CN111979494B - Ti-containing carburizing steel for thin-wall annular gear, manufacturing method thereof and thin-wall annular gear forming method - Google Patents
Ti-containing carburizing steel for thin-wall annular gear, manufacturing method thereof and thin-wall annular gear forming method Download PDFInfo
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- 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
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- 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
- C23C8/80—After-treatment
Abstract
The invention discloses a Ti-containing carburizing steel for a thin-wall ring gear, a manufacturing method thereof and a forming method of the thin-wall ring gear, wherein the Ti-containing carburizing steel for the thin-wall ring gear comprises the following chemical components in percentage by mass: 0.15-0.30% of C, 0.90-1.40% of Mn, less than or equal to 0.035% of P, 0.015-0.045% of S, 0.90-1.40% of Cr, 0.015-0.035% of Al, less than or equal to 0.25% of Si, 0.010-0.030% of Ti, 0.02-0.04% of Nb, less than or equal to 0.0015% of O, 0.012-0.017% of N, less than or equal to 0.20% of Ni, 0.10-0.20% of Cu, less than or equal to 0.06% of Mo, less than or equal to 0.04% of V, and the balance of Fe and inevitable impurities. The thin-wall inner gear ring can not cause the reduction of local hardenability, has small fluctuation of the hardenability of materials, has uniform deformation of parts subjected to subsequent heat treatment, and can effectively control the heat treatment deformation of the inner thin-wall gear ring.
Description
Technical Field
The invention belongs to the technical field of metallurgy and manufacturing of inner gear rings, and particularly relates to a Ti-containing carburizing steel for a thin-wall inner gear ring, a manufacturing method thereof and a thin-wall inner gear ring forming method.
Background
The domestic heavy gearbox mostly adopts a planet auxiliary box structure, an inner gear ring of the auxiliary box is a thin-wall annular part, the outer diameter is phi 277mm, the wall thickness is 22mm, the width is 104mm, as shown in figure 2, the roundness and the taper are required to be controlled within 0.10mm, the tooth direction fH beta is not more than 50 mu m, the carburizing heat treatment deformation is large, and the domestic widely applied carburizing steel 20CrMnTiH series cannot meet the requirements. Wherein GB/T5216 stipulates the mass percent (%) of alloy elements of the material: 0.17-0.22 percent of C, less than or equal to 0.37 percent of Si, 1.10-1.40 percent of Mn, 1.00-1.30 percent of Cr, 0.04-0.10 percent of Ti, less than or equal to 0.035 percent of residual elements, less than or equal to 0.035 percent of S, less than or equal to 0.25 percent of Cu, less than or equal to 0.30 percent of Ni, and austenite grain size not less than 5 grades.
The Mn-Cr-Ti series carburizing steel in the standard CGMA001-1 formulated by the China Gear professional Association specifies the alloy elements by mass percent (%): 0.17-0.23 percent of C, less than or equal to 0.12 percent of Si, 1.10-1.50 percent of Mn, 1.00-1.30 percent of Cr, 0.04-0.10 percent of Ti, less than or equal to 0.030 percent of residual elements P, 0.02-0.35 percent of S, less than or equal to 0.20 percent of Cu, less than or equal to 0.30 percent of Ni, and austenite grain size not less than 5 grade. Because Ti content in steel is high, Ti and N are easy to form high-melting-point large-particle liquated TiN, and the TiN is easily formed into banded segregation due to the influence of factors such as Ti adding process, mode and the like, so that the reliability of parts is reduced. Austenite Ti forms TiC easily with C, solid solution carbon atoms in a local austenite region are reduced, hardenability is reduced, the particles are used as austenite decomposition nucleation, austenite stability is reduced, austenite transformation is accelerated, hardenability is reduced, and the material hardenability is uneven, so that part heat treatment deformation is increased and is difficult to control.
The Chinese invention patent CN101275204A discloses Cr-Mn-Ti gear steel and a preparation method thereof, wherein the alloy elements are as follows: 0.17-0.23% of C, 0.17-0.37% of Si, 0.8-1.15% of Mn, 1.00-1.35% of Cr, 0.01-0.0.38% of Ti, less than or equal to 20ppm of oxygen content and 30-120 ppm of N content, so that the Ti content is reduced, but the equilibrium concentration product of TiN in molten steel is not controlled in the smelting process, and liquated TiN particles are still generated in the casting process, so that the reliability of the material is influenced.
The thin-wall annular parts are molded by ring rolling in China, and then isothermal normalizing process by using isothermal normalizing or forging waste heat isothermal normalizing process is adopted. By controlling the isothermal normalizing process parameters, the pearlite transformation is carried out at the isothermal temperature to obtain the pearlite + ferrite with uniform equiaxial, which is convenient for subsequent cutting and processing and reduces the heat treatment deformation. Due to the influence of factors such as chemical composition of materials, metallurgical segregation, forming modes and the like, metallographic structures formed by all parts of the forging stock are difficult to be uniform, and hardness dispersion is larger than HB10, so that heat treatment deformation of parts in the subsequent carburizing process is difficult to control. A continuous furnace carburizing and pressure quenching process is adopted for thin-wall ring parts in China, the diffusion temperature of the carburizing heat treatment process is 870-890 ℃, the carbon potential is controlled to be 0.85%, and the pressure quenching temperature is 860 ℃, so that the part deformation is easily caused.
In summary, the thin-wall ring gear material in the prior art has the following disadvantages: (1) the thin-wall annular gear has high Ti content, so that the material has large hardenability fluctuation and large-particle liquated TiN. (2) The forging stock pretreatment adopts an isothermal normalizing process or a forging waste heat isothermal normalizing process, the tissues of all parts of the forging are not uniform, and the hardness dispersion is greater than HB 10. (3) The thin-wall ring piece adopts a continuous furnace carburizing and pressure quenching process, and the diffusion temperature and the carbon potential of the carburizing heat treatment are high, so that the residual austenite content on the surface of the part is high, the pressure quenching temperature is high, and the heat treatment deformation is large.
Disclosure of Invention
The invention aims to solve the defects of the background technology and provides a Ti-containing carburizing steel for a thin-wall ring gear, a manufacturing method thereof and a thin-wall ring gear forming method.
In order to achieve the purpose, the invention adopts the technical scheme that: the Ti-containing carburizing steel for the thin-wall annular gear comprises the following chemical components in percentage by mass: 0.15-0.30% of C, 0.90-1.40% of Mn, less than or equal to 0.035% of P, 0.015-0.045% of S, 0.90-1.40% of Cr, 0.015-0.035% of Al, less than or equal to 0.25% of Si, 0.010-0.030% of Ti, 0.02-0.04% of Nb, less than or equal to 0.0015% of O, 0.012-0.017% of N, less than or equal to 0.20% of Ni, 0.10-0.20% of Cu, less than or equal to 0.06% of Mo, less than or equal to 0.04% of V, and the balance of Fe and inevitable impurities.
In a preferred embodiment, the Ti-containing carburizing steel for the thin-wall ring gear comprises the following chemical components in percentage by mass: 0.19-0.21% of C, 1.05-1.10% of Mn1.05%, not more than 0.017% of P, 0.025-0.026% of S, 1.19-1.24% of Cr, 0.020-0.025% of Al, 0.022-0.026% of Ti, 0.021-0.022% of Nb0.012, 0.014% of N, 0.20% or less of Ni, 0.074-0.13% of Cu, 0.06% or less of Mo, 0.04% or less of V, and the balance of Fe and inevitable impurities.
The invention also provides a manufacturing method of the Ti-containing carburizing steel for the thin-wall ring gear, which comprises the following steps:
1) primary smelting: controlling the furnace temperature to 1620-1670 ℃, pre-deoxidizing before tapping, tapping at 1600-1650 ℃, and adding synthetic slag;
2) LF refining: reducing the content of O, S and inclusions in molten steel, wherein O is less than or equal to 0.0015%, S is less than or equal to 0.045%, the temperature is controlled to be 1520-1620 ℃, N is less than or equal to 0.006% in a ladle, and refining is carried out for 30-50 min;
3) Rh/vD vacuum: the vacuum degree is less than 140ppm, N in the steel ladle is less than or equal to 0.006 percent, the temperature is controlled to 1530-1650 ℃, and the vacuum time is 15-25 min;
4) continuous casting: protecting and pouring the ladle to a tundish long nozzle, protecting a tundish liquid surface covering agent, and controlling the superheat degree of tundish molten steel at 15-25 ℃;
5) rolling: the heating temperature is 1130-1250 ℃, the time is 2-4 h, the initial rolling temperature is 1100-1200 ℃, and the final rolling temperature is not less than 860 ℃.
In the technical scheme, in the step 2), the Ti wire is fed 5-10 min before tapping, the content of Ti is controlled to be 0.010-0.030%, and Nb is added, and the content is controlled to be 0.02-0.04%.
In the technical scheme, in the step 3), the content of [ Ti ] [ N ] is controlled to be less than or equal to 0.00033, and MnN is added so that the content of N reaches 0.012-0.017%.
In the technical scheme, in the step 4), the pouring is protected by a submerged nozzle from the tundish to the crystallizer, the liquid level of the crystallizer is used for protecting slag, the pulling speed of the steel billet is 1.1-1.20 m/min, and the process adopts dynamic soft reduction.
The invention also provides a method for forming the thin-wall annular gear, which comprises the following steps:
1) ring rolling and forming: blanking the thin-wall annular gear by using Ti-containing carburizing steel, carrying out induction heating at 1100-1250 ℃, and carrying out upsetting, punching and ring rolling forming;
2) quenching by grinding ring waste heat: quenching treatment at the temperature of not lower than 880 ℃ after ring rolling and forming;
3) high-temperature tempering: heating to 710-740 ℃, preserving heat for 1.5-2 h, discharging from the furnace, cooling to room temperature, and transforming the structure into spherical pearlite;
4) gear hobbing: turning the inner circle, the outer circle and the end face of the annular forging, processing an inner wall annular groove, and precisely inserting the inner rolling teeth;
5) carburizing and heat treating, and pressure quenching: carburizing heat treatment and pressure quenching are carried out by adopting a continuous furnace, and then tempering is carried out at the temperature of 145-180 ℃.
In the above technical scheme, in the step 2), the quenching medium is PAG water-based quenching agent or quenching oil, the structure is transformed into martensite or bainite, and the oxide skin is removed by shot blasting.
In the above technical scheme, in the step 4), the roundness and taper of the inner gear ring are controlled within 0.05mm, and the tooth direction fH beta is not more than 20 μm.
In the above technical scheme, in the step 5), the carburizing heat treatment pressure quenching specifically comprises the following steps: pre-oxidation treatment is carried out at 460-500 ℃, strong infiltration treatment is carried out at 900-920 ℃, the carbon potential is 0.9-1.0%, high-temperature diffusion is carried out at 860-880 ℃, the carbon potential is 0.65-0.75%, low-temperature diffusion is carried out at 830-850 ℃, the carbon potential is 0.65-0.70%, and pressure quenching is carried out at 810-830 ℃.
Compared with the prior art, the method has the following beneficial effects:
firstly, the content of Ti in steel is reduced by 0.010-0.030%, the [ Ti ] [ N ] solid solution is controlled to be not more than 0.00033 in the smelting process, the problem of large-particle TiN liquation is solved, Ti is precipitated above 1200 ℃ of austenite, micro TiN is precipitated, Ti and C are not combined below 1200 ℃, the local hardenability is not reduced, the hardenability fluctuation of materials is small, and the deformation of parts subjected to subsequent heat treatment is uniform.
Secondly, ring rolling waste heat quenching can enable an austenitized ring blank to be quenched from an austenitizing temperature, different from an isothermal normalizing process and ring rolling waste heat isothermal normalizing, the quenched structure is completely transformed into martensite or bainite, the structure distribution is more uniform, high-temperature tempering at 710-740 ℃ is adopted after quenching, the temperature is kept for 1.5-2 h, then the ring rolling waste heat quenching furnace is taken out of the furnace and cooled to room temperature, the structure is transformed into uniform spherical pearlite, the hardness is HB 175-190, the ring rolling waste heat quenching method is more suitable for subsequent cutting processing, the hardness dispersion is not larger than HB8, and the carburization heat treatment deformation is smaller.
Thirdly, the thin-wall ring gear adopts continuous furnace carburization and pressure quenching, high-temperature diffusion at 860-880 ℃, carbon potential is 0.65-0.75%, residual austenite on the surface of a quenched part is reduced, surface hardness is improved to be not less than HRC60, pressure quenching is carried out at a temperature slightly lower than that of a two-phase region of AC3, a small amount of ferrite is separated out in the center of the ring gear before quenching, and heat treatment deformation is reduced.
Fourthly, the invention obviously improves the tissue uniformity of each part after the carburization and quenching of the part, and effectively controls the heat treatment deformation.
Fifthly, the process for manufacturing the thin-wall inner gear ring by using the Ti-containing carburizing steel reduces the fluctuation of hardenability of materials and reduces the heat treatment deformation of parts.
Sixthly, the process for manufacturing the thin-wall annular gear by using the Ti-containing carburizing steel enables metallographic structures of different parts of a forging stock to be more consistent and forms a fine and uniform spheroidized pearlite structure;
seventhly, the thin-wall annular gear part achieves the requirements that the roundness and the taper are controlled within 0.10mm, and the tooth direction fH beta is not more than 50 mu m.
Drawings
FIG. 1 is a flow chart of a method for forming a thin-walled ring gear;
FIG. 2 is a front view structural schematic diagram of a gearbox ring gear of embodiment 1;
FIG. 3 is a schematic perspective view of a ring gear of the transmission according to embodiment 1;
in the figure, 1-gearbox ring gear.
Detailed Description
The present invention will be described in further detail with reference to specific examples to facilitate the clear understanding of the invention, but the present invention is not limited thereto.
Example 1:
and (3) carrying out carburizing and pressure quenching production on the inner gear ring of the auxiliary box of a certain heavy gearbox, wherein the depth of a carburized process layer is required to be 0.8-1.1 mm.
The thin-wall inner gear ring of the embodiment is made of Ti-containing carburizing steel, and comprises the following chemical components in percentage by mass: : 0.19 percent of C, 0.21 percent of Si, 1.05 percent of Mn, 0.016 percent of P, 0.026 percent of S, 1.19 percent of Cr, 0.020 percent of Al, 0.025 percent of Ti, 0.021 percent of Nb0.021 percent, less than or equal to 0.0015 percent of O, 0.012 percent of N, 0.030 percent of Ni, 0.13 percent of Cu, less than or equal to 0.06 percent of Mo, less than or equal to 0.04 percent of V, and the balance of Fe and inevitable impurities.
As shown in fig. 1, the method for manufacturing the Ti-containing carburized steel for a thin-walled ring gear of the present embodiment includes the steps of:
1) primary smelting: an electric furnace or a converter is adopted, the furnace temperature is controlled at 1650 ℃, pre-deoxidation is carried out before tapping, tapping is carried out at 1620 ℃, and synthetic slag is added.
2) LF refining: the content of O, S and inclusions in molten steel is reduced, O is less than or equal to 0.0015%, S is not more than 0.04%, the temperature is controlled to be 1600 ℃, N in a steel ladle is less than or equal to 0.006%, Ti wires are fed 8min before steel tapping for 40min of refining, the content of Ti is controlled to be 0.020-0.026%, Nb is added, the content is controlled to be 0.02-0.04%, and steel tapping is performed.
3) Rh/vD vacuum: the vacuum degree is less than 140ppm, N in the ladle is less than or equal to 0.006 percent, the temperature is controlled to be 1600 ℃, the vacuum time is 20min, and the [ Ti ] [ N ] is controlled to be less than or equal to 0.00033, and the MnN is added to ensure that the N content reaches 0.012 percent.
4) Continuous casting: the ladle is poured to a tundish long nozzle in a protection way, a tundish liquid surface covering agent is used for protection, and the superheat degree of tundish molten steel is controlled at 20 ℃. Pouring is protected by a submerged nozzle from a tundish to a crystallizer for pouring, slag is protected on the liquid surface of the crystallizer, the pulling speed of a steel billet is 1.1m/min, and dynamic soft reduction is adopted in the process.
5) Rolling: the billet or steel ingot is heated to the uniform temperature of 1200 ℃ for 3h, the initial rolling temperature is 1150 ℃, and the final rolling temperature is not less than 860 ℃.
As shown in fig. 2 to 3, the method for forming the thin-wall ring gear of the present invention includes the following steps:
heating the Ti-containing carburizing steel to 1200 ℃, and performing upsetting, punching and ring rolling forming, wherein the temperature of ring rolling is not lower than 880 ℃ for oil quenching; heating the parts to 710 ℃ within 1 hour after quenching, keeping the temperature for 2 hours, discharging from the furnace, cooling to room temperature, and converting the structure into spherical pearlite with the hardness of HB 175-180 and the hardness dispersion of HB 5. And turning the inner circle, the outer circle and the end face of the annular forging, machining an inner wall annular groove, and precisely inserting rolling internal teeth, wherein the roundness and the taper are within 0.05mm, and the tooth direction fH beta is 20-25 mu m. Adopting a continuous furnace for carburizing: placing the part into a furnace, carrying out pre-oxidation treatment at 470 ℃, carrying out forced infiltration treatment at 915 ℃, carrying out carbon potential 1.0%, high-temperature diffusion at 880 ℃, carbon potential 0.75%, low-temperature diffusion at 850 ℃, carbon potential 0.65%, reducing temperature 830 ℃, carrying out pressure quenching, and carrying out quenching medium Derungbao MARQUENCH729, temperature 120 ℃ and tempering temperature 170 ℃.
Example 2:
and (3) carrying out carburizing and pressure quenching production on the inner gear ring of the auxiliary box of a certain heavy gearbox, wherein the depth of a carburized process layer is required to be 0.8-1.1 mm.
The thin-wall inner gear ring of the embodiment is made of Ti-containing carburizing steel, and comprises the following chemical components in percentage by mass: 0.21% of C, 0.24% of Si, 1.10% of Mn, 0.017% of P, 0.025% of S, 1.24% of Cr, 0.25% of Al, 0.022% of Ti, 0.022% of Nb, less than or equal to 0.0015% of O, 0.015% of N, 0.040% of Ni, 0.074% of Cu, less than or equal to 0.06% of Mo, less than or equal to 0.04% of V, and the balance of Fe and inevitable impurities.
The manufacturing method of the Ti-containing carburizing steel for the thin-wall ring gear of the embodiment includes the following steps:
1) primary smelting: an electric furnace or a converter is adopted, the furnace temperature is controlled at 1650 ℃, pre-deoxidation is carried out before tapping, tapping is carried out at 1620 ℃, and synthetic slag is added.
2) LF refining: the contents of O, S and inclusions in molten steel are reduced, O is less than or equal to 0.0015 percent, S is not more than 0.04 percent, the temperature is controlled at 1600 ℃, N in a ladle is less than or equal to 0.006 percent, Ti wires are fed 8min before 40min of steel tapping in refining, the content of Ti is controlled to be 0.020-0.024 percent, Nb is added, the content is controlled to be 0.022 percent, and steel is tapped.
3) Rh/vD vacuum: the vacuum degree is less than 140ppm, N in the steel ladle is less than or equal to 0.006 percent, the temperature is controlled to be 1600 ℃, the vacuum time is 20min, and the [ Ti ] [ N ] is controlled to be less than or equal to 0.00033, and the MnN is added to ensure that the N content reaches 0.015 percent.
4) Continuous casting: the ladle is poured to a tundish long nozzle in a protection way, a tundish liquid surface covering agent is used for protection, and the superheat degree of tundish molten steel is controlled at 20 ℃. Pouring is protected by a submerged nozzle from a tundish to a crystallizer for pouring, slag is protected on the liquid surface of the crystallizer, the pulling speed of the billet is 1.2m/min, and the process adopts dynamic soft reduction.
5) Rolling: the billet or steel ingot is heated to the uniform temperature of 1200 ℃ for 3h, the initial rolling temperature is 1150 ℃, and the final rolling temperature is not less than 860 ℃.
The invention discloses a method for forming a thin-wall ring gear, which comprises the following steps:
heating the Ti-containing carburizing steel to 1150 ℃, and performing upsetting, punching and ring rolling molding, wherein the temperature of ring rolling is not lower than 880 ℃ for oil quenching; heating the parts to 740 ℃ within 1h after quenching, keeping the temperature for 2h, discharging the parts from the furnace, and cooling the parts to room temperature, wherein the structure is transformed into spherical pearlite with the hardness of HB 185-190 and the hardness dispersion of HB 5. And turning the inner circle, the outer circle and the end face of the annular forging, machining an inner wall annular groove, and precisely inserting rolling internal teeth, wherein the roundness and the taper are within 0.05mm, and the tooth direction fH beta is 15-23 mu m. Adopting a continuous furnace for carburizing: the parts are put into a furnace, pre-oxidation treatment is carried out at 480 ℃, strong infiltration treatment is carried out at 915 ℃, the carbon potential is 1.05 percent, high-temperature diffusion is carried out at 880 ℃, the carbon potential is 0.76 percent, low-temperature diffusion is carried out at 850 ℃, the carbon potential is 0.70 percent, the temperature is reduced, pressure quenching is carried out at 830 ℃, the quenching medium is Derungbao MARQUENCH729, the temperature is 115 ℃, and the tempering temperature is 170 ℃.
Example 3:
and (3) carrying out carburizing and pressure quenching production on the inner gear ring of an auxiliary box of a certain gearbox, wherein the depth of a carburized process layer is required to be 0.8-1.1 mm.
The thin-wall inner gear ring of the embodiment is made of Ti-containing carburizing steel, and comprises the following chemical components in percentage by mass: 0.30 percent of C, 1.40 percent of Mn1, less than or equal to 0.035 percent of P, 0.045 percent of S, 1.40 percent of Cr1, 0.035 percent of Al, 0.22 percent of Si, 0.030 percent of Ti, 0.04 percent of Nb, less than or equal to 0.0015 percent of O, 0.012 percent of N, 0.20 percent of Ni, 0.20 percent of Cu, less than or equal to 0.06 percent of Mo, less than or equal to 0.04 percent of V, and the balance of Fe and inevitable impurities.
The manufacturing method of the Ti-containing carburizing steel for the thin-wall ring gear of the embodiment includes the following steps:
1) primary smelting: an electric furnace or a converter is adopted, the furnace temperature is controlled at 1670 ℃, pre-deoxidation is carried out before tapping, tapping is carried out at 1650 ℃, and synthetic slag is added.
2) LF refining: the content of O, S and inclusions in molten steel is reduced, O is less than or equal to 0.0015%, S is not more than 0.04%, the temperature is controlled to be 1620 ℃, N in a ladle is less than or equal to 0.006%, Ti wires are fed 5-10 min before steel tapping is carried out for 30-50 min of refining, the content of Ti is controlled to be 0.028-0.030%, Nb is added, the content is controlled to be 0.04%, and steel tapping is carried out.
3) Rh/vD vacuum: the vacuum degree is less than 140ppm, N in the ladle is less than or equal to 0.006 percent, the temperature is controlled to 1650 ℃, the vacuum time is 25min, and the [ Ti ] [ N ] is controlled to be less than or equal to 0.00033, and the MnN is added to ensure that the N content reaches 0.012 percent.
4) Continuous casting: the ladle is poured to a tundish long nozzle in a protection way, a tundish liquid surface covering agent is used for protection, and the superheat degree of tundish molten steel is controlled at 25 ℃. Pouring is protected by a submerged nozzle from a tundish to a crystallizer for pouring, slag is protected on the liquid surface of the crystallizer, the pulling speed of a steel billet is 1.1m/min, and dynamic soft reduction is adopted in the process.
5) Rolling: the billet or steel ingot is heated to the uniform temperature of 1250 ℃ for 4h, the initial rolling temperature is 1200 ℃, and the final rolling temperature is not less than 860 ℃.
The invention discloses a method for forming a thin-wall ring gear, which comprises the following steps:
heating the Ti-containing carburizing steel to 1250 ℃, and performing upsetting, punching and ring rolling forming, wherein the temperature of ring rolling is not lower than 880 ℃ for oil quenching; heating the parts to 740 ℃ within 1h after quenching, keeping the temperature for 2h, discharging the parts from the furnace, and cooling the parts to room temperature, wherein the structure is transformed into spherical pearlite with the hardness of HB 185-190 and the hardness dispersion of HB 5. And turning the inner circle, the outer circle and the end face of the annular forging, machining an inner wall annular groove, and precisely inserting rolling internal teeth, wherein the roundness and the taper are within 0.05mm, and the tooth direction fH beta is 15-23 mu m. Adopting a continuous furnace for carburizing: the parts are put into a furnace, pre-oxidation treatment is carried out at 500 ℃, strong infiltration treatment is carried out at 920 ℃, the carbon potential is 1.0 percent, high-temperature diffusion is carried out at 860 ℃ and 880 ℃, the carbon potential is 0.75 percent, low-temperature diffusion is carried out at 850 ℃, the carbon potential is 0.70 percent, pressure quenching is carried out at 830 ℃ reduced temperature, quenching medium Derungbao MARQUENCH729, the temperature is 115 ℃ and the tempering temperature is 145 ℃.
Example 4:
and (3) carrying out carburizing and pressure quenching production on the inner gear ring of an auxiliary box of a certain gearbox, wherein the depth of a carburized process layer is required to be 0.8-1.1 mm.
The thin-wall inner gear ring of the embodiment is made of Ti-containing carburizing steel, and comprises the following chemical components in percentage by mass: 0.15 percent of C, 0.90 percent of Mn, less than or equal to 0.035 percent of P, 0.015 percent of S, 0.90 percent of Cr, 0.015 percent of Al, 0.12 percent of Si, 0.010 percent of Ti, 0.02 percent of Nb, less than or equal to 0.0015 percent of O, 0.017 percent of N, 0.10 percent of Ni, 0.10 percent of Cu, less than or equal to 0.06 percent of Mo, less than or equal to 0.04 percent of V, and the balance of Fe and inevitable impurities.
The manufacturing method of the Ti-containing carburizing steel for the thin-wall ring gear of the embodiment includes the following steps:
1) primary smelting: an electric furnace or a converter is adopted, the furnace temperature is controlled to 1620 ℃, pre-deoxidation is carried out before tapping, and tapping is carried out at 1600 ℃ and synthetic slag is added.
2) LF refining: the contents of O, S and inclusions in molten steel are reduced, O is less than or equal to 0.0015 percent, S is not more than 0.04 percent, the temperature is controlled to 1520 ℃, N in a ladle is less than or equal to 0.006 percent, Ti wires are fed 5min before 30min of steel tapping in refining, the content of Ti is controlled to be 0.010 percent, Nb is added, the content is controlled to be 0.02 percent, and steel tapping is carried out.
3) Rh/vD vacuum: the vacuum degree is less than 140ppm, N in the steel ladle is less than or equal to 0.006 percent, the temperature is controlled to 1530 ℃, the vacuum time is 15min, and the [ Ti ] [ N ] is controlled to be less than or equal to 0.00033, so that the content of N reaches 0.017 percent by adding MnN.
4) Continuous casting: the ladle is poured to a tundish long nozzle in a protection way, a tundish liquid surface covering agent is used for protection, and the superheat degree of tundish molten steel is controlled at 15 ℃. Pouring is protected by a submerged nozzle from a tundish to a crystallizer for pouring, slag is protected on the liquid surface of the crystallizer, the pulling speed of a steel billet is 1.1m/min, and dynamic soft reduction is adopted in the process.
5) Rolling: heating billet or steel ingot at uniform temperature of 1130 ℃ for 2h, the initial rolling temperature of 1100 ℃ and the final rolling temperature of not less than 860 ℃.
The invention discloses a method for forming a thin-wall ring gear, which comprises the following steps:
heating the Ti-containing carburizing steel to 1100 ℃, and performing upsetting, punching and ring rolling forming, wherein the temperature of ring rolling is not lower than 880 ℃ for oil quenching; heating the parts to 740 ℃ within 1h after quenching, keeping the temperature for 2h, discharging the parts from the furnace, and cooling the parts to room temperature, wherein the structure is transformed into spherical pearlite with the hardness of HB 185-190 and the hardness dispersion of HB 5. And turning the inner circle, the outer circle and the end face of the annular forging, machining an inner wall annular groove, and precisely inserting rolling internal teeth, wherein the roundness and the taper are within 0.05mm, and the tooth direction fH beta is 15-23 mu m. Adopting a continuous furnace for carburizing: the parts are put into a furnace, pre-oxidation treatment is carried out at 460 ℃, strong infiltration treatment is carried out at 900 ℃, the carbon potential is 0.9 percent, high-temperature diffusion is carried out at 860 ℃, the carbon potential is 0.65 percent, low-temperature diffusion is carried out at 830 ℃, the carbon potential is 0.65 percent, pressure quenching is carried out at the reduced temperature of 810 ℃, quenching medium Derunbao MARQUENCH729 is carried out at 125 ℃ and the tempering temperature is 180 ℃.
The above description is only for the specific embodiments of the present invention, and it should be noted that the remaining detailed descriptions are related to the prior art, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the protection scope of the present invention.
Claims (3)
1. A method for forming a thin-wall annular gear is characterized by comprising the following steps: the method comprises the following steps:
1) ring rolling and forming: blanking the thin-wall annular gear by using Ti-containing carburizing steel, carrying out induction heating at 1100-1250 ℃, and carrying out upsetting, punching and ring rolling forming;
the thin-wall inner gear ring comprises the following chemical components in percentage by mass: 0.15-0.30% of C, 0.90-1.40% of Mn, less than or equal to 0.035% of P, 0.015-0.045% of S, 0.90-1.40% of Cr, 0.015-0.035% of Al, less than or equal to 0.25% of Si, 0.010-0.030% of Ti, 0.02-0.04% of Nb, less than or equal to 0.0015% of O, 0.012-0.017% of N, less than or equal to 0.20% of Ni, 0.10-0.20% of Cu, less than or equal to 0.06% of Mo, less than or equal to 0.04% of V, and the balance of Fe and inevitable impurities;
2) quenching by grinding ring waste heat: quenching treatment at the temperature of not lower than 880 ℃ after ring rolling and forming;
3) high-temperature tempering: heating to 710-740 ℃, preserving heat for 1.5-2 h, discharging from the furnace, cooling to room temperature, and transforming the structure into spherical pearlite;
4) gear hobbing: turning the inner circle, the outer circle and the end face of the annular forging, processing an inner wall annular groove, and precisely inserting the inner rolling teeth;
5) carburizing and heat treating, and pressure quenching: carrying out carburizing heat treatment and pressure quenching by adopting a continuous furnace, and then tempering at the temperature of 145-180 ℃; the carburizing heat treatment pressure quenching comprises the following specific steps: pre-oxidation treatment is carried out at 460-500 ℃, strong infiltration treatment is carried out at 900-920 ℃, the carbon potential is 0.9-1.0%, high-temperature diffusion is carried out at 860-880 ℃, the carbon potential is 0.65-0.75%, low-temperature diffusion is carried out at 830-850 ℃, the carbon potential is 0.65-0.70%, and pressure quenching is carried out at 810-830 ℃.
2. The molding method of a thin-walled ring gear according to claim 1, characterized in that: in the step 2), the quenching medium is PAG water-based quenching agent or quenching oil, the structure is transformed into martensite or bainite, and the oxide skin is removed by shot blasting.
3. The molding method of a thin-walled ring gear according to claim 1, characterized in that: in the step 4), the roundness and the taper of the inner gear ring are controlled within 0.05mm, and the tooth direction fH beta is not more than 20 μm.
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| CN113388783B (en) * | 2021-06-24 | 2022-04-29 | 马鞍山钢铁股份有限公司 | Nb, V and Ti microalloyed gear steel and preparation method, heat treatment method, carburization method and carburized gear steel thereof |
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| JP5760453B2 (en) * | 2010-01-27 | 2015-08-12 | Ｊｆｅスチール株式会社 | Carburized material |
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