the content of this article and appropriately improve the process parameters to achieve it. It is particularly important to point out that all similar substitutions and modifications are obvious to those skilled in the art, and they are all considered to be included in the present invention. The method and application of the present invention have been described through preferred embodiments, and relevant personnel can obviously modify or appropriately change and combine the method and application of this article without departing from the content, spirit and scope of the present invention to implement and apply the technology of the present invention.

[0026] The process provided by the present invention first requires the alloy ingots to be loaded into the furnace, specifically including: ① before loading the furnace, the temperature of the soaking furnace is lowered to below 300°C; ② multiple ingots are loaded into one furnace, and ≥100mm spacers are placed between the ingots to facilitate lifting and hot air circulation; ③ a thermocouple is placed at the upper right part of the hot end, the lower part of the hot end, and the upper left part of the cold end of each furnace. ④ when installing the thermocouple, a hole is directly drilled at the corresponding position of the ingot, with a hole diameter of Φ4.5~6.5mm and a hole depth of 30±5mm; ⑤ insert the thermocouple into the hole and plug it with glass cloth; ⑥ the temperature of the inserted thermocouple is used as the soaking metal temperature of the ingot, and the insulation time is calculated only when all three thermocouples enter the insulation temperature range.

[0027] The alloy ingot used in this embodiment is 2A55 alloy, and its composition is shown in Table 1:

[0028] Table 1

[0029]

[0030] The present invention will be further described below in conjunction with embodiments:

[0031] Example 1

[0032] The homogenization heat treatment process of the 2A55 alloy provided in this embodiment includes the following steps:

[0033] In the first step, when the temperature of the heating furnace is 285°C, 2A55 alloy is loaded into the heating furnace.

[0034] In the second step, the temperature of the first stage homogenization heat treatment was 467 °C and the holding time was 16 h.

[0035] In the third step, the temperature of the second-stage homogenization heat treatment is 516 °C and the holding time is 28 h.

[0036] Step 4: Air cool after taking out of the oven.

[0037] like Figure 1 As shown, Figure 1 This is a 50x SEM image of the 2A55 alloy obtained in Example 1 of the present invention. Through the double-stage homogenization treatment and cooling treatment, severe element segregation of the 2A55 alloy is avoided, ensuring that the chemical composition of the alloy is fully homogenized.

[0038] Example 2

[0039] The homogenization heat treatment process of the 2A55 alloy provided in this embodiment includes the following steps:

[0040] In the first step, when the temperature of the heating furnace is 291°C, 2A55 alloy is loaded into the heating furnace.

[0041] In the second step, the temperature of the first stage homogenization heat treatment was 471 °C and the holding time was 16 h.

[0042] In the third step, the temperature of the second-stage homogenization heat treatment is 520 °C and the holding time is 28 h.

[0043] Step 4: Air cool after taking out of the oven.

[0044] like Figure 2 As shown, Figure 2 This is a 50x SEM image of the 2A55 alloy obtained in Example 2 of the present invention. Through the double-stage homogenization treatment and cooling treatment, severe element segregation of the 2A55 alloy is avoided, ensuring that the chemical composition of the alloy is fully homogenized.

[0045] Example 3

[0046] The homogenization heat treatment process of the 2A55 alloy provided in this embodiment includes the following steps:

[0047] In the first step, when the temperature of the heating furnace is 285°C, 2A55 alloy is loaded into the heating furnace.

[0048] In the second step, the temperature of the first stage homogenization heat treatment was 474 °C and the holding time was 16 h.

[0049] In the third step, the temperature of the second-stage homogenization heat treatment is 523 °C and the holding time is 28 h.

[0050] Step 4: Air cool after taking out of the oven.

[0051] like Figure 3 As shown, Figure 3 This is a 50x SEM image of the 2A55 alloy obtained in Example 3 of the present invention. Through the double-stage homogenization treatment and cooling treatment, severe element segregation of the 2A55 alloy is avoided, ensuring that the chemical composition of the alloy is fully homogenized.

[0052] Comparative Example 1

[0053] The homogenization heat treatment process of the alloy provided in this comparative example comprises the following steps:

[0054] In the first step, when the temperature of the heating furnace is 295°C, 2A55 alloy is loaded into the heating furnace.

[0055] In the second step, the temperature of the first stage homogenization heat treatment was 466 °C and the holding time was 16 h.

[0056] In the third step, the temperature of the second-stage homogenization heat treatment is 530 °C and the holding time is 28 h.

[0057] Step 4: Air cool after taking out of the oven.

[0058] like Figure 4 As shown, Figure 4 This is a 50x SEM image of the 2A55 alloy obtained in Comparative Example 1 of the present invention. The two-stage homogenization treatment process used in this comparative example is not within the process range provided in the present application, resulting in severe element segregation and overburning.

[0059] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A homogenization heat treatment process for a Zr-containing aluminum alloy, characterized in that: The following steps are involved: The Zr-containing aluminum alloy ingot is subjected to a first-stage heat preservation and a second-stage heat preservation in sequence; The temperature of the first stage of insulation is 465°C to 475°C, and the time of the first stage of insulation is 15 h to 17 h; The temperature of the second stage insulation is 515°C to 525°C, and the time of the second stage insulation is 27 h to 29 h.

2. The homogenization heat treatment process of the Zr-containing aluminum alloy according to claim 1, characterized in that: The temperature of the first stage of insulation is 467°C~474°C; The temperature of the second stage insulation is 516°C~523°C.

3. The homogenization heat treatment process of the Zr-containing aluminum alloy according to claim 1, characterized in that: A thermocouple is provided in the Zr-containing aluminum alloy ingot, and temperature monitoring is performed by the thermocouple; The first-stage heat preservation time starts to be calculated only when the thermocouples all reach the first-stage heat preservation temperature; The second-stage heat preservation time starts to be calculated only when the thermocouples all reach the second-stage heat preservation temperature.

4. The homogenization heat treatment process of the Zr-containing aluminum alloy according to claim 3, characterized in that: The thermocouples are arranged at the hot end and the cold end of the Zr-containing aluminum alloy ingot; The first-stage heat preservation time starts to be calculated only when all the thermocouples reach the first-stage heat preservation temperature; The second-stage heat preservation time starts to be calculated only when all the thermocouples reach the second-stage heat preservation temperature.

5. The homogenization heat treatment process of the Zr-containing aluminum alloy according to claim 4, characterized in that: The thermocouple is arranged at a depth of 25 to 35 mm in the Zr-containing aluminum alloy ingot.

6. The homogenization heat treatment process of the Zr-containing aluminum alloy according to claim 1, characterized in that: The Zr-containing aluminum alloy comprises: Si: ≤0.10 wt%; Fe: ≤0.15 wt%; Cu: 3.7~4.1 wt%; Mn: 0.20~0.40 wt%; Mg: 0.20~0.60 wt%; Cr: ≤0.05 wt%; Zn: 0.20~0.60 wt%; Ti: 0.02~0.10 wt%; Zr: 0.09~0.14 wt%; Li: 1.15~1.35 wt%; Ag: 0.20~0.55 wt%; The balance is Al.

7. The homogenization heat treatment process of the Zr-containing aluminum alloy according to claim 6, characterized in that: The Zr-containing aluminum alloy is 2A55 aluminum alloy.

8. The homogenization heat treatment process of the Zr-containing aluminum alloy according to claim 1, characterized in that: Placing the Zr-containing aluminum alloy ingot in a soaking furnace and sequentially performing first-stage heat preservation and second-stage heat preservation; Before placing the Zr-containing aluminum alloy ingot in the soaking furnace, the temperature of the soaking furnace is below 300°C.

9. The homogenization heat treatment process of the Zr-containing aluminum alloy according to claim 1, characterized in that: When the number of the Zr-containing aluminum alloy ingots exceeds one, the distance between the Zr-containing aluminum alloy ingots is greater than 100 mm.

10. The homogenization heat treatment process of the Zr-containing aluminum alloy according to any one of claims 1 to 3, characterized in that: After the Zr-containing aluminum alloy ingot is subjected to the first stage heat preservation and the second stage heat preservation in sequence, the Zr-containing aluminum alloy ingot is immediately cooled.

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