16Cr3NiWoMoVNbE steel hot-rolled bar and preparation method thereof

Abstract

The invention discloses a 16Cr3NiWoMoVNbE steel hot-rolled bar and a preparation method thereof. The 16Cr3NiWoMoVNbE steel hot-rolled bar comprises the following components in percentage by mass: 0.16-0.18% of C, 0.16-0.18% of Ni, 0.18-0.18% of Ni, 0.18-0.18% of Ni, 0.18-0.18% of Ni, 0.18-0.18% of Ni, mn: 0.55 to 0.65%; 0.75 to 0.85% of Si; s: < = 0.005; p: < = 0.005; 1.20 to 1.33 parts of Ni; 2.70 to 2.90% of Cr; 0.45 to 0.55 percent of Mo; 1.10 to 1.20 parts of W (tungsten); 0.40 to 0.50% of V; 0.12 to 0.18% of Nb; 0.01 to 0.05 part of Ce; 0.04 to 0.06 part of Al and the balance of Fe. According to the method, the 16Cr3NiWoMoVNbE steel bar with the diameter of 90-130 mm is obtained through hot rolling, the 16Cr3NiWoMoVNbE steel hot-rolled bar does not have coarse grain defects through transverse low-power acid leaching corrosion detection, the 16Cr3NiWoMoVNbE steel hot-rolled bar has good tensile property and impact toughness under the room temperature condition, the problems of quality risks and cost increase caused by bar forging machining are avoided, and the quality of the 16Cr3NiWoMoVNbE steel bar is improved. And the shape, the surface quality characteristic, the mechanical property index and the microscopic structure of the product are fully met.

Description

Technical Field

[0001] The present invention relates to the technical field of steel preparation, and more particularly to a 16Cr3NiWoMoVNbE steel hot-rolled bar and a preparation method thereof. Background Art

[0002] 16Cr3NiWoMoVNbE steel is a premium, high-quality structural steel, primarily strengthened by martensite and multi-element precipitation. It exhibits excellent hardenability, high tensile strength, and high toughness and ductility. It also exhibits outstanding high-temperature performance and can operate for long periods below 300°C. Therefore, 16Cr3NiWoMoVNbE steel is widely used in the manufacture of transmission gears for aircraft engines, meeting the high power, high speed, and high meshing temperature requirements of engine gear transmissions and possessing promising market prospects.

[0003] 16Cr3NiWoMoVNbE steel has a high degree of alloying, with carbide precipitation playing a dominant role in strengthening. Improper control of process parameters such as deformation amount, deformation rate, and temperature during hot working of steel bars can lead to uneven carbide microstructure distribution and fragmentation, abnormal grain growth during pressure deformation, and the finished product is prone to low-magnification coarse grains and mixed-grain defects, failing to meet technical standards and adversely affecting mechanical properties. Currently, bars with diameters of 20 to 89 mm are produced using hot rolling, exhibiting excellent physical and chemical properties. Bars with diameters of 90 to 130 mm are produced using a forging process, exhibiting severe low-magnification coarse grain defects.

[0004] Therefore, it is necessary to develop a preparation and heat treatment method for 16Cr3NiWoMoVNbE steel bars to solve the problem of low-magnification coarse grains in Ф90-130mm bars and improve the stability of the mechanical properties of the steel. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a 16Cr3NiWoMoVNbE steel hot-rolled bar and a preparation method thereof, so as to solve the problems in the background technology.

[0006] In order to solve the above technical problems, the technical solutions adopted by the present invention are as follows.

[0007] A 16Cr3NiWoMoVNbE steel hot-rolled bar, wherein the mass percentages of the components in the 16Cr3NiWoMoVNbE steel hot-rolled bar are as follows: C: 0.16-0.18; Mn: 0.55-0.65; Si: 0.75-0.85; S: ≤0.005; P: ≤0.005; Ni: 1.20-1.33; Cr: 2.70-2.90; Mo: 0.45-0.55; W: 1.10-1.20; V: 0.40-0.50; Nb: 0.12-0.18; Ce: 0.01-0.05; Al: 0.04-0.06, and the balance is Fe.

[0008] A method for preparing a 16Cr3NiWoMoVNbE steel hot-rolled bar comprises the following steps: S1. The electrode rods are formed by high-temperature casting of 16Cr3NiWoMoVNbE hot-rolled steel bars in a proportioned manner using vacuum induction melting technology; the cast electrode rods are remelted in an electroslag remelting continuous directional crystallizer and cooled to obtain electroslag ingots; S2. The electroslag ingot is heated to 1030°C~1160°C for 3~4h, placed on a fast forging machine, and subjected to a fire of upsetting forging to form a square billet; S3. The forged billet is heated to 1150°C~1200°C and then hot-rolled in one heat after holding. The billet is then rough-rolled in a continuous rolling mill and finished. S4. Rolling uses the residual heat of hot rolling for straightening to avoid structural changes and abnormal grain size growth caused by reheating; S5. Air cool the hot-rolled and straightened black leather material to 700°C. After the surface color turns black, place it in a slow cooling box for ≥24h. S6. The black bark material after slow cooling is subjected to high-temperature tempering treatment to eliminate residual stress during thermal deformation, thereby obtaining 16Cr3NiWoMoVNbE steel hot-rolled bars.

[0009] To further optimize the technical solution, in step S1, the 16Cr3NiWoMoVNbE steel hot-rolled bar is cast at a high temperature of 1560°C to 1580°C.

[0010] To further optimize the technical solution, in step S2, the start forging temperature is ≥930°C, and the final forging temperature is ≥830°C.

[0011] To further optimize the technical solution, in step S3, during hot rolling, the starting rolling temperature is 1000°C to 1150°C, and the finishing rolling temperature is 900°C to 1000°C.

[0012] To further optimize the technical solution, in step S3, the hot rolling is performed once to form a finished product, with 10 to 15 passes, a deformation of 6% to 10% in each pass, and a total deformation of 70% to 90%.

[0013] To further optimize the technical solution, in step S4, the straightening temperature is 890°C to 990°C.

[0014] The technical solution is further optimized. In step S6, the tempering temperature is 650° C. to 720° C. and the time is ≥ 25 h.

[0015] Due to the adoption of the above technical solution, the technical progress achieved by the present invention is as follows.

[0016] The present invention provides a 16Cr3NiWoMoVNbE steel hot-rolled bar and a preparation method thereof. A rolling and forging process is adopted to obtain a 16Cr3NiWoMoVNbE steel bar with a diameter of 90 to 130 mm through hot rolling. A transverse low-magnification acid immersion corrosion test of the 16Cr3NiWoMoVNbE steel hot-rolled bar shows no coarse-grain defects, and the bar has good tensile properties and impact toughness at room temperature. Quality risks and increased costs caused by bar forging are avoided, and product shape, surface quality characteristics, mechanical performance indicators, and microstructural structure are fully met. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of the bar rolling forming process of the present invention in which the Y direction is the rolling direction; Figure 2 This is a rolling diagram of the hot-rolled bar during rough rolling and slab formation according to the present invention; Figure 3 The hot-rolled bar of the present invention is finished into a rolling diagram; Figure 4 OM structure diagram of the hot-rolled steel bar of the present invention; Figure 5 This is a low-magnification test piece of the transverse acid leaching of the hot-rolled steel bar and forged bar of the present invention; Figure 6 OM grain size diagram of hot-rolled and forged steel bars in the present invention. DETAILED DESCRIPTION

[0018] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0019] A 16Cr3NiWoMoVNbE steel hot-rolled bar comprises the following components by mass percentage: C: 0.16-0.18; Mn: 0.55-0.65; Si: 0.75-0.85; S: ≤0.005; P: ≤0.005; Ni: 1.20-1.33; Cr: 2.70-2.90; Mo: 0.45-0.55; W: 1.10-1.20; V: 0.40-0.50; Nb: 0.12-0.18; Ce: 0.01-0.05; Al: 0.04-0.06, and the balance is Fe.

[0020] A method for preparing a 16Cr3NiWoMoVNbE steel hot-rolled bar comprises the following steps: S1. Melting: Hot-rolled 16Cr3NiWoMoVNbE steel bars are cast at a temperature of 1560°C to 1580°C using vacuum induction melting technology to form electrode rods.

[0021] Electroslag remelting: Eliminate defects such as iron oxide scale, bulges, and dust on the surface of the electrode rod, and use the electroslag remelting continuous directional crystallizer to remelt the cast electrode rod, cool it, and prepare electroslag ingots with a diameter of 360~590mm. Argon is filled before power is supplied, and the Ar flow rate is 6m 3 / h, oxygen content ≤3%; electroslag remelting rate is 3.5-6.5kg / min, and the slag used is SD-73 (Al2O3:CaF2 = 30%:70% binary slag system) pre-melted slag. The total cooling time is 36-72h.

[0022] S2. Forging: Heat the electroslag ingot to 1030°C~1160°C for 3~4 hours, place it on a high-speed forging machine, and perform a single-fire upsetting forging to obtain a square billet with a side length of 200~300mm. The starting forging temperature is ≥930°C, and the final forging temperature is ≥830°C.

[0023] S3. Hot rolling: The forged billet is heated to 1150℃~1200℃, and kept at the above temperature. The holding time is calculated according to the thickness of the ingot and is calculated based on 1~1.5mm / min. Then hot rolling is carried out. The starting rolling temperature is 1000℃~1150℃, and the final rolling temperature is 900℃~1000℃. The billet is rough rolled using a continuous rolling mill and the finished product is finished. Hot rolling is a single pass process, with 10 to 15 passes, each pass has a deformation of 6% to 10%, and a total deformation of 70% to 90%. Figure 1 As shown, Figure 2 This is the rolling diagram for rough rolling. Figure 3 This is the rolling diagram of the finished product.

[0024] S4. Straightening: Rolling uses waste heat for straightening to avoid defects such as organizational changes and abnormal grain size growth caused by reheating. Within the designed heating temperature range, the final rolling temperature is 900℃~1000℃, and the straightening temperature is 890℃~990℃, which can meet the straightening conditions for varieties with hardness less than 230.

[0025] S5. Slow cooling: After hot rolling and straightening, the black leather material is air-cooled to 700℃. After the surface color turns black, it is put into the slow cooling box for ≥24h.

[0026] S6. Heat treatment: After slow cooling, the black bark is subjected to high temperature tempering treatment to eliminate the residual stress during thermal deformation and improve the stability of the bar to obtain 16Cr3NiWoMoVNbE steel hot-rolled bar. The tempering temperature is 650℃~720℃ and the time is ≥25h. The OM structure diagram of the hot-rolled steel bar is as follows: Figure 4 shown.

[0027] Preparation Example 1 provides a 16Cr3NiWoMoVNbE steel ingot, and the preparation method includes the following steps: 1.1 Melting: Vacuum induction melting technology is used to prepare raw materials according to the following chemical composition content by mass percentage, and high-temperature pouring is performed at 1560℃~1580℃ to form electrode rods with a diameter of 340mm; The chemical composition of 16Cr3NiWoMoVNbE steel is as follows: C: 0.175; Mn: 0.63; Si: 0.780; S: ≤0.005; P: ≤0.005; Ni: 1.25; Cr: 2.80; Mo: 0.50; W: 1.15; V: 0.45; Nb: 0.15; Ce: 0.03; Al: 0.06, and the balance is Fe.

[0028] 1.2 Electroslag remelting: The electrode rods cast in step 1.1 were remelted using an electroslag remelting continuous directional crystallizer and cooled to produce a steel ingot with a diameter of 480 mm. The electroslag remelting rate was 5.0 kg / min, and the hood cooling time was 56 h. The slag system used was SD-73 (Al2O3:CaF2=30%:70% binary slag system) pre-melted slag.

[0029] The composition of the 16Cr3NiWoMoVNbE steel ingot obtained in Preparation Example 1 was tested, and the results are shown in Table 1.

[0030] Table 1 Composition and content of the steel ingot provided in Preparation Example 1 Example

[0031] Provided is a method for preparing a 16Cr3NiWoMoVNbE steel hot-rolled bar, comprising the following steps: 1. Smelting: Smelting was carried out according to the method of Preparation Example 1 to obtain a 16Cr3NiWoMoVNbE steel electroslag ingot with a diameter of 480 mm.

[0032] 2. Forging: First, the 16Cr3NiWoMoVNbE steel electroslag ingot undergoes a multi-stage homogenization treatment to reduce the degree of alloy element segregation and provide softening conditions for forging. The ingot is heated to 1140°C and held at this temperature for 3.5 hours. The ingot is then subjected to a single hot upsetting and drawing process using a 25MN high-speed forging machine to produce a 280mm square billet. The initial forging temperature is 980°C, and the final forging temperature is 930°C.

[0033] 3. Hot rolling: The square billet with a side length of 280 mm obtained by forging is heated to 1170°C and kept at this temperature for 3.5 hours, and then hot rolled. The billet is rough rolled using a continuous rolling mill and then finished by finish rolling.

[0034] Specifically, the rough rolling process involves nine passes, with diameters from 280mm to 170mm. Finishing rolling involves four passes, with two square holes, one oval hole, and one round hole, with diameters from 170mm to 130mm. The finished product is formed in one heat, with a starting rolling temperature of 1055°C and a finishing temperature of 970°C.

[0035] 4. Straightening: The residual heat of rolling is used for straightening. The straightness of the straightened bar is less than 5mm / m.

[0036] 5. Slow cooling: The black leather material after hot rolling and straightening is air-cooled to 700℃. After the surface color turns black, it enters the slow cooling box and slowly cools for 24 hours.

[0037] 6. Heat treatment: After slow cooling, the black bark is subjected to high-temperature tempering treatment at 685°C for 25 hours. The bar is then furnace cooled to 300°C and air-cooled to obtain 16Cr3NiWoMoVNbE hot-rolled steel bars. Example

[0038] A method for preparing a 16Cr3NiWoMoVNbE steel hot-rolled bar, which differs from Example 1 in that the hot rolling is specifically as follows: 3. Hot rolling: The square billet with a side length of 280 mm obtained by forging is heated to 1170°C and kept at this temperature for 3.5 hours, and then hot rolled. The billet is rough rolled using a continuous rolling mill and then finished by finish rolling.

[0039] Specifically, the rough rolling process involves nine passes, with diameters from 280mm to 170mm. The finishing process involves five passes, with two square holes, two oval holes, and one round hole, with diameters from 170mm to 120mm. The finished product is formed in one heat, with a starting rolling temperature of 1035°C and a finishing temperature of 960°C.

[0040] 4. Straightening: The residual heat of rolling is used for straightening. The straightness of the straightened bar is less than 5mm / m.

[0041] 5. Slow cooling: The black leather material after hot rolling and straightening is air-cooled to 700℃. After the surface color turns black, it enters the slow cooling box and slowly cools for 24 hours.

[0042] 6. Heat treatment: After slow cooling, the black bark is subjected to high-temperature tempering treatment at 685°C for 25 hours. The bar is then furnace cooled to 300°C and air-cooled to obtain 16Cr3NiWoMoVNbE hot-rolled steel bars.

[0043] A method for preparing 16Cr3NiWoMoVNbE steel forged bars is provided, which differs from the embodiment in that: forging and hot rolling are specifically as follows: 2. Forging: First, the 16Cr3NiWoMoVNbE steel electroslag ingot is subjected to multi-stage homogenization treatment to reduce the degree of alloy element segregation and provide softening conditions for forging. Then, the blank is quickly forged and hammer forged into material.

[0044] 2.1 Rapid Forging: A 480mm diameter electroslag ingot was heated to 1100°C for 3.5 hours. A 25MN rapid forging machine was used to perform a single upsetting and drawing operation to produce a 250mm square billet with a deformation of 65.4%. The initial forging temperature was 960°C, and the final forging temperature was 910°C.

[0045] 2.2 Hammer forging: The square billet with a side length of 250 mm obtained by the above rapid forging is hammer forged for 3 times. The specific steps are as follows: First heat: The billet after rapid forging is heated to 1100°C and held at this temperature for 1.5 hours. It is then hammer forged to obtain a 170mm square billet with a deformation of 53.8%. The starting forging temperature is 950°C and the final forging temperature is 900°C.

[0046] Second heat: A 170mm square billet is heated to 1080°C for 1.5 hours. It is then hammer-forged to produce a 130mm diameter rough round billet with a deformation of 54.1%. The initial forging temperature is 930°C, and the final forging temperature is 880°C.

[0047] Third heat: Heat the 130mm diameter billet to 1030°C for 25 minutes, then hammer forge to produce a 118mm diameter bar with a deformation of 24.2%. The initial forging temperature is 910°C, and the final forging temperature is 860°C.

[0048] 5. Slow cooling: Slow cooling of black leather material after hammer forging for 48 hours.

[0049] 6. Heat treatment: The black skin material after slow cooling is subjected to normalizing + high temperature tempering treatment, wherein the normalizing temperature is 945℃, the holding time is 5h, the tempering temperature is 685℃, the holding time is 25h, and then the furnace is cooled to 300℃ and air-cooled to obtain 16Cr3NiWoMoVNbE steel forged bars.

[0050] The mechanical properties and grain size of the 16Cr3NiWoMoVNbE steel bars obtained in Examples 1-2 and Comparative Example 1 were tested by performance testing. The testing methods for the mechanical properties, macroscopic magnification, and grain size are as follows: (1) According to the Q / S10-0361-2004 standard, the mechanical properties specimens were quenched and tempered at 910°C for 1 hour, oil cooling, and 330°C for 3 hours, followed by air cooling. The grain size specimens were quenched at 900°C for 1 hour, followed by oil cooling.

[0051] (2) According to GB / T 228-1987, the above-mentioned specimen blanks were machined and tested for tensile properties at room temperature, including tensile strength Rp, yield strength Rm, elongation after fracture A, and cross-sectional shrinkage Z.

[0052] (3) According to GB / T 229, the above-mentioned specimen blanks were machined and tested for impact toughness KU2 at room temperature.

[0053] (4) According to GB / T 6394 standard, the above-mentioned grain size samples were ground, polished and etched and the grain size grade was tested.

[0054] The test results are shown in Table 2 below.

[0055] Table 2 Mechanical properties test results of 16Cr3NiWoMoVNbE steel bars of Examples 1-2 and Comparative Example 1 Rp (MPa) Rm (MPa) A% Z% KU2 (J) Grain size Example 1 1410 1181 15 63 104.4 9.5 Example 2 1400 1172 15.5 61 106.5 9.5 Comparative Example 1 1358 1143 13 61 78.8 7.0-10.0（45%） From the room temperature tensile test results, it can be seen that the room temperature tensile strength Rp of the 16Cr3NiWoMoVNbE steel hot-rolled bars prepared in Examples 1-2 of the present application is 1410-1400 MPa, the room temperature yield strength Rm is 1181-1172 MPa, the elongation after fracture A is 15% to 15.5%, and the cross-sectional reduction rate is 63% to 61%; while the room temperature tensile strength Rp of the 16Cr3NiWoMoVNbE steel forged bar prepared in Comparative Example 1 is 1358 MPa, the room temperature yield strength Rm is 1143 MPa, the elongation after fracture A is 13%, and the cross-sectional reduction rate is 61%, indicating that the tensile properties of the 16Cr3NiWoMoVNbE steel bars prepared in Examples 1-2 are better than those in Comparative Example 1 at room temperature.

[0056] From the room temperature impact test results, it can be seen that the room temperature impact toughness of the 16Cr3NiWoMoVNbE steel hot-rolled bars prepared in Examples 1-2 of the present application is 104.4~106.5J; while the room temperature impact toughness of the 16Cr3NiWoMoVNbE steel forged bars prepared in Comparative Example 1 is 78.8J; this shows that the impact toughness of the 16Cr3NiWoMoVNbE steel bars prepared in Examples 1-2 is better than that in Comparative Example 1 at room temperature.

[0057] From the results of the horizontal low-magnification acid immersion corrosion test, it can be seen that the acid immersion low-magnification test piece is Figure 5 As shown, Figure 5 (a) is the acid leaching low magnification test piece of hot rolled bar, Figure 5 (b) is a low-magnification test piece of acid-immersed forged bar. After acid-immersed hot corrosion for 20 minutes, no coarse grains or other metallurgical defects were observed on the surface of the low-magnification test piece of the 16Cr3NiWoMoVNbE steel hot-rolled bar prepared in Examples 1-2 of the present application. Figure 5 (a); while the edge of the low-magnification test piece of the 16Cr3NiWoMoVNbE steel forging bar prepared in Comparative Example 1 has a coarse grain defect of about 20 mm, as shown in FIG. Figure 5 (b) shows that the macrostructure of the 16Cr3NiWoMoVNbE steel bar obtained in Example 1-2 meets the technical standard requirements and there are no metallurgical defects such as shrinkage cavities, macroscopic coarse grains, slag inclusions and white spots that can be seen by the naked eye.

[0058] From the grain size test results, we can see that Figure 6 As shown, Figure 6 (a) is the grain size of hot rolled bar, Figure 6 (b) is the grain size of the forged bar. The grain size of the 16Cr3NiWoMoVNbE steel hot-rolled bar obtained in Examples 1-2 of the present application is 9.5. Figure 6 (a); while the grain size of the 16Cr3NiWoMoVNbE steel hot forging bar obtained in Comparative Example 1 is 8.0 level and there is a 5.0 level mixed crystal phenomenon, as shown in FIG. Figure 6 As shown in (b), it is shown that the uniformity of the grain structure of the 16Cr3NiWoMoVNbE steel bar prepared in Example 1-2 is significantly improved compared with that in Comparative Example 1, and this phenomenon shows a clear positive correlation with the mechanical property test results.

[0059] In summary, the preparation method of 16Cr3NiWoMoVNbE steel hot-rolled bar provided in this application can prepare 16Cr3NiWoMoVNbE steel hot-rolled bar with a diameter of 90~130mm. No coarse grain defects were found in the low-magnification corrosion test of the material, and the material has excellent tensile strength, yield strength and impact toughness at room temperature, meeting the technical standard requirements.

Claims

1. A 16Cr3NiWoMoVNbE steel hot-rolled bar, characterized by: The mass percentages of the components in the 16Cr3NiWoMoVNbE steel hot-rolled bar are: C: 0.16-0.18; Mn: 0.55~0.65; Si: 0.75~0.85; S: ≤0.005; P: ≤0.005; Ni: 1.20~1.33; Cr: 2.70~2.90; Mo: 0.45~0.55; W：1.10~1.20； V：0.40~0.50； Nb ：0.12~0.18； Ce: 0.01~0.05; Al: 0.04~0.06, the balance is Fe.

2. The method for preparing a 16Cr3NiWoMoVNbE steel hot-rolled bar according to claim 1, characterized in that: The following steps are involved: S1. The electrode rods are formed by high-temperature casting of 16Cr3NiWoMoVNbE hot-rolled steel bars in a proportioned manner using vacuum induction melting technology; the cast electrode rods are remelted in an electroslag remelting continuous directional crystallizer and cooled to obtain electroslag ingots; S2. The electroslag ingot is heated to 1030°C~1160°C for 3~4h, placed on a fast forging machine, and subjected to a fire of upsetting forging to form a square billet; S3. The forged billet is heated to 1150°C~1200°C and then hot-rolled in one heat after holding. The billet is then rough-rolled in a continuous rolling mill and finished. S4. Rolling uses the residual heat of hot rolling for straightening to avoid structural changes and abnormal grain size growth caused by reheating; S5. Air cool the hot-rolled and straightened black leather material to 700°C. After the surface color turns black, place it in a slow cooling box for ≥24h. S6. The black bark material after slow cooling is subjected to high-temperature tempering treatment to eliminate residual stress during thermal deformation, thereby obtaining 16Cr3NiWoMoVNbE steel hot-rolled bars.

3. The method for preparing a 16Cr3NiWoMoVNbE steel hot-rolled bar according to claim 2, characterized in that: In step S1, the 16Cr3NiWoMoVNbE steel hot-rolled bar is cast at a high temperature of 1560° C. to 1580° C.

4. The method for preparing a 16Cr3NiWoMoVNbE steel hot-rolled bar according to claim 2, characterized in that: In the step S2, the start forging temperature is ≥930°C, and the final forging temperature is ≥830°C.

5. The method for preparing a 16Cr3NiWoMoVNbE steel hot-rolled bar according to claim 2, characterized in that: In step S3, during hot rolling, the starting rolling temperature is 1000°C to 1150°C, and the finishing rolling temperature is 900°C to 1000°C.

6. The method for preparing a 16Cr3NiWoMoVNbE steel hot-rolled bar according to claim 2, characterized in that: In step S3, the hot rolling is performed for 10 to 15 passes, with a deformation of 6% to 10% in each pass and a total deformation of 70% to 90%.

7. The method for preparing a 16Cr3NiWoMoVNbE steel hot-rolled bar according to claim 2, characterized in that: In step S4, the straightening temperature is 890° C. to 990° C.

8. The method for preparing a 16Cr3NiWoMoVNbE steel hot-rolled bar according to claim 2, characterized in that: In step S6, the tempering temperature is 650° C. to 720° C., and the time is ≥ 25 h.

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