Production method of 15CrMo steel plate with low ductile-brittle transition temperature and low yield strength ratio

Abstract

The invention discloses a method for producing a 15CrMo steel plate with low toughness-brittle transition temperature and low yield strength ratio, including electric furnace smelting, continuous casting, heating and rolling processes; wherein the rolling process adopts hot rolling + water cooling controlled red return + stacking process, and controls the final rolling temperature to be ≥950°C; after rolling, the steel plate is cooled in water, the water temperature is ≥890°C, the roller speed is 2-7m / min, and the water red return temperature is 500-600°C; the steel temperature is 400-500°C, and the stacking is 24-30h. The 15CrMo steel plate produced by the above process has a ton steel production cost reduced by 200-400 yuan / ton steel, a toughness-brittle transition temperature ≤-35°C, a tensile strength of 480-590MPa, a yield strength of 310-460MPa, and a yield strength ratio ≤0.85.

Description

Technical Field

[0001] The invention belongs to the technical field of iron and steel metallurgy, and in particular relates to a production method of a 15CrMo steel plate with low ductile-brittle transition temperature and low yield strength ratio. Background Art

[0002] 15CrMo steel plate is an alloy structural steel plate, which is often used to make mechanical parts and various engineering components. In order to ensure the safe use of mechanical parts and engineering components, it is particularly important for the steel plate to have excellent mechanical properties.

[0003] According to the characteristics of steel, if the use temperature of steel is lower than its ductile-brittle transition temperature, the impact performance of steel will drop drastically, the toughness will drop sharply, and brittle fracture will occur easily. For alloy structural steel plates used in areas with low ambient temperature or large temperature difference between day and night, if the use temperature of steel plates is lower than the ductile-brittle transition temperature, the steel plates will be in danger of brittle fracture.

[0004] During the deformation process, steel first undergoes elastic deformation. After the elastic deformation reaches a certain amount, it enters the yield stage, and the steel begins to deform plastically. As the deformation increases, the steel plate breaks. For steel plates used in engineering structures, after entering the yield stage, the steel plate breaks after a very small deformation. Before the structural parts break, it is difficult to detect the plastic deformation of the structural parts, and it is impossible to remedy the structural parts in advance.

[0005] In order to ensure that the steel plate has a low ductile-brittle transition temperature and low yield strength ratio, the early production process of this type of steel plate is rolling + quenching + tempering or rolling + tempering. The process is complicated and the production cost is high, which is not conducive to mass production of steel plates.

[0006] The present invention optimizes the steel plate production process based on the steel plate smelting and rolling process, and only adopts hot rolling + controlled cooling + stacking process for production, which reduces the steel plate production cost, simplifies the production process, and develops low-cost, low-toughness-brittleness transition temperature and low yield strength ratio 15CrMo steel plate. Summary of the invention

[0007] The technical problem to be solved by the present invention is to provide a method for producing a 15CrMo steel plate with low toughness-brittleness transition temperature and low yield strength ratio.

[0008] In order to solve the above technical problems, the technical solution provided by the present invention is:

[0009] A method for producing a 15CrMo steel plate with a low toughness-brittle transition temperature and a low yield strength ratio comprises the steps of electric furnace smelting, continuous casting, heating and rolling; wherein the rolling step adopts a hot rolling + water cooling controlled red return + stacking process, and the final rolling temperature is controlled to be ≥950°C; after rolling, the steel plate is cooled in water, the water inlet temperature is ≥890°C, the roller speed is 2-7m / min, and the water outlet red return temperature is 500-600°C; the steel lower temperature is 400-500°C, and the stacking is 24-30h.

[0010] In the electric furnace steelmaking process of the present invention, the oxygen supply gun flow rate is 2000-3000m 3 / h, add lime 10-15kg / t steel to ensure that the P content of the steel out of the electric furnace is ≤0.005%; after refining, vacuum treatment is carried out, the holding time is 5-15min, the vacuum degree is 20-40Pa, and the argon pressure during the vacuum process is 0.3-0.7MPa.

[0011] The continuous casting process of the present invention adopts electromagnetic stirring, with a current of 300-400A and a voltage of 250-350V.

[0012] In the heating process of the present invention, the billet is heated in a continuous furnace at a temperature of 1200-1220°C.

[0013] The chemical composition and mass percentage of the 15CrMo steel plate of the present invention are: C 0.13-0.17%, Si 0.20-0.32%, Mn 0.45-0.64%, Cr 0.85-1.05%, and Mo 0.45-0.55%.

[0014] The steel plate of the present invention has a thickness of 60-100 mm.

[0015] The alloy steel plate of the present invention refers to the standard GB / T 3077-2015.

[0016] The beneficial effects of adopting the above technical scheme are: 1) the production cost of a ton of steel is reduced by 200-400 yuan / ton of steel; 2) the 15CrMo steel plate provided by the present invention has a ductile-brittle transition temperature of ≤-35°C, a tensile strength of 480-590MPa, a yield strength of 310-460MPa, and a yield strength ratio of ≤0.85; 3) the production method provided by the present invention only innovates the production process without increasing equipment investment.

[0017] The method for producing a 15CrMo steel plate with a low toughness-brittle transition temperature and a low yield ratio provided by the present invention controls a relatively high final rolling temperature, thereby reducing deformation-induced precipitation generated by the steel plate in the later stage of rolling; after rolling, the steel plate is cooled in water at a temperature higher than the austenite transformation temperature, thereby converting the internal structure of the steel plate into a bainite structure with a good strength-toughness ratio; after rolling, the steel plate is stacked at a high temperature, thereby further reducing the strength of the steel plate and improving the toughness; during the electric furnace steelmaking process, the oxygen flow is precisely controlled, and a large amount of lime is used for smelting, thereby further reducing the P content of the molten steel; during the vacuum treatment process, the vacuum degree and the argon pressure are precisely controlled, thereby purifying the molten steel and reducing the inclusions in the molten steel; during the continuous casting process, electromagnetic stirring is turned on to reduce the segregation of the billet components; and the billet is heated at a low temperature to avoid grain growth. DETAILED DESCRIPTION

[0018] The present invention will be further described in detail below in conjunction with specific embodiments.

[0019] Example 1

[0020] The chemical composition of the 15CrMo steel plate in this embodiment is shown in Table 1. The thickness of the steel plate is 100 mm. The production method includes electric furnace smelting, continuous casting, heating, and rolling processes, which are specifically as follows:

[0021] (1) Electric furnace steelmaking: oxygen supply gun flow rate 3000m 3 / h, add lime 10kg / t steel, electric furnace steel P content 0.005%. After refining, vacuum treatment is carried out, holding time 15min, vacuum degree 20Pa, argon pressure 0.7MPa during vacuum process.

[0022] (2) Continuous casting: electromagnetic stirring, current 400A, voltage 350V.

[0023] (3) Heating: The billet continuous furnace heating temperature is 1220℃.

[0024] (4) Rolling: Control the final rolling temperature at 950℃; after rolling, cool in water at 890℃, roll speed at 7m / min, water return temperature at 500℃; lower steel temperature at 400℃, stacking for 30h.

[0025] The cost reduction and steel plate properties of the 15CrMo steel plate provided in this embodiment are shown in Table 2.

[0026] Example 2

[0027] The chemical composition of the 15CrMo steel plate of this embodiment is shown in Table 1. The thickness of the steel plate is 60 mm. The production method includes electric furnace smelting, continuous casting, heating, and rolling processes, which are specifically as follows:

[0028] (1) Electric furnace steelmaking: oxygen supply gun flow rate 2000m 3 / h, add lime 15kg / t steel, the P content of the steel out of the electric furnace is 0.004%. After the refining is completed, vacuum treatment is carried out, the holding time is 5min, the vacuum degree is 40Pa, and the argon pressure during the vacuum process is 0.3MPa.

[0029] (2) Continuous casting: electromagnetic stirring, current 300A, voltage 250V.

[0030] (3) Heating: The billet is heated in a continuous furnace at a temperature of 1200°C.

[0031] (4) Rolling: Control the final rolling temperature at 960°C; cool in water after rolling, with the water temperature at 899°C, the roller speed at 2m / min, and the water return temperature at 600°C; the steel temperature at 500°C and stacking for 24h.

[0032] The cost reduction and steel plate properties of the 15CrMo steel plate provided in this embodiment are shown in Table 2.

[0033] Example 3

[0034] The chemical composition of the 15CrMo steel plate of this embodiment is shown in Table 1. The thickness of the steel plate is 80 mm. The production method includes electric furnace smelting, continuous casting, heating, and rolling processes, which are specifically as follows:

[0035] (1) Electric furnace steelmaking: oxygen supply gun flow rate 2620m 3 / h, add lime 13kg / t steel, electric furnace steel P content 0.003%; after refining, vacuum treatment is carried out, the holding time is 9min, the vacuum degree is 31Pa, and the argon pressure during the vacuum process is 0.4MPa. .

[0036] (2) Continuous casting: electromagnetic stirring, current 363A, voltage 296V.

[0037] (3) Heating: The continuous furnace heating temperature of the billet is 1212°C.

[0038] (4) Rolling: Control the final rolling temperature at 969°C; after rolling, cool in water at 903°C, roll speed at 3 m / min, water return temperature at 563°C; lower steel temperature at 483°C, stacking for 26 hours.

[0039] The cost reduction and steel plate properties of the 15CrMo steel plate provided in this embodiment are shown in Table 2.

[0040] Example 4

[0041] The chemical composition of the 15CrMo steel plate of this embodiment is shown in Table 1. The thickness of the steel plate is 96 mm. The production method includes electric furnace smelting, continuous casting, heating, and rolling processes, which are specifically as follows:

[0042] (1) Electric furnace steelmaking: oxygen supply gun flow rate 2059m 3 / h, add lime 11kg / t steel, electric furnace steel P content 0.005%; after refining, vacuum treatment is carried out, the holding time is 13min, the vacuum degree is 29Pa, and the argon pressure during the vacuum process is 0.6MPa. .

[0043] (2) Continuous casting: electromagnetic stirring, current 329A, voltage 328V.

[0044] (3) Heating: The continuous furnace heating temperature of the billet is 1202℃.

[0045] (4) Rolling: Control the final rolling temperature at 970°C; after rolling, cool in water at 909°C, roll speed at 4m / min, water return temperature at 529°C; lower steel temperature at 453°C, stacking for 28h.

[0046] The cost reduction and steel plate properties of the 15CrMo steel plate provided in this embodiment are shown in Table 2.

[0047] Example 5

[0048] The chemical composition of the 15CrMo steel plate of this embodiment is shown in Table 1. The thickness of the steel plate is 80 mm. The production method includes electric furnace smelting, continuous casting, heating, and rolling processes, which are specifically as follows:

[0049] (1) Electric furnace steelmaking: oxygen supply gun flow rate 2620m 3 / h, add lime 13kg / t steel, electric furnace steel P content 0.003%; after refining, vacuum treatment is carried out, the holding time is 9min, the vacuum degree is 31Pa, and the argon pressure during the vacuum process is 0.4MPa. .

[0050] (2) Continuous casting: electromagnetic stirring, current 363A, voltage 296V.

[0051] (3) Heating: The continuous furnace heating temperature of the billet is 1212°C.

[0052] (4) Rolling: Control the final rolling temperature at 969°C; after rolling, cool in water at 903°C, roll speed at 3 m / min, water return temperature at 563°C; lower steel temperature at 483°C, stacking for 26 hours.

[0053] The cost reduction and steel plate properties of the 15CrMo steel plate provided in this embodiment are shown in Table 2.

[0054] Example 6

[0055] The chemical composition of the 15CrMo steel plate of this embodiment is shown in Table 1. The thickness of the steel plate is 96 mm. The production method includes electric furnace smelting, continuous casting, heating, and rolling processes, which are specifically as follows:

[0056] (1) Electric furnace steelmaking: oxygen supply gun flow rate 2830m 3 / h, add lime 11kg / t steel, the P content of the steel out of the electric furnace is 0.004%; after refining, vacuum treatment is carried out, the holding time is 13min, the vacuum degree is 28Pa, and the argon pressure during the vacuum process is 0.6MPa. .

[0057] (2) Continuous casting: electromagnetic stirring, current 326A, voltage 302V.

[0058] (3) Heating: The continuous furnace heating temperature of the billet is 1209°C.

[0059] (4) Rolling: Control the final rolling temperature at 953°C; after rolling, cool in water at 893°C, roll speed at 6 m / min, water return temperature at 578°C; lower steel temperature at 483°C, stacking for 25 hours.

[0060] The cost reduction and steel plate properties of the 15CrMo steel plate provided in this embodiment are shown in Table 2.

[0061] Example 7

[0062] The chemical composition of the 15CrMo steel plate of this embodiment is shown in Table 1. The thickness of the steel plate is 75 mm. The production method includes electric furnace smelting, continuous casting, heating, and rolling processes, which are specifically as follows:

[0063] (1) Electric furnace steelmaking: oxygen supply gun flow rate 2459m 3 / h, adding lime 13kg / t steel, electric furnace steel P content 0.005%; after refining, vacuum treatment is carried out, holding time 6min, vacuum degree 23Pa, argon pressure during vacuum process 0.5MPa.

[0064] (2) Continuous casting: electromagnetic stirring, current 309A, voltage 342V.

[0065] (3) Heating: The continuous furnace heating temperature of the billet is 1203°C.

[0066] (4) Rolling: Control the final rolling temperature at 961°C; after rolling, cool in water at 906°C, roll speed at 3 m / min, water return temperature at 524°C; lower steel temperature at 429°C, stacking for 26 hours.

[0067] The cost reduction and steel plate properties of the 15CrMo steel plate provided in this embodiment are shown in Table 2.

[0068] Example 8

[0069] The chemical composition of the 15CrMo steel plate of this embodiment is shown in Table 1. The thickness of the steel plate is 75 mm. The production method includes electric furnace smelting, continuous casting, heating, and rolling processes, which are specifically as follows:

[0070] (1) Electric furnace steelmaking: oxygen supply gun flow rate 2290m 3 / h, add lime 14kg / t steel, electric furnace steel P content 0.002%; after refining, vacuum treatment is carried out, the holding time is 9min, the vacuum degree is 21Pa, and the argon pressure during the vacuum process is 0.4MPa. .

[0071] (2) Continuous casting: electromagnetic stirring, current 316A, voltage 343V.

[0072] (3) Heating: The continuous furnace heating temperature of the billet is 1216°C.

[0073] (4) Rolling: Control the final rolling temperature at 964°C; after rolling, cool in water at 907°C, roll speed at 3 m / min, water return temperature at 503°C; lower steel temperature at 419°C, stacking for 29 hours.

[0074] The cost reduction and steel plate properties of the 15CrMo steel plate provided in this embodiment are shown in Table 2.

[0075] Table 1 Chemical composition of 15CrMo steel plates in various embodiments (wt %)

[0076]

[0077] Table 2 Cost reduction and steel plate properties of 15CrMo steel plates in various embodiments

[0078]

[0079] It can be seen from Table 2 that the technical solution provided by the present invention reduces the production cost of 15CrMo steel plates; the produced 15CrMo steel plates have a lower ductile-brittle transition temperature, exhibit good low-temperature impact toughness, and the steel plate has a relatively low yield strength, exhibiting good engineering application performance.

[0080] The above embodiments are only used to illustrate rather than limit the technical solutions of the present invention. Although the present invention is described in detail with reference to the above embodiments, those skilled in the art should understand that the present invention can still be modified or replaced by equivalents. Any modification or partial replacement that does not depart from the spirit and scope of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A method for producing a 15CrMo steel plate with a low toughness-brittle transition temperature and a low yield strength ratio, characterized in that: It includes electric furnace smelting, continuous casting, heating and rolling processes; wherein the rolling process adopts hot rolling + water cooling controlled red return + stacking process, and controls the final rolling temperature to be ≥950℃; after rolling, water cooling is performed, the water inlet temperature is ≥890℃, the roller speed is 2-7m / min, the water outlet red return temperature is 500-600℃; the steel temperature is 400-500℃, and the stacking is 24-30h; Electric furnace steelmaking process, oxygen supply gun flow rate 2000-3000m 3 / h, add lime 10-15kg / t steel to ensure that the P content of steel out of the electric furnace is ≤0.005%.

2. The method for producing a 15CrMo steel plate with a low toughness-to-brittle transition temperature and a low yield ratio according to claim 1, characterized in that: In the electric furnace steelmaking process, vacuum treatment is performed after refining, with a holding time of 5-15 minutes, a vacuum degree of 20-40 Pa, and an argon pressure of 0.3-0.7 MPa during the vacuum process.

3. The method for producing a 15CrMo steel plate with a low toughness-to-brittle transition temperature and a low yield ratio according to claim 1, characterized in that: The continuous casting process adopts electromagnetic stirring, with a current of 300-400A and a voltage of 250-350V.

4. The method for producing a 15CrMo steel plate with a low toughness-to-brittle transition temperature and a low yield ratio according to claim 1, characterized in that: In the heating process, the billet is heated in a continuous furnace at a temperature of 1200-1220°C.

5. The method for producing a 15CrMo steel plate with a low toughness-to-brittle transition temperature and a low yield ratio according to claim 1, characterized in that: The chemical composition and mass percentage of the 15CrMo steel plate are: C 0.13-0.17%, Si 0.20-0.32%, Mn 0.45-0.64%, Cr 0.85-1.05%, and Mo 0.45-0.55%.

6. The method for producing a 15CrMo steel plate with a low toughness-to-brittle transition temperature and a low yield ratio according to claim 1, characterized in that: The steel plate has a thickness of 60-100 mm.

Images