Chromium-molybdenum alloy steel forge piece for nuclear island mechanical penetration piece and manufacturing method of chromium-molybdenum alloy steel forge piece

Abstract

The invention provides a chromium-molybdenum alloy steel forge piece for a nuclear island mechanical penetration piece, which consists of the following components in percentage by weight: 0.16 to 0.20 percent of C, 0.50 to 0.80 percent of Mn, 0.10 to 0.20 percent of Si, less than or equal to 0.012 percent of P, less than or equal to 0.010 percent of S, 0.90 to 1.10 percent of Cr, 0.45 to 0.65 percent of Mo, less than or equal to 0.05 percent of Co and the balance of iron. The invention further provides a manufacturing method of the chromium-molybdenum alloy steel forge piece for the nuclear island mechanical penetration piece. The chromium-molybdenum alloy steel forge piece for the nuclear island mechanical penetration piece, provided by the invention, has relatively good mechanical property and hardenability.

Description

Technical Field

[0001] This invention belongs to the field of alloy forging, specifically relating to a chromium-molybdenum alloy steel forging for nuclear island mechanical penetration parts and its manufacturing method. Background Technology

[0002] Mechanical penetrations in the containment structure of a nuclear power plant's nuclear island are divided into electrical penetrations and piping penetrations. These penetrations connect the inside and outside of the containment structure and are one of the key components of the nuclear island. Previously, mechanical penetrations were welded together, but now they are designed as a single integrated forging. This design results in larger forgings, increasing manufacturing difficulty. Moreover, the forgings for the end caps are relatively thick, and the design requires that mechanical properties be met even at greater depths. Existing ordinary chromium-molybdenum alloy steel is insufficient to meet the high requirements of mechanical penetrations in the containment structure of a nuclear power plant's nuclear island. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a chromium-molybdenum alloy steel forging for nuclear island mechanical penetration parts, which has good mechanical properties and hardenability.

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

[0005] A chromium-molybdenum alloy steel forging for a nuclear island mechanical penetrating component is composed of the following components by weight percentage: C 0.16-0.20%, Mn 0.50-0.80%, Si 0.10-0.20%, P≤0.012%, S≤0.010%, Cr 0.90-1.10%, Mo 0.45-0.65%, Co≤0.05%, with the remainder being iron.

[0006] Another technical problem to be solved by the present invention is to provide a method for manufacturing the chromium-molybdenum alloy steel forgings for the above-mentioned nuclear island mechanical penetration parts.

[0007] To solve the above technical problems, the technical solution is as follows:

[0008] A method for manufacturing a chromium-molybdenum alloy steel forging for a mechanical penetrating component of a nuclear island includes the following steps:

[0009] S1. Electric furnace smelting: Raw materials are prepared according to weight percentage, placed in an electric furnace, and smelted until the temperature reaches 1610-1650℃ to obtain molten steel.

[0010] S2. Ladle refining: The molten steel obtained in step S1 is placed in a refining furnace and refined for 50-60 minutes. Then, it is vacuum degassed for 25-35 minutes and then cast into steel ingot billets.

[0011] S3. Forging: The steel ingot blank obtained in step S2 is forged using an air hammer and a press to obtain forgings;

[0012] S4. Heat treatment: The forgings obtained in step S3 are placed in an industrial resistance furnace for preheating treatment. After being taken out, they are placed in a cooling pool for quenching and finally tempered to obtain chromium-molybdenum alloy steel forgings for nuclear island mechanical penetration parts.

[0013] S5. Inspection: Perform physical and chemical tests and non-destructive tests on the chromium-molybdenum alloy steel forgings of the nuclear island mechanical penetration parts obtained in step S4.

[0014] Furthermore, in step S2 of the present invention, argon gas is used for protection throughout the ladle refining process, the vacuum degree during vacuum degassing is 50-60 Pa, and the temperature of the molten steel during casting is 1450-1550℃.

[0015] Furthermore, in step S3 of the present invention, the cutting ratio of the ingot head of the steel ingot billet is 10%, the cutting ratio of the ingot tail of the steel ingot billet is 5%, the initial forging temperature is 1190-1230℃, the final forging temperature is 750-800℃, and the total forging ratio is ≥5.0.

[0016] Furthermore, in step S4 of the present invention, the temperature of the preheating treatment is 890-910℃.

[0017] Furthermore, in step S4 of the present invention, the quenching temperature is 910-930℃, and the cooling pool is filled with coolant during quenching. The coolant is composed of the following components by weight percentage: 12-15% polyethylene glycol monooctyl ether, 2-3% sodium hydroxide, 1-2% 1-hydroxyethyl-2-oleoylimidazoline, 0.3-0.6% dimethylheptadecylbenzylammonium chloride, 0.5-0.9% samarium nitrate, and the remainder is deionized water.

[0018] Furthermore, the preparation steps of the coolant described in this invention are as follows:

[0019] Prepare each component by weight percentage. Add polyethylene glycol monooctyl ether and dimethylheptadecyl benzyl ammonium chloride to water, stir for 5-10 minutes, then add sodium hydroxide, 1-hydroxyethyl-2-oleoylimidazoline and samarium nitrate, and continue stirring for 45-60 minutes to obtain the cooling liquid.

[0020] Furthermore, in the preparation step of the coolant described in this invention, the stirring speed is 100-200 r / min.

[0021] Furthermore, in step S4 of the present invention, the tempering temperature is 610-630℃.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1) By appropriately increasing the content of C, Mn and Cr elements to near the upper limit, the present invention can improve the hardenability and corrosion resistance of forgings and balance strength and toughness. In addition, the present invention appropriately reduces the content of P and S elements, which can reduce the content of non-metallic inclusions in forgings.

[0024] 2) The present invention appropriately controls the forging heating temperature to prevent the material from overheating and burning. The appropriate increase in the forging ratio can improve the forging effect. Forging the micro-defects makes the material more compact, thereby refining the grains and improving the overall performance of the material.

[0025] 3) This invention adds a preheating treatment to prepare the microstructure for the tempering process, which can also refine the grains and appropriately reduce the quenching heating temperature to prevent grain growth.

[0026] 4) The present invention uses a coolant composed of polyethylene glycol monooctyl ether, sodium hydroxide, 1-hydroxyethyl-2-oleoimidazoline, dimethylheptadecylbenzylammonium chloride, samarium nitrate and deionized water during quenching. This coolant can effectively improve the hardenability and crack resistance of the forging. In addition, the present invention effectively improves the strength of the forging by adjusting the tempering temperature. Detailed Implementation

[0027] The present invention will now be described in detail with reference to specific embodiments. The illustrative embodiments and descriptions of the present invention are used to explain the present invention, but are not intended to limit the present invention.

[0028] Example 1

[0029] The chromium-molybdenum alloy steel forgings used for the mechanical penetration parts of the nuclear island are composed of the following components by weight percentage: C 0.19%, Mn 0.70%, Si 0.18%, P 0.010%, S 0.009%, Cr 1.05%, Mo 0.60%, Co 0.04%, with the remainder being iron.

[0030] The manufacturing method of Example 1 includes the following steps:

[0031] S1. Electric furnace smelting: Raw materials are prepared according to weight percentage, placed in an electric furnace, and smelted until the temperature reaches 1630℃ to obtain molten steel.

[0032] S2. Ladle refining: Argon protection throughout the process. The molten steel obtained in step S1 is placed in a refining furnace and refined for 55 minutes. Then, it is vacuum degassed at 55 Pa for 30 minutes and then cast into steel ingots. The temperature of the molten steel during casting is 1500℃.

[0033] S3. Forging: The steel ingot billet obtained in step S2 is forged using an air hammer and a press to obtain forgings. The cutting ratio of the ingot head of the steel ingot billet is 10%, the cutting ratio of the ingot tail of the steel ingot billet is 5%, the initial forging temperature is 1210℃, the final forging temperature is 770℃, and the total forging ratio is 5.2.

[0034] S4. Heat treatment: The forgings obtained in step S3 are placed in an industrial resistance furnace for pre-heat treatment at a temperature of 900°C. After being removed, they are placed in a cooling pool for quenching at 920°C and finally tempered at 620°C to obtain chromium-molybdenum alloy steel forgings for the nuclear island mechanical penetration parts. During quenching, the cooling pool is filled with coolant, which consists of the following components by weight percentage: 14% polyethylene glycol monooctyl ether, 2.7% sodium hydroxide, 1.6% 1-hydroxyethyl-2-oleoylimidazoline, 0.5% dimethylheptadecylbenzylammonium chloride, 0.8% samarium nitrate, and the remainder is deionized water.

[0035] S5. Inspection: Perform physical and chemical tests and non-destructive tests on the chromium-molybdenum alloy steel forgings of the nuclear island mechanical penetration parts obtained in step S4.

[0036] The preparation steps of the coolant are as follows:

[0037] Prepare each component by weight percentage. Add polyethylene glycol monooctyl ether and dimethylheptadecyl benzyl ammonium chloride to water, stir at 150 r / min for 8 min, then add sodium hydroxide, 1-hydroxyethyl-2-oleoylimidazoline and samarium nitrate, and continue stirring for 55 min to obtain the cooling liquid.

[0038] Example 2

[0039] The chromium-molybdenum alloy steel forgings used for the mechanical penetration parts of the nuclear island are composed of the following components by weight percentage: C 0.16%, Mn 0.60%, Si 0.20%, P 0.011%, S 0.008%, Cr 0.90%, Mo 0.50%, Co 0.04%, with the remainder being iron.

[0040] The manufacturing method of Example 2 includes the following steps:

[0041] S1. Electric furnace smelting: Raw materials are prepared according to weight percentage, placed in an electric furnace, and smelted until the temperature reaches 1610℃ to obtain molten steel.

[0042] S2. Ladle refining: Argon protection throughout the process. The molten steel obtained in step S1 is placed in a refining furnace and refined for 60 minutes. Then, it is vacuum degassed at 50 Pa for 35 minutes and then cast into steel ingots. The temperature of the molten steel during casting is 1450℃.

[0043] S3. Forging: The steel ingot billet obtained in step S2 is forged using an air hammer and a press to obtain forgings. The cutting ratio of the ingot head of the steel ingot billet is 10%, the cutting ratio of the ingot tail of the steel ingot billet is 5%, the initial forging temperature is 1190℃, the final forging temperature is 750℃, and the total forging ratio is 5.1.

[0044] S4. Heat treatment: The forgings obtained in step S3 are placed in an industrial resistance furnace for pre-heat treatment at a temperature of 890°C. After being removed, they are placed in a cooling pool for quenching at 910°C and finally tempered at 610°C to obtain chromium-molybdenum alloy steel forgings for the nuclear island mechanical penetration parts. During quenching, the cooling pool is filled with coolant, which is composed of the following components by weight percentage: 12% polyethylene glycol monooctyl ether, 2% sodium hydroxide, 1% 1-hydroxyethyl-2-oleoylimidazoline, 0.3% dimethylheptadecylbenzylammonium chloride, 0.5% samarium nitrate, and the remainder is deionized water.

[0045] S5. Inspection: Perform physical and chemical tests and non-destructive tests on the chromium-molybdenum alloy steel forgings of the nuclear island mechanical penetration parts obtained in step S4.

[0046] The preparation steps of the coolant are as follows:

[0047] Prepare each component by weight percentage. Add polyethylene glycol monooctyl ether and dimethylheptadecyl benzyl ammonium chloride to water. Stir at 100 r / min for 10 min, then add sodium hydroxide, 1-hydroxyethyl-2-oleoylimidazoline and samarium nitrate. Continue stirring for 60 min to obtain the cooling liquid.

[0048] Example 3

[0049] The chromium-molybdenum alloy steel forgings used for the mechanical penetration parts of the nuclear island are composed of the following components by weight percentage: C 0.20%, Mn 0.50%, Si 0.10%, P 0.012%, S 0.009%, Cr 0.95%, Mo 0.65%, Co 0.05%, with the remainder being iron.

[0050] The manufacturing method of Example 3 includes the following steps:

[0051] S1. Electric furnace smelting: Raw materials are prepared according to weight percentage, placed in an electric furnace, and smelted until the temperature reaches 1650℃ to obtain molten steel.

[0052] S2. Ladle refining: Argon protection throughout the process. The molten steel obtained in step S1 is placed in a refining furnace and refined for 50 minutes. Then, it is vacuum degassed under a vacuum of 60 Pa for 25 minutes and then cast into steel ingot billets. The temperature of the molten steel during casting is 1550℃.

[0053] S3. Forging: The steel ingot billet obtained in step S2 is forged using an air hammer and a press to obtain forgings. The cutting ratio of the ingot head of the steel ingot billet is 10%, the cutting ratio of the ingot tail of the steel ingot billet is 5%, the initial forging temperature is 1230℃, the final forging temperature is 800℃, and the total forging ratio is 5.0.

[0054] S4. Heat treatment: The forgings obtained in step S3 are placed in an industrial resistance furnace for pre-heat treatment at a temperature of 910°C. After being removed, they are placed in a cooling pool for quenching at 930°C and finally tempered at 630°C to obtain chromium-molybdenum alloy steel forgings for the nuclear island mechanical penetration parts. During quenching, the cooling pool is filled with coolant, which is composed of the following components by weight percentage: 15% polyethylene glycol monooctyl ether, 3% sodium hydroxide, 2% 1-hydroxyethyl-2-oleoylimidazoline, 0.6% dimethylheptadecylbenzylammonium chloride, 0.9% samarium nitrate, and the remainder is deionized water.

[0055] S5. Inspection: Perform physical and chemical tests and non-destructive tests on the chromium-molybdenum alloy steel forgings of the nuclear island mechanical penetration parts obtained in step S4.

[0056] The preparation steps of the coolant are as follows:

[0057] Prepare each component by weight percentage. Add polyethylene glycol monooctyl ether and dimethylheptadecyl benzyl ammonium chloride to water, stir at 200 r / min for 5 min, then add sodium hydroxide, 1-hydroxyethyl-2-oleoylimidazoline and samarium nitrate, and continue stirring for 45 min to obtain the cooling liquid.

[0058] Example 4

[0059] The chromium-molybdenum alloy steel forgings used for the mechanical penetration parts of the nuclear island are composed of the following components by weight percentage: C 0.18%, Mn 0.80%, Si 0.15%, P 0.011%, S 0.010%, Cr 1.10%, Mo 0.55%, Co 0.03%, with the remainder being iron.

[0060] The manufacturing method of Example 4 includes the following steps:

[0061] S1. Electric furnace smelting: Raw materials are prepared according to weight percentage, placed in an electric furnace, and smelted until the temperature reaches 1640℃ to obtain molten steel.

[0062] S2. Ladle refining: Argon protection throughout the process. The molten steel obtained in step S1 is placed in a refining furnace and refined for 57 minutes. Then, it is vacuum degassed at 52 Pa for 33 minutes and then cast into steel ingot billets. The temperature of the molten steel during casting is 1520℃.

[0063] S3. Forging: The steel ingot billet obtained in step S2 is forged using an air hammer and a press to obtain forgings. The cutting ratio of the ingot head of the steel ingot billet is 10%, the cutting ratio of the ingot tail of the steel ingot billet is 5%, the initial forging temperature is 1220℃, the final forging temperature is 780℃, and the total forging ratio is 5.1.

[0064] S4. Heat treatment: The forgings obtained in step S3 are placed in an industrial resistance furnace for pre-heat treatment at a temperature of 905°C. After being removed, they are placed in a cooling pool for quenching at 925°C and finally tempered at 625°C to obtain chromium-molybdenum alloy steel forgings for the nuclear island mechanical penetration parts. During quenching, the cooling pool is filled with coolant, which consists of the following components by weight percentage: 13% polyethylene glycol monooctyl ether, 2.5% sodium hydroxide, 1.4% 1-hydroxyethyl-2-oleoylimidazoline, 0.4% dimethylheptadecylbenzylammonium chloride, 0.7% samarium nitrate, and the remainder is deionized water.

[0065] S5. Inspection: Perform physical and chemical tests and non-destructive tests on the chromium-molybdenum alloy steel forgings of the nuclear island mechanical penetration parts obtained in step S4.

[0066] The preparation steps of the coolant are as follows:

[0067] Prepare each component by weight percentage. Add polyethylene glycol monooctyl ether and dimethylheptadecyl benzyl ammonium chloride to water. Stir at 150 r / min for 9 min, then add sodium hydroxide, 1-hydroxyethyl-2-oleoylimidazoline and samarium nitrate. Continue stirring for 54 min to obtain the cooling liquid.

[0068] Comparative Example 1

[0069] The composition of the forging is the same as in Example 1. The difference from Example 1 is that step S4 does not include a pre-heat treatment operation.

[0070] Comparative Example 2

[0071] The composition of the forging is the same as in Example 1. The difference from Example 1 is that the coolant in the cooling tank in step S4 is replaced with water.

[0072] Comparative Example 3

[0073] The composition of the forging is the same as in Example 1. The difference from Example 1 is that the coolant in the cooling pool in step S4 does not include dimethylheptadecylbenzylammonium chloride.

[0074] Comparative Example 4

[0075] The composition of the forging is the same as in Example 1. The difference from Example 1 is that the coolant in the cooling pool in step S4 does not include samarium nitrate.

[0076] Experiment Example 1: Mechanical Property Testing

[0077] The chromium-molybdenum alloy steel forgings for nuclear island mechanical penetrations prepared in Examples 1-4 were subjected to room temperature tensile tests according to ASTM A370. The specimen size was φ12.5mm. The test results are shown in Table 1.

[0078] Rp0.2 (MPa) Rm (MPa) Specified value ≥275 485-660 Example 1 352 618 Example 2 356 624 Example 3 347 611 Example 4 359 630

[0079] Table 1

[0080] As can be seen from Table 1, Rp0.2 and Rm in Examples 1-4 all meet the specified value requirements, indicating that the chromium-molybdenum alloy steel forgings for nuclear island mechanical penetration parts prepared by the present invention have good mechanical properties.

[0081] Experimental Example 2: Grain Size Test

[0082] The chromium-molybdenum alloy steel forgings of the nuclear island mechanical penetration parts prepared in Examples 1-4 and Comparative Example 1 were subjected to grain size tests according to ASTM E112. The test results are shown in Table 2.

[0083] Grain size level Example 1 6.5 Example 2 6 Example 3 6 Example 4 6.5 Comparative Example 1 4

[0084] Table 2

[0085] As shown in Table 2, the grain size levels of Examples 1-4 are all above level 5, indicating that the chromium-molybdenum alloy steel forgings for nuclear island mechanical penetration parts prepared by this invention have good grain size. Compared with Example 1, the grain size of Comparative Example 1 is significantly reduced, indicating that the pre-heat treatment operation in step S4 of this invention can effectively refine the grains.

[0086] Experiment Example 3: Hardenability Test

[0087] The end hardenability tests of the chromium-molybdenum alloy steel forgings for nuclear island mechanical penetration parts prepared in Examples 1-4 and Comparative Example 2 were conducted according to GB / T225-2006. The test results are shown in Table 3.

[0088] Hardness (HRC) at 15mm from the quenched end Example 1 35.5 Example 2 35 Example 3 34 Example 4 34.5 Comparative Example 2 30.5

[0089] Table 3

[0090] As shown in Table 3, the hardness at 15 mm from the quenching end is relatively high in Examples 1-4, indicating that the chromium-molybdenum alloy steel forgings for nuclear island mechanical penetration parts prepared by this invention have good hardenability. Compared with Example 1, the hardness at 15 mm from the quenching end is reduced in Comparative Example 2, indicating that the coolant used in this invention can effectively improve the hardenability of the forgings.

[0091] Experiment Example 4: Residual Stress Test

[0092] The chromium-molybdenum alloy steel forgings for nuclear island mechanical penetration parts prepared in Examples 1-4 and Comparative Example 4 were subjected to residual stress tests according to GB / T7704-2008. The test results are shown in Table 4.

[0093] Residual stress (MPa) at a distance of 0.25 mm from the surface of the forging. Example 1 34 Example 2 38 Example 3 33 Example 4 36 Comparative Example 4 61

[0094] Table 4

[0095] As shown in Table 4, the residual stress at a distance of 0.25 mm from the surface of the forgings in Examples 1-4 is relatively low, indicating that the residual stress of the chromium-molybdenum alloy steel forgings for nuclear island mechanical penetration parts prepared by this invention is low. Compared with Example 1, the residual stress at a distance of 0.25 mm from the surface of the forging in Comparative Example 4 is increased, indicating that samarium nitrate in the coolant used in this invention can effectively reduce the residual stress of the forgings.

[0096] Experiment Example 5: Crack Resistance Test

[0097] The chromium-molybdenum alloy steel forgings for nuclear island mechanical penetration parts prepared in Examples 1-4 and Comparative Example 3 were subjected to crack resistance tests according to GB / T21143-2014. The test results are shown in Table 5.

[0098] Crack tip opening displacement (mm) Example 1 0.1345 Example 2 0.1410 Example 3 0.1324 Example 4 0.1372 Comparative Example 3 0.1596

[0099] Table 5

[0100] As shown in Table 5, the crack tip opening displacement in Examples 1-4 is relatively small, indicating that the chromium-molybdenum alloy steel forgings for nuclear island mechanical penetration parts prepared by this invention have good crack resistance. Compared with Example 1, the crack tip opening displacement in Comparative Example 3 is increased, indicating that the dimethylheptadecylbenzylammonium chloride in the coolant used in this invention can effectively improve the crack resistance of the forgings.

[0101] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A chromium-molybdenum alloy steel forging for a nuclear island mechanical penetration, characterized by: Consists of the following ingredients by weight percentage: C 0.16-0.20%, Mn 0.50-0.80%, Si 0.10-0.20%, P≤0.012%, S≤0.010%, Cr 0.90-1.10%, Mo 0.45-0.65%, Co≤0.05%, and the rest is iron.

2. The method of manufacturing a chrome molybdenum alloy steel forging for a nuclear island mechanical penetration as claimed in claim 1, wherein: Comprise the following steps: S1. Electric furnace smelting: raw materials are prepared according to weight percentage, and the raw materials are placed in an electric furnace and smelted until the temperature reaches 1610-1650 DEG C to obtain molten steel by tapping; S2. Secondary refining: the molten steel obtained in step S1 is placed in a refining furnace, refined for 50-60 min, vacuum degassed for 25-35 min, and then cast into an ingot blank; S3. Forging: the ingot blank obtained in step S2 is forged using an air hammer and a press to obtain a forged piece; S4. Heat treatment: the forged piece obtained in step S3 is placed in an industrial resistance furnace for preliminary heat treatment, taken out and quenched in a cooling pool, and finally tempered to obtain a chromium-molybdenum alloy steel forged piece for nuclear island mechanical penetrations; S5. Detection: the chromium-molybdenum alloy steel forged piece for nuclear island mechanical penetrations obtained in step S4 is subjected to physical and chemical detection and non-destructive testing.

3. The method of manufacturing a chrome molybdenum alloy steel forging for a nuclear island mechanical penetration as claimed in claim 2, wherein: In the step S2, the secondary refining is protected by argon gas throughout the process, the vacuum degree during vacuum degassing is 50-60 Pa, and the temperature of the molten steel during casting is 1450-1550 DEG C.

4. The method of manufacturing a chrome molybdenum alloy steel forging for a nuclear island mechanical penetration as claimed in claim 2, wherein: In the step S3, the ingot head of the ingot blank is removed at a ratio of 10%, the ingot tail of the ingot blank is removed at a ratio of 5%, the initial forging temperature is 1190-1230 DEG C, the final forging temperature is 750-800 DEG C, and the total forging ratio is ≥5.

0.

5. The method of manufacturing a chrome molybdenum alloy steel forging for a nuclear island mechanical penetration of claim 2, wherein: In the step S4, the temperature of the preliminary heat treatment is 890-910 DEG C.

6. The method of manufacturing a chrome molybdenum alloy steel forging for a nuclear island mechanical penetration as claimed in claim 2, wherein: In the step S4, the quenching temperature is 910-930 DEG C, and the cooling pool contains a cooling liquid during quenching, wherein the cooling liquid consists of the following components by weight percentage: tetrapropylene glycol monooctyl ether 12-15%, sodium hydroxide 2-3%, 1-hydroxyethyl-2-octyl imidazoline 1-2%, dimethyl heptadecyl benzyl ammonium chloride 0.3-0.6%, samarium nitrate 0.5-0.9%, and the rest is deionized water.

7. The method of manufacturing a chrome molybdenum alloy steel forging for a nuclear island mechanical penetration as claimed in claim 6, wherein: The preparation steps of the cooling liquid are as follows: The components are prepared according to weight percentage, tetrapropylene glycol monooctyl ether and dimethyl heptadecyl benzyl ammonium chloride are added to water, stirred for 5-10 min, then sodium hydroxide, 1-hydroxyethyl-2-octyl imidazoline and samarium nitrate are added, and continue to stir for 45-60 min to obtain the cooling liquid.

8. The method of manufacturing a chrome molybdenum alloy steel forging for a nuclear island mechanical penetration of claim 7, wherein: In the preparation steps of the cooling liquid, the stirring speed is 100-200 r / min.

9. The method of manufacturing a chrome molybdenum alloy steel forging for a nuclear island mechanical penetration of claim 2, wherein: In the step S4, the tempering temperature is 610-630 DEG C.