CN111893391A - Nano bainite hot work die steel and preparation method thereof - Google Patents
Nano bainite hot work die steel and preparation method thereof Download PDFInfo
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/18—Hardening; Quenching with or without subsequent tempering
- C21D1/19—Hardening; Quenching with or without subsequent tempering by interrupted quenching
- C21D1/20—Isothermal quenching, e.g. bainitic hardening
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- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/18—Hardening; Quenching with or without subsequent tempering
- C21D1/25—Hardening, combined with annealing between 300 degrees Celsius and 600 degrees Celsius, i.e. heat refining ("Vergüten")
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- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/26—Methods of annealing
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- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/002—Heat treatment of ferrous alloys containing Cr
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- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/005—Heat treatment of ferrous alloys containing Mn
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- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/008—Heat treatment of ferrous alloys containing Si
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
- C21D8/0263—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment following hot rolling
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- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/0081—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for slabs; for billets
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C33/00—Making ferrous alloys
- C22C33/04—Making ferrous alloys by melting
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/22—Ferrous alloys, e.g. steel alloys containing chromium with molybdenum or tungsten
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/24—Ferrous alloys, e.g. steel alloys containing chromium with vanadium
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/001—Austenite
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/002—Bainite
Abstract
The invention discloses a nanometer bainite hot work die steel, which belongs to the technical field of die steel and comprises the following components in percentage by mass: 0.32-0.45% of C, 0.80-1.5% of Si, 0.20-0.50% of Mn, 4.75-5.05% of Cr, 1.10-1.75% of Mo, 0.8-1.00% of V, 0.02% of P and 0.01% of S, and the balance of Fe and inevitable impurities, wherein the hot-work die steel structure is nano bainite. In addition, the invention also discloses a preparation method of the nanometer bainite hot work die steel. The invention has the beneficial effects that: 1. the irregular shape and distribution of carbides in the forged structure are improved through the quenching and tempering pretreatment; 2. the Si element content is high, the precipitation of carbide in the isothermal quenching process is inhibited, and the nano bainite structure is ensured to be obtained; 3. the unnotched impact energy of the secondary tempered sample of the nano bainite hot work die steel is not less than 500J, the tensile strength is not less than 1900MPa, and the hardness is not less than 52 HRC; 4. the preparation process flow is simple and easy to implement, is beneficial to industrial production, and has high preparation efficiency.
Description
Technical Field
The invention relates to the technical field of die steel, in particular to nano bainite hot work die steel and a preparation method thereof.
Background
Hot work die steels are most widely used in the die industry, with the predominant steel type in hot work die steels being the medium carbon chromium based H13 steel. After H13 steel is introduced in China, the H13 steel rapidly occupies the domestic hot work die steel market due to the advantages of high heat strength and the like. In recent years, colleges and universities, enterprises and scientific research units have improved the components, the smelting and forging technology and the heat treatment process of H13 steel, and various new types of H13 steel are developed.
Patent document CN101240400B proposes a low-cost hot-work die steel, the final heat treatment adopts quenching and tempering processes, the hardness after 600 ℃ tempering is not more than 46HRC, and the tensile strength is not more than 1500 MPa. The patent document with publication number CN110484812A proposes a high-performance hot stamping die steel and a manufacturing process thereof, wherein the final heat treatment adopts a quenching and tempering process, and the impact energy at room temperature is more than or equal to 260J.
The following technical problems mainly exist in the prior art:
the tempering properties of the die steel need to be improved, and further improvement of the composition and heat treatment process is required.
The nanometer superfine bainite structure has high strength, high toughness and excellent comprehensive performance, and may be used widely in bridge, ship, rolling bearing, rail, automobile deck, etc. Bainite has higher toughness and thermal stability than martensite, so that nano bainite can show performance advantages when being used for hot work die steel, and is one of the development directions for improving tempering performance of the die steel. However, there are few studies and documents related to the preparation of hot work die steel having a nano bainite structure.
Disclosure of Invention
The invention aims to solve the technical problem of providing the nanometer bainite hot work die steel and the preparation method thereof, and the nanometer bainite structure is obtained through component design and a heat treatment process, so that excellent tempering performance is obtained.
In order to solve the technical problems, the invention adopts the technical scheme that:
a nanometer bainite hot work die steel comprises the following components by mass percent: 0.32-0.45% of C, 1.20-1.50% of Si, 0.20-0.50% of Mn0.75-5.05% of Cr, 1.10-1.75% of Mo, 0.80-1.00% of V, 0.02% of P and 0.01% of S, and the balance of Fe and inevitable impurities, wherein the hot-work die steel structure is nano bainite.
In addition, the invention also provides a preparation method of the nanometer bainite hot work die steel, which comprises the following steps:
(1) and smelting: feeding according to the composition design requirements of steel, wherein the steel comprises the following components in percentage by mass: 0.32-0.45% of C, 1.20-1.50% of Si, 0.20-0.50% of Mn, 4.75-5.05% of Cr, 1.10-1.75% of Mo, 0.80-1.00% of V, 0.02% of P, 0.01% of S and the balance of Fe and inevitable impurities, and then smelting in a vacuum induction furnace and casting into steel ingots;
(2) annealing and hot rolling: annealing and hot rolling the steel ingot, and air cooling to room temperature after hot rolling to obtain a hot rolled slab;
(3) and (3) tempering pretreatment: heating the hot-rolled plate blank obtained in the step (2) to 1050-1150 ℃, preserving heat for 10-15 min, cooling oil to room temperature, then tempering at 710-730 ℃, preserving heat for 1-1.5 h, discharging and air cooling to room temperature;
(4) and isothermal quenching treatment: heating the hot rolled plate blank subjected to the heat treatment in the step (3) to 1020-1040 ℃, preserving heat for 10-15 min, then quickly placing the hot rolled plate blank into a salt bath furnace at 345-365 ℃, carrying out isothermal treatment for 1-1.5 h, and then carrying out air cooling to room temperature to obtain an isothermal quenching sample;
(5) and tempering treatment: and (3) heating the hot-rolled plate blank subjected to the heat treatment in the step (4) to 555-565 ℃, preserving heat for 1-1.5 hours, discharging from the furnace, air cooling, heating to 575-585 ℃, preserving heat for 1-1.5 hours, discharging from the furnace, and air cooling.
The technical route of the invention is as follows: the hot die steel is heated to 1030 ℃ for austenitizing after quenching and tempering pretreatment, then is put into a salt bath furnace with the temperature slightly higher than the martensite starting point for isothermal bainite transformation, and then is air-cooled to room temperature to obtain a nano bainite structure.
The physical metallurgy principle of the invention is as follows: the hot die steel is subjected to quenching and tempering pretreatment to obtain tempered troostite and spherical undissolved carbide which keep the orientation relation of quenched martensite, and the form and distribution of the carbide are improved. In the second austenitizing and heating process of the pretreated sample, fine unmelted carbide is used as grain nucleation particles to refine grains, and grain boundaries are pinned in the heat preservation process to prevent the grains from growing. Then bainite transformation occurs in the process of isothermal quenching at low temperature (slightly higher than the martensite starting point of austenite) in a salt bath furnace, and because Si element has the function of inhibiting carbide precipitation in the process of isothermal transformation, thin-film residual austenite is distributed among bainite laths, namely nano bainite is formed. Then, the nanometer bainite hot work die steel is obtained after cooling to the room temperature.
The invention has the beneficial effects that: 1. the irregular shape and distribution of carbides in the forged structure are improved through the quenching and tempering pretreatment; 2. the content of Si element is high, the precipitation of carbide in the isothermal quenching process is inhibited, and the nanometer bainite structure, namely bainite ferrite and film-shaped residual austenite among ferrite laths is ensured to be obtained, wherein the thickness of the bainite ferrite laths is 95-112 nm; 3. the unnotched impact energy of the secondary tempered sample of the nano bainite hot work die steel is not less than 500J, the tensile strength is not less than 1900MPa, and the hardness is not less than 52 HRC; 4. the preparation process flow is simple and easy to implement, is beneficial to industrial production, and has high preparation efficiency.
The present invention will be described in detail with reference to the accompanying drawings.
Drawings
FIG. 1 is a scanning electron micrograph of a quenched and tempered sample of the nano bainite hot work die steel prepared in example 1;
FIG. 2 is a scanning electron micrograph of a quenched and tempered sample of the nano bainite hot work die steel prepared in example 2;
FIG. 3 is a scanning electron micrograph of a quenched and tempered sample of the nano bainite hot work die steel prepared in example 3;
FIG. 4 is a scanning electron micrograph of an austempered specimen of the nano bainite hot work die steel prepared in example 4;
FIG. 5 is a scanning electron micrograph of an austempered specimen of the nano bainite hot work die steel prepared in example 5;
FIG. 6 is a scanning electron micrograph of an austempered specimen of the nano bainite hot work die steel prepared in example 6;
FIG. 7 is a scanning electron micrograph of an austempered specimen of the nano bainite hot work die steel prepared in example 7;
FIG. 8 is a SEM photograph of austempered and twice tempered samples of the nano bainite hot work die steel prepared in example 8;
FIG. 9 is a SEM photograph of austempered and twice tempered samples of the nano bainite hot work die steel prepared in example 9;
FIG. 10 is a SEM photograph of austempered + secondary tempered sample of the nano bainite hot work die steel prepared in example 10;
FIG. 11 is a SEM image of austempered + secondary tempered sample of nano bainite hot work die steel prepared in example 11.
Detailed Description
The invention provides a nanometer bainite hot work die steel, which comprises the following components in percentage by mass: 0.32 to 0.45 percent of C, 1.20 to 1.5 percent of Si, 0.20 to 0.50 percent of Mn, 4.75 to 5.05 percent of Cr, 1.10 to 1.75 percent of Mo, 0.8 to 1.00 percent of V, 0.02 percent of P, 0.01 percent of S, and the balance of Fe and inevitable impurities, and the hot-work die steel structure is nano bainite.
Preferably, the hot work die steel comprises the following components in percentage by mass: 0.38 percent of C, 1.5 percent of Si, 0.26 percent of Mn, 5.05 percent of Cr, 1.37 percent of Mo, 1.00 percent of V, 0.0082 percent of P, 0.0042 percent of S, and the balance of Fe and inevitable impurities.
The invention also provides a preparation method of the nanometer bainite hot work die steel, which comprises the following steps.
(1) And smelting: feeding according to the composition design requirements of steel, wherein the steel comprises the following components in percentage by mass: 0.32-0.45% of C, 1.20-1.50% of Si, 0.20-0.50% of Mn, 4.75-5.05% of Cr, 1.10-1.75% of Mo, 0.80-1.00% of V, 0.02% of P, 0.01% of S and the balance of Fe and inevitable impurities, and then smelting in a vacuum induction furnace and casting into steel ingots. Preferably, the steel comprises the following components in percentage by mass: 0.38 of C, 1.50 of Si, 0.26 of Mn, 5.05 of Cr, 1.37 of Mo1, 1.00 of V, 0.0082 of P, 0.0042 of S, and the balance of Fe and inevitable impurities.
(2) Annealing and hot rolling: and annealing and hot rolling the steel ingot, and air cooling to room temperature after hot rolling to obtain a hot rolled slab.
(3) And (3) tempering pretreatment: and (3) heating the hot-rolled plate blank in the step (2) to 1050-1150 ℃, preserving heat for 10-15 min, cooling the hot-rolled plate blank to room temperature with oil, then tempering at 710-730 ℃, preserving heat for 1-1.5 h, discharging the hot-rolled plate blank out of the furnace, and air cooling to room temperature.
(4) And isothermal quenching treatment: and (4) heating the hot-rolled plate blank subjected to the heat treatment in the step (3) to 1020-1040 ℃, preserving heat for 10-15 min, then quickly placing the hot-rolled plate blank into a salt bath furnace at 345-365 ℃, carrying out isothermal treatment for 1-1.5 h, and then carrying out air cooling to room temperature to obtain an isothermal quenching sample.
(5) And tempering treatment: and (3) heating the hot-rolled plate blank subjected to the heat treatment in the step (4) to 555-565 ℃, preserving heat for 1-1.5 hours, discharging from the furnace, air cooling, heating to 575-585 ℃, preserving heat for 1-1.5 hours, discharging from the furnace, and air cooling.
The present invention will be described in detail with reference to specific examples.
Example 1, see figure 1, in this example:
A. the charging proportion is calculated according to the mixture ratio of C0.38, Si 1.5, Mn0.26, Cr 5.05, Mo1.37, V1.00, P0.0082 and S0.0042 in percentage by mass and the balance of Fe, and the mixture is smelted in a vacuum high-frequency induction furnace and then poured into a round ingot with the diameter phi of 80mm after electroslag remelting.
B. Annealing and hot rolling: heating the steel ingot to 1150 ℃, preserving heat for 5 hours, carrying out homogenizing annealing, and cooling along with the furnace. Then, hot rolling and cogging the round ingot at 1150 ℃ into a steel plate with the thickness of 25 mm; and finally, annealing the hot-rolled and cogging steel plate after forging, wherein the annealing heating temperature is 880 ℃, and cooling along with the furnace after heat preservation for 1.5 hours.
C. Tempering pretreatment: and heating the hot rolled plate blank in the furnace again to 1050 ℃, preserving heat for 10min, and quickly putting the hot rolled plate blank into oil for quenching and cooling to room temperature after discharging to obtain a quenched plate blank. And reheating the quenched plate blank to 720 ℃, preserving the temperature for 1h, and air-cooling to room temperature after discharging.
Scanning Electron Microscope (SEM) analysis is carried out on the plate prepared in the experimental example, and the picture of the microstructure of the quenching and tempering pretreatment is shown in the attached figure 1, and can be seen from the attached figure 1: in this example, tempered troostite and more spherical undissolved carbides were prepared.
Example 2, see figure 2, in this example:
A. the charging proportion is calculated according to the mixture ratio of C0.38, Si 1.5, Mn0.26, Cr 5.05, Mo1.37, V1.00, P0.0082 and S0.0042 in percentage by mass and the balance of Fe, and the mixture is smelted in a vacuum high-frequency induction furnace and then poured into a round ingot with the diameter phi of 80mm after electroslag remelting.
B. Annealing and hot rolling: heating the steel ingot to 1150 ℃, preserving heat for 5 hours, carrying out homogenizing annealing, and cooling along with the furnace. Then, hot rolling and cogging the round ingot at 1150 ℃ into a steel plate with the thickness of 25 mm; and finally, annealing the hot-rolled and cogging steel plate after forging, wherein the annealing heating temperature is 880 ℃, and cooling along with the furnace after heat preservation for 1.5 hours.
C. Tempering pretreatment: and heating the hot rolled plate blank in the furnace again to 1100 ℃, preserving the heat for 10min, and quickly putting the hot rolled plate blank into oil for quenching and cooling to room temperature after discharging to obtain a quenched plate blank. And reheating the quenched plate blank to 720 ℃, preserving the temperature for 1h, and air-cooling to room temperature after discharging.
Scanning Electron Microscope (SEM) analysis is carried out on the plate prepared in the experimental example, and the picture of the microstructure of the quenching and tempering pretreatment is shown in the attached figure 2, which can be seen from the attached figure 2: tempered troostite and a small amount of spherical undissolved carbide were prepared in this experimental example.
Example 3, see figure 3, in this example:
A. the charging proportion is calculated according to the mixture ratio of C0.38, Si 1.5, Mn0.26, Cr 5.05, Mo1.37, V1.00, P0.0082 and S0.0042 in percentage by mass and the balance of Fe, and the mixture is smelted in a vacuum high-frequency induction furnace and then poured into a round ingot with the diameter phi of 80mm after electroslag remelting.
B. Annealing and hot rolling: heating the steel ingot to 1150 ℃, preserving heat for 5 hours, carrying out homogenizing annealing, and cooling along with the furnace. Then, hot rolling and cogging the round ingot at 1150 ℃ into a steel plate with the thickness of 25 mm; and finally, annealing the hot-rolled and cogging steel plate after forging, wherein the annealing heating temperature is 880 ℃, and cooling along with the furnace after heat preservation for 1.5 hours.
C. Tempering pretreatment: and heating the hot rolled plate blank in the furnace again to 1150 ℃, preserving the heat for 10min, and quickly putting the hot rolled plate blank into oil for quenching and cooling to room temperature after being taken out of the furnace to obtain a quenched plate blank. And reheating the quenched plate blank to 720 ℃, preserving the temperature for 1h, and air-cooling to room temperature after discharging.
Scanning Electron Microscope (SEM) analysis is carried out on the plate prepared in the experimental example, and the picture of the microstructure of the quenching and tempering pretreatment is shown in the attached figure 3, which can be seen from the attached figure 3: tempered troostite and a very small amount of spherical undissolved carbides were prepared in this experimental example.
Example 4, see figure 4, in this example:
the plate material after the thermal refining treatment in the example 1 is put into a furnace with the temperature of 1030 ℃ for heat preservation for 10min, then is quickly put into a salt bath furnace with the temperature of 350 ℃ for moderate temperature for 1.5h, and then is taken out of the furnace for air cooling to the room temperature.
The sheet material obtained in this example was subjected to Scanning Electron Microscope (SEM) analysis, hardness, impact and tensile tests, and the results are shown in table 1 and fig. 4. As can be seen in fig. 4: this example prepares a nano-bainite die steel. Wherein the size of the nanometer bainite lath is 95.2nm, the hardness is 52.8HRC, the unnotched impact energy is not lower than 500J, the tensile strength is 1996MPa, and the standard elongation is 11%. See table 1 for data.
Example 5, see figure 5, in this example:
the plate material after the thermal refining treatment in the example 2 is put into a furnace with the temperature of 1030 ℃, the temperature is kept for 10min, then the plate material is quickly put into a salt bath furnace with the temperature of 360 ℃ for moderate temperature for 1h, and then the plate material is taken out of the furnace and cooled to the room temperature.
The sheets obtained in this example were subjected to Scanning Electron Microscope (SEM) analysis, hardness, impact and tensile tests, and the results are shown in table 1 and fig. 5. As can be seen in fig. 5: this example prepares a nano-bainite die steel. Wherein the size of the nanometer bainite lath is 106.1nm, the hardness is 53.7HRC, the unnotched impact energy is not lower than 500J, the tensile strength is 1935MPa, and the standard elongation is 7.2%. See table 1 for data.
Example 6, see fig. 6, in this example:
the plate material after the thermal refining treatment in the embodiment 3 is put into a furnace with the temperature of 1030 ℃, the temperature is kept for 10min, then the plate material is quickly put into a salt bath furnace with the temperature of 350 ℃ for moderate temperature for 1.5h, and then the plate material is taken out of the furnace and cooled to the room temperature.
The sheets obtained in this example were subjected to Scanning Electron Microscope (SEM) analysis, hardness, impact and tensile tests, and the results are shown in table 1 and fig. 6. As can be seen in fig. 6: this example prepares a nano-bainite die steel. Wherein the size of the nanometer bainite lath is 95nm, the hardness is 52.4HRC, the unnotched impact energy is not lower than 400J, the tensile strength is 1960MPa, and the standard elongation is 9.8%. See table 1 for data.
Example 7, see fig. 7, in this example:
the plate material after the thermal refining treatment in the embodiment 3 is put into a furnace with the temperature of 1030 ℃, the temperature is kept for 10min, then the plate material is quickly put into a salt bath furnace with the temperature of 360 ℃ for moderate temperature for 1h, and then the plate material is taken out of the furnace and cooled to the room temperature.
The sheets obtained in this example were subjected to Scanning Electron Microscope (SEM) analysis, hardness, impact and tensile tests, and the results are shown in table 1 and fig. 7. As can be seen in fig. 6: this example prepares a nano-bainite die steel. Wherein the size of the nanometer bainite lath is 112.5nm, the hardness is 53.1HRC, the unnotched impact energy is not lower than 370J, the tensile strength is 1965MPa, and the standard elongation is 8.9%. See table 1 for data.
Example 8, see fig. 8, in this example:
the austempered sheet of example 4 was placed in a box furnace at 560 ℃ and tempered for 1 hour, taken out of the furnace and air-cooled to room temperature. Then putting the mixture into a box type furnace for the second time, heating the mixture to 580 ℃, tempering the mixture for 1 hour, taking the mixture out of the furnace, and cooling the mixture to room temperature.
The sheets obtained in this example were subjected to Scanning Electron Microscope (SEM) analysis, hardness, impact and tensile tests, and the results are shown in table 2 and fig. 8. As can be seen in fig. 8: in this example, tempered bainite, tempered martensite and spherical undissolved carbide structures were prepared. The hardness is 52.8HRC, the unnotched impact energy is not less than 500J, the tensile strength is 1950MPa, and the standard elongation is 8.9%. See table 2 for data in particular.
Example 9, see fig. 9, in this example:
the austempered sheet of example 5 was placed in a box furnace at 560 ℃ and tempered for 1 hour, taken out of the furnace and air-cooled to room temperature. Then putting the mixture into a box type furnace for the second time, heating the mixture to 580 ℃, tempering the mixture for 1 hour, taking the mixture out of the furnace, and cooling the mixture to room temperature.
The sheets obtained in this example were subjected to Scanning Electron Microscope (SEM) analysis, hardness, impact and tensile tests, and the results are shown in table 2 and fig. 9. As can be seen in fig. 9: in this example, tempered bainite, tempered martensite and spherical undissolved carbide structures were prepared. The hardness is 52.4HRC, the unnotched impact energy is not less than 500J, the tensile strength is 1900MPa, and the standard elongation is 6.9%. See table 2 for data in particular.
Example 10, referring to fig. 10, in this example:
the austempered sheet of example 6 was placed in a box furnace at 560 ℃ and tempered for 1 hour, taken out of the furnace and air-cooled to room temperature. Then putting the mixture into a box type furnace for the second time, heating the mixture to 580 ℃, tempering the mixture for 1 hour, taking the mixture out of the furnace, and cooling the mixture to room temperature.
The sheets obtained in this example were subjected to Scanning Electron Microscope (SEM) analysis, hardness, impact and tensile tests, and the results are shown in table 2 and fig. 10. As can be seen in fig. 10: in this example, tempered bainite, large tempered martensite, a small amount of spherical undissolved carbides, and a secondary carbide structure were prepared. The hardness is 52.1HRC, the unnotched impact energy is not less than 500J, the tensile strength is 1960MPa, and the standard elongation is 8.0%. See table 2 for data in particular.
Example 11, see fig. 11, in this example:
the austempered sheet of example 7 was placed in a box furnace at 560 ℃ and tempered for 1 hour, taken out of the furnace and air-cooled to room temperature. Then putting the mixture into a box type furnace for the second time, heating the mixture to 580 ℃, tempering the mixture for 1 hour, taking the mixture out of the furnace, and cooling the mixture to room temperature.
The sheets obtained in this example were subjected to Scanning Electron Microscope (SEM) analysis, hardness, impact and tensile tests, and the results are shown in table 2 and fig. 11. As can be seen in fig. 11: in this example, tempered bainite, large tempered martensite, a small amount of spherical undissolved carbides, and a secondary carbide structure were prepared. The hardness is 52.1HRC, the unnotched impact energy is not less than 500J, the tensile strength is 1935MPa, and the standard elongation is 8.2%. See table 2 for data in particular.
The microstructure and mechanical properties of the austempered samples of the nano-bainite die steel in examples 4 to 7 are shown in table 1.
Table 1:
the mechanical properties of the austempered and twice tempered samples of the nano-bainite die steel in examples 8 to 11 are shown in table 2.
Table 2:
as seen from the examples and the tables, the die steel obtained by the scheme of the invention has high preparation efficiency and excellent tempering performance.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention and not to limit it; although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art will understand that: modifications to the specific embodiments of the invention or equivalent substitutions for parts of the technical features may be made; without departing from the spirit of the present invention, it is intended to cover all aspects of the invention as defined by the appended claims.
Claims (7)
1. The nanometer bainite hot work die steel is characterized by comprising the following components in percentage by mass: 0.32 to 0.45 percent of C, 1.20 to 1.50 percent of Si, 0.20 to 0.50 percent of Mn, 4.75 to 5.05 percent of Cr, 1.10 to 1.75 percent of Mo, 0.80 to 1.00 percent of V, 0.02 percent of P, 0.01 percent of S, and the balance of Fe and inevitable impurities,
the hot work die steel structure is nanometer bainite.
2. The nano bainite hot work die steel according to claim 1, wherein the hot work die steel is, in mass percent: 0.38 percent of C, 1.50 percent of Si, 0.26 percent of Mn, 5.05 percent of Cr, 1.37 percent of Mo, 1.00 percent of V, 0.0082 percent of P, 0.0042 percent of S, and the balance of Fe and inevitable impurities.
3. The nano bainite hot work die steel according to claim 1, wherein the unnotched impact energy of the hot work die steel is not less than 500J.
4. The nano bainite hot work die steel according to claim 1, wherein the tensile strength of the hot work die steel is not less than 1900 MPa.
5. The nano bainite hot work die steel according to claim 1, wherein the hardness of the hot work die steel is not less than 52 HRC.
6. A preparation method of nanometer bainite hot work die steel is characterized by comprising the following steps:
(1) and smelting: feeding according to the design requirements of the components of the steel, smelting in a vacuum induction furnace and casting into steel ingots,
the steel comprises the following components in percentage by mass: 0.32 to 0.45 percent of C, 1.20 to 1.50 percent of Si, 0.20 to 0.50 percent of Mn, 4.75 to 5.05 percent of Cr, 1.10 to 1.75 percent of Mo, 0.80 to 1.00 percent of V, 0.02 percent of P, 0.01 percent of S, and the balance of Fe and inevitable impurities;
(2) annealing and hot rolling: annealing and hot rolling the steel ingot, and air cooling to room temperature after hot rolling to obtain a hot rolled slab;
(3) and (3) tempering pretreatment: heating the hot-rolled plate blank obtained in the step (2) to 1050-1150 ℃, preserving heat for 10-15 min, cooling oil to room temperature, then tempering at 710-730 ℃, preserving heat for 1-1.5 h, discharging and air cooling to room temperature;
(4) and isothermal quenching treatment: heating the hot rolled plate blank subjected to the heat treatment in the step (3) to 1020-1040 ℃, preserving heat for 10-15 min, then quickly placing the hot rolled plate blank into a salt bath furnace at 345-365 ℃, carrying out isothermal treatment for 1-1.5 h, and then carrying out air cooling to room temperature to obtain an isothermal quenching sample;
(5) and tempering treatment: and (3) heating the hot-rolled plate blank subjected to the heat treatment in the step (4) to 555-565 ℃, preserving heat for 1-1.5 hours, discharging from the furnace, air cooling, heating to 575-585 ℃, preserving heat for 1-1.5 hours, discharging from the furnace, and air cooling.
7. The method for preparing nano bainite hot work die steel according to claim 6, wherein the steel material comprises the following components by mass percent: 0.38 percent of C, 1.50 percent of Si, 0.26 percent of Mn, 5.05 percent of Cr, 1.37 percent of Mo, 1.00 percent of V, 0.0082 percent of P, 0.0042 percent of S, and the balance of Fe and inevitable impurities.
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| CN113897547A (en) * | 2021-10-08 | 2022-01-07 | 内蒙古北方重工业集团有限公司 | Cr-Mo-V type medium carbon hot work die steel and tissue spheroidizing method thereof |
| CN114703431A (en) * | 2022-04-18 | 2022-07-05 | 燕山大学 | Heat treatment process for homogenizing hot-work die steel and annealing structure |
| CN114717392A (en) * | 2022-03-22 | 2022-07-08 | 江苏大学 | Dievar steel and heat treatment method thereof |
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| CN115161544A (en) * | 2022-04-07 | 2022-10-11 | 燕山大学 | Secondary hardening nano bainite hot work die steel and preparation method thereof |
| CN115181901A (en) * | 2022-04-07 | 2022-10-14 | 燕山大学 | High-strength-toughness hard low-temperature bainite hot-work die steel and preparation method thereof |
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| CN113897547A (en) * | 2021-10-08 | 2022-01-07 | 内蒙古北方重工业集团有限公司 | Cr-Mo-V type medium carbon hot work die steel and tissue spheroidizing method thereof |
| CN114717392A (en) * | 2022-03-22 | 2022-07-08 | 江苏大学 | Dievar steel and heat treatment method thereof |
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| CN115161544A (en) * | 2022-04-07 | 2022-10-11 | 燕山大学 | Secondary hardening nano bainite hot work die steel and preparation method thereof |
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| CN115181901B (en) * | 2022-04-07 | 2023-09-26 | 燕山大学 | High-strength and high-toughness hard low-temperature bainite hot work die steel and preparation method thereof |
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