Stainless steel for a high-level radioactive waste vitrification encapsulation container

Abstract

The present invention discloses a stainless steel for high-level radioactive waste vitrification encapsulation containers, which is made of elements with the following mass contents: C 0.05% - 0.2%, N 0.05% - 0.5%, Si 0.2% - 1.0%, Cr 18% - 24%, Ni 12% - 17%, Nb 0.03% - 1.0%, Ce 0 - 0.1%, Mn 1.0% - 2.0%, Mo + W 0 - 10%, Co ≤ 0.3%, S ≤ 0.01%, P ≤ 0.02%, and the balance is Fe. By adding C, N, Nb, Mo, and W, the present invention exerts the effects of solid solution strengthening and multi-phase precipitation strengthening, significantly improving the high-temperature strength. At the same time, the combined action of Mo, W, N, and Nb improves the pitting corrosion resistance. The obtained stainless steel has good mechanical and high-temperature properties as well as corrosion resistance, and is suitable for the manufacture of high-level radioactive waste vitrification encapsulation containers and components in its high-temperature field.

Description

Technical Field

[0001] The present invention belongs to the technical field of stainless steel for solidification encapsulation containers, and particularly relates to a stainless steel for glass solidification encapsulation containers with excellent mechanical properties at room temperature and high temperature as well as corrosion resistance. Background Art

[0002] High-level radioactive waste with high radioactive concentration, high heat release rate and strong toxicity is generated during the nuclear fuel cycle. In order to ensure the safety of high-level radioactive waste disposal, after more than half a century of exploration, it has been found that glass can well contain radionuclides and has good chemical stability and radiation resistance. The glass solidification process technology is also the only industrial method for treating high-level radioactive waste at present. During the glass solidification process, oxide additives containing elements such as silicon and boron are generally added to the high-level radioactive waste, and then melted at high temperature to form glass. After the glass is melted, it needs to be encapsulated in a container and then sent out for interim storage. The temperature of the molten glass is ~1150°C, and the loading weight is generally above 400 kg. Therefore, it is required that the packaging container has certain high-temperature mechanical properties. In addition, considering that the material of the glass solidification encapsulation container needs to be processed by processes such as bending and also needs to be stacked and placed, the material must have certain mechanical properties at room temperature. Finally, the high-level radioactive waste solidified by glass ultimately needs geological disposal, and groundwater usually contains ~150 ppm Cl − , so the material must have certain pitting corrosion resistance. In summary, the glass solidification encapsulation container must simultaneously have excellent mechanical properties at room temperature and high temperature as well as pitting corrosion resistance.

[0003] 309S austenitic stainless steel has good high-temperature strength, oxidation resistance, corrosion resistance and excellent processing performance, and is often used as parts used in high-temperature and high-pressure environments in industries such as nuclear power, thermal power generation, automotive exhaust systems and chemical engineering and petroleum. Compared with high-temperature alloys such as nickel-based alloys, 309S austenitic stainless steel has a low price and is suitable for large-scale use. Therefore, 309S austenitic stainless steel is the preferred material for high-level radioactive waste glass solidification encapsulation containers. However, at present, there are still some problems in the use of 309S austenitic stainless steel: 1) Since the temperature of the molten glass reaches 1150°C, while the maximum service temperature of commercial 309S stainless steel is 950°C. The high-temperature strength of 309S stainless steel is insufficient at higher temperatures, resulting in the risk that the container is prone to deformation and even cracking during the encapsulation process; 2) The designed service life of the encapsulation container is 100 years, and in the complex environment of groundwater containing Cl − , the corrosion resistance of 309S stainless steel is difficult to meet the design requirements.

[0004] In the prior art, the patent with the publication number CN 111690864 A discloses a preparation method of nuclear-grade stainless steel for high-level radioactive waste glass solidification containers. This stainless steel has insufficient high-temperature strength above 1000°C and its corrosion resistance at room temperature does not meet the service life of 100 years. In this patent, the main focus is on improving the high-temperature strength of the stainless steel at 600°C, and its precipitated phases are mainly Cr 23 C6 and Cr2N. However, above 1000°C, due to the N content being less than 0.2%, Cr2N will no longer precipitate, that is, above 1000°C, it mainly precipitates as Cr 23 C6, and its precipitation strengthening effect is limited. In addition, the corrosion resistance of the stainless steel in this patent has not been studied, and the pitting potential of the stainless steel generally does not exceed 0.4V. However, the research on the corrosion resistance of stainless steel for high-level radioactive waste glass solidification encapsulation containers is the focus of research in various countries around the world, and improving the corrosion resistance of stainless steel is the key to ensuring the service life of the encapsulation containers.

[0005] Therefore, it is of great engineering significance to develop austenitic stainless steel with excellent mechanical properties at room and high temperatures and pitting corrosion resistance. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide stainless steel for high-level radioactive waste glass solidification encapsulation containers in view of the deficiencies of the above prior art. Based on traditional stainless steel, this stainless steel adds N, Nb, Mo, and W, further increasing the total content of the second phase in the steel and the precipitation strengthening effect, enabling the stainless steel to precipitate phases such as Cr 23 C6, Cr2N, Nb(C, N), and Laves at high temperatures, providing multiple precipitation strengthening effects. At the same time, the addition of Mo and W can play a solid solution strengthening role. Under the combined action of multi-phase precipitation strengthening and solid solution strengthening, the high-temperature strength of the stainless steel can be significantly improved.

[0007] To solve the above technical problems, the technical solution adopted by the present invention is: A stainless steel for high-level radioactive waste glass solidification encapsulation containers, characterized in that the stainless steel is made of the following components by mass fraction: C 0.05% - 0.2%, N 0.05% - 0.5%, Si 0.2% - 1.0%, Cr 18% - 24%, Ni 12% - 17%, Nb 0.03% - 1.0%, Ce 0 - 0.1%, Mn 1.0% - 2.0%, Mo + W 0 - 10%, Co ≤ 0.3%, S ≤ 0.01%, P ≤ 0.02%, and the balance is Fe.

[0008] The stainless steel for the high-level radioactive waste vitrification encapsulation container described above is characterized in that the stainless steel is made of the following components by mass fraction: C 0.07% - 0.15%, N 0.15% - 0.3%, Si 0.2% - 1.0%, Cr 18% - 24%, Ni 12% - 17%, Nb 0.03% - 0.6%, Ce 0.02% - 0.08%, Mn 1.0% - 2.0%, Mo + W 4% - 8%, Co ≤ 0.3%, S ≤ 0.01%, P ≤ 0.02%, and the balance is Fe.

[0009] The stainless steel for the high-level radioactive waste vitrification encapsulation container of the present invention is austenitic stainless steel, and the reasons for the limitation of the main component elements are as follows:

[0010] C 0.05% - 0.2%, N 0.05% - 0.5%:

[0011] C and N are austenite phase stabilizing elements, which can replace the addition of Ni, thereby reducing costs. In addition, the addition of C and N can play a role in solid solution strengthening and participate in the formation of the second phase, providing a precipitation strengthening effect, thereby improving the high-temperature strength of the stainless steel. At the same time, the addition of N also improves the pitting corrosion resistance of the stainless steel. However, C and N can form intermetallic compounds with Cr, resulting in the emergence of Cr-depleted regions and a decrease in the pitting corrosion resistance of the stainless steel, especially the C element. Excessive C and N will also cause severe coarsening of carbonitrides, resulting in a weakening of the precipitation strengthening effect. Therefore, the content of C is set to 0.05 - 0.2%, and the preferred C content range is 0.07% - 0.15%. The content of N is set to 0.05 - 0.5%, and the preferred N content range is 0.15% - 0.3%.

[0012] Nb 0.03% - 1.0%:

[0013] The solubility of Nb in stainless steel is small, and it is easy to form MC (Nb(C, N)) phase with C and N. When the Nb content in stainless steel is relatively high, due to the high precipitation temperature of the Nb(C, N) phase, it is difficult to perform solution treatment, and the Nb(C, N) phase is mainly distributed in the steel in a dispersed state, so the improvement of high-temperature strength is limited. At this time, Nb in stainless steel mainly acts jointly with N to promote the formation of Nb-containing oxides, significantly improving the corrosion resistance of the steel. However, excessive addition of Nb leads to severe coarsening of the MC (Nb(C, N)) phase, further deteriorating the plasticity and toughness of the stainless steel. In addition, excessive addition of Nb is likely to cause severe segregation during the welding process of stainless steel, which is not conducive to the welding performance of stainless steel. If you want to obtain Nb(C, N) phase precipitated at the grain boundary, the Nb content in stainless steel needs to be between 0.03% and 0.06%. At the same time, in order to ensure the corrosion resistance of stainless steel, the contents of Mo and W must be increased. Therefore, the content of Nb is set to 0.03% - 1.0%, and the preferred Nb content range is 0.03% - 0.6%.

[0014] Mo + W 0~10%:

[0015] The common second phases in austenitic stainless steel are carbonitrides. These second phases have an increasing volume fraction with the increase of C and N contents, and also have an increasing coarsening rate at high temperatures. In order to inhibit the severe coarsening of carbonitrides at high temperatures, the content of carbonitrides is strictly restricted. In order to increase the volume fraction of the second phase and improve the precipitation strengthening effect, intermetallic compounds without C and N are particularly introduced to achieve the multi-phase precipitation strengthening effect. The Laves phase structure is A2B (A is mainly Fe and Cr, and B is mainly Ti, Nb, Mo, W, etc.), and it does not contain C and N elements. Among them, Mo and W elements do not participate in the formation of carbonitrides such as Cr 23 C6, Cr2N, Nb(C, N), etc. Therefore, the addition of Mo and W elements has little effect on the precipitation behavior of the above carbonitrides. Mo and W, as metal atoms with high melting points and large sizes, have a relatively low diffusion rate in austenite, and the formed Fe2Mo and Fe2W have a lower coarsening rate compared with other Laves phases. In addition, Mo and W atoms have large sizes, and their solid solution strengthening effect is more significant. The addition of Mo and W can also improve the corrosion resistance of the steel. In addition, the high-level radioactive waste liquid in the vitrified encapsulation container is mainly irradiated. The addition of Mo and W can play a good shielding role. Especially, W element has a strong gamma-ray shielding effect, which can significantly reduce the environmental pollution caused by irradiation. However, excessive Mo and W will cause the instability of the austenite structure and the coarsening of the Laves phase. Therefore, the content of Mo + W is set to 0~10%, and the preferred content range of Mo + W is 4%~8%. In the prior art, the contents of Mo and W are relatively low. When used above 1000 °C, Mo and W elements can only play a solid solution strengthening effect and cannot form Laves phases to provide precipitation phase effects. The precipitation strengthening effect at high temperatures is significantly greater than the solid solution strengthening effect, and the solid solution strengthening effect of Mo and W elements is limited. In contrast, the Mo + W content in the optimized composition range of the present invention can precipitate Laves phases above 1000 °C and coexist with Cr 23 C6, Cr2N, Nb(C, N) and other multiple precipitation phases to provide multiple precipitation strengthening effects, which can significantly improve the high-temperature strength of the steel.

[0016] Cr 18%~24%:

[0017] The addition of Cr can ensure the oxidation resistance of stainless steel at high temperatures and improve the corrosion resistance of the steel at the same time. However, Cr is a ferrite stabilizing element and also a harmful brittle phase -Fe and σ phase forming element. Excessive Cr content will reduce the stability of the austenite phase at high temperatures and increase the harmful brittle phases -Fe and σ phases, resulting in a decrease in the high-temperature strength of the steel. Therefore, in order to meet the use of the steel above 1000 °C, the content of Cr is set to 18%~24%.

[0018] Ni 12% - 17%:

[0019] Ni is an austenite stabilizing element. The addition of Ni element is the key to ensuring the stability of the austenite structure, and it can also reduce the formation of high-temperature ferrite -Fe in the steel grade. However, Ni is expensive, and excessive addition will lead to an increase in cost. The content of Ni varies with the contents of Cr, Mo, and W, so the content of Ni is set at 12% - 17%.

[0020] Si 0.2% - 1.0%:

[0021] The addition of Si can improve the high-temperature oxidation resistance of the steel, save the consumption of Cr, and at the same time play a deoxidizing role to reduce the oxygen content in the steel. However, Si will reduce the solid solubility of N in the steel, leading to the easy precipitation of nitrides and reducing the solid solution strengthening effect of N. Therefore, the content of Si is set at 0.2% - 1.0%.

[0022] Mn 1.0% - 2.0%:

[0023] Mn is also an austenite stabilizing element. The addition of Mn can replace part of Ni and reduce the cost. At high temperatures, Mn participates in the formation of the oxide film. When the content of Mn exceeds 2.0%, the Mn oxide of spinel will lead to a decrease in the bonding force of the oxide film, which is instead not conducive to the oxidation resistance of the steel. Therefore, the content of Mn is set at 1.0% - 2.0%.

[0024] Ce 0 - 0.1%:

[0025] Rare earth elements have a good affinity with S and P. The addition of rare earth elements can play a role in purifying the molten steel, but excessive addition will instead lead to an increase in the number and size of inclusions, which is instead not conducive to the plasticity of the steel. Compared with other rare earth elements, rare earth element Ce has an important function, that is, it increases the compactness of the oxide film at high temperatures and improves the high-temperature performance of the steel. Therefore, only rare earth element Ce is added in the present invention, the content of Ce is set at 0 - 0.1%, and the preferred content range of Ce is 0.02% - 0.08%.

[0026] Compared with the existing domestic S30908 steel, more C, N, Nb, W, and Mo are added to the stainless steel of the present invention to form various carbonitrides (such as Nb(C, N), Cr2N, Cr 23The multiple precipitation strengthening effect is composed of Cr (such as C6, etc.) and Laves phase, significantly improving the tensile strength and creep fracture strength of stainless steel at high temperatures. The Nb content of the present invention is relatively low, and the total precipitation amount of Nb (C, N) is limited, ensuring the plasticity and toughness of stainless steel and its welded joints at room temperature. The second phases formed by other elements such as C, N, W, and Mo can be subjected to high-temperature solution treatment at 1100°C to 1300°C. The stainless steel of the present invention can ensure the mechanical properties and pitting corrosion resistance of stainless steel at room temperature and high temperature only through conventional high-temperature solution treatment.

[0027] The stainless steel for a high-level radioactive waste vitrification encapsulation container described above is characterized in that the elongation after fracture A of the stainless steel at room temperature 50 ≥40%, and the tensile strength R m ≥650 MPa, the pitting potential E' b100 ≥0.5 V, and the creep fracture strength R at 1000°C for 2 h u 2 / 1000 ≥45 Mpa, and the tensile strength R m ≥80 MPa.

[0028] The stainless steel for a high-level radioactive waste vitrification encapsulation container described above is characterized in that the stainless steel is used to prepare a high-level radioactive waste vitrification encapsulation container.

[0029] The stainless steel for a high-level radioactive waste vitrification encapsulation container of the present invention is prepared by the following steps:

[0030] Step 1: Mix the raw materials and conduct vacuum induction melting to obtain a stainless steel ingot. Then, peel the ingot, heat it to 1200°C, hold it for 7 h, and then forge it. Air-cool it to room temperature to obtain a stainless steel slab with a thickness of 80 mm.

[0031] Step 2: Polish the surface of the stainless steel slab obtained in Step 1, then heat it to 1200°C, hold it for 3 h, and then perform hot rolling. The starting rolling temperature during hot rolling is 1150°C, the final rolling temperature is 950°C, and the total reduction ratio is 92.5%. Then, perform solution annealing treatment at 1100°C to 1200°C for 40 min to 60 min, and air-cool it to room temperature to obtain a stainless steel plate with a thickness of 6 mm.

[0032] The present invention has the following advantages compared with the prior art:

[0033] 1. On the basis of traditional stainless steel, the present invention adds N, Nb, Mo, and W, further increasing the total content of the second phase and the precipitation strengthening effect in the steel, so that Cr will precipitate in the stainless steel at high temperatures 23Phases such as C6, Cr2N, Nb(C, N), and Laves provide a multiple precipitation strengthening effect. At the same time, the addition of Mo and W can play a solution strengthening role. Under the combined action of multi-phase precipitation strengthening and solution strengthening, the high-temperature strength of stainless steel can be significantly improved.

[0034] 2. By controlling the contents of N, Nb, Mo, and W in stainless steel, the present invention improves the pitting potential of stainless steel. Among them, N and Nb are combined. N can promote the formation of Nb-containing oxide films, which can greatly improve the pitting corrosion resistance of stainless steel, making the pitting potential E′ of stainless steel at room temperature b100 ≥0.5V, superior to traditional nuclear-grade stainless steel.

[0035] 3. The room-temperature and high-temperature strengths and pitting corrosion resistance of the stainless steel of the present invention are superior to those of the commonly used domestic steel grade S30908 and imported 309S, and can cope with the working environment around 1000°C to 1100°C, and are suitable for high-level radioactive waste vitrification encapsulation containers.

[0036] The technical solutions of the present invention will be further described in detail below through examples. Specific embodiments

[0037] Example 1

[0038] This example includes the following steps:

[0039] Step 1: Mix the raw materials and then conduct vacuum induction melting to obtain a stainless steel ingot. Then, peel the ingot, heat it to 1200°C and hold for 7 hours, and then forge it. Air-cool it to room temperature to obtain a stainless steel slab with a thickness of 80 mm. The stainless steel ingot is composed of the following elements by mass percentage: C 0.05%, N 0.498%, Si 0.21%, Cr 22.37%, Ni 12.07%, Nb 0.2%, Mn 1.98%, Co 0.3%, S 0.01%, P 0.02%, and the balance is Fe;

[0040] Step 2: Grind the surface of the stainless steel slab obtained in Step 1, then heat it to 1200°C and hold for 3 hours, and then conduct hot rolling. The starting rolling temperature during hot rolling is 1150°C, the final rolling temperature is 950°C, the total reduction ratio is 92.5%, and then conduct solution annealing treatment at 1100°C to 1200°C for 50 minutes, and air-cool it to room temperature to obtain a stainless steel plate with a thickness of 6 mm.

[0041] Example 2

[0042] This example includes the following steps:

[0043] Step 1: Mix the raw materials and then conduct vacuum induction melting to obtain a stainless steel ingot. After peeling the ingot, heat it to 1200°C and hold for 7 hours, then perform forging, and air cool to room temperature to obtain a stainless steel slab with a thickness of 80 mm. The stainless steel ingot consists of the following elements by mass percentage: C 0.2%, N 0.05%, Si 1.0%, Cr 23.97%, Ni 12.87%, Nb 1.0%, Ce 0.098%, Mn 1.01%, Co 0.04%, S 0.005%, P 0.008%, and the balance is Fe;

[0044] Step 2: Grind the surface of the stainless steel slab obtained in Step 1, then heat it to 1200°C and hold for 3 hours, and then perform hot rolling. The starting rolling temperature during hot rolling is 1150°C, the final rolling temperature is 950°C, the total reduction ratio is 92.5%, and then perform solution annealing treatment at 1100°C - 1200°C for 40 minutes, and air cool to room temperature to obtain a stainless steel plate with a thickness of 6 mm.

[0045] Example 3

[0046] This example includes the following steps:

[0047] Step 1: Mix the raw materials and then conduct vacuum induction melting to obtain a stainless steel ingot. After peeling the ingot, heat it to 1200°C and hold for 7 hours, then perform forging, and air cool to room temperature to obtain a stainless steel slab with a thickness of 80 mm. The stainless steel ingot consists of the following elements by mass percentage: C 0.15%, N 0.301%, Si 0.21%, Cr 23.97%, Ni12.03%, Nb 0.6%, Ce 0.02%, Co 0.3%, Mn 1.0%, W 4.05%, S 0.01%, P 0.02%, and the balance is Fe;

[0048] Step 2: Grind the surface of the stainless steel slab obtained in Step 1, then heat it to 1200°C and hold for 3 hours, and then perform hot rolling. The starting rolling temperature during hot rolling is 1150°C, the final rolling temperature is 950°C, the total reduction ratio is 92.5%, and then perform solution annealing treatment at 1100°C - 1200°C for 60 minutes, and air cool to room temperature to obtain a stainless steel plate with a thickness of 6 mm.

[0049] Example 4

[0050] This example includes the following steps:

[0051] Step 1: Mix the raw materials and then conduct vacuum induction melting to obtain a stainless steel ingot. After peeling the ingot, heat it to 1200 °C and hold for 7 h, then perform forging, and air cool to room temperature to obtain a stainless steel slab with a thickness of 80 mm. The stainless steel ingot is composed of the following elements by mass percentage: C 0.07%, N 0.15%, Si 1.01%, Cr 18.06%, Ni 17.02%, Nb 0.03%, Ce 0.02%, Mn 2.0%, W 6.05%, Mo 2.03%, Co 0.04%, S 0.004%, P 0.007%, and the balance is Fe;

[0052] Step 2: Grind the surface of the stainless steel slab obtained in Step 1, then heat it to 1200 °C and hold for 3 h, then perform hot rolling. The starting rolling temperature during hot rolling is 1150 °C, the final rolling temperature is 950 °C, the total reduction ratio is 92.5%, and then perform solution annealing treatment at 1100 °C - 1200 °C for 50 min, and air cool to room temperature to obtain a stainless steel plate with a thickness of 6 mm.

[0053] Example 5

[0054] This example includes the following steps:

[0055] Step 1: Mix the raw materials and then conduct vacuum induction melting to obtain a stainless steel ingot. After peeling the ingot, heat it to 1200 °C and hold for 7 h, then perform forging, and air cool to room temperature to obtain a stainless steel slab with a thickness of 80 mm. The stainless steel ingot is composed of the following elements by mass percentage: C 0.07%, N 0.15%, Si 0.97%, Cr 18.02%, Ni 16.95%, Nb 0.03%, Ce 0.08%, Mn 1.57%, W 6.02%, Mo 4.03%, Co 0.1%, S 0.003%, P 0.006%, and the balance is Fe;

[0056] Step 2: Grind the surface of the stainless steel slab obtained in Step 1, then heat it to 1200 °C and hold for 3 h, then perform hot rolling. The starting rolling temperature during hot rolling is 1150 °C, the final rolling temperature is 950 °C, the total reduction ratio is 92.5%, and then perform solution annealing treatment at 1100 °C - 1200 °C for 50 min, and air cool to room temperature to obtain a stainless steel plate with a thickness of 6 mm.

[0057] Comparative Example 1

[0058] The stainless steel plate of this comparative example is a hot-rolled annealed plate with a thickness of 6 mm produced by Taiyuan Iron and Steel (Group) Co., Ltd., and is composed of the following elements in mass percentage: C 0.055%, N 0.068%, Cr 22.27%, Ni 12.1%, Si 0.32%, Mn 1.42%, S 0.005%, P 0.023%, Co 0.03%, and the balance is Fe.

[0059] Comparative Example 2

[0060] The stainless steel plate of this comparative example is an imported 309S hot-rolled annealed plate with a thickness of 6 mm, and is composed of the following elements in mass percentage: C 0.067%, N 0.036%, Cr 22.04%, Ni 12.89%, Si 0.64%, Mn 1.68%, Co 0.2%, S 0.005%, P 0.019%, and the balance is Fe.

[0061] The room temperature and high temperature mechanical properties and pitting potential of the stainless steel plates of Examples 1 to 5 and Comparative Examples 1 to 2 of the present invention were tested. Among them, the room temperature and high temperature mechanical property tests were carried out in accordance with GB / T228.1-2010 "Metallic materials - Tensile testing - Part 1: Method of test at room temperature", GB / T228.2-2015 "Metallic materials - Tensile testing - Part 2: Method of test at elevated temperature" and GB / T2039-2012 "Metallic materials - Uniaxial tensile creep testing method" to make standard tensile specimens of the stainless steel plates, and measure the room temperature and high temperature tensile strength R m , elongation after fracture A 50 and the 2-hour creep fracture strength R at 1000 °C u 2 / 1000 , where the tensile speed at room temperature is 3 mm / min, and the high temperature tensile strain rate is 0.084 min -1 ; the pitting potential test was carried out in accordance with the national standard GB / T17899-1999 "Method for measuring pitting potential of stainless steel": after making a stainless steel specimen and passivating it in nitric acid, it was sealed with epoxy resin. The test solution was 3.5% sodium chloride solution (35 g of sodium chloride was dissolved in 965 mL of deionized water). The test results were represented by the potential value corresponding to the current density of 100 A / cm 2 on the anodic polarization curve as the pitting potential E' b100 , and the results are shown in Table 1 below.

[0062] Table 1

[0063]

[0064] As can be seen from Table 1, the elongation after fracture A of the stainless steel plates of Examples 1 to 5 of the present invention at room temperature50 ≥40%, tensile strength R m ≥650 MPa, pitting potential E′ at room temperature b100 ≥0.5 V, creep rupture strength R at 1000°C for 2 h u 2 / 1000 ≥45 Mpa, tensile strength R at 1000°C m ≥80 MPa, and the strength and pitting potential are significantly better than those of domestic and imported stainless steel plates in Comparative Example 1 and Comparative Example 2. It shows that in the stainless steel plate of the present invention, by adding C, N, Nb, Mo and W, a multi-phase precipitation strengthening mechanism is introduced, significantly improving the strength of the stainless steel plate, especially the high-temperature strength. In addition, the combined action of Mo and W with N and Nb also significantly improves the pitting corrosion resistance of stainless steel. By adopting the high-temperature solution annealing process, the room-temperature plastic damage of the stainless steel is reduced, and its elongation exceeds 40%, meeting the preparation requirements of the glass solidification encapsulation container. The stainless steel of the present invention has excellent high-temperature mechanical properties and can be used not only for the preparation of glass solidification encapsulation containers but also in other high-temperature fields.

[0065] The above are only the preferred embodiments of the present invention and do not limit the present invention in any way. Any simple modification, change and equivalent change made to the above embodiments according to the technical essence of the invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A stainless steel for a glass solidification encapsulation container of high-level radioactive waste liquid, characterized in that, This stainless steel is made of the following components by mass fraction: C 0.05% - 0.2%, N 0.15% - 0.3%, Si 0.2% - 1.0%, Cr 18% - 24%, Ni 12% - 17%, Nb 0.03% - 1.0%, Ce 0 - 0.1%, Mn 1.0% - 2.0%, Mo + W 4% - 8%, Co ≤ 0.3%, S ≤ 0.01%, P ≤ 0.02%, and the balance is Fe, where Mo and W exist simultaneously; the elongation after fracture A of the stainless steel at room temperature 50 ≥ 42.3%, the tensile strength R m ≥ 846 MPa, the pitting potential E´ b100 ≥ 1.09 V, the creep rupture strength R at 1000 °C for 2 h u 2 / 1000 ≥ 76 Mpa, the tensile strength R m ≥ 169 MPa.

2. The stainless steel for a high-level radioactive waste vitrification encapsulation container according to claim 1, wherein The stainless steel is made of the following components by mass fraction: C 0.07% - 0.15%, N 0.15% - 0.3%, Si 0.2% - 1.0%, Cr 18% - 24%, Ni 12% - 17%, Nb 0.03% - 0.6%, Ce 0.02% - 0.08%, Mn 1.0% - 2.0%, Mo + W 4% - 8%, Co ≤ 0.3%, S ≤ 0.01%, P ≤ 0.02%, and the balance is Fe.

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