CN108559909B - High-strength high-toughness and good-weldability steel for mining machinery and production method thereof - Google Patents
High-strength high-toughness and good-weldability steel for mining machinery and production method thereof Download PDFInfo
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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
- C22C38/02—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
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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
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- C21D6/004—Heat treatment of ferrous alloys containing Cr and Ni
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- 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
- C21D8/005—Modifying the physical properties by deformation combined with, or followed by, heat treatment of ferrous alloys
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- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
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Abstract
The invention discloses steel with high strength and toughness and good weldability for mining machinery and a production method thereof, wherein the steel for the mining machinery comprises the following chemical components in percentage by mass: c: 0.22 to 0.29%, Si: 0.16-0.30%, Mn: 0.35-0.60%, Cr: 1.24-1.58%, Ni: 1.20-1.60%, Mo: 0.23-0.30%, Al: 0.021-0.035%, P is less than or equal to 0.020%, S is less than or equal to 0.015%, and the balance of Fe and inevitable impurities; the production method comprises the working procedures of smelting, continuous casting, heating, rolling and quenching and tempering. According to the invention, through chemical component matching, Ni ensures high toughness, Cr, Ni, Mo and the like ensure high strength, C content is reduced, welding performance is improved, the problem that similar steel cannot have high strength and toughness and good weldability is solved, and the requirements of steel for mining machinery are met.
Description
Technical Field
The invention belongs to the technical field of metallurgy, and particularly relates to high-strength and high-toughness and good-weldability steel for mining machinery and a production method thereof.
Background
The coal cutter is important equipment for coal production, and a tooth holder of a working part of a roller of the coal cutter is directly welded on a spiral vane plate, so that a cutting tooth is fixed, and the power of an engine can be transmitted to the cutting tooth, thereby realizing the coal cutting process. The working environment of the coal mining machine is severe, and the surface of the tooth seat of the coal mining machine unit is subjected to impact force and abrasion from a coal bed or rocks in the coal mining process, so that the failure phenomenon of the tooth seat of the roller of the coal mining machine often occurs; and because the top plate and the bottom plate are frequently changed, the stress of the coal mining machine in the cutting process is variable, and the frequent welding opening of the roller tooth seat of the unit seriously influences the coal production. It can be seen that the material for the tooth socket needs to have high wear resistance and impact resistance, and good welding performance. It is therefore imperative to provide high quality tooth holder materials with high wear resistance, impact resistance and good weldability. The steel for the roller tooth holder is suitable for improving the comprehensive mechanical property of the roller tooth holder, so that the service life of the roller can be prolonged, and the use requirement of high productivity and high reliability can be met.
At present, 35CrMnSiA, 20CrNiMo, 42CrMo and ZG40Cr1 are mainly used as the material of the roller tooth holder of the coal mining machine at home and abroad. The 35CrMnSiA material has high strength but poor toughness; the 20CrNiMo material has good weldability, small tendency of forming welding cold crack, but low strength and hardness; 42CrMo has high strength and toughness, but poor weldability. Several materials used at present can not be suitable for the comprehensive mechanical property of the steel for the roller tooth holder, and the development of the steel for the roller tooth holder, which has wear resistance and impact resistance and good welding performance, is urgently needed. The high-toughness and good-weldability steel for mining machinery disclosed by the invention has high toughness and good weldability, solves the problem that other steels cannot have high toughness and good weldability, and meets the requirements of the steel for mining machinery.
Disclosure of Invention
The invention aims to solve the technical problem of providing the steel for the mining machinery with high strength and toughness and good weldability; the invention also provides a production method of the steel with high strength and toughness and good weldability for mining machinery.
In order to solve the technical problems, the invention adopts the technical scheme that: the steel for the mining machinery with high strength and toughness and good weldability comprises the following chemical components in percentage by mass: c: 0.22 to 0.29%, Si: 0.16-0.30%, Mn: 0.35-0.60%, Cr: 1.24-1.58%, Ni: 1.20-1.60%, Mo: 0.23-0.30%, Al: 0.021-0.035%, P is less than or equal to 0.020%, S is less than or equal to 0.015%, and the balance of Fe and inevitable impurities.
The action mechanism of each chemical component in the steel is as follows:
c: the main elements for improving the hardness and the strength of the steel are that the content of C is too low, the strength of the material after heat treatment is too low, and the strength requirement required by the roller tooth holder cannot be met; the higher the C content is, the more easily a hardened structure is generated in a heat affected zone during welding, the lower the plasticity and toughness of the material is, the more easily cracking is generated, and meanwhile, the welding property is influenced by the increase of the carbon equivalent, and the welding strength is not enough.
Si: ferrite is obviously strengthened and is an essential element for ensuring the strength, and the strength is not enough when the ferrite is too low; too high causes the ferrite matrix to become brittle and the toughness to decrease.
Mn: the proper Mn content can ensure that the steel has higher hardenability, no temper brittleness, good weldability and small tendency of forming cold cracks.
Cr: the alloy elements for reducing the pearlite transformation temperature are added simultaneously, so that the pearlite lamellar spacing can be effectively reduced, and the strength and the toughness of the steel are improved; however, if the Cr content is too high, the steel structure and the hardness uniformity tend to be deteriorated.
Ni: obviously improves the toughness and plasticity and can also improve the strength of the steel. Ni does not form carbides in steel, but dissolves in austenite and ferrite, and plays roles in refining grains, strengthening ferrite, and improving toughness, particularly low-temperature impact toughness, and is particularly useful for parts having high toughness requirements.
Mo: can be dissolved in ferrite, austenite and carbide in a solid solution way, has the solid solution strengthening effect, improves the strength and the wear resistance of the steel, enhances the tempering stability of the steel and prevents the tempering brittleness.
Al: the AlN is combined with N to form AlN to strengthen precipitation and refine crystal grains, so that the toughness is improved; however, too high Al content easily causes poor fluidity during continuous casting, increases the production difficulty of steel, increases the content and size of TiN inclusions in the steel, and damages the toughness of the steel.
S: too high control of the elements may reduce the cleanliness of the steel and deteriorate the properties of the steel.
P: increasing the brittleness of steel, reducing the impact property and controlling the content of P element not to exceed 0.020%.
The carbon equivalent CEQ of the steel for mining machinery is less than or equal to 0.8 percent.
The mechanical property of the steel for mining machinery is as follows: the tensile strength Rm is more than or equal to 1380MPa, the yield strength ReL is more than or equal to 1200MPa, the impact toughness Aku is more than or equal to 55J at the room temperature of 23 +/-5 ℃, and the weldability of the steel is good.
The invention also provides a production method of the steel with high strength and toughness and good weldability for the mining machinery, which comprises the working procedures of smelting, continuous casting, heating, rolling and quenching and tempering; the quenching and tempering process adopts an oil quenching and air cooling tempering heat treatment process.
In the smelting process, 35-45 kg/t of ferronickel is added in the converter, and 8-12 kg/t of steel is added in a steel ladle in the converter tapping process; and (3) carrying out VD vacuum degassing treatment for vacuum keeping for 10-20 min, and feeding 0.1-0.5 kg/t of aluminum wire after the VD vacuum degassing treatment.
According to the continuous casting process, a casting blank is put into a slow cooling pit for cooling, the temperature of the casting blank in the pit is more than or equal to 600 ℃, and the pit cooling time is more than or equal to 24 hours; the casting blank comprises the following chemical components in percentage by mass: c: 0.22 to 0.29%, Si: 0.16-0.30%, Mn: 0.35-0.60%, Cr: 1.24-1.58%, Ni: 1.20-1.60%, Mo: 0.23-0.30%, Al: 0.021-0.035%, P is less than or equal to 0.020%, S is less than or equal to 0.015%, and the balance of Fe and inevitable impurities.
In the heating process, the billet is heated to 1150-1250 ℃ and is kept warm for 0.5-0.8 h.
In the rolling process, the initial rolling temperature is 1090-1150 ℃, the final rolling temperature is 980-1050 ℃, the rolled steel enters a slow cooling pit for slow cooling, the pit entering temperature is more than or equal to 350 ℃, and the pit leaving temperature is less than 150 ℃.
The quenching and tempering process adopts a quenching and tempering heat treatment process, wherein the oil quenching temperature is 845-875 ℃, and the air cooling tempering temperature is 160-200 ℃.
The steel product standard reference GB/T3077-2015 for the mining machinery with high strength and toughness and good weldability is provided; the product performance detection method is in standard reference GB/T228.1 and GB/T229.
Adopt the produced beneficial effect of above-mentioned technical scheme to lie in: 1. according to the invention, Al is added to form AlN particles, so that crystal grains are refined, the strength is improved, and the toughness of the steel is improved. 2. According to the invention, through chemical component matching, the Ni content ensures high toughness, the contents of alloy elements such as Cr, Ni and Mo ensure high strength, and the C content is reduced to improve the welding performance. 3. The product of the invention has high strength and toughness and good weldability, solves the problem that other steels cannot have both high strength and toughness and good weldability, and meets the requirements of the steels for mining machinery. 4. The mechanical property of the steel for mining machinery is as follows: the tensile strength Rm is more than or equal to 1380MPa, the yield strength ReL is more than or equal to 1200MPa, the impact toughness Aku is more than or equal to 55J at the room temperature of 23 +/-5 ℃, and the weldability of the steel is good. 5. The invention adopts the processes of smelting, continuous casting, heating, rolling and quenching and tempering to produce, thereby ensuring the components and the mechanical properties of the product.
Detailed Description
The present invention will be described in further detail with reference to specific examples.
Example 1
The chemical composition and the mass percentage of the steel for mining machinery with high strength and toughness and good weldability in the embodiment are shown in table 1.
The production method of the high-strength and high-toughness and good-weldability steel for mining machinery in the embodiment comprises the working procedures of smelting, continuous casting, heating, rolling and quenching and tempering, and the specific process steps are as follows:
(1) smelting: charging ferronickel into a converter by 42kg/t steel, and adding nickel plate into a steel ladle by 8kg/t steel during converter tapping; VD vacuum degassing treatment is carried out for vacuum keeping time of 10min, and 0.3kg/t steel of aluminum wires is fed after VD vacuum degassing treatment;
(2) and (3) continuous casting process: cooling the casting blank in a slow cooling pit at the pit temperature of 656 ℃ for 30 h; the chemical component composition and the mass percentage content of the casting blank are shown in the table 1;
(3) a heating procedure: heating the steel billet to 1172 ℃, and keeping the temperature for 0.8 h;
(4) a rolling procedure: the initial rolling temperature is 1115 ℃, the final rolling temperature is 1002 ℃, the rolled steel enters a slow cooling pit for slow cooling, the pit entering temperature is 412 ℃, and the pit discharging temperature is 66 ℃;
(5) a quenching and tempering process: the quenching and tempering heat treatment process is adopted, and the heating is carried out by a resistance furnace, wherein the oil quenching temperature is 862 ℃, and the air cooling tempering temperature is 195 ℃.
The properties of the steel for mining machinery of this example, which has high toughness and good weldability, are shown in Table 4.
Example 2
The chemical composition and the mass percentage of the steel for mining machinery with high strength and toughness and good weldability in the embodiment are shown in table 1.
The production method of the high-strength and high-toughness and good-weldability steel for mining machinery in the embodiment comprises the working procedures of smelting, continuous casting, heating, rolling and quenching and tempering, and the specific process steps are as follows:
(1) smelting: charging ferronickel into a converter by 42.8kg/t steel, and adding nickel plate into a steel ladle in the tapping process of the converter by 8kg/t steel; VD vacuum degassing treatment is carried out for vacuum keeping time of 20min, and 0.32kg/t steel of aluminum wires is fed after VD vacuum degassing treatment;
(2) and (3) continuous casting process: cooling the casting blank in a slow cooling pit at the pit temperature of 632 ℃ for 30 h; the chemical component composition and the mass percentage content of the casting blank are shown in the table 1;
(3) a heating procedure: heating the steel billet to 1178 ℃, and keeping the temperature for 0.75 h;
(4) a rolling procedure: the initial rolling temperature is 1120 ℃, the final rolling temperature is 1011 ℃, the rolled steel enters a slow cooling pit for slow cooling, the pit entering temperature is 430 ℃, and the pit discharging temperature is 80 ℃;
(5) a quenching and tempering process: the quenching and tempering heat treatment process is adopted, the resistance furnace is used for heating, the oil quenching temperature is 847 ℃, and the air cooling tempering temperature is 165 ℃.
The properties of the steel for mining machinery of this example, which has high toughness and good weldability, are shown in Table 4.
Example 3
The chemical composition and the mass percentage of the steel for mining machinery with high strength and toughness and good weldability in the embodiment are shown in table 1.
The production method of the high-strength and high-toughness and good-weldability steel for mining machinery in the embodiment comprises the working procedures of smelting, continuous casting, heating, rolling and quenching and tempering, and the specific process steps are as follows:
(1) smelting: charging ferronickel into a converter by 42kg/t steel, and adding nickel plate into a steel ladle by 12kg/t steel in the tapping process of the converter; VD vacuum degassing treatment is carried out for vacuum keeping time of 10min, and 0.3kg/t steel of aluminum wires is fed after VD vacuum degassing treatment;
(2) and (3) continuous casting process: cooling the casting blank in a slow cooling pit at the temperature of 600 ℃ for 25 h; the chemical component composition and the mass percentage content of the casting blank are shown in the table 1;
(3) a heating procedure: heating the steel billet to 1180 ℃, and keeping the temperature for 0.5 h;
(4) a rolling procedure: the initial rolling temperature is 1122 ℃, the final rolling temperature is 1010 ℃, the rolled steel enters a slow cooling pit for slow cooling, the pit entering temperature is 395 ℃, and the pit discharging temperature is 50 ℃;
(5) a quenching and tempering process: the quenching and tempering heat treatment process is adopted, the resistance furnace is used for heating, the oil quenching temperature is 855 ℃, and the air cooling tempering temperature is 185 ℃.
The properties of the steel for mining machinery of this example, which has high toughness and good weldability, are shown in Table 4.
Example 4
The chemical composition and the mass percentage of the steel for mining machinery with high strength and toughness and good weldability in the embodiment are shown in table 1.
The production method of the high-strength and high-toughness and good-weldability steel for mining machinery in the embodiment comprises the working procedures of smelting, continuous casting, heating, rolling and quenching and tempering, and the specific process steps are as follows:
(1) smelting: charging ferronickel into a converter, adding 40kg/t of steel, and adding 12kg/t of steel with a nickel plate into a steel ladle in the tapping process of the converter; VD vacuum degassing treatment is carried out for vacuum keeping time of 20min, and 0.34kg/t steel of aluminum wires is fed after VD vacuum degassing treatment;
(2) and (3) continuous casting process: cooling the casting blank in a slow cooling pit at the temperature of 660 ℃ for 28 h; the chemical component composition and the mass percentage content of the casting blank are shown in the table 1;
(3) a heating procedure: heating the steel billet to 1220 ℃, and preserving heat for 0.6 h;
(4) a rolling procedure: the initial rolling temperature is 1129 ℃, the final rolling temperature is 1016 ℃, the rolled steel enters a slow cooling pit for slow cooling, the pit entering temperature is 350 ℃, and the pit discharging temperature is 40 ℃;
(5) a quenching and tempering process: the quenching and tempering heat treatment process is adopted, the resistance furnace is used for heating, the oil quenching temperature is 858 ℃, and the air cooling tempering temperature is 180 ℃.
The properties of the steel for mining machinery of this example, which has high toughness and good weldability, are shown in Table 4.
Example 5
The chemical composition and the mass percentage of the steel for mining machinery with high strength and toughness and good weldability in the embodiment are shown in table 1.
The production method of the high-strength and high-toughness and good-weldability steel for mining machinery in the embodiment comprises the working procedures of smelting, continuous casting, heating, rolling and quenching and tempering, and the specific process steps are as follows:
(1) smelting: charging ferronickel into a converter by 42kg/t steel, and adding nickel plate into a steel ladle by 10kg/t steel in the tapping process of the converter; VD vacuum degassing treatment is carried out for vacuum keeping time of 15min, and 0.47kg/t steel of aluminum wires is fed after VD vacuum degassing treatment;
(2) and (3) continuous casting process: cooling the casting blank in a slow cooling pit at the pit temperature of 620 ℃ for 24 h; the chemical component composition and the mass percentage content of the casting blank are shown in the table 1;
(3) a heating procedure: heating the steel billet to 1232 ℃, and keeping the temperature for 0.6 h;
(4) a rolling procedure: the initial rolling temperature is 1130 ℃, the final rolling temperature is 1026 ℃, the rolled steel enters a slow cooling pit for slow cooling, the pit entering temperature is 410 ℃, and the pit discharging temperature is 49 ℃;
(5) a quenching and tempering process: the quenching and tempering heat treatment process is adopted, and the electric resistance furnace is used for heating, wherein the oil quenching temperature is 868 ℃, and the air cooling tempering temperature is 198 ℃.
The properties of the steel for mining machinery of this example, which has high toughness and good weldability, are shown in Table 4.
Example 6
The chemical composition and the mass percentage of the steel for mining machinery with high strength and toughness and good weldability in the embodiment are shown in table 1.
The production method of the high-strength and high-toughness and good-weldability steel for mining machinery in the embodiment comprises the working procedures of smelting, continuous casting, heating, rolling and quenching and tempering, and the specific process steps are as follows:
(1) smelting: charging ferronickel into a converter, adding 36kg/t of steel, and adding 9kg/t of steel with a nickel plate into a steel ladle in the tapping process of the converter; VD vacuum degassing treatment is carried out for vacuum keeping time of 12min, and 0.11kg/t steel of aluminum wires is fed after VD vacuum degassing treatment;
(2) and (3) continuous casting process: cooling the casting blank in a slow cooling pit, wherein the temperature of the casting blank in the pit is 680 ℃, and the pit cooling time is 29 h; the chemical component composition and the mass percentage content of the casting blank are shown in the table 1;
(3) a heating procedure: heating the steel billet to 1230 ℃, and keeping the temperature for 0.65 h;
(4) a rolling procedure: the initial rolling temperature is 1110 ℃, the final rolling temperature is 1013 ℃, the rolled steel enters a slow cooling pit for slow cooling, the pit entering temperature is 386 ℃, and the pit discharging temperature is 52 ℃;
(5) a quenching and tempering process: the quenching and tempering heat treatment process is adopted, the electric resistance furnace is used for heating, the oil quenching temperature is 875 ℃, and the air cooling tempering temperature is 200 ℃.
The properties of the steel for mining machinery of this example, which has high toughness and good weldability, are shown in Table 4.
Example 7
The chemical composition and the mass percentage of the steel for mining machinery with high strength and toughness and good weldability in the embodiment are shown in table 1.
The production method of the high-strength and high-toughness and good-weldability steel for mining machinery in the embodiment comprises the working procedures of smelting, continuous casting, heating, rolling and quenching and tempering, and the specific process steps are as follows:
(1) smelting: charging ferronickel into a converter, adding 45kg/t of steel, and adding nickel plate into a steel ladle in the tapping process of the converter, wherein 11kg/t of steel is added; VD vacuum degassing treatment is carried out for vacuum keeping time of 17min, and 0.5kg/t steel of aluminum wires is fed after VD vacuum degassing treatment;
(2) and (3) continuous casting process: cooling the casting blank in a slow cooling pit at 670 ℃ for 30 h; the chemical component composition and the mass percentage content of the casting blank are shown in the table 1;
(3) a heating procedure: heating the steel billet to 1250 ℃, and preserving heat for 0.5 h;
(4) a rolling procedure: the initial rolling temperature is 1150 ℃, the final rolling temperature is 1050 ℃, the rolled steel enters a slow cooling pit for slow cooling, the pit entering temperature is 425 ℃, and the pit discharging temperature is 55 ℃;
(5) a quenching and tempering process: the quenching and tempering heat treatment process is adopted, the electric resistance furnace is used for heating, the oil quenching temperature is 870 ℃, and the air cooling tempering temperature is 185 ℃.
The properties of the steel for mining machinery of this example, which has high toughness and good weldability, are shown in Table 4.
Example 8
The chemical composition and the mass percentage of the steel for mining machinery with high strength and toughness and good weldability in the embodiment are shown in table 1.
The production method of the high-strength and high-toughness and good-weldability steel for mining machinery in the embodiment comprises the working procedures of smelting, continuous casting, heating, rolling and quenching and tempering, and the specific process steps are as follows:
(1) smelting: charging ferronickel into a converter, adding 40kg/t of steel, and adding nickel plates into a steel ladle in the tapping process of the converter, wherein 10kg/t of steel is added; VD vacuum degassing treatment is carried out for vacuum keeping time of 16min, and 0.4kg/t steel of aluminum wires is fed after VD vacuum degassing treatment;
(2) and (3) continuous casting process: cooling the casting blank in a slow cooling pit at the pit temperature of 630 ℃ for 26 h; the chemical component composition and the mass percentage content of the casting blank are shown in the table 1;
(3) a heating procedure: heating the steel billet to 1150 ℃, and preserving heat for 0.8 h;
(4) a rolling procedure: the initial rolling temperature is 1090 ℃, the final rolling temperature is 980 ℃, the rolled steel enters a slow cooling pit for slow cooling, the pit entering temperature is 440 ℃, and the pit leaving temperature is 60 ℃;
(5) a quenching and tempering process: the quenching and tempering heat treatment process is adopted, and the resistance furnace is used for heating, wherein the oil quenching temperature is 865 ℃, and the air cooling tempering temperature is 180 ℃.
The properties of the steel for mining machinery of this example, which has high toughness and good weldability, are shown in Table 4.
Example 9
The chemical composition and the mass percentage of the steel for mining machinery with high strength and toughness and good weldability in the embodiment are shown in table 1.
The production method of the high-strength and high-toughness and good-weldability steel for mining machinery in the embodiment comprises the working procedures of smelting, continuous casting, heating, rolling and quenching and tempering, and the specific process steps are as follows:
(1) smelting: charging ferronickel into a converter, adding 35kg/t of steel, and adding 9kg/t of steel with a nickel plate into a steel ladle in the tapping process of the converter; VD vacuum degassing treatment is carried out for vacuum holding time of 18min, and 0.1kg/t steel of aluminum wires is fed after VD vacuum degassing treatment;
(2) and (3) continuous casting process: cooling the casting blank in a slow cooling pit at the pit temperature of 645 ℃ for pit cooling time of 27 h; the chemical component composition and the mass percentage content of the casting blank are shown in the table 1;
(3) a heating procedure: heating the steel billet to 1200 ℃, and preserving heat for 0.7 h;
(4) a rolling procedure: the initial rolling temperature is 1100 ℃, the final rolling temperature is 1000 ℃, the rolled steel enters a slow cooling pit for slow cooling, the pit entering temperature is 415 ℃, and the pit discharging temperature is 53 ℃;
(5) a quenching and tempering process: the quenching and tempering heat treatment process is adopted, the resistance furnace is used for heating, the oil quenching temperature is 845 ℃, and the air cooling tempering temperature is 160 ℃.
The properties of the steel for mining machinery of this example, which has high toughness and good weldability, are shown in Table 4.
Comparative examples 1 to 4
The chemical components and the mass percentage of the steel for the mining machinery in the comparative examples 1 to 4 are shown in the table 2;
comparative examples 1-4 steel for mining machinery is produced by smelting, continuous casting, heating, rolling and quenching and tempering, and the technological parameters are shown in Table 3;
comparative examples 1 to 4 the properties of the steel for mining machines are shown in Table 4.
TABLE 1
Examples 1 to 9 high toughness and good weldability Steel for mining machines and casting blank chemical composition and mass percent (%)
In table 1, the balance of the composition is Fe and inevitable impurities.
TABLE 2 COMPARATIVE EXAMPLES 1-4 CHEMICAL COMPONENTS AND QUALITY% OF CAST BLANK FOR MINE MACHINERY
In table 2, the balance of the composition is Fe and inevitable impurities.
TABLE 3 comparative examples 1-4 Rolling and Heat treatment Process parameters for steels for mining machines
TABLE 4 test results of Properties of steels for mining machines of examples 1 to 9 and comparative examples 1 to 4
From the product performance detection results in table 4, it can be seen that the steel for mining machinery in examples 1-9, which has high strength and toughness and good weldability, has strength, impact resistance and welding performance which are obviously superior to those of comparative examples 1-4, and meets the requirements of high productivity and reliability.
Although the present invention has been described in detail with reference to the above embodiments, it should be understood by those skilled in the art that: modifications and equivalents may be made thereto without departing from the spirit and scope of the invention and it is intended to cover in the claims the invention as defined in the appended claims.
Claims (6)
1. The steel for the mining machinery with high strength and toughness and good weldability is characterized by comprising the following chemical components in percentage by mass: c: 0.22 to 0.29%, Si: 0.16-0.30%, Mn: 0.35-0.60%, Cr: 1.24-1.58%, Ni: 1.20-1.60%, Mo: 0.23-0.30%, Al: 0.021-0.035%, P is less than or equal to 0.020%, S is less than or equal to 0.015%, and the balance of Fe and inevitable impurities;
the carbon equivalent CEQ of the steel for the mining machinery is less than or equal to 0.8 percent;
the mechanical property of the steel for mining machinery is as follows: the tensile strength Rm is more than or equal to 1380MPa, the yield strength ReL is more than or equal to 1200MPa, and the impact toughness Aku is more than or equal to 55J at the room temperature of 23 +/-5 ℃.
2. The production method of the steel for mining machinery with high strength and toughness and good weldability according to claim 1, characterized in that the production method comprises the working procedures of smelting, continuous casting, heating, rolling and quenching and tempering; the quenching and tempering process adopts an oil quenching and air cooling tempering heat treatment process;
the quenching and tempering process adopts a quenching and tempering heat treatment process, wherein the oil quenching temperature is 845-875 ℃, and the air cooling tempering temperature is 160-200 ℃.
3. The production method of the steel with high strength and toughness and good weldability for mining machinery as claimed in claim 2, wherein in the smelting process, 35-45 kg/t of ferronickel is added into a converter, and 8-12 kg/t of steel is added into a steel ladle in the converter tapping process; and (3) carrying out VD vacuum degassing treatment for vacuum keeping for 10-20 min, and feeding 0.1-0.5 kg/t of aluminum wire after the VD vacuum degassing treatment.
4. The production method of the steel with high strength and toughness and good weldability for mining machinery as claimed in claim 2, wherein in the continuous casting process, a casting blank is cooled in a slow cooling pit, the pit-entering temperature is more than or equal to 600 ℃, and the pit cooling time is more than or equal to 24 hours; the casting blank comprises the following chemical components in percentage by mass: c: 0.22 to 0.29%, Si: 0.16-0.30%, Mn: 0.35-0.60%, Cr: 1.24-1.58%, Ni: 1.20-1.60%, Mo: 0.23-0.30%, Al: 0.021-0.035%, P is less than or equal to 0.020%, S is less than or equal to 0.015%, and the balance of Fe and inevitable impurities.
5. The method for producing the steel for mining machinery having high toughness and good weldability according to any one of claims 2 to 4, wherein in the heating step, the steel slab is heated to 1150 to 1250 ℃ and is kept warm for 0.5 to 0.8 h.
6. The production method of the steel with high strength and toughness and good weldability for mining machinery as claimed in any one of claims 2 to 4, characterized in that in the rolling process, the initial rolling temperature is 1090-1150 ℃, the final rolling temperature is 980-1050 ℃, the steel enters a slow cooling pit after rolling and is slowly cooled, the pit entering temperature is more than or equal to 350 ℃, and the pit leaving temperature is less than 150 ℃.
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