A heat treatment method for refining grains of a high-tungsten-content nickel alloy

Abstract

This invention belongs to the field of metal heat treatment technology and discloses a heat treatment method for refining the grains of high-tungsten content nickel alloys. The heat treatment method for refining the grains of high-tungsten content nickel alloys involves: subjecting the high-tungsten content nickel alloy to be treated to high-temperature homogenization treatment at 1250℃~1400℃, followed by water cooling; then performing aging treatment at 950℃~1100℃; followed by heating to 1100℃~1250℃ for holding heat treatment; and finally water cooling, to obtain a high-tungsten content nickel alloy with refined grains. This invention, by sequentially performing high-temperature homogenization treatment, aging treatment, holding heat treatment, and water cooling, and by controlling the temperature of each treatment process, can effectively eliminate the Ni content in high-tungsten content nickel alloys. x W y The segregation of the precipitated phase and the W phase solves the problem that high-tungsten nickel alloys have poor plasticity and are difficult to form through plastic processing methods such as forging, thus refining the grains and controlling the microstructure and properties; at the same time, it can also refine the grains and improve the alloy properties.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metal heat treatment, and particularly relates to a heat treatment method for grain refinement of high-tungsten-content nickel alloy. BACKGROUND

[0002] Nickel is an important strategic metal and is widely used in industrial production, and has good plasticity and super strong solid solution capacity. Tungsten has super high melting point (3380 DEG C) and density (19.35 g / cm 3 The solubility of tungsten in nickel can reach 39.9 wt.%, and the introduction of tungsten can significantly improve the strength, hardness, density and high-temperature resistance of nickel, so that the nickel-tungsten alloy has wide application in aerospace, weapon equipment, automobile manufacturing, energy chemical industry and other fields.

[0003] At present, the common preparation process of the nickel-tungsten alloy is powder metallurgy and smelting. However, due to the super high melting point of tungsten, it is difficult to prepare the nickel-tungsten alloy by using the powder metallurgy and smelting. Moreover, in the process of preparing the nickel-tungsten alloy by using the powder metallurgy or smelting, tungsten will segregate, and various Ni x W y Phases will be precipitated, which will significantly deteriorate the plasticity of the nickel-tungsten alloy, cause the nickel-tungsten alloy to be difficult to process, and be difficult to be shaped by forging and other plastic processing, grain refinement and regulation of the organization performance, which seriously limits the application and development of the alloy. SUMMARY

[0004] In order to solve the above technical problems, the present application provides a heat treatment method for grain refinement of high-tungsten-content nickel alloy. By sequentially performing high-temperature homogenization treatment, aging treatment, heat preservation and water cooling after heat treatment, and by regulating the temperature of each treatment process, the present application can effectively eliminate the segregation of Ni x W y Precipitated phase and W phase, thereby solving the problem that the high-tungsten-content nickel alloy is difficult to be shaped by forging and other plastic processing methods due to poor plasticity, grain refinement and regulation of the organization performance.

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

[0006] The heat treatment method for grain refinement of 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 DEG C to 1400 DEG C, and then water-cooled to room temperature to obtain a first alloy.

[0009] It should be noted that the present application does not limit the specific components of the high-tungsten-content nickel alloy to be treated, and the corresponding high-tungsten-content nickel alloy can be selected according to the implementation requirements. In some preferred embodiments of the present application, the high-tungsten-content nickel alloy to be treated is a nickel-tungsten alloy with a tungsten content of 25wt% to 40wt% of the total mass of the alloy. For example, in some more preferred embodiments of the present application, the high-tungsten-content nickel alloy to be treated has the following component composition 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 balance being Ni and unavoidable trace elements and impurities, totaling 100%.

[0010] The present application takes into account that for high-tungsten nickel alloys, in addition to the Ni x W y precipitated phase, there will also be a large amount of pure W phase precipitated along the grain, and the re-dissolution elimination temperature of the pure W phase is much higher than 1250℃, so the present application preferably uses 1250℃ to 1400℃ as the treatment temperature for high-temperature homogenization treatment, so that during the high-temperature homogenization treatment at this temperature, the Ni x W y precipitated phase and the W phase can be completely re-dissolved, eliminating component segregation.

[0011] In some preferred embodiments of the present application, the treatment time for the high-temperature homogenization treatment is 3h to 30h, to ensure that the Ni x W y precipitated phase and the pure W phase can be completely re-dissolved.

[0012] Step 2, aging treatment:

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

[0014] It should be noted that the present application controls the aging treatment temperature to be 950℃ to 1100℃, so that a large amount of Ni x W y precipitated phase in the first alloy is precipitated and grown to split the original grain boundaries, thereby achieving the purpose of refining the grains. In some preferred embodiments of the present application, the treatment time for the aging treatment is 3h to 30h, to ensure that the above-mentioned grain refinement effect can be achieved.

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

[0016] Step 3, heat preservation treatment:

[0017] The second alloy is heated to 1100-1250 DEG C and then isothermal heat treated, and then water cooled to room temperature, to obtain a high tungsten content nickel alloy with refined grains.

[0018] It should be noted that the treatment temperature of the isothermal heat treatment is 1100-1250 DEG C, so that a large amount of Ni x W y precipitates and grows during the aging treatment x W y precipitates again, and the refined grain size is fixed. In some preferred embodiments of the present application, the isothermal heat treatment is performed for 3-30 hours, so that the above-mentioned Ni x W y precipitates and the grain size is fixed.

[0019] In some preferred embodiments of the present application, before the high temperature homogenization treatment, a layer of anti-oxidation paint is coated on the surface of the high tungsten content nickel alloy to be treated, and after the anti-oxidation paint is solidified, an anti-oxidation coating is formed on the surface of the high tungsten content nickel alloy to be treated, so that the alloy is prevented from being excessively oxidized.

[0020] In some preferred embodiments of the present application, the anti-oxidation paint is a tungsten alloy high temperature protective paint, and the coating thickness of the anti-oxidation paint on the surface of the high tungsten content nickel alloy to be treated is 0.5-2 mm, so that the alloy is prevented from being excessively oxidized. The type of the tungsten alloy high temperature protective paint is not particularly limited in the present application, and a commonly used tungsten alloy high temperature protective paint can be used. Those skilled in the art should know this, and thus the present application will not be described in detail.

[0021] In some preferred embodiments of the present application, before the aging treatment, a layer of anti-oxidation paint is also coated on the surface of the first alloy, and after the anti-oxidation paint is solidified, the aging treatment is performed; the coating thickness of the anti-oxidation paint on the surface of the first alloy is 0.5-2 mm, so that the alloy is prevented from being excessively oxidized.

[0022] It should be noted that the second alloy can be directly heated to 1100-1250 DEG C and then heat treated, or the second alloy can be water cooled to room temperature and then re-heated to 1100-1250 DEG C and then heat treated. When the second alloy is water cooled to room temperature and then re-heated to 1100-1250 DEG C and then heat treated, an anti-oxidation coating is applied to the surface of the second alloy before the heat treatment, and the heat treatment is performed after the anti-oxidation coating is solidified. The thickness of the anti-oxidation coating on the surface of the second alloy is 0.5-2 mm, so as to prevent the alloy from being excessively oxidized.

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

[0024] The present application can completely dissolve Ni x W y precipitation phase and W phase by first uniformly treating the high-tungsten-content nickel alloy to be treated at 1250-1400 DEG C, and then water cooling to room temperature. x W y The present application can effectively eliminate the segregation of Ni x W y precipitation phase and W phase by adjusting the temperature of each treatment process after sequentially performing high-temperature homogenization treatment, aging treatment and heat treatment, thereby solving the problems of poor plasticity of high-tungsten-content nickel alloy, difficulty in forming by plastic processing such as forging, grain refinement, and regulation of microstructure and properties. x W y precipitation phase and fixing the refined grain size.

[0025] The present application can effectively eliminate the segregation of Ni x W y precipitation phase and W phase by adjusting the temperature of each treatment process after sequentially performing high-temperature homogenization treatment, aging treatment and heat treatment, thereby solving the problems of poor plasticity of high-tungsten-content nickel alloy, difficulty in forming by plastic processing such as forging, grain refinement, and regulation of microstructure and properties. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 The microstructure of the high-tungsten-content nickel alloy prepared in Example 1 is shown in the figure.

[0027] Figure 2 The microstructure of the high-tungsten-content nickel alloy prepared in Comparative Example 1 is shown in the figure.

[0028] Figure 3The microstructure pattern of the high tungsten content nickel alloy prepared for Comparative Example 2. DETAILED DESCRIPTION

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

[0030] Example 1

[0031] The present 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 the present embodiment, a nickel tungsten alloy bar with a specification of Ф100mm x 200mm and a composition of 30wt% W content and 70wt% Ni content 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. After uniformly coating the surface of the nickel tungsten alloy bar with a layer of anti-oxidation coating with a thickness of 1mm and allowing it to dry, the nickel tungsten alloy bar is loaded into a furnace at 750℃, and after being kept at a uniform temperature for 1h, the temperature is increased to 1400℃ in the furnace, and after being kept at 1400℃ for 7h, the nickel tungsten alloy bar is water-cooled to room temperature to obtain a first alloy.

[0034] Step 2, aging treatment:

[0035] After re-coating the surface of the first alloy with a layer of anti-oxidation coating with a thickness of 1mm and allowing it to dry, the first alloy is loaded into a furnace at 1050℃, and after being kept at 1050℃ for 7h, a second alloy is obtained.

[0036] Step 3, heat treatment with holding:

[0037] The second alloy is directly heated to 1250℃ and kept at 1250℃ for 1.5h, and then water-cooled to room temperature to obtain a high tungsten content nickel alloy with grain refinement.

[0038] Example 2

[0039] The present 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] The embodiment takes a nickel-tungsten alloy plate with a size of 400mmx400x50mm and a composition of 30wt% W content and 70wt% Ni content as the high-tungsten-content nickel alloy to be treated, takes a tungsten alloy high-temperature protective coating as the anti-oxidation coating, coats the surface of the nickel-tungsten alloy bar with a layer of the anti-oxidation coating with a thickness of 1mm, then dries the coating, loads the bar into a furnace at 750°C, uniformly heats the bar for 1h, then increases the temperature of the bar to 1400°C, keeps the bar at 1400°C for 5h, then water-cools the bar to room temperature, and obtains a first alloy.

[0042] Step 2, aging treatment:

[0043] coats the surface of the first alloy with a layer of the anti-oxidation coating with a thickness of 1mm, then dries the coating, loads the alloy into a furnace at 1050°C, keeps the alloy at 1050°C for 5h, then water-cools the alloy to room temperature, and obtains a second alloy.

[0044] Step 3, heat treatment:

[0045] coats the surface of the second alloy with a layer of the anti-oxidation coating with a thickness of 1mm, then dries the coating, loads the alloy into a furnace at 750°C, increases the temperature of the alloy to 1250°C, keeps the alloy at 1250°C for 1.5h, and then water-cools the alloy to room temperature, and obtains the high-tungsten-content nickel alloy with refined grains.

[0046] Embodiment 3

[0047] The embodiment provides a heat treatment method for refining grains of a high-tungsten-content nickel alloy, which includes the following steps.

[0048] Step 1, high-temperature homogenization treatment:

[0049] The embodiment takes a nickel-tungsten alloy profiled piece with a wall thickness of 10mm and a composition of 30wt% W content and 70wt% Ni content as the high-tungsten-content nickel alloy to be treated, takes a tungsten alloy high-temperature protective coating as the anti-oxidation coating, coats the surface of the nickel-tungsten alloy bar with a layer of the anti-oxidation coating with a thickness of 1mm, then dries the coating, loads the bar into a furnace at 750°C, uniformly heats the bar for 1h, then increases the temperature of the bar to 1400°C, keeps the bar at 1400°C for 3h, and then water-cools the bar to room temperature, and obtains a first alloy.

[0050] Step 2, aging treatment:

[0051] coats the surface of the first alloy with a layer of the anti-oxidation coating with a thickness of 1mm, then dries the coating, loads the alloy into a furnace at 1050°C, keeps the alloy at 1050°C for 3h, and then obtains a second alloy.

[0052] Step 3, heat treatment:

[0053] directly increases the temperature of the second alloy to 1250°C, keeps the alloy at 1250°C for 1.5h, and then water-cools the alloy to room temperature, and obtains the nickel-tungsten alloy profiled piece with refined grains.

[0054] Comparative Example 1

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

[0056] A nickel tungsten alloy bar with a specification of Ф100mm x 200mm and a composition of 30wt% W content and 70wt% Ni content 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. After uniformly coating the surface of the nickel tungsten alloy bar with a layer of anti-oxidation coating with a thickness of 1mm and air-drying, the bar is loaded into a furnace at 750°C, uniformly heated for 1h, then the temperature is increased to 1400°C in the furnace, and after being kept at 1400°C for 7h, the bar is water-cooled to room temperature to obtain the high tungsten content nickel alloy.

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

[0058] The present comparative example does not perform aging treatment and heat treatment.

[0059] Comparative Example 2

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

[0061] Step 1, high temperature homogenization treatment:

[0062] A nickel tungsten alloy bar with a specification of Ф100mm x 200mm and a composition of 30wt% W content and 70wt% Ni content 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. After uniformly coating the surface of the nickel tungsten alloy bar with a layer of anti-oxidation coating with a thickness of 1mm and air-drying, the bar is loaded into a furnace at 750°C, uniformly heated for 1h, then the temperature is increased to 1400°C in the furnace, and after being kept at 1400°C for 7h, the bar is water-cooled to room temperature to obtain the first alloy.

[0063] Step 2, aging treatment:

[0064] After re-coating the surface of the first alloy with a layer of anti-oxidation coating with a thickness of 1mm and air-drying, the bar is loaded into a furnace at 1050°C, and after being kept at 1050°C for 7h, the bar is water-cooled to room temperature to obtain the high tungsten content nickel alloy.

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

[0066] The present comparative example does not perform heat treatment.

[0067] Experimental Section

[0068] The high-tungsten-content nickel alloy prepared in Embodiment 1 to Embodiment 3 has similar microstructure, and therefore, in order to further illustrate the influence of each step on the microstructure of the high-tungsten-content nickel alloy, the microstructure of the high-tungsten-content nickel alloy prepared in Embodiment 1, Comparative Example 1 and Comparative Example 2 is tested, and the test results are shown in Table 1. Figures 1-3

[0069] Figure 1 The microstructure diagram of the high-tungsten-content nickel alloy prepared in Embodiment 1 can be seen that the grain of the nickel-tungsten alloy after the treatment in Embodiment 1 is obviously refined.

[0070] Figure 2 The microstructure diagram of the high-tungsten-content nickel alloy prepared in Comparative Example 1 can be seen that after the high-temperature homogenization treatment of the nickel-tungsten alloy, the precipitated phase is dissolved, and the grain growth is relatively coarse. And through comparison, it can be known that when the aging treatment and the holding heat treatment are omitted, it is difficult to effectively refine the grain of the nickel-tungsten alloy, which shows that the aging treatment and the holding heat treatment after the high-temperature homogenization treatment can effectively refine the grain of the nickel-tungsten alloy. Figure 1

[0071] Figure 3 The microstructure diagram of the high-tungsten-content nickel alloy prepared in Comparative Example 2 can be seen that after the long-time aging treatment of the nickel-tungsten alloy, a large amount of Ni x W y phase is precipitated, and the precipitated phase is separated from the original grain boundary, and the grain is refined. And through comparison, it can be known that after the treatment in Embodiment 1, the Ni x W y phase precipitated in the aging process can be dissolved, and the refined grain size is retained. Figure 1

[0072] As can be known from the above, when the holding heat treatment, or the aging treatment and the holding heat treatment are omitted, it is difficult to effectively refine the grain of the nickel-tungsten alloy, which shows that the present application can effectively eliminate the segregation of the Ni x W y precipitated phase and the W phase in the high-tungsten-content nickel alloy, which is not realized by a step, but is realized by the high-temperature homogenization treatment, the aging treatment and the holding heat treatment and the water cooling in sequence, and is realized by adjusting the temperature of each treatment process, so as to solve the problem that the high-tungsten-content nickel alloy is difficult to be refined by plastic processing such as forging due to poor plasticity, and the problem of adjusting the microstructure and performance. At the same time, the treatment method of the present application can also refine the grain and improve the alloy performance.

[0073] ​​​Obviously, the above embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by a person of ordinary skill in the art without creative labor shall fall within the protection scope of the present application.

Claims

1. A heat treatment method for grain refinement of a high tungsten content nickel alloy, characterized by, The method comprises the following steps: homogenizing the high-tungsten-content nickel alloy to be treated at 1250-1400 DEG C, and then water-cooling to room temperature to obtain a first alloy; aging the first alloy at 950-1100 DEG C to obtain a second alloy; heating the second alloy to 1100-1250 DEG C, and then performing a heat preservation treatment, and then water-cooling to room temperature to obtain a high-tungsten-content nickel alloy with refined grains; the high-tungsten-content nickel alloy to be treated is a nickel-tungsten alloy with tungsten content of 25-40 wt% of the total mass of the alloy; before the high-temperature homogenization treatment, a layer of anti-oxidation paint is coated on the surface of the high-tungsten-content nickel alloy to be treated, and the anti-oxidation paint is solidified before the high-temperature homogenization treatment; before the aging treatment, a layer of anti-oxidation paint is also coated on the surface of the first alloy, and the anti-oxidation paint is solidified before the aging treatment.

2. The heat treatment method for grain refinement of high tungsten content nickel alloy according to claim 1, wherein The high-temperature homogenization treatment is performed for 3-30 hours.

3. The heat treatment method for grain refinement of high tungsten content nickel alloy according to claim 1, wherein The aging treatment is performed for 3-30 hours.

4. The heat treatment method for grain refinement of high tungsten content nickel alloy according to claim 1, wherein The heat preservation treatment is performed for 1.5-5 hours.

5. The heat treatment method for grain refinement of high tungsten content nickel alloy according to claim 1, wherein The anti-oxidation paint is a tungsten alloy high-temperature protective paint.

6. The heat treatment method for grain refinement of high tungsten content nickel alloy according to claim 5, wherein Before the high-temperature homogenization treatment, the coating thickness of the anti-oxidation paint on the surface of the high-tungsten-content nickel alloy to be treated is 0.5-2 mm.

7. The heat treatment method for grain refinement of high tungsten content nickel alloy according to claim 1, wherein The coating thickness of the anti-oxidation paint on the surface of the first alloy is 0.5-2 mm.

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