Steel plate for a nuclear power plant main shaft sleeve and method for producing the same

Abstract

The application discloses a steel plate for a nuclear power project main shaft sleeve and a production method thereof. The steel plate has the following chemical components and mass percentages thereof: C: 0.15%-0.17%, Mn: 1.35%-1.45%, Cr: 0.15%-0.20%, Nb: 0.025%-0.030%, V: 0.075%-0.080%, CEV<=0.46%, wherein CEV=C+Mn / 6+ (Cr+Mo+V) / 5+ (Ni+Cu) / 15, and the rest is Fe and inevitable impurities. The production process comprises rolling and a heat treatment process. The heat treatment process comprises the following steps: furnace loading at room temperature, furnace temperature rising, heating to 800-850 DEG C, no heat preservation, furnace discharging and air cooling. The steel plate provided by the application has low surface hardness, high strength, R p0.2 >=460MPa, R m >=590MPa, A>=21%, surface hardness HB<=192.

Description

Technical Field

[0001] This invention belongs to the field of metallurgical technology, specifically relating to a steel plate for the main shaft sleeve of a nuclear power project and its production method. Background Technology

[0002] In recent years, with the popularization of new energy sources, nuclear power projects have been vigorously developed, and the production of steel plates for nuclear power projects has continued to increase. The steel plate provided by this invention is used for spindle sleeves in nuclear power projects. Spindles typically use materials with lower strength grades, tensile strength ≤585MPa, and hardness HB=195-225. To prevent excessive wear on the spindle, the surface hardness of the steel plate used for the sleeve must be lower than that of the spindle surface, while its strength grade must be higher than that of the spindle material, thus protecting the spindle. Therefore, providing a steel plate for sleeves with lower hardness and higher strength is particularly important. Summary of the Invention

[0003] The technical problem to be solved by this invention is to provide a steel plate for the main shaft sleeve of nuclear power projects, which has low surface hardness and high strength. p0.2 ≥460MPa, R m ≥590MPa, A≥21%, surface hardnessHB≤192.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0005] A steel plate for a main shaft sleeve in a nuclear power project has the following chemical composition and mass percentage: C: 0.15%-0.17%, Mn: 1.35%-1.45%, Cr: 0.15%-0.20%, Nb: 0.025%-0.030%, V: 0.075%-0.080%, CEV≤0.46%, where CEV=C+Mn / 6+(Cr+Mo+V) / 5+(Ni+Cu) / 15, and the remainder is Fe and unavoidable impurities.

[0006] The steel plate for the main shaft sleeve of the nuclear power project described in this invention is produced through a rolling and heat treatment process.

[0007] The rolling process described in this invention adopts a two-stage controlled rolling + ACC controlled cooling production, and the red temperature after ACC is controlled at 500℃-720℃.

[0008] The heat treatment process described in this invention is as follows: the furnace is loaded at room temperature, the temperature is increased with the furnace, heated to 800℃-850℃, without heat preservation, and then air-cooled after being removed from the furnace.

[0009] The heat treatment process described in this invention involves heat treatment in a single furnace, with steel loaded in layers and separated by steel spacers.

[0010] The thickness of the steel plate described in this invention is 20mm-100mm.

[0011] Another objective of this invention is to provide a method for producing steel plates for main shaft sleeves in nuclear power projects, including rolling and heat treatment processes.

[0012] The rolling process described in this invention adopts a two-stage controlled rolling + ACC controlled cooling production, and the red temperature after ACC is controlled at 500℃-720℃.

[0013] The heat treatment process described in this invention is as follows: the furnace is loaded at room temperature, the temperature is increased with the furnace, heated to 800℃-850℃, without heat preservation, and then air-cooled after being removed from the furnace.

[0014] The heat treatment process described in this invention involves heat treatment in a single furnace, with steel loaded in layers and separated by steel spacers.

[0015] The steel plate for the main shaft sleeve of the nuclear power project described in this invention has low hardness and high strength, and its specific performance indicators are as follows: R p0.2 ≥460MPa, R m ≥590MPa, A≥21%, surface hardnessHB≤192.

[0016] The beneficial effects of adopting the above technical solution are as follows:

[0017] (1) By adding Nb and V to the steel plate and controlling the reasonable controlled rolling and cooling process, the present invention achieves the purpose of refining the grains, increasing the dislocation density of the internal microstructure, and improving the strength.

[0018] (2) Through the heat treatment process described in this invention, the surface of the steel plate undergoes a structural transformation, but the interior of the steel plate does not undergo a structural transformation. The high density of dislocations and fine grains ensure the strength of the steel plate, thereby achieving the goal of low surface hardness and high strength.

[0019] (3) The steel plate of the present invention is heat-treated in a single furnace, with multiple layers of steel, and the heating time is short, which greatly saves production costs. Implementation

[0020] The present invention will be further described in detail below with reference to specific embodiments. Example 1

[0021] The steel plate used for the main shaft sleeve in the nuclear power project described in this embodiment has a thickness of 20mm. Its chemical composition and mass percentage are as follows: C: 0.15%, Mn: 1.36%, Cr: 0.16%, Nb: 0.025%, V: 0.078%, CEV=0.43%, with the remainder being Fe and unavoidable impurities. Its production process includes rolling and heat treatment processes, specifically:

[0022] Rolling process: Stage II controlled rolling + ACC cooling is adopted, and the red temperature after ACC is 710℃-720℃.

[0023] Heat treatment process: heat treatment is carried out in a single furnace, with steel loaded in 7 layers and separated by steel blocks in the middle; the steel plates are loaded into the furnace at room temperature and heated with the furnace. After being heated to 800°C, they are taken out of the furnace and air cooled.

[0024] The mechanical properties of the 7-layer steel plate provided in this embodiment were tested, and the results are shown in Table 1.

[0025] Table 1 Mechanical properties of steel plates in Example 1

[0026] Serial Number <![CDATA[R p0.2 (MPa)]]> <![CDATA[R m (MPa)]]> A（%） <![CDATA[R p0.2 / R m ]]> Hardness HB 1 492 622 24 0.79 187 2 501 633 26 0.79 190 3 498 623 26 0.80 185 4 508 642 24 0.79 187 5 512 639 27 0.80 188 6 487 624 26 0.78 190 7 500 631 25 0.79 185 Example 2

[0027] The steel plate used for the main shaft sleeve in the nuclear power project described in this embodiment has a thickness of 25mm. Its chemical composition and mass percentage are: C: 0.16%, Mn: 1.36%, Cr: 0.15%, Nb: 0.025%, V: 0.075%, CEV=0.44%, with the remainder being Fe and unavoidable impurities. Its production process includes rolling and heat treatment processes, specifically:

[0028] Rolling process: Stage II controlled rolling + ACC cooling is adopted, and the red temperature after ACC is 710℃-720℃.

[0029] Heat treatment process: The steel is heat treated in a single furnace, with 7 layers of steel loaded and separated by steel blocks in between; the steel plates are loaded into the furnace at room temperature and heated with the furnace. After being heated to 810°C, they are taken out of the furnace and air cooled.

[0030] The mechanical properties of the 7-layer steel plate provided in this embodiment were tested, and the results are shown in Table 2.

[0031] Table 2 Mechanical properties of steel plates in Example 2

[0032] Serial Number <![CDATA[R p0.2 (MPa)]]> <![CDATA[R m (MPa)]]> A（%） <![CDATA[R p0.2 / R m ]]> Hardness HB 1 482 634 26 0.76 192 2 491 633 26 0.78 190 3 497 629 25 0.79 187 4 485 640 23.5 0.76 187 5 485 645 24 0.75 188 6 487 638 26 0.76 190 7 501 640 25 0.78 188 Example 3

[0033] The steel plate used for the main shaft sleeve in the nuclear power project described in this embodiment has a thickness of 35mm. Its chemical composition and mass percentage are: C: 0.16%, Mn: 1.35%, Cr: 0.17%, Nb: 0.027%, V: 0.078%, CEV=0.44%, with the remainder being Fe and unavoidable impurities. Its production process includes rolling and heat treatment processes, specifically:

[0034] Rolling process: Stage II controlled rolling + ACC cooling is adopted, and the red temperature after ACC is 690℃-700℃.

[0035] Heat treatment process: The steel is heat treated in a single furnace, with 6 layers of steel loaded and separated by steel blocks in between; the steel plates are loaded into the furnace at room temperature and heated with the furnace. After being heated to 820°C, they are taken out of the furnace and air cooled.

[0036] The mechanical properties of the 6-layer steel plate provided in this embodiment were tested, and the results are shown in Table 3.

[0037] Table 3 Mechanical properties of steel plates in Example 3

[0038] Serial Number <![CDATA[R p0.2 (MPa)]]> <![CDATA[R m (MPa)]]> A（%） <![CDATA[R p0.2 / R m ]]> Hardness HB 1 484 634 26 0.76 192 2 495 633 24 0.78 190 3 490 645 25 0.79 187 4 489 640 24 0.76 187 5 492 645 24 0.75 188 6 502 652 23 0.76 190 Example 4

[0039] The steel plate used for the main shaft sleeve in the nuclear power project described in this embodiment has a thickness of 60mm. Its chemical composition and mass percentage are: C: 0.16%, Mn: 1.39%, Cr: 0.18%, Nb: 0.027%, V: 0.078%, CEV=0.45%, with the remainder being Fe and unavoidable impurities. Its production process includes rolling and heat treatment processes, specifically:

[0040] Rolling process: Stage II controlled rolling + ACC cooling is adopted, and the red temperature after ACC is 610℃-620℃.

[0041] Heat treatment process: Heat treatment is carried out in a single furnace, with steel loaded in 4 layers and separated by steel blocks in the middle; the steel plates are loaded into the furnace at room temperature and heated with the furnace. After being heated to 830°C, they are taken out of the furnace and air cooled.

[0042] The mechanical properties of the four-layer steel plate provided in this embodiment were tested, and the results are shown in Table 4.

[0043] Table 4 Mechanical properties of steel plates in Example 4

[0044] Serial Number <![CDATA[R p0.2 (MPa)]]> <![CDATA[R m (MPa)]]> A（%） <![CDATA[R p0.2 / R m ]]> Hardness HB 1 472 621 24 0.76 186 2 483 618 26 0.78 179 3 492 625 23 0.79 185 4 478 623 24 0.77 187 Example 5

[0045] The steel plate used for the main shaft sleeve in the nuclear power project described in this embodiment has a thickness of 75mm. Its chemical composition and mass percentage are: C: 0.15%, Mn: 1.45%, Cr: 0.20%, Nb: 0.027%, V: 0.075%, CEV=0.45%, with the remainder being Fe and unavoidable impurities. Its production process includes rolling and heat treatment processes, specifically:

[0046] Rolling process: Stage II controlled rolling + ACC cooling is adopted, and the red temperature after ACC is 570℃-580℃.

[0047] Heat treatment process: Heat treatment is carried out in a single furnace, with steel loaded in 4 layers and separated by steel blocks in the middle; the steel plates are loaded into the furnace at room temperature and heated with the furnace. After being heated to 830°C, they are taken out of the furnace and air cooled.

[0048] The mechanical properties of the four-layer steel plate provided in this embodiment were tested, and the results are shown in Table 5.

[0049] Table 5 Mechanical properties of steel plates in Example 5

[0050] Serial Number <![CDATA[R p0.2 (MPa)]]> <![CDATA[R m (MPa)]]> A（%） <![CDATA[R p0.2 / R m ]]> Hardness HB 1 468 625 25 0.75 190 2 472 634 24 0.74 182 3 470 639 23 0.74 185 4 465 628 26 0.74 184 Example 6

[0051] The steel plate used for the main shaft sleeve in the nuclear power project described in this embodiment has a thickness of 90mm. Its chemical composition and mass percentage are: C: 0.16%, Mn: 1.40%, Cr: 0.20%, Nb: 0.030%, V: 0.080%, CEV=0.46%, with the remainder being Fe and unavoidable impurities. Its production process includes rolling and heat treatment processes, specifically:

[0052] Rolling process: Stage II controlled rolling + ACC cooling is adopted, and the red temperature after ACC is 530℃-540℃.

[0053] Heat treatment process: Heat treatment is carried out in a single furnace, with steel loaded in 3 layers and separated by steel blocks in the middle; the steel plates are loaded into the furnace at room temperature and heated with the furnace. After being heated to 850°C, they are taken out of the furnace and air cooled.

[0054] The mechanical properties of the three-layer steel plate provided in this embodiment were tested, and the results are shown in Table 6.

[0055] Table 6 Mechanical properties of steel plates in Example 6

[0056] Serial Number <![CDATA[R p0.2 (MPa)]]> <![CDATA[R m (MPa)]]> A（%） <![CDATA[R p0.2 / R m ]]> Hardness HB 1 492 638 24 0.77 175 2 485 642 24 0.76 182 3 490 645 25 0.76 185 Example 7

[0057] The steel plate used for the main shaft sleeve in the nuclear power project described in this embodiment has a thickness of 90mm. Its chemical composition and mass percentage are: C: 0.17%, Mn: 1.35%, Cr: 0.18%, Nb: 0.025%, V: 0.077%, CEV=0.45%, with the remainder being Fe and unavoidable impurities. Its production process includes rolling and heat treatment processes, specifically:

[0058] Rolling process: Stage II controlled rolling + ACC cooling is adopted, and the red temperature after ACC is 510℃-520℃.

[0059] Heat treatment process: Heat treatment is carried out in a single furnace, with steel loaded in 3 layers and separated by steel blocks in the middle; the steel plates are loaded into the furnace at room temperature and heated with the furnace. After being heated to 850°C, they are taken out of the furnace and air cooled.

[0060] The mechanical properties of the three-layer steel plate provided in this embodiment were tested, and the results are shown in Table 7.

[0061] Table 7 Mechanical properties of steel plates in Example 7

[0062] Serial Number <![CDATA[R p0.2 (MPa)]]> <![CDATA[R m (MPa)]]> A（%） <![CDATA[R p0.2 / R m ]]> Hardness HB 1 472 645 24 0.75 177 2 465 645 23 0.72 186 3 470 648 22 0.73 179 Example 8

[0063] The steel plate used for the main shaft sleeve in the nuclear power project described in this embodiment has a thickness of 100mm; its chemical composition and mass percentage are: C: 0.17%, Mn: 1.40%, Cr: 0.18%, Nb: 0.025%, V: 0.080%, CEV=0.46%, with the remainder being Fe and unavoidable impurities; its production process includes rolling and heat treatment processes, specifically:

[0064] Rolling process: Stage II controlled rolling + ACC cooling is adopted, and the red temperature after ACC is 500℃-510℃.

[0065] Heat treatment process: Heat treatment is carried out in a single furnace. The steel is loaded in two layers and separated by steel blocks. The steel plates are loaded into the furnace at room temperature and heated with the furnace. After being heated to 850°C, they are taken out of the furnace and air-cooled.

[0066] The mechanical properties of the two-layer steel plate provided in this embodiment were tested, and the results are shown in Table 8.

[0067] Table 8 Mechanical properties of steel plates in Example 8

[0068] Serial Number <![CDATA[R p0.2 (MPa)]]> <![CDATA[R m (MPa)]]> A（%） <![CDATA[R p0.2 / R m ]]> Hardness HB 1 460 635 26 0.72 174 2 464 644 25 0.72 180

[0069] As can be seen from Examples 1-8, the steel plate for the main shaft sleeve of nuclear power projects provided by the present invention has moderate strength and low surface hardness, which fully meets the requirements for use.

[0070] The above embodiments are only used to illustrate and not limit the technical solutions of the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the present invention without departing from the spirit and scope of the present invention. Any modifications or partial substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A steel plate for a spindle sleeve in a nuclear power project, characterized in that, The chemical composition and mass percentage of the steel plate are as follows: C: 0.15%-0.17%, Mn: 1.35%-1.45%, Cr: 0.15%-0.20%, Nb: 0.025%-0.030%, V: 0.075%-0.080%, CEV≤0.46%, where CEV=C+Mn / 6+(Cr+Mo+V) / 5+(Ni+Cu) / 15, and the remainder is Fe and unavoidable impurities; The steel plate production process includes rolling and heat treatment processes; the rolling process adopts a two-stage controlled rolling + ACC controlled cooling production, and the red-heat temperature after ACC is controlled at 500℃-720℃; The heat treatment process is as follows: the furnace is loaded at room temperature, the temperature is increased with the furnace, heated to 800℃-850℃, without heat preservation, and then air-cooled after being removed from the furnace.

2. The steel plate for the main shaft sleeve of a nuclear power project according to claim 1, characterized in that, The thickness of the steel plate is 20mm-100mm.

3. The steel plate for the main shaft sleeve of a nuclear power project according to claim 1, characterized in that, The performance indicators of the steel plate are as follows: R p0.2 ≥460MPa, R m ≥590MPa, A≥21%, surface hardnessHB≤192.

4. The steel plate for the main shaft sleeve of a nuclear power project according to claim 1, characterized in that, The heat treatment process involves heat treatment in a single furnace, with steel loaded in layers and separated by steel spacers.

5. The method for producing steel plates for main shaft sleeves in nuclear power projects according to claim 1, characterized in that, It includes rolling and heat treatment processes; the heat treatment process is as follows: the furnace is loaded at room temperature, the temperature is increased with the furnace, heated to 800℃-850℃, without heat preservation, and then air-cooled after being removed from the furnace.

6. The method for producing steel plates for main shaft sleeves in nuclear power projects according to claim 5, characterized in that, The heat treatment process involves heat treatment in a single furnace, with steel loaded in layers and separated by steel spacers.