A radiation embrittlement resistant nickel-based alloy and its manufacturing method and application

Abstract

A radiation-resistant embrittled nickel-based alloy and its manufacturing method and application belong to the field of nuclear engineering materials. The radiation-resistant embrittled nickel-based alloy contains, by weight, 14.0%-18.0% Cr, 10.0%-16.0% Fe, 0.5%-1.5% Mn, 2.0%-4.0% Mo, 5.0%-10.0% W, 0.1%-0.3% Al, 0.05%-0.1% C, and the remainder is Ni and unavoidable impurities. The alloy replaces part of Ni with Fe and Mn, thereby reducing the helium bubbles generated by the transmutation of Ni under neutron irradiation conditions; by controlling the W content, the irradiation-induced grain boundary segregation is suppressed, the embrittlement tendency of the alloy to fracture along the grain after neutron irradiation is reduced, and the alloy's resistance to neutron irradiation damage is improved. The present invention also provides a method for manufacturing a radiation-resistant embrittled nickel-based alloy and an application of a radiation-resistant embrittled nickel-based alloy for manufacturing structural parts.

Description

Technical Field

[0001] The invention belongs to the field of nuclear engineering materials, and in particular relates to a radiation embrittlement resistant nickel-based alloy and a manufacturing method and application thereof. Background Art

[0002] Small reactors represented by heat pipe micro-reactors have good application prospects in deep hole exploration, offshore development, heating and power supply in remote areas due to their small size, rapid deployment and inherent safety. However, such application scenarios are often far away from cities, lack external auxiliary and support facilities, and even need to operate under unmanned conditions for a long time. Therefore, the durability and reliability of reactor structural materials are particularly important. Nickel-based high-temperature alloys have good stability and mechanical properties under high temperature conditions, strong machinability, and resistance to radiation swelling, so they are widely used in the manufacture of reactor structural parts. However, existing nickel-based alloys such as 230 alloys have a tendency to become brittle in irradiated environments, which affects the life and reliability of nickel-based alloys as reactor structural materials, and it is difficult to meet the performance requirements of small reactors for structural materials. Therefore, providing a nickel-based alloy that is resistant to radiation embrittlement is of positive significance for further improving the safety of small reactors. Summary of the invention

[0003] The purpose of the present invention is to provide a radiation embrittlement resistant nickel-based alloy to increase the service life of the nickel-based alloy in a neutron irradiation environment. The present invention also provides a manufacturing method and application of the radiation embrittlement resistant nickel-based alloy.

[0004] According to an embodiment of one aspect of the present invention, a radiation embrittlement resistant nickel-based alloy is provided, which contains, by weight, 14.0%-18.0% Cr, 10.0%-16.0% Fe, 0.5%-1.5% Mn, 2.0%-4.0% Mo, 5.0%-10.0% W, 0.1%-0.3% Al, 0.05%-0.1% C, and the balance is Ni and unavoidable impurities.

[0005] The alloy reduces the content of Ni by adding a high proportion of Fe and Mn, thereby reducing the density of helium bubbles generated by the transmutation of Ni under high-temperature irradiation conditions, avoiding excessive aggregation of helium bubbles at grain boundaries to induce helium embrittlement; the W content is controlled to reduce the radiation-induced segregation of W at grain boundaries; thereby improving the tolerance of nickel-based alloys to radiation embrittlement and reducing the tendency of intergranular fracture.

[0006] Furthermore, in some embodiments, among the unavoidable impurities, Co<0.05% and B<1wppm. Controlling the contents of Co and B can reduce the generation of harmful substances under neutron irradiation.

[0007] Furthermore, in some embodiments, the alloy contains, by weight, 14.0%-18.0% Cr, 12.0%-16.0% Fe, 0.5%-1.5% Mn, 2.0%-4.0% Mo, 5.0%-6.0% W, 0.1%-0.3% Al, 0.05%-0.1% C, and the balance is Ni and unavoidable impurities.

[0008] Furthermore, in some embodiments, the grain size of the radiation embrittlement resistant nickel-based alloy is level 4-6.

[0009] Furthermore, in some embodiments, after the radiation-resistant embrittled nickel-based alloy is irradiated with neutrons at 1073K / 3dpa, the elongation of the tensile test at room temperature is not less than 2%, the elongation of the tensile test at 973K is not less than 12%, and the elongation of the tensile test at 1073K is not less than 18%.

[0010] According to an embodiment of another aspect of the present invention, a method for manufacturing a radiation embrittlement resistant nickel-based alloy is provided, comprising the following steps:

[0011] According to the weight ratio of Cr 14.0%-18.0%, Fe 10.0%-16.0%, Mn 0.5%-1.5%, Mo 2.0%-4.0%, W5.0%-10.0%, Al 0.1%-0.3%, C 0.05%-0.1%, and the balance Ni, raw materials are provided and vacuum smelted, and cast into alloy blanks;

[0012] The alloy blank is hot forged, subjected to a two-stage heat treatment, and water-cooled to obtain a radiation embrittlement-resistant nickel-based alloy product.

[0013] Furthermore, in some embodiments, in the alloy blank, the impurities Co<0.05% and B<1wppm are controlled.

[0014] Furthermore, in some embodiments, in the raw material, Fe accounts for 12.0%-16.0%, and W accounts for 5.0%-6.0%.

[0015] Furthermore, in some embodiments, in the double-stage heat treatment, the first stage heat treatment is carried out at 873K-1073K for 1h±10min, and the second stage heat treatment is carried out at 1473K-1573K for 2h±10min.

[0016] Furthermore, in some embodiments, the method is used to manufacture the radiation embrittlement resistant nickel-based alloy provided in any of the aforementioned embodiments.

[0017] According to another embodiment of the present invention, there is provided an application of a radiation embrittlement resistant nickel-based alloy for manufacturing a structural component. The structural component is manufactured using the radiation embrittlement resistant nickel-based alloy provided in any of the aforementioned embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a metallographic structure photograph in Example 1;

[0019] Figure 2 This is a metallographic structure photograph in Example 2;

[0020] Figure 3 This is the metallographic structure photograph in Example 3.

[0021] The purpose of the above drawings is to explain the present invention in detail so that those skilled in the art can understand the technical concept of the present invention, but it is not intended to limit the present invention. DETAILED DESCRIPTION

[0022] The present invention is further described in detail below through specific embodiments.

[0023] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present invention. The phrase appearing in various locations in the specification does not necessarily refer to the same embodiment, nor is it limited to mutually exclusive independent or alternative embodiments. Those skilled in the art should be able to understand that the embodiments herein may be combined with other embodiments without causing structural conflicts.

[0024] In the description of this article, the terms "first", "second" and the like are only used to distinguish different objects, and cannot be understood as indicating relative importance or limiting the quantity, specific order or primary and secondary relationship of the described technical features. In the description of this article, the meaning of "plurality" is at least two.

[0025] Heat pipe cooled reactors (heat pipe micro reactors) have the advantages of core static heat transfer, simplified system structure, small size and high inherent safety due to their phase change heat transfer and thermoelectric conversion systems. They have broad application prospects in the fields of national social economy and national defense and military industry, such as power supply and heating in remote areas, deep space exploration and deep sea exploration. However, the service temperature of the core of heat pipe reactors is relatively high, and the requirements for fuel materials are more stringent. It is necessary to select a material with high temperature resistance, excellent creep performance, radiation damage resistance and strong machinability as the fuel cladding material of heat pipe micro reactors. Nickel-based high temperature alloys usually have the advantages of good high temperature stability, excellent mechanical properties, strong machinability and resistance to radiation swelling. For example, alloys such as 718 and 230 are often used in high temperature structural parts in the aerospace field, 700 ℃ advanced ultra-supercritical boiler materials, and heat exchanger materials for ultra-high temperature gas-cooled reactors. However, due to the inherent characteristics of nickel-based alloys, their radiation embrittlement problem has always been one of the risk points in the application of nuclear energy. These factors restrict the application of nickel-based alloys in heat pipe cooled reactors.

[0026] In order to solve the above problems, an embodiment of one aspect of the present invention provides a radiation embrittlement resistant nickel-based alloy, wherein the composition of the alloy, by weight, contains 14.0%-18.0% Cr, 10.0%-16.0% Fe, 0.5%-1.5% Mn, 2.0%-4.0% Mo, 5.0%-10.0% W, 0.1%-0.3% Al, 0.05%-0.1% C, and the balance is Ni and unavoidable impurities.

[0027] Taking 230 alloy as an example, the important reason for the embrittlement of nickel-based alloys is that Ni atoms undergo transmutation under neutron irradiation conditions to produce He, which accumulates in the alloy matrix and tends to gather at defective positions such as grain boundaries to form helium bubbles. When the number of helium bubbles and the pressure accumulate to a certain extent, it will induce the intergranular fracture of the nickel-based alloy, resulting in the nickel-based alloy showing obvious embrittlement under neutron irradiation conditions. After a large number of research and experiments, the present invention has found that by increasing the element content of Fe and Mn in the nickel-based alloy and replacing part of Ni, the total amount of He produced by transmutation in the nickel-based alloy can be effectively reduced under the premise of ensuring the overall strength and high temperature performance of the nickel-based alloy, and the formation of helium bubbles can be reduced, thereby achieving the effect of inhibiting the tendency of irradiation embrittlement. At the same time, by controlling W within the range of 5%-10%, it is possible to avoid the segregation of W at the grain boundary under irradiation conditions while ensuring the comprehensive performance of the nickel-based alloy, and further improve the performance of the nickel-based alloy under neutron irradiation conditions. Therefore, in a preferred embodiment, the Fe content is further controlled to 12%-16%, and the W content is further controlled to 5%-6%.

[0028] Furthermore, the Co element will produce relatively strong induced radioactivity under the influence of neutron irradiation, and the B element will increase the production of transmutation gas, so the content of Co and B in the impurity elements needs to be strictly controlled.

[0029] At the same time, through reasonable deformation processing and heat treatment processes, the grains of nickel-based alloys are refined to reach level 4-6 as specified in GB / T6394-2017. On the one hand, grain refinement can improve the overall strength of nickel-based alloys, and on the other hand, the increased grain boundary area can adsorb the gas generated by transmutation to avoid local helium bubble aggregation, and capture radiation damage defects such as voids, thereby improving the tolerance of nickel-based alloys to neutron radiation damage.

[0030] The radiation embrittlement resistant nickel-based alloy provided in the above embodiment, after neutron irradiation treatment at 1073K / 3dpa (i.e., 3dpa of off-site damage dose at 800°C), has an elongation of not less than 2% in room temperature tensile test, not less than 12% in 973K (700°C), and not less than 18% in 1073K (800°C). In comparison, after the same neutron irradiation treatment, the 230 alloy was subjected to tensile test at room temperature, and its elongation was less than 1%. It can be seen that the radiation embrittlement resistant nickel-based alloy provided in the above embodiment has good resistance to neutron irradiation, and still has good plastic deformation ability after neutron irradiation.

[0031] According to an embodiment of another aspect of the present invention, the radiation embrittlement resistant nickel-based alloy can be manufactured by the following method:

[0032] First, raw materials are provided according to a weight ratio of Cr 14.0%-18.0%, Fe 10.0%-16.0%, Mn 0.5%-1.5%, Mo 2.0%-4.0%, W 5.0%-10.0%, Al 0.1%-0.3%, C 0.05%-0.1%, and the balance Ni, and vacuum melted and cast into an alloy billet.

[0033] Next, the alloy billet is hot forged to break up the solidified structure in the alloy, eliminate casting defects such as looseness and pinholes, and undergo dynamic recrystallization to promote homogenization of the structure and grain refinement in the alloy billet.

[0034] The hot forged alloy is placed in a muffle furnace for two-stage heat treatment, wherein the first stage is kept at 873K-1073K for 1h±10min, and the second stage is kept at 1473K-1573K for 2h±10min. Finally, the alloy is taken out and water-cooled to obtain a finished product of the radiation-resistant embrittlement nickel-based alloy.

[0035] The radiation-resistant embrittled nickel-based alloy can be used to manufacture the fuel cladding of heat pipe micro-reactors, the intermediate heat exchanger structure of high-temperature gas-cooled reactors or the structural material of molten salt reactors. It can also be used to manufacture other structural parts inside the reactor containment serving under high-dose neutron irradiation conditions.

[0036] In preferred embodiment 1, a manufacturing process of a radiation embrittlement resistant nickel-based alloy is as follows:

[0037] The raw materials are prepared according to Cr 15.2%, Fe 10.1%, Mn 0.8%, Mo 3.0%, W 8.6%, Al 0.1%, C 0.05%, Co<0.05%, B<1 wppm, and Ni balance. The raw materials are vacuum melted and hot forged. After double-stage heat treatment, a nickel-based alloy product with a grain size of 5 is obtained. Its metallographic structure is as follows: Figure 1 shown.

[0038] After neutron irradiation treatment at 1073K / 3dpa, the alloy has a room temperature tensile elongation of 2.5%, an elongation of 12.6% at 973K, and an elongation of 18.2% at 1073K, maintaining good plasticity.

[0039] In preferred embodiment 2, a manufacturing process of a radiation embrittlement resistant nickel-based alloy is as follows:

[0040] Raw materials are prepared according to Cr 15.5%, Fe 13.9%, Mn 1.1%, Mo 3.4%, W 7.4%, Al 0.1%, C 0.05%, Co<0.05%, B<1 wppm, and Ni balance. The raw materials are vacuum melted and hot forged. After double-stage heat treatment, a nickel-based alloy product with a grain size of 5 is obtained. Its metallographic structure is as follows: Figure 2 shown.

[0041] After neutron irradiation treatment at 1073K / 3dpa, the alloy has a room temperature tensile elongation of 2.0%, an elongation of 12.8% at 973K, and an elongation of 20.3% at 1073K, maintaining good plasticity.

[0042] In a preferred embodiment, a manufacturing process of a radiation embrittlement resistant nickel-based alloy is as follows:

[0043] Raw materials are prepared according to Cr 15.1%, Fe 15.7%, Mn 0.9%, Mo 3.2%, W 5.6%, Al 0.1%, C 0.05%, Co<0.05%, B<1 wppm, and Ni balance. The raw materials are vacuum melted and hot forged. After double-stage heat treatment, a nickel-based alloy product with a grain size of 4 is obtained. Its metallographic structure is as follows: Figure 3 shown.

[0044] After neutron irradiation treatment at 1073K / 3dpa, the alloy has a room temperature tensile elongation of 2.9%, an elongation of 15.4% at 973K, and an elongation of 22.5% at 1073K, maintaining good plasticity.

[0045] The radiation embrittlement resistant nickel-based alloy provided in the above embodiment has a high content of Fe and Mn elements, which reduces the helium bubbles generated by Ni transmutation; through the low W content, the radiation-induced W segregation at the grain boundary in the neutron irradiation environment is avoided; through hot forging and double-stage annealing treatment, the grain refinement of the alloy structure is achieved, and while achieving fine grain strengthening, the radiation defects are effectively captured through the high-density grain boundary, thereby improving the alloy's resistance to neutron radiation embrittlement. By controlling the total amount of Co and B elements, the generation of harmful substances is reduced.

[0046] The purpose of the above embodiments is to explain the present invention in detail so that those skilled in the art can understand the technical concept of the present invention. Within the scope of the present invention, the optimization or equivalent replacement of the components and method steps involved, and the combination of the implementation methods in different embodiments without conflict of structure and principle, all fall within the protection scope of the present invention.

Claims

1. A radiation embrittlement resistant nickel-based alloy, characterized in that: By weight, it contains 14.0%-18.0% Cr, 10.0%-16.0% Fe, 0.5%-1.5% Mn, 2.0%-4.0% Mo, 5.0%-10.0% W, 0.1%-0.3% Al, 0.05%-0.1% C, and the balance is Ni and unavoidable impurities; The radiation embrittlement resistant nickel-based alloy is manufactured by the following method: Providing raw materials according to the proportion and performing vacuum melting, and casting into alloy blanks; The alloy blank is hot forged, subjected to two-stage heat treatment, and water-cooled to obtain a radiation-resistant embrittlement nickel-based alloy product; Wherein, in the two-stage heat treatment, the first stage heat treatment is kept at 873K-1073K for 1h±10min, and the second stage heat treatment is kept at 1473K-1573K for 2h±10min; After the radiation-resistant embrittled nickel-based alloy is irradiated with neutrons at 1073K / 3dpa, the elongation of the tensile test at room temperature is not less than 2%, the elongation of the tensile test at 973K is not less than 12%, and the elongation of the tensile test at 1073K is not less than 18%.

2. The radiation embrittlement resistant nickel-based alloy according to claim 1, characterized in that: Among the unavoidable impurities, Co<0.05%, B<1wppm.

3. The radiation embrittlement resistant nickel-based alloy according to claim 1 or 2, characterized in that: By weight, it contains 14.0%-18.0% Cr, 12.0%-16.0% Fe, 0.5%-1.5% Mn, 2.0%-4.0% Mo, 5.0%-6.0% W, 0.1%-0.3% Al, 0.05%-0.1% C, and the balance is Ni and unavoidable impurities.

4. The radiation embrittlement resistant nickel-based alloy according to claim 1 or 2, characterized in that: The grain size of the radiation embrittlement resistant nickel-based alloy is level 4-6.

5. A method for manufacturing a radiation embrittlement resistant nickel-based alloy, characterized in that: The following steps are involved: Raw materials are provided according to the weight ratio of Cr 14.0%-18.0%, Fe 10.0%-16.0%, Mn 0.5%-1.5%, Mo 2.0%-4.0%, W 5.0%-10.0%, Al 0.1%-0.3%, C 0.05%-0.1%, and the balance Ni, and vacuum smelted and cast into alloy blanks; The alloy blank is hot forged, subjected to two-stage heat treatment, and water-cooled to obtain a radiation-resistant embrittlement nickel-based alloy product; Among them, in the double-stage heat treatment, the first stage heat treatment is kept at 873K-1073K for 1h±10min, and the second stage heat treatment is kept at 1473K-1573K for 2h±10min.

6. The method for manufacturing the radiation embrittlement resistant nickel-based alloy according to claim 5, characterized in that: In the alloy blank, impurities such as Co<0.05% and B<1wppm are controlled.

7. The method for manufacturing the radiation embrittlement resistant nickel-based alloy according to claim 5, characterized in that: In the raw materials, Fe accounts for 12.0%-16.0%, and W accounts for 5.0%-6.0%.

8. The method for producing a radiation embrittlement resistant nickel-based alloy according to any one of claims 5 to 7, characterized in that: Used for producing the radiation embrittlement resistant nickel-based alloy according to any one of claims 1 to 4.

9. An application of a radiation embrittlement resistant nickel-based alloy for manufacturing structural parts, characterized in that: The invention is manufactured by using the radiation embrittlement resistant nickel-based alloy as claimed in any one of claims 1 to 4.

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