CN111850412A - Steel material for carburized gear and preparation method thereof - Google Patents
Steel material for carburized gear and preparation 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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- 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
- 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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- 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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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
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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
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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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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- 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
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
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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
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C8/06—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases
- C23C8/08—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases only one element being applied
- C23C8/20—Carburising
- C23C8/22—Carburising of ferrous surfaces
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Abstract
The invention discloses a steel material for a carburized gear, which comprises the following chemical components in percentage by mass: c: 0.20-0.22 percent; si: 0.17-0.37%; mn: 1.0-1.2%; mo: 0.25-0.30%; ni: 0.10-0.30%; cr: 1.30-1.40%; ti is less than or equal to 0.010 percent; cu is less than or equal to 0.10 percent; 0.018-0.03% of Al; v is less than or equal to 0.03 percent; the balance of Fe and inevitable impurities. The steel material for the carburized gear can effectively improve hardenability and mechanical property, and end quenching tests show that the hardness of the steel material can reach 33HRC and phi 57 at a position 40mm away from an end face, and the steel material can be used as a furnace test bar and has normal-temperature impact power KV2The average value is 50J, and the method has the advantage of low production cost.
Description
Technical Field
The invention relates to the technical field of steel for a carburized gear, in particular to steel for a carburized gear with good hardenability and large impact toughness and a preparation method of the steel for the carburized gear.
Background
Carburizing steel generally refers to steel that is used after being carburized, quenched and tempered at low temperature. It is generally a high quality carbon structural steel and alloy structural steel of low carbon, which may also be referred to as carbon carburized steel and alloy carburized steel, respectively. The components are characterized by low carbon content, generally 0.1 to 0.25 percent; the main alloying elements include Ni, Cr, Mn, etc., and the auxiliary alloying elements include W, Mo, V, Ti, etc. The steel for carburizing has higher hardenability, and a plurality of machine parts such as transmission gears of automobiles and tractors, cams and piston pins on internal combustion engines, partial measuring tools and the like are all made of carburizing steel, and the steel for carburizing is widely applied to manufacturing gear parts with larger impact load, contact stress and abrasion resistance.
However, as the size of the part is increased, the comprehensive performance of the core part of the part is correspondingly reduced after corresponding heat treatment due to the influence of hardenability, and the service life of the gear is influenced. Therefore, how to obtain a high-cost-performance steel for a carburized gear by improving the comprehensive properties such as hardenability, impact toughness and the like through controlling the chemical components and metallurgical quality of the carburized alloy steel becomes one of the targets of the industry.
Disclosure of Invention
In order to overcome the defects in the prior art, the invention aims to provide the steel for the carburized gear, which has better hardenability and larger impact toughness.
In order to achieve the above objects and other related objects, the present invention provides the following technical solutions: the steel material for the carburized gear comprises the following chemical components in percentage by mass:
C：0.20-0.22％；
Si：0.17-0.37％；
Mn：1.0-1.2％；
Mo：0.25-0.30％；
Ni：0.10-0.30％；
Cr：1.30-1.40％；
Ti:≤0.010％；
Cu:≤0.10％；
Al:0.018-0.03％；
V:≤0.03％；
the balance of Fe and inevitable impurities.
Preferably, the impurities in the steel material for the carburized gear comprise, by mass, P less than or equal to 0.015 percent and S less than or equal to 0.012 percent.
Preferably, the impurities in the steel material for the carburized gear comprise less than or equal to 1.8ppm by mass fraction H; o is less than or equal to 18 ppm; n is less than or equal to 80 ppm.
Preferably, the steel material for a carburized gear has a mass ratio of Al to N of 2 to 4.
Preferably, the steel material for carburized gears contains harmful metal elements in mass percent of Sn: less than or equal to 0.010 percent; pb: less than or equal to 0.0100%; bi: less than or equal to 0.0100%; as is less than or equal to 0.015 percent; sb is less than or equal to 0.0030 percent; the total content of As, Sn, Pb, Sb and Bi is less than or equal to 0.030 percent by mass.
The patent also discloses a preparation method of the steel material for the carburized gear, which comprises the following steps: c is prepared from the following chemical components in percentage by mass: 0.20-0.22%; si: 0.17-0.37%; mn: 1.0-1.2%; mo: 0.25-0.30%; ni: 0.10-0.30%; cr: 1.30-1.40%; ti is less than or equal to 0.010 percent; cu is less than or equal to 0.10 percent; 0.018-0.03% of Al; v, smelting steel with the ratio of less than or equal to 0.03 percent by adopting an electric arc furnace, then refining outside the furnace, carrying out vacuum degassing, casting a steel ingot and forging, wherein the ratio of the section of the steel ingot to the cross section of a final forged piece is more than or equal to 4.
Preferably, the forgings after normalizing treatment are not allowed to have Widmannstatten structures, and the banded structures are required to be less than or equal to 2.0 grade.
Preferably, the cross section acid leaching macroscopic test piece of the forging cannot have visible defects of residual shrinkage cavity, air bubble, crack, inclusion, peeling, white point and the like, and the macroscopic structure of the forging has the following requirements: the central porosity is less than or equal to 1.5 grade; the general looseness is less than or equal to 1.5 grade; ingot type segregation is less than or equal to 1.5 grade; the center segregation is less than or equal to 1.5 grade; the general spot-like segregation and the edge spot-like segregation are not allowed to occur.
Preferably, the heat treatment of the forged piece made of the steel material for the carburized gear comprises the following steps:
1) preheating treatment: heating the workpiece to 800 +/-10 ℃ at a certain heating rate, and preserving heat for 1-2 hours;
2) carburizing: heating the preheated workpiece to 920 +/-10 ℃ at a certain heating rate for carburizing, wherein the carburizing is divided into a strong carburizing stage and a diffusion stage, the carbon potential in the strong carburizing stage is 1.10-1.20 percent and reaches 70-80 percent of the set depth of a carburized layer, and the carbon potential in the diffusion stage is 0.85-0.90 percent and reaches the set depth of the carburized layer;
3) air cooling treatment: cooling the carburized workpiece to 850 +/-10 ℃, and then discharging the workpiece out of the furnace for air cooling for 2-3 hours;
4) high-temperature tempering treatment: heating the workpiece subjected to air cooling treatment to 650 +/-10 ℃ for heat preservation for 2-4 hours;
5) quenching treatment: heating the workpiece to 840 +/-10 ℃, preserving heat for 3-5 hours, and then putting the workpiece into quenching oil for quenching treatment;
6) low-temperature tempering treatment: and (3) heating the quenched workpiece to 200 +/-5 ℃ for tempering for 8-10 hours.
Preferably, the workpiece in the step 5) is put into rapid bright quenching oil at 65 +/-5 ℃ for quenching treatment.
The technical scheme has the following beneficial effects:
1) the steel material for the carburized gear accurately controls the mass percent of beneficial alloy elements, simultaneously increases the requirements on five harmful alloy elements and AL/N, reduces the content of S, P, H, O harmful elements, effectively improves the hardenability and mechanical property, and has the hardness of 33HRC at the position 40mm away from the end surface as shown by an end quenching test, and after quenching (840 ℃) and tempering (200 ℃) by using a test bar with phi 57, the steel material has normal temperature impact energy KV2The average value is 50J, the tensile strength is more than or equal to 1180MPa, the yield strength is more than or equal to 885MPa, the reduction of area is more than or equal to 10 percent, the elongation is more than or equal to 45 percent, and the mechanical property is excellent;
2) the smelting mode and the forging ratio of the forging piece and the grain size, the microstructure, the macrostructure, the nonmetallic inclusion and the microstructure of the part after the forging normalizing are precisely required, so that the stability of the quality of the raw material is ensured;
3) the steel material for the carburized gear tends to the comprehensive performance of 18CrNiMo7-6, but the price of the raw material is only about 85-90% of that of the 18CrNiMo7-6 material, so that the production cost can be effectively reduced.
Detailed Description
Example embodiments will now be described more fully below. Example embodiments may, however, be embodied in many different forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of example embodiments to those skilled in the art. The described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to provide a thorough understanding of embodiments of the invention. One skilled in the relevant art will recognize, however, that the invention may be practiced without one or more of the specific details, or with other methods, components, devices, steps, and so forth. In other instances, well-known technical solutions have not been shown or described in detail to avoid obscuring aspects of the invention.
The first embodiment is as follows:
the embodiment discloses a steel material for a carburized gear, which comprises the following chemical components in percentage by mass: 0.20 percent; si: 0.17 percent; mn: 1.0 percent; mo: 0.25 percent; ni: 0.10 percent; cr: 1.30 percent; 0.010 percent of Ti; 0.10 percent of Cu; 0.018% of Al; 0.03 percent of V; the balance of Fe and inevitable impurities. The carbon in the steel material can improve the hardenability and the strength and the hardness of the product, and the manganese can strongly improve the hardenability of the steel and is an important strengthening and toughening element, so that the percentage content interval of the manganese is correspondingly adjusted according to the use condition; molybdenum can improve hardenability and heat strength and prevent temper brittleness; nickel can improve hardenability, is a common strengthening element, and has small damage to the plastic toughness of steel while improving the strength; chromium can improve hardenability and is an important strengthening and toughening element, titanium can play a role in improving hardenability and refining grains, and copper has a function of reducing the toughness of steel in certain environments, so that the mass percent of copper cannot be too high; aluminum contributes to grain refinement, wherein the mass ratio of Al to N is 2 to 4, which further improves the toughness of the steel, while vanadium serves to improve hardenability and toughness and to refine grains.
As a preferred embodiment, because sulfur and phosphorus are elements harmful to toughness, the content is better, and P is less than or equal to 0.015 percent and S is less than or equal to 0.012 percent by mass in the impurities of the invention; according to mass fraction, H is less than or equal to 1.8 ppm; o is less than or equal to 18 ppm; n is less than or equal to 80 ppm. The five harmful metal elements comprise, by mass, not more than 0.010% of Sn, not more than 0.0100% of Pb, not more than 0.0100% of Bi, not more than 0.015% of As, not more than 0.0030% of Sb, and not more than 0.030% of total content of As, Sn, Pb, Sb and Bi.
The preparation method of the steel material for the carburized gear comprises the following steps: firstly, the paint comprises the following chemical components in percentage by mass: c: 0.20 percent; mn: 1.0 percent; mo: 0.25 percent; ni: 0.10 percent; cr: 1.30 percent; 0.010 percent of Ti; 0.10 percent of Cu; 0.018% of Al; 0.03 percent of V, the invention accurately controls the ranges of the chemical compositions in percentage by mass, and also accurately requires the smelting mode and the forging ratio of a forging piece and the grain size, the microstructure, the macrostructure, the nonmetallic inclusion and the microstructure of a part after normalizing. The method specifically comprises the following steps:
1) smelting method
Adopting the modes of electric arc furnace smelting (EAF), external refining (LF) and vacuum degassing (RH), firstly adopting the electric arc furnace smelting, then carrying out the external refining, carrying out the vacuum degassing, casting a steel ingot and forging.
2) Deformation ratio
The ratio of the cross section of the steel ingot to the cross section of the final forged piece is as follows: forging ratio is more than or equal to 4
3) Microstructure of
The forgings after normalizing treatment are not allowed to have Widmannstatten structures, and the banded structures are required to be less than or equal to 2.0 grade.
4) Low power
The cross section of the forged piece is subjected to acid leaching, and the defects of residual shrinkage cavity, air bubble, crack, inclusion, peeling, white spot and the like which are visible are avoided. Macroscopic tissue requirements: the central porosity is less than or equal to 1.5 grade; the general looseness is less than or equal to 1.5 grade; ingot type segregation is less than or equal to 1.5 grade; the center segregation is less than or equal to 1.5 grade; general spotted segregation and edge spotted segregation are not allowed to occur, and the rating is in accordance with GB/T1979.
5) Non-metallic inclusions
The non-metallic inclusion is tested according to GB/T10561 standard A method, and the qualified grade of the non-metallic inclusion accords with the regulation of table 1.
TABLE 1 non-metallic inclusion grade requirement (Unit: grade)
6) Grain size of finished product
The actual grain size is finer than grade 6 according to the detection of the GB/T6394 standard. Grains coarser than 3.0 order are not allowed to occur.
7) The heat treatment process comprises the following steps:
firstly, preheating is carried out, the workpiece is heated to 800 +/-10 ℃ at the heating rate of not more than 150 ℃/h, and the temperature is kept for 1-2 hours, generally 1 hour, so that the gear workpiece is uniformly heated, the thermal stress in the workpiece is reduced, and larger deformation is avoided. Then carrying out carburizing treatment, heating the preheated workpiece to 920 +/-10 ℃ at a heating rate of not more than 150 ℃/h for carburizing, wherein the carburizing is divided into a strong carburizing stage and a diffusion stage, the carbon potential in the strong carburizing stage is 1.10-1.20%, the carburizing degree reaches 70-80% of the set depth of a carburized layer, the carbon potential in the diffusion stage is 0.85-0.90%, and the set depth of the carburized layer is reached; and then cooling the carburized workpiece to 850 +/-10 ℃, and then discharging the workpiece out of the furnace for air cooling for 2-3 hours. Because the carburization time of the large gear workpiece is longer, the growth trend of crystal grains is obvious, and the influence of deformation is considered, the large gear workpiece is cooled to 850 ℃ and then discharged from the furnace for air cooling, so that the deformation is ensured to be in a reasonable range, and the purpose of refining the crystal grains is achieved.
And (3) performing high-temperature tempering treatment on the workpiece subjected to air cooling, heating to 650 +/-10 ℃ at a heating rate of not more than 150 ℃/h, and performing heat preservation treatment for 2-4 hours to eliminate the carburized layer reticular carbide, spheroidize the carbide and eliminate internal stress, so that the wear resistance of the product is improved, and the service life of the product is prolonged.
Then quenching treatment is carried out, the workpiece is heated to 840 +/-10 ℃ at the heating rate of not more than 150 ℃/h, and the temperature is kept for 4 h. Then putting the workpiece into 65 +/-5 ℃ quick bright quenching oil for quenching, wherein the structure transformation process of the workpiece is that pearlite is transformed into austenite, the austenite is transformed into martensite, and carbide permeates into the austenite in the quenching and heating stage, so that the high strength and the high hardness of the quenched martensite are ensured, and the comparison shows that the quenching performance at 840 ℃ is optimal. And finally, low-temperature tempering treatment is carried out, the workpiece is heated to 200 ℃ again, the tempering treatment is carried out, tests show that after the workpiece is tempered for three times at 200 ℃, the retained austenite on the surface is decomposed into martensite, the heat treatment stress is eliminated, the high hardness of the surface of the gear is met, the toughness of the core is improved, and the effect is optimal.
The heat treatment process can effectively improve the comprehensive performance of the steel for gear carburizing, and the heat treatment process is adopted to carry out heat treatment on the large gear, and the obtained technical parameters are as follows: the surface hardness is 60-62 HRC, the core hardness is 32-37 HRC, the surface martensite and residual austenite grades are 1-3, and the core structure is 1-3. The technical requirements in the industry are as follows: surface hardness is 58-62 HRC, core hardness is 28-32 HRC, surface martensite and retained austenite grades are 1-4, and core structure is 1-4. Compared with the technical parameters in the industry, the method has the advantages that the technical parameters are greatly improved; quenching with a test bar with phi 57 and carrying out furnace treatment, wherein the mechanical properties are as follows: the average value of normal-temperature impact energy KV2 is 50J, the tensile strength is more than or equal to 1180MPa, the yield strength is more than or equal to 950MPa, the reduction of area is more than or equal to 15%, the elongation is more than or equal to 60%, and the mechanical property is excellent.
Example two:
in the embodiment, the steel material for the carburized gear consists of the following chemical components in percentage by mass: 0.22 percent; si: 0.37 percent; (ii) a Mn: 1.2 percent; mo: 0.30 percent; ni: 0.30 percent; cr: 1.40 percent; 0.005 percent of Ti; 0.08 percent of Cu; 0.03 percent of Al; 0.02 percent of V; the balance of Fe and inevitable impurities. Wherein the impurities comprise P less than or equal to 0.015 percent and S less than or equal to 0.012 percent according to the mass percentage; h is less than or equal to 1.8ppm by weight; o is less than or equal to 18 ppm; n is less than or equal to 80 ppm. The five harmful metal elements comprise, by mass, not more than 0.010% of Sn, not more than 0.0100% of Pb, not more than 0.0100% of Bi, not more than 0.015% of As, not more than 0.0030% of Sb, and not more than 0.030% of total content of As, Sn, Pb, Sb and Bi.
The preparation method in this embodiment is basically similar to that in the first embodiment, and the alloy ratio needs to be adjusted accordingly, so detailed description is omitted here.
Example three:
in the embodiment, the steel material for the carburized gear consists of the following chemical components in percentage by mass: c: 0.21 percent; si: 0.25 percent; mn: 1.1 percent; mo: 0.27 percent; ni: 0.20 percent; cr: 1.35 percent; 0.003 percent of Ti; 0.05 percent of Cu; 0.024 percent of Al; 0.01 percent of V; the balance of Fe and inevitable impurities. Wherein the impurities comprise P less than or equal to 0.015 percent and S less than or equal to 0.012 percent according to the mass percentage; h is less than or equal to 1.8ppm by weight; o is less than or equal to 18 ppm; n is less than or equal to 80 ppm. The five harmful metal elements comprise, by mass, not more than 0.010% of Sn, not more than 0.0100% of Pb, not more than 0.0100% of Bi, not more than 0.015% of As, not more than 0.0030% of Sb, and not more than 0.030% of total content of As, Sn, Pb, Sb and Bi.
The preparation method in this embodiment is basically similar to that in the first embodiment, and the alloy ratio needs to be adjusted accordingly, so detailed description is omitted here.
1) The steel material for the carburized gear accurately controls the mass percent of beneficial alloy elements, simultaneously increases the requirements on five harmful alloy elements and AL/N, reduces the content of S, P, H, O harmful elements, effectively improves the hardenability and mechanical property, and has the hardness of 33HRC at the position 40mm away from the end surface as shown by an end quenching test, and after quenching (840 ℃) and tempering (200 ℃) by using a test bar with phi 57, the steel material has normal temperature impact energy KV2The average value is 50J, the tensile strength is more than or equal to 1180MPa, the yield strength is more than or equal to 885MPa, the reduction of area is more than or equal to 10 percent, the elongation is more than or equal to 45 percent, and the mechanical property is excellent;
2) the smelting mode and the forging ratio of the forging piece and the grain size, the microstructure, the macrostructure, the nonmetallic inclusion and the microstructure of the part after the forging normalizing are precisely required, so that the stability of the quality of the raw material is ensured;
3) the steel material for the carburized gear tends to the comprehensive performance of 18CrNiMo7-6, but the price of the raw material is only about 85-90% of that of the 18CrNiMo7-6 material, so that the production cost can be effectively reduced.
The foregoing embodiments are merely illustrative of the principles of the present invention and its efforts and are not to be construed as limiting the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.
Claims (10)
1. The steel material for the carburized gear is characterized by comprising the following chemical components in percentage by mass:
C：0.20-0.22%；
Si：0.17-0.37%；
Mn：1.0-1.2%；
Mo：0.25-0.30%；
Ni：0.10-0.30%；
Cr：1.30-1.40%；
Ti: ≤0.010%；
Cu: ≤0.10%；
Al: 0.018-0.03%；
V: ≤0.03%；
the balance of Fe and inevitable impurities.
2. The steel material for a carburized gear according to claim 1, wherein impurities in the steel material for a carburized gear include, in mass percentage, P ≤ 0.015%, and S ≤ 0.012%.
3. The steel material for a carburized gear according to claim 1, characterized in that impurities in the steel material for a carburized gear include H1.8 ppm or less in mass fraction; o is less than or equal to 18 ppm; n is less than or equal to 80 ppm.
4. The steel material for a carburized gear according to claim 1, wherein a mass ratio of Al to N in the steel material for a carburized gear is 2 to 4.
5. The steel material for a carburized gear according to claim 1, characterized in that a harmful metal element in the steel material for a carburized gear includes, in mass percent, Sn: less than or equal to 0.010 percent; pb: less than or equal to 0.0100%; bi: less than or equal to 0.0100%; as is less than or equal to 0.015 percent; sb is less than or equal to 0.0030 percent; the total content of As, Sn, Pb, Sb and Bi is less than or equal to 0.030 percent by mass.
6. A preparation method of a steel material for a carburized gear is characterized by comprising the following steps:
according to the following chemical components in percentage by mass C: 0.20-0.22%; si: 0.17-0.37%; mn: 1.0-1.2%; mo: 0.25-0.30%; ni: 0.10-0.30%; cr: 1.30-1.40%; ti is less than or equal to 0.010 percent; cu is less than or equal to 0.10 percent; 0.018-0.03% of Al; v, smelting steel by using an alloy with the concentration of less than or equal to 0.03%, smelting by using an electric arc furnace, then refining outside the furnace, carrying out vacuum degassing, casting a steel ingot and forging, wherein the ratio of the section of the steel ingot to the cross section of a final forged piece is more than or equal to 4.
7. The method for producing a steel material for a carburized gear according to claim 6, characterized in that the forging after the normalizing treatment is not allowed to have a widmannstatten structure, and a ribbon structure is required to be not more than 2.0 grade.
8. The method for producing a steel material for a carburized gear according to claim 6, characterized in that defects such as residual shrinkage cavities, bubbles, cracks, inclusions, flaking, white spots, and the like, which are visible visually, are not found on the cross-sectional acid-dipped macroscopic test piece of the forging, and the macroscopic structure of the forging is required to be: the central porosity is less than or equal to 1.5 grade; the general looseness is less than or equal to 1.5 grade; ingot type segregation is less than or equal to 1.5 grade; the center segregation is less than or equal to 1.5 grade; the general spot-like segregation and the edge spot-like segregation are not allowed to occur.
9. The method for producing a steel material for a carburized gear according to claim 6, characterized in that the heat treatment of a forged piece using the steel material for a carburized gear comprises the steps of:
1) preheating treatment: heating the workpiece to 800 +/-10 ℃ at a certain heating rate, and preserving heat for 1-2 hours;
2) carburizing: heating the preheated workpiece to 920 +/-10 ℃ at a certain heating rate for carburizing, wherein the carburizing is divided into a strong carburizing stage and a diffusion stage, the carbon potential in the strong carburizing stage is 1.10-1.20 percent and reaches 70-80 percent of the set depth of a carburized layer, and the carbon potential in the diffusion stage is 0.85-0.90 percent and reaches the set depth of the carburized layer;
3) air cooling treatment: cooling the carburized workpiece to 850 +/-10 ℃, and then discharging the workpiece out of the furnace for air cooling for 2-3 hours;
4) high-temperature tempering treatment: heating the workpiece subjected to air cooling treatment to 650 +/-10 ℃ for heat preservation for 2-4 hours;
5) quenching treatment: heating the workpiece to 840 +/-10 ℃, preserving heat for 3-5 hours, and then putting the workpiece into quenching oil for quenching treatment;
6) low-temperature tempering treatment: and (3) heating the quenched workpiece to 200 +/-5 ℃ for tempering for 8-10 hours.
10. The method for producing a steel material for a carburized gear according to claim 9, characterized in that in step 6), the workpiece is put in a rapid bright quenching oil at 65 ± 5 ℃ to be quenched.
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| CN112831723A (en) * | 2020-12-31 | 2021-05-25 | 钢铁研究总院 | High-temperature carburization resistant gear steel with large crystal grains and control method |
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| CN115011911A (en) * | 2022-08-08 | 2022-09-06 | 苏州亚太精睿传动科技股份有限公司 | Method for controlling heat treatment deformation of large-modulus gear |
| CN115011882A (en) * | 2022-08-08 | 2022-09-06 | 苏州亚太精睿传动科技股份有限公司 | Efficient and energy-saving heat treatment method applied to gear |
| WO2022228216A1 (en) * | 2021-04-29 | 2022-11-03 | 宝山钢铁股份有限公司 | Steel for high-temperature carburized gear shaft and manufacturing method for steel |
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