Heat treatment method for grain refinement of nickel alloy with high tungsten content

Abstract

The invention belongs to the technical field of metal heat treatment, and discloses a heat treatment method for grain refinement of nickel alloy with high tungsten content. The heat treatment method for grain refinement of the high-tungsten-content nickel alloy comprises the steps that the to-be-treated high-tungsten-content nickel alloy is subjected to high-temperature homogenization treatment at the temperature of 1250-1400 DEG C and then subjected to water cooling, aging treatment is conducted at the temperature of 950-1100 DEG C, then the temperature is increased to 1100-1250 DEG C, heat preservation heat treatment and water cooling are conducted, and the high-tungsten-content nickel alloy obtained after grain refinement is obtained. According to the method, high-temperature homogenization treatment, aging treatment, heat preservation heat treatment and water cooling are sequentially carried out, and the temperature of each treatment process is regulated and controlled, so that the segregation condition of a NixWy precipitated phase and a W phase of the high-tungsten-content nickel alloy can be effectively eliminated, and the problems that the high-tungsten-content nickel alloy is poor in plasticity and is difficult to form through plastic processing modes such as forging and the like, and the plasticity of the high-tungsten-content nickel alloy is poor are solved. The problems of grain refinement and structure property regulation and control are solved; and meanwhile, grains can be refined, and the alloy performance is improved.

Description

Technical Field

[0001] The invention relates to the technical field of metal heat treatment, and in particular to a heat treatment method for grain refinement of a nickel alloy with a high tungsten content. Background Art

[0002] Nickel is an important strategic metal, widely used in industrial production, with good plasticity and strong solid solubility. Tungsten has a very high melting point (3380℃) and density (19.35g / cm 3 ), the solubility of tungsten in nickel can reach up to 39.9wt.%. The introduction of tungsten can significantly improve the strength, hardness, density and high temperature resistance of nickel, making nickel-tungsten alloy widely used in aerospace, weapons and equipment, automobile manufacturing, energy and chemical industries and other fields.

[0003] At present, the common preparation processes of nickel-tungsten alloy are powder metallurgy and smelting. However, due to the extremely high melting point of tungsten, it is difficult to prepare nickel-tungsten alloy by powder metallurgy and smelting. Moreover, in the process of preparing nickel-tungsten alloy by powder metallurgy or smelting, tungsten will segregate, and there will be a variety of Ni x W y The precipitation of phase will significantly deteriorate the plasticity of nickel-tungsten alloy, resulting in difficulty in processing nickel-tungsten alloy. It is difficult to form, refine grains and regulate organizational properties through plastic processing such as forging, which seriously limits the application and development of the alloy. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a heat treatment method for grain refinement of nickel alloy with high tungsten content. The present invention can effectively eliminate the grain refinement of nickel alloy with high tungsten content by sequentially performing high temperature homogenization treatment, aging treatment, heat preservation heat treatment and water cooling, and by regulating the temperature of each treatment process. x W y The segregation of the precipitate phase and the W phase is solved, thereby solving the problem that the nickel alloy with high tungsten content has poor plasticity and is difficult to be formed through plastic processing such as forging, refines the grains, and regulates the organizational properties.

[0005] The heat treatment method for grain refinement of a high tungsten content nickel alloy of the present invention is achieved by the following technical scheme:

[0006] A heat treatment method for grain refinement of a high tungsten content nickel alloy comprises the following steps:

[0007] Step 1, high temperature homogenization treatment:

[0008] The high-tungsten-content nickel alloy to be treated is subjected to high-temperature homogenization treatment at 1250° C. to 1400° C., and then water-cooled to room temperature to obtain a first alloy.

[0009] It should be noted that the present invention does not limit the specific composition of the nickel alloy with high tungsten content to be treated, and the corresponding nickel alloy with high tungsten content can be selected according to the implementation requirements. In some preferred embodiments of the present invention, the nickel alloy with high tungsten content to be treated is a nickel-tungsten alloy in which the tungsten content accounts for 25wt% to 40wt% of the total mass of the alloy. For example, in some more preferred embodiments of the present invention, the nickel alloy with high tungsten content to be treated has the following components in terms of mass percentage: W 25% to 40%, Nb 0 to 10%, Ta 0 to 10%, Mo 0 to 10%, Co 0 to 10%, Al 0 to 1.5%, Ti 0 to 1.5%, and the remainder is Ni and unavoidable trace elements and impurity elements, totaling 100%.

[0010] The present invention takes into account that for high tungsten nickel alloy, the segregation structure is Ni x W y In addition to the precipitated phase, there will be a large amount of pure W phase precipitated along the crystal. The dissolution elimination temperature of the pure W phase is much higher than 1250°C. Therefore, the present invention preferably uses 1250°C to 1400°C as the treatment temperature for high-temperature homogenization treatment, so that Ni can be completely dissolved during the high-temperature homogenization treatment at this temperature. x W y Precipitation phase and W phase, eliminating component segregation.

[0011] In some preferred embodiments of the present invention, the high temperature homogenization treatment time is 3h to 30h to ensure that Ni x W y The precipitated phase and the pure W phase completely dissolve back.

[0012] Step 2, aging treatment:

[0013] The first alloy is subjected to aging treatment at 950° C. to 1100° C. to obtain a second alloy.

[0014] It should be noted that the present invention controls the aging treatment temperature to be 950°C to 1100°C so that a large amount of Ni is precipitated in the first alloy. x W y The precipitated phase grows up to divide the original grain boundary, thereby achieving the purpose of grain refinement. In some preferred embodiments of the present invention, the aging treatment time is 3h to 30h to ensure that the above-mentioned grain refinement effect can be achieved.

[0015] In some preferred embodiments of the present invention, the aging treatment is followed by cooling to room temperature and then performing a heat preservation treatment.

[0016] Step 3, heat treatment:

[0017] The second alloy is heated to 1100° C. to 1250° C., then subjected to heat preservation heat treatment, and then water-cooled to room temperature to obtain a grain-refined nickel alloy with a high tungsten content.

[0018] It should be noted that the treatment temperature of the heat treatment in the present invention is 1100°C to 1250°C, so as to precipitate a large amount of Ni x W y The precipitated phase was dissolved and then water-cooled to prevent Ni x W y The precipitated phase precipitates again, and the refined grain size is fixed. In some preferred embodiments of the present invention, the heat treatment time is 3h to 30h to ensure that the Ni x W y The effect of dissolution of precipitated phase and solid solution grain size.

[0019] In some preferred embodiments of the present invention, before the high-temperature homogenization treatment is performed, a layer of anti-oxidation coating is first coated on the surface of the high-tungsten-content nickel alloy to be treated. After the anti-oxidation coating to be coated is cured, a layer of anti-oxidation coating is formed on the surface of the high-tungsten-content nickel alloy to be treated to prevent excessive oxidation of the alloy.

[0020] In some preferred embodiments of the present invention, the anti-oxidation coating is a tungsten alloy high-temperature protective coating, and the coating thickness of the anti-oxidation coating on the surface of the nickel alloy with high tungsten content to be treated is 0.5 mm to 2 mm to prevent the alloy from being over-oxidized. The present invention does not specifically limit the type of tungsten alloy high-temperature protective coating used, and the common tungsten alloy high-temperature protective coating in the art can be used, which should be known to those skilled in the art, so this application will not be repeated.

[0021] In some preferred embodiments of the present invention, before the aging treatment, a layer of anti-oxidation coating is also coated on the surface of the first alloy, and the aging treatment is performed after the coated anti-oxidation coating is cured; wherein the coating thickness of the anti-oxidation coating on the surface of the first alloy is 0.5 mm to 2 mm to prevent excessive oxidation of the alloy.

[0022] It should be noted that the second alloy can be directly heated to 1100℃~1250℃ and then subjected to heat preservation heat treatment, or the second alloy can be water-cooled to room temperature and then heated to 1100℃~1250℃ and then subjected to heat preservation heat treatment. Wherein, when the second alloy is water-cooled to room temperature and then heated to 1100℃~1250℃ and then subjected to heat preservation heat treatment, before the heat preservation heat treatment, a layer of anti-oxidation coating is first applied to the surface of the second alloy, and the heat preservation heat treatment is performed after the anti-oxidation coating is cured; wherein, the coating thickness of the anti-oxidation coating on the surface of the second alloy is 0.5mm~2mm to prevent excessive oxidation of the alloy.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The invention firstly performs a high temperature homogenization treatment on the nickel alloy with high tungsten content to be treated at 1250°C to 1400°C, and then cools the nickel alloy to room temperature to completely dissolve the nickel. x W y The precipitate phase and W phase are separated to eliminate the component segregation. Then, the Ni x W y The precipitated phase precipitates and grows in large quantities to divide the original grain boundaries, thereby achieving the purpose of grain refinement. Then, a heat treatment is carried out at 1100℃~1250℃ to convert the Ni precipitated and grown in large quantities during the aging treatment into x W y The precipitated phase was dissolved and then water-cooled to prevent Ni x W y The precipitated phase precipitates again and fixes the refined grain size.

[0025] The present invention can effectively eliminate the high tungsten content nickel alloy Ni by sequentially performing high temperature homogenization treatment, aging treatment and heat preservation heat treatment followed by water cooling, and by regulating the temperature of each treatment process. x W y The precipitate phase and the W phase segregate, thereby solving the problem that the high-tungsten-content nickel alloy has poor plasticity and is difficult to be formed by plastic processing such as forging, refines the grains, and regulates the organizational properties. At the same time, the processing method of the present invention can also refine the grains and improve the alloy properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a microstructure diagram of the high tungsten content nickel alloy prepared in Example 1.

[0027] Figure 2 This is the organizational morphology diagram of the high tungsten content nickel alloy prepared in Comparative Example 1.

[0028] Figure 3This is the organizational morphology diagram of the high tungsten content nickel alloy prepared in Comparative Example 2. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present invention will be described clearly and completely below. It should be noted that in the following embodiments and comparative examples of the present invention, the tungsten alloy high temperature protective coatings used are all W-47 high temperature protective coatings purchased from Beijing Tianlichuang Glass Technology Development Co., Ltd.

[0030] Example 1

[0031] This embodiment provides a heat treatment method for grain refinement of a high tungsten content nickel alloy, comprising the following steps:

[0032] Step 1, high temperature homogenization treatment:

[0033] In this embodiment, a nickel-tungsten alloy rod with a specification of Ф100mm×200mm and a composition of 30wt% W and 70wt% Ni is used as the high-tungsten-content nickel alloy to be treated, and a tungsten alloy high-temperature protective coating is used as the anti-oxidation coating. A layer of anti-oxidation coating with a thickness of 1mm is uniformly coated on the surface of the nickel-tungsten alloy rod and then dried. The rod is then loaded into a furnace at 750°C, and after averaging the temperature for 1h, the temperature is raised to 1400°C with the furnace. After being kept at 1400°C for 7h, the rod is cooled to room temperature with water to obtain a first alloy.

[0034] Step 2, aging treatment:

[0035] A layer of anti-oxidation coating with a thickness of 1 mm was re-coated on the surface of the first alloy and then dried, and then loaded into a furnace at 1050° C. and kept at 1050° C. for 7 hours to obtain a second alloy.

[0036] Step 3, heat treatment:

[0037] The second alloy is directly heated to 1250° C., kept at this temperature for 1.5 hours, and water-cooled to room temperature to obtain a grain-refined nickel alloy with a high tungsten content.

[0038] Example 2

[0039] This embodiment provides a heat treatment method for grain refinement of a high tungsten content nickel alloy, comprising the following steps:

[0040] Step 1, high temperature homogenization treatment:

[0041] In this embodiment, a nickel-tungsten alloy plate having a size of 400 mm × 400 mm × 50 mm in length, width and height and a composition of 30 wt% W and 70 wt% Ni is used as the high-tungsten-content nickel alloy to be treated, and a tungsten alloy high-temperature protective coating is used as the anti-oxidation coating. A layer of anti-oxidation coating with a thickness of 1 mm is uniformly coated on the surface of the nickel-tungsten alloy rod and then dried. The rod is then loaded into a furnace at 750°C, and after averaging the temperature for 1 hour, the temperature is raised to 1400°C with the furnace. After being kept at 1400°C for 5 hours, the rod is cooled to room temperature with water to obtain a first alloy.

[0042] Step 2, aging treatment:

[0043] A layer of anti-oxidation coating with a thickness of 1 mm was re-coated on the surface of the first alloy and then dried, loaded into a furnace at 1050° C., kept at 1050° C. for 5 hours, and then water-cooled to room temperature to obtain a second alloy.

[0044] Step 3, heat treatment:

[0045] The second alloy is re-coated with a layer of anti-oxidation coating with a thickness of 1 mm and then air-dried, loaded into a furnace at 750° C., heated to 1250° C. with the furnace, kept warm for 1.5 hours, and water-cooled to room temperature to obtain a high tungsten content nickel alloy with refined grains.

[0046] Example 3

[0047] This embodiment provides a heat treatment method for grain refinement of a high tungsten content nickel alloy, comprising the following steps:

[0048] Step 1, high temperature homogenization treatment:

[0049] In this embodiment, a nickel-tungsten alloy special-shaped part with a wall thickness of 10 mm and a composition of 30wt% W and 70wt% Ni is used as the high-tungsten-content nickel alloy to be processed, and a tungsten alloy high-temperature protective coating is used as the anti-oxidation coating. A layer of anti-oxidation coating with a thickness of 1 mm is uniformly coated on the surface of the nickel-tungsten alloy rod and then dried. The rod is then loaded into a furnace at 750°C, and after averaging the temperature for 1 hour, the temperature is raised to 1400°C with the furnace. After being kept at 1400°C for 3 hours, the rod is cooled to room temperature with water to obtain a first alloy.

[0050] Step 2, aging treatment:

[0051] A layer of anti-oxidation coating with a thickness of 1 mm was re-coated on the surface of the first alloy and then dried, and then loaded into a furnace at 1050° C. and kept at 1050° C. for 3 hours to obtain a second alloy.

[0052] Step 3, heat treatment:

[0053] The second alloy is directly heated to 1250° C., kept at this temperature for 1.5 hours, and water-cooled to room temperature to obtain a nickel-tungsten alloy special-shaped part with refined grains.

[0054] Comparative Example 1

[0055] This comparative example provides a heat treatment method for grain refinement of a high tungsten content nickel alloy, comprising the following steps:

[0056] A nickel-tungsten alloy rod with a specification of Ф100mm×200mm and a composition of 30wt% W and 70wt% Ni is used as the high-tungsten-content nickel alloy to be treated, and a tungsten alloy high-temperature protective coating is used as the anti-oxidation coating. A layer of 1mm thick anti-oxidation coating is evenly coated on the surface of the nickel-tungsten alloy rod and then dried. The rod is then loaded into a furnace at 750°C, and after averaging the temperature for 1h, the temperature is raised to 1400°C with the furnace. After keeping the temperature at 1400°C for 7h, the rod is cooled to room temperature with water to obtain a high-tungsten-content nickel alloy.

[0057] That is, the difference between this comparative example and Example 1 is only that:

[0058] This comparative example does not undergo aging treatment and heat preservation treatment.

[0059] Comparative Example 2

[0060] This comparative example provides a heat treatment method for grain refinement of a high tungsten content nickel alloy, comprising the following steps:

[0061] Step 1, high temperature homogenization treatment:

[0062] A nickel-tungsten alloy rod with a specification of Ф100mm×200mm and a composition of 30wt% W and 70wt% Ni is used as the high-tungsten-content nickel alloy to be treated, and a tungsten alloy high-temperature protective coating is used as the anti-oxidation coating. A layer of 1mm thick anti-oxidation coating is evenly coated on the surface of the nickel-tungsten alloy rod and then dried. The rod is then loaded into a furnace at 750°C, and after averaging the temperature for 1h, the temperature is raised to 1400°C with the furnace. After being kept at 1400°C for 7h, the rod is cooled to room temperature with water to obtain a first alloy.

[0063] Step 2, aging treatment:

[0064] A layer of anti-oxidation coating with a thickness of 1 mm is re-coated on the surface of the first alloy and then dried, loaded into a furnace at 1050° C., kept at 1050° C. for 7 hours, and then cooled to room temperature with water to obtain a nickel alloy with a high tungsten content.

[0065] That is, the difference between this comparative example and Example 1 is only that:

[0066] This comparative example does not undergo heat preservation treatment.

[0067] Experimental Section

[0068] The high tungsten content nickel alloys prepared in Examples 1 to 3 of the present invention have similar organizational morphologies. Therefore, in order to further illustrate the influence of each step on the organizational morphology of the high tungsten content nickel alloy, the present invention takes the high tungsten content nickel alloys prepared in Example 1, Comparative Example 1 and Comparative Example 2 as examples, and tests are performed on their organizational morphologies, and the test results are as follows: Figure 1 to Figure 3 shown.

[0069] Figure 1 This is a microstructure diagram of the high tungsten content nickel alloy prepared in Example 1. It can be seen that the grains of the nickel-tungsten alloy treated in Example 1 are significantly refined.

[0070] Figure 2 The microstructure of the high tungsten content nickel alloy prepared in Comparative Example 1 shows that after the nickel-tungsten alloy is treated with high temperature homogenization, the precipitated phase is dissolved back and the grains grow relatively coarse. Figure 1 By comparison, it can be seen that when the aging treatment and the insulation heat treatment are omitted, it is difficult to effectively refine the nickel-tungsten alloy grains. This indicates that the present invention can effectively refine the nickel-tungsten alloy grains by performing aging treatment and insulation heat treatment after high-temperature homogenization treatment.

[0071] Figure 3 The microstructure of the high tungsten content nickel alloy prepared in Comparative Example 2 shows that a large amount of Ni is precipitated after the nickel-tungsten alloy is subjected to long-term aging treatment. x W y phase, and the precipitation phase divides the original grain boundary, and the grains are refined. Figure 1 By comparison, after treatment in Example 1, the Ni precipitated during the aging process can be dissolved back. x W y phase and retain the refined grain size.

[0072] In summary, it can be seen that it is difficult to effectively refine the nickel-tungsten alloy grains when the insulation heat treatment is omitted or the aging treatment and insulation heat treatment are performed. This shows that the present invention can effectively eliminate the high tungsten content nickel alloy Ni x W y The segregation of the precipitated phase and the W phase is not achieved by a certain step, but is achieved by high-temperature homogenization treatment, aging treatment, and water cooling after heat preservation heat treatment, and by regulating the temperature of each treatment process, thereby solving the problem that the high-tungsten nickel alloy has poor plasticity and is difficult to refine the grains and regulate the organizational properties through plastic processing methods such as forging. At the same time, the processing method of the present invention can also refine the grains and improve the alloy properties.

[0073] Obviously, the above embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

Claims

1. A heat treatment method for grain refinement of a high tungsten content nickel alloy, characterized in that: The following steps are involved: The high-tungsten-content nickel alloy to be treated is subjected to high-temperature homogenization treatment at 1250° C. to 1400° C., and then water-cooled to room temperature to obtain a first alloy; Performing an aging treatment on the first alloy at 950° C. to 1100° C. to obtain a second alloy; The second alloy is heated to 1100° C. to 1250° C., then subjected to heat preservation heat treatment, and then water-cooled to room temperature to obtain a grain-refined nickel alloy with a high tungsten content.

2. The heat treatment method for grain refinement of a high tungsten content nickel alloy according to claim 1, characterized in that: The high temperature homogenization treatment takes 3 to 30 hours.

3. The heat treatment method for grain refinement of a high tungsten content nickel alloy according to claim 1, characterized in that: The aging treatment time is 3h to 30h.

4. The heat treatment method for grain refinement of a high tungsten content nickel alloy according to claim 1, characterized in that: The insulation time of the insulation heat treatment is 1.5h to 5h.

5. The heat treatment method for grain refinement of a high tungsten content nickel alloy according to claim 1, characterized in that: The nickel alloy with high tungsten content to be processed is a nickel-tungsten alloy in which the tungsten content accounts for 25wt% to 40wt% of the total mass of the alloy.

6. The heat treatment method for grain refinement of a high tungsten content nickel alloy according to claim 1, characterized in that: Before the high-temperature homogenization treatment is performed, a layer of anti-oxidation coating is firstly coated on the surface of the nickel alloy with high tungsten content to be treated, and the high-temperature homogenization treatment is performed after the anti-oxidation coating to be coated is cured.

7. The heat treatment method for grain refinement of a high tungsten content nickel alloy according to claim 6, characterized in that: The anti-oxidation coating is a tungsten alloy high-temperature protective coating.

8. The heat treatment method for grain refinement of a high tungsten content nickel alloy according to claim 7, characterized in that: Before the high-temperature homogenization treatment is performed, the coating thickness of the anti-oxidation coating on the surface of the nickel alloy with high tungsten content to be treated is 0.5 mm to 2 mm.

9. The heat treatment method for grain refinement of a high tungsten content nickel alloy according to claim 7, characterized in that: Before the aging treatment is performed, a layer of anti-oxidation coating is also coated on the surface of the first alloy, and the aging treatment is performed after the coated anti-oxidation coating is cured.

10. The heat treatment method for grain refinement of a high tungsten content nickel alloy according to claim 9, characterized in that: The coating thickness of the anti-oxidation coating on the surface of the first alloy is 0.5 mm to 2 mm.

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