CN114410947A - Efficient heat treatment process for carburized driven gear blank for railway locomotive - Google Patents
Efficient heat treatment process for carburized driven gear blank for railway locomotive Download PDFInfo
- Publication number
- CN114410947A CN114410947A CN202210091574.9A CN202210091574A CN114410947A CN 114410947 A CN114410947 A CN 114410947A CN 202210091574 A CN202210091574 A CN 202210091574A CN 114410947 A CN114410947 A CN 114410947A
- Authority
- CN
- China
- Prior art keywords
- driven gear
- carburized
- heat treatment
- gear blank
- temperature
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 238000010438 heat treatment Methods 0.000 title claims abstract description 85
- 238000000034 method Methods 0.000 title claims abstract description 48
- 230000003137 locomotive effect Effects 0.000 title claims abstract description 27
- 239000010959 steel Substances 0.000 claims abstract description 21
- 238000001816 cooling Methods 0.000 claims description 30
- 238000004321 preservation Methods 0.000 claims description 15
- 238000007599 discharging Methods 0.000 claims description 9
- 239000000203 mixture Substances 0.000 claims description 8
- 239000000126 substance Substances 0.000 claims description 7
- 238000003672 processing method Methods 0.000 claims 1
- 238000010079 rubber tapping Methods 0.000 claims 1
- 229910001562 pearlite Inorganic materials 0.000 abstract description 25
- 229910000831 Steel Inorganic materials 0.000 abstract description 19
- 229910001566 austenite Inorganic materials 0.000 abstract description 18
- 229910000859 α-Fe Inorganic materials 0.000 abstract description 18
- 230000009466 transformation Effects 0.000 abstract description 11
- 238000004904 shortening Methods 0.000 abstract description 3
- 238000011534 incubation Methods 0.000 abstract description 2
- 230000000052 comparative effect Effects 0.000 description 23
- 238000012360 testing method Methods 0.000 description 14
- 238000004519 manufacturing process Methods 0.000 description 12
- 238000005242 forging Methods 0.000 description 11
- 229910001563 bainite Inorganic materials 0.000 description 10
- 238000007781 pre-processing Methods 0.000 description 5
- 238000009826 distribution Methods 0.000 description 4
- 229910045601 alloy Inorganic materials 0.000 description 3
- 239000000956 alloy Substances 0.000 description 3
- 238000005255 carburizing Methods 0.000 description 3
- 238000003754 machining Methods 0.000 description 3
- 238000005259 measurement Methods 0.000 description 3
- 241000519995 Stachys sylvatica Species 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 238000013211 curve analysis Methods 0.000 description 2
- 238000009792 diffusion process Methods 0.000 description 2
- 230000035772 mutation Effects 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 238000010583 slow cooling Methods 0.000 description 2
- 239000002436 steel type Substances 0.000 description 2
- 238000005496 tempering Methods 0.000 description 2
- 229910000851 Alloy steel Inorganic materials 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 238000005275 alloying Methods 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 229910001567 cementite Inorganic materials 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- KSOKAHYVTMZFBJ-UHFFFAOYSA-N iron;methane Chemical compound C.[Fe].[Fe].[Fe] KSOKAHYVTMZFBJ-UHFFFAOYSA-N 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 230000006032 tissue transformation Effects 0.000 description 1
Images
Classifications
-
- 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
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/32—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for gear wheels, worm wheels, or the like
-
- 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
-
- 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
- C21D11/00—Process control or regulation for heat treatments
-
- 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
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/004—Heat treatment of ferrous alloys containing Cr and Ni
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/005—Ferrite
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/009—Pearlite
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
Abstract
The invention provides a heat treatment method of carburized driven gear blank for railway locomotive, which is characterized in that a carburized gear steel blank is treated in (A)c3‑30℃)‑Ac3The method comprises the steps of carrying out sub-temperature austenitization within the range to form austenite with low stability and reserving part of untransformed ferrite, and then carrying out isothermal treatment in a temperature range with a short pearlite transformation incubation period, wherein the austenite with low stability completes ferrite-pearlite transformation more quickly, and the banded structure is improved due to ferrite redistribution, so that the aims of remarkably shortening the heat treatment time required for obtaining a complete ferrite-pearlite structure and improving the banded structure are fulfilled.
Description
Technical Field
The invention belongs to the technical field of mechanical part production, and relates to a heat treatment method of a carburized driven gear blank for a railway locomotive.
Background
The carburizing gear steel for rail transit mainly comprises 18CrNiMo7-6, 12CrNi3, 20CrNi2Mo, 20CrNiMo, 20CrMnTi, 8860H, 15CrNi6, 8822H and the like, and the gear manufactured by the carburizing gear steel has comprehensive performances of high wear resistance, pressure resistance, impact resistance, plastic deformation resistance, surface contact fatigue resistance, bending fatigue resistance and the like.
The production process of the carburized gear is divided into two major links of driven gear blank manufacturing and gear manufacturing. The blank of the driven gear for the locomotive belongs to a middle and large-size workpiece, the diameter is 630-1050mm, and the manufacturing process comprises the following steps: gear steel production → heating → forging and rolling forming → slow cooling → heat treatment, wherein the heat treatment process usually comprises high-temperature normalizing and high-temperature tempering or high-temperature austenitizing and isothermal treatment, the common requirement is that the heat-treated gear blank is low, usually about 200HB, and the main purpose is to facilitate the subsequent gear preprocessing.
By adopting the high-temperature normalizing and high-temperature tempering process, because the carburized gear steel has high hardenability, a microstructure after heat treatment is low-hardness tempered bainite, although the carburized gear steel is easy to process, due to high plasticity, a cutter is easy to stick in the gear preprocessing process, and a cutting nodule is easy to form to cause rough processing surface, so that the final surface hardness uniformity of the gear is influenced, and in addition, the bainite tissue has strong inheritance, so that the carburized layer and the matrix of the gear can be influenced badly.
The high-temperature austenitizing and isothermal treatment process is adopted, the microstructure after heat treatment is a ferrite-pearlite structure with low hardness, the preprocessing performance is good, but the austenite stability is high, the isothermal treatment time required for obtaining complete ferrite-pearlite is extremely long, for example, for 8822H gear steel, the isothermal treatment time needs to be more than 15 hours, the production efficiency is very low, the production cost is very high, in addition, because the driven gear blank has large size and low cooling speed, the banded structure can be fully developed, the uniformity of hardness in an effective hardened layer after the gear carburizing treatment can be influenced, and the service performance of the gear can be reduced.
Therefore, the invention is particularly necessary to provide a driven gear blank heat treatment technology which is efficient and low in cost and can improve the gear preprocessing performance and the final heat treatment quality.
Disclosure of Invention
The invention aims to provide a heat treatment method of a carburized driven gear blank for a railway locomotive, which provides a heat treatment process of a carburized gear steel blank for sub-temperature austenitizing and then carrying out isothermal treatment based on the structure transformation rule of steel in the austenitizing process.
The specific technical scheme of the invention is as follows:
a heat treatment method of a carburized driven gear blank for a railway locomotive comprises the following steps:
s1: cooling a forged carburized driven gear blank to room temperature;
s2: calculating A according to the chemical composition of carburized driven gear steelc3Putting the carburized driven gear blank treated in the step 1) into a heating furnace, and heating to (A)c3-30℃)～Ac3Keeping the temperature, immediately discharging the blank out of the furnace for air cooling, and reducing the temperature of the carburized driven gear blank to be close to the isothermal treatment temperature;
s3: then placing the driven gear blank after air cooling into a heating furnace for isothermal treatment;
s4: and (4) taking the carburized driven gear blank treated in the step (S3) out of the heating furnace, and air-cooling.
Step S1, putting the forged carburized driven gear blank for the railway locomotive into a heat source-free slow cooling pit, and cooling the pit to room temperature to finish the tissue transformation, wherein the process mainly aims at preventing white spots;
preferably, in step S2, heating is carried out to (A)c3-30℃)～(Ac3-20℃)；
The C content of the carburized driven gear blank for the railway locomotive is 0.15-0.25%; preferably, the carburized driven gear blank for the railway locomotive is 8822H, 20CrNi2Mo and 18CrNiMo7-6 driven gear blank;
when the carburized driven gear blank for the railway locomotive is an 8822H driven gear blank, the heat preservation temperature of isothermal treatment is 800-820 ℃;
when the carburized driven gear blank for the railway locomotive is a 20CrNi2Mo driven gear blank, the heat preservation temperature of isothermal treatment is 790-810 ℃;
when the carburized driven gear blank for the railway locomotive is an 18CrNiMo7-6 driven gear blank, the heat preservation temperature of isothermal treatment is 790-810 ℃.
In step S2Ac3The calculation formula of (2) is as follows: a. theC3＝910-203×C1/215.2 XNi +44.7 XSi +104 XV +31.5 XMo +13.1 XW. equation 1;
in the step S2, the heating rate is controlled to be less than or equal to 10 ℃/min;
in the step S2, the heat preservation is carried out for 2-6 h;
in step S2, immediately discharging from the furnace and air cooling for 20-40 min;
in step S2, the temperature of the carburized driven gear blank is decreased to a temperature close to the isothermal processing temperature by: the temperature of the carburized driven gear blank is reduced to be +/-20 ℃ away from the isothermal treatment temperature;
carrying out isothermal treatment in the step S3, wherein the heat preservation temperature is 580-620 ℃; the heat preservation time is 10.0-18.0 h;
the isothermal treatment time in the step S3 varies with the steel type, specification, furnace type and charging number, and preferably, the heat preservation time of the isothermal treatment is generally 10.0 to 11.0 hours, 15.0 to 17.0 hours and 16.0 to 18.0 hours for the driven gear blanks in the ranges of 8822H, 20CrNi2Mo and 18CrNiMo 7-6.
When the carburized driven gear blank for the railway locomotive is an 8822H driven gear blank with the outer diameter of 630-1050mm, the heat preservation time of isothermal treatment is generally 10.0-11.0H;
when the carburized driven gear blank for the railway locomotive is a 20CrNi2Mo driven gear blank with the outer diameter of 630-1050mm, the heat preservation time of isothermal treatment is generally 15.0-17.0 h;
when the carburized driven gear blank for the railway locomotive is an 18CrNiMo7-6 driven gear blank with the outer diameter of 630-1050mm, the heat preservation time of isothermal treatment is generally 16.0-18.0 h.
The product after heat treatment has a banded structure less than or equal to 0.5 grade and a gamma grain size more than or equal to 8.5 grade; the surface hardness of the product is 180-210 HB, and the yield strength Rp0.2950～1300Mpa，Rm1200-1500 Mpa, and the elongation A is more than or equal to 13%.
The carburized gear steel is low-carbon low-alloy steel with the C content of 0.15-0.25%, and because of high hardenability, a driven gear blank manufactured by the carburized gear steel is forged, rolled, formed and slowly cooled to form a bainite and ferrite mixed structure, and because of low carbon content and large blank size, the cooling speed is low, the ferrite content is high, and the continuity is strong. As the bainite is a mixture consisting of supersaturated alpha-solid solution (bainite ferrite) and cementite, the mixed structure of the bainite and the ferrite is in a state of seriously uneven distribution of C and alloy elements, namely, the bainite area C and the alloy element content are high, the ferrite area C and the alloy element content are low, and the content is lower than Ac3The following high temperature region (A)c3-30℃)～Ac3On re-austenitizing at temperature, on the one hand, bainite and most of the ferrite are transformed into austenite, but due to limited diffusion conditions, C and alloying elements cannot be homogenized in the formed austenite to reduce the austenite stability, and subsequently at ar1When the isothermal treatment is performed, the time for the super-cooled austenite to complete the diffusion ferrite-pearlite transformation is obviously shortened; on the other hand, isothermal processed junctionAfter the heat treatment, the ferrite is composed of two parts, namely, a small part of ferrite which is dispersed and distributed and is not transformed in the austenitizing process, and secondly, the ferrite which is generated after the super-cooled austenite finishes the phase transformation, and the generation areas of the ferrite and the super-cooled austenite are different to generate a redistribution effect, so that the distribution uniformity of the ferrite is improved, and the level of a banded structure is reduced. Therefore, the invention adopts the method of sub-temperature austenitizing and then isothermal treatment, and can achieve the purposes of obviously shortening the heat treatment time required for obtaining the complete ferrite-pearlite structure and simultaneously improving the banded structure.
The invention is to mix (A) carburized gear steel blankc3-30℃)～Ac3The method comprises the steps of carrying out sub-temperature austenitization within the range to form austenite with low stability and reserving part of untransformed ferrite, and then carrying out isothermal treatment in a temperature range with a short pearlite transformation incubation period, wherein the austenite with low stability completes ferrite-pearlite transformation more quickly, and the banded structure is improved due to ferrite redistribution, so that the aims of remarkably shortening the heat treatment time required for obtaining a complete ferrite-pearlite structure and improving the banded structure are fulfilled.
Compared with the prior art, the invention can greatly shorten the heat treatment time required for obtaining the complete ferrite-pearlite structure, obviously improve the production efficiency of the driven gear blank, simplify the production process and reduce the production cost; on the other hand, the distribution uniformity of the ferrite-pearlite structure is improved, so that the preprocessing performance of the gear is improved, the hardness uniformity in an effective hardened layer after carburization is improved, and the service performance of the driven gear can be improved. And the process is simple and easy to implement and is convenient for industrial production.
Drawings
FIG. 1 is an isothermal temperature versus time curve for a gear blank of example 1;
FIG. 2 is an isothermal temperature versus time curve for a gear blank of comparative example 1;
FIG. 3 is a microstructure of a gear blank of example 1 after heat treatment;
FIG. 4 is a microstructure of a gear blank of comparative example 1 after heat treatment;
FIG. 5 is a microstructure of a gear blank of comparative example 2 after heat treatment;
FIG. 6 is a microstructure of a gear blank of comparative example 3 after heat treatment;
FIG. 7 is the austenite grain size of the gear blank of example 1 after heat treatment;
FIG. 8 is an austenite grain size of the gear blank of comparative example 1 after heat treatment.
Detailed Description
For a further understanding of the present invention, reference will now be made in detail to the embodiments illustrated in the drawings.
The invention provides a heat treatment method of a carburized driven gear blank for a railway locomotive, which comprises the following steps:
s1: cooling a forged carburized gear steel blank pit to room temperature to complete the structure transformation, wherein the process mainly aims at preventing white spots;
s2: based on the chemical composition of the steel, A is estimated according to equation 1c3Placing the carburized driven gear blank obtained in the step S1 into a heating furnace, and heating to the temperature (A) at the temperature of 3 ℃/minc3-30℃)～Ac3Keeping the temperature for 2-4 h, immediately discharging from the furnace and air-cooling for 20-40min to enable the temperature of the driven gear blank to be close to the isothermal temperature;
AC3＝910-203×C1/215.2 XNi +44.7 XSi +104 XV +31.5 XMo +13.1 XW. equation 1;
8822H, 20CrNi2Mo, 18CrNiMo7-6 driven gear blank, Ac3The temperature is 800-820 ℃, 790-810 ℃ and 790-810 ℃ respectively;
s3: then, placing the driven gear blank subjected to air cooling into a heating furnace for isothermal treatment, wherein the set heat preservation temperature of the isothermal furnace is 600-620 ℃; the isothermal treatment time is different according to steel types, specifications, furnace types and charging quantity, and the heat preservation time of isothermal treatment is generally 10.0-11.0H, 15.0-17.0H and 16.0-18.0H for driven gear blanks with the outer diameters of 8822H, 20CrNi2Mo and 18CrNiMo7-6 within the range of 630-1050 mm.
S4: and (4) taking out the carburized driven gear blank obtained in the step (S3) from the heating furnace, and air-cooling.
According to the above method, the heat treatment method of each specific example is as follows:
example 1
A heat treatment method of a carburized driven gear blank for a railway locomotive comprises the following steps:
the steel grade of the embodiment is 8822H gear steel, Ac3According to the chemical composition, the heat treatment is carried out after pit cooling to room temperature after finish forging at the temperature of 1000-1050 ℃ by closed die forging forming of an oil press at the temperature of about 830 ℃ and the forging heating temperature of 1200-1250 ℃ estimated by an empirical formula.
As shown in FIG. 1, the temperature change during the heat treatment was continuously recorded in the tooth root portion of the gear blank before the heat treatment at a data recording frequency of 0.2 s/time. Performing sub-temperature austenitizing heating and temperature equalization at the temperature of 800-820 ℃ for 3.0h according to the table 1, pulling out the trolley, performing air cooling for 30min, transferring the gear blank into another bench furnace with the temperature of 610 +/-10 ℃ for isothermal treatment, pulling out the trolley when the third mutation occurs in the externally transmitted measured temperature in the isothermal treatment process, wherein the time corresponding to the isothermal temperature keeping is t11(curves are shown in FIG. 1), air-cooled to room temperature.
The heat treatment process of the gear blank in the embodiment 1 is shown in a table 1, according to the change rule of a mixed structure of bainite and ferrite of the gear blank in the heating process, the original bainite structure is converted into austenite with fine grains and poor stability through heat preservation in a two-phase region, most of the original ferrite is converted into austenite, so that the distribution uniformity of the original ferrite is improved, the isothermal treatment is further carried out, the time required for obtaining complete ferrite-pearlite is greatly shortened, and meanwhile, a banded structure is improved.
Comparative example 1
A heat treatment method of a carburized driven gear blank for a railway locomotive comprises the following steps:
the gear blank adopted in the comparative example is forged in the same batch with the same furnace number and the same specification as those of the example 1, and after the finish forging, the gear blank is subjected to heat treatment after pit cooling to room temperature, and the differences are only heat treatment parameters, and specific parameters of the comparative example 1 are shown in table 1. Continuously measuring the temperature change in the heat treatment process in the same manner as in example 1, discharging the sample from the furnace, air-cooling to room temperature when the third sudden change of the temperature is occurred in the externally-transmitted measurement temperature, and keeping the isothermal treatment time at t12The curve is shown in fig. 2.
Ferrite-pearlite transformation is an exothermic reaction, and from the 1 st and 2 nd temperature mutations (fig. 1 and 2) on the temperature-time curve, the time corresponding to the beginning and the end of ferrite-pearlite transformation can be judged, the total time of ferrite-pearlite transformation from furnace cooling for example 1 and comparative example 1 is shown in table 2, and the time for obtaining complete ferrite-pearlite for example is reduced by 45% compared with comparative example; the gear blank tooth root is sampled for microstructure analysis, and as shown in figures 3 and 4, the embodiment 1 and the comparative example 1 are ferrite-pearlite structures; the band structure test was carried out according to GB/T13299, the results are shown in Table 2, and the band structure grade of example 1 is significantly lower than that of the comparative example; the surface hardness test of the gear blank is carried out according to GB/T231, the result is shown in Table 2, and the embodiment 1 is equivalent to the comparative example 1; sampling gear blanks according to GB/T2975 and GB/T228.1, performing tensile property test after small sample heat treatment, and obtaining results shown in Table 2, wherein example 1 is equivalent to comparative example 1; samples were taken from the gear blanks and examined for austenite grain size according to GB/T6394, see FIGS. 7, 8 and Table 2, with example 1 being better than comparative example 1. It can be seen that example 1 can efficiently achieve the purposes of obtaining complete ferrite-pearlite, reducing hardness and improving the uniformity of the structure, and can provide a better initial state for subsequent gear machining and heat treatment.
Example 2
A heat treatment method of a carburized driven gear blank for a railway locomotive comprises the following steps:
the 20CrNi2Mo gear steel of the embodiment has the chemical composition of Ac3Estimated empirically using the chemical composition to be about 810 c. The specification of the blank, the forging process and the cooling process after forging were the same as those of example 1, and heat treatment was performed, which was different from example 1 only in the parameters, and is specifically shown in table 1. Continuously measuring the temperature change in the heat treatment process in the same way as the embodiment, discharging the furnace and air-cooling to the room temperature when the third sudden change of the externally-transmitted measured temperature occurs, wherein the corresponding time is t21The curve is similar to that shown in fig. 1.
Comparative example 2
A heat treatment method of a carburized driven gear blank for a railway locomotive comprises the following steps:
the gear blank used in this comparative example was forged in the same batch with the same furnace number and the same specification as in example 2, and after finish forging, pit cooling was performed to room temperature, and then heat treatment was performed, which was different from example 1 only in the parameters. Continuously measuring the temperature change in the heat treatment process in the same manner as in example 1, discharging the sample from the furnace, air cooling to room temperature when the third sudden change of the temperature is occurred in the externally-transmitted measurement temperature, and the corresponding time is t22The curve is similar to that shown in fig. 3.
Temperature-time curve analysis, texture test, surface hardness test, test of tensile properties after heat treatment of the test piece and austenite grain size test were carried out with reference to example 1 and comparative example 1, and the results are shown in Table 2. It can be seen that the time for obtaining the complete ferrite-pearlite in example 2 is reduced by 43% compared with the comparative example, the purposes of obtaining the complete ferrite-pearlite, reducing the hardness and improving the uniformity of the structure can be efficiently achieved, and a better initial state can be provided for subsequent gear machining and heat treatment.
Example 3
A heat treatment method of a carburized driven gear blank for a railway locomotive comprises the following steps:
the 18CrNiMo7-6 gear blank of this example, Ac3Estimated empirically using the formula for chemical composition, is about 818 ℃. The specification of the blank, the forging process and the cooling process after forging were the same as those of example 1, and heat treatment was performed, which was different from example 1 only in the parameters, and is specifically shown in table 1. Continuously measuring the temperature change in the heat treatment process in the same way as the embodiment, discharging the furnace and air-cooling to the room temperature when the third sudden change of the externally-transmitted measured temperature occurs, wherein the corresponding time is t31The curve is similar to that shown in fig. 1.
Comparative example 3
A heat treatment method of a carburized driven gear blank for a railway locomotive comprises the following steps:
the gear blank adopted in the comparative example is forged in the same batch with the same furnace number and the same specification as those of the example 2, and after finish forging, pit cooling is carried out to room temperature, then heat treatment is carried out, and then heat treatment is carried out, which is different from the example 1 only in parameters, and the specific parameters are shown in the table 1. In the same manner as in example 1, the temperature change during the heat treatment was continuously measured,when the third sudden change of the external transmission measurement temperature occurs, discharging from the furnace, air-cooling to room temperature, wherein the corresponding time is t32The curve is similar to that shown in fig. 2.
Temperature-time curve analysis, texture test, surface hardness test, test of tensile properties after heat treatment of the test piece and austenite grain size test were carried out with reference to example 1 and comparative example 1, and the results are shown in Table 2. It can be seen that the time for obtaining the complete ferrite-pearlite in the example 3 is reduced by 41.2% compared with the comparative example 3, the purposes of obtaining the complete ferrite-pearlite, reducing the hardness and improving the uniformity of the structure can be efficiently achieved, and a better initial state can be provided for subsequent gear machining and heat treatment.
TABLE 1 Heat treatment Process for Gear blank
TABLE 2 Gear blank test results
The invention greatly shortens the heat treatment time for obtaining the complete ferrite-pearlite structure from the carburized gear steel blank, and the time for obtaining the complete ferrite-pearlite structure is obviously superior to that of the traditional process; and the banded structure is improved, the production efficiency of the driven gear blank is obviously improved, the cost is obviously reduced, and simultaneously, favorable conditions are created for improving the heat treatment quality of the gear.
The above-described process for the efficient heat treatment of a carburized gear steel blank for railway locomotive is described in detail with reference to the following examples and drawings, which are intended to be illustrative and not limiting, and several examples are given by way of limitation, and thus variations and modifications thereof without departing from the general concept of the present invention are intended to be within the scope of the present invention.
Claims (7)
1. A heat treatment method of a carburized driven gear blank for a railway locomotive, characterized by comprising the steps of:
s1: cooling a forged carburized driven gear blank to room temperature;
s2: calculating A according to the chemical composition of carburized driven gear steelc3Putting the carburized driven gear blank treated in the step 1) into a heating furnace, and heating to (A)c3-30℃)～Ac3Keeping the temperature, immediately discharging the blank out of the furnace for air cooling, and reducing the temperature of the carburized driven gear blank to be close to the isothermal treatment temperature;
s3: then placing the driven gear blank after air cooling into a heating furnace for isothermal treatment;
s4: and (4) taking the carburized driven gear blank treated in the step (S3) out of the heating furnace, and air-cooling.
2. The heat treatment method according to claim 1, wherein the carburized driven gear blank for a railway locomotive has a C content of 0.15 to 0.25%.
3. The heat treatment process of claim 1 or 2, wherein the carburized driven gear blank for a railway locomotive is an 8822H, 20CrNi2Mo, 18CrNiMo7-6 driven gear blank.
4. The thermal processing method according to claim 1, wherein in step S2, the heating is performed at a heating rate of 3 ℃/min.
5. The heat treatment method according to claim 1 or 4, wherein in step S2, the heat preservation is performed for 2-6 h.
6. The heat treatment method according to claim 1 or 4, wherein in step S2, the immediately subsequent tapping air cooling time is 20-40 min.
7. The heat treatment method as claimed in claim 1 or 4, wherein the isothermal treatment in step S3 is carried out at 580-620 ℃; the heat preservation time is 10.0-18.0 h.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210091574.9A CN114410947B (en) | 2022-01-26 | 2022-01-26 | Efficient heat treatment process for carburized driven gear blank for railway locomotive |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210091574.9A CN114410947B (en) | 2022-01-26 | 2022-01-26 | Efficient heat treatment process for carburized driven gear blank for railway locomotive |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN114410947A true CN114410947A (en) | 2022-04-29 |
| CN114410947B CN114410947B (en) | 2024-01-16 |
Family
ID=81277591
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202210091574.9A Active CN114410947B (en) | 2022-01-26 | 2022-01-26 | Efficient heat treatment process for carburized driven gear blank for railway locomotive |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN114410947B (en) |
Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20080210352A1 (en) * | 2005-03-16 | 2008-09-04 | Honda Motor Co., Ltd. | Method for Heat-Treating Steel Material |
| CN103352173A (en) * | 2013-06-30 | 2013-10-16 | 贵州安大航空锻造有限责任公司 | Preheat treatment method for 18CrNiMo7-6 alloy steel forged pieces |
| CN105969949A (en) * | 2016-06-02 | 2016-09-28 | 溧阳市金昆锻压有限公司 | 18CrNiMo7-6 gear shaft forging preheating isothermal annealing process |
| CN108453202A (en) * | 2018-02-13 | 2018-08-28 | 无锡宏达重工股份有限公司 | A kind of manufacturing process of large marine shafting forging manufacture |
| CN109082628A (en) * | 2018-08-17 | 2018-12-25 | 中车戚墅堰机车车辆工艺研究所有限公司 | A kind of Gear Carbonization Process and its application |
| EP3591081A1 (en) * | 2018-07-05 | 2020-01-08 | Deutsche Edelstahlwerke Specialty Steel GmbH & Co. KG | Use of a steel for producing a steel component, namely for a gearwheel, a shaft, an axle or a tool holder to a thermochemically cured edge layer and such steel component having a thermochemically cured edge layer |
| CN111485085A (en) * | 2020-05-22 | 2020-08-04 | 无锡派克新材料科技股份有限公司 | Method for improving grain growth resistance of 18CrNiMo7-6 alloy at 930-950 DEG C |
| CN111518996A (en) * | 2020-04-15 | 2020-08-11 | 大冶特殊钢有限公司 | Heat treatment method of 18CrNiMo7-6 steel |
-
2022
- 2022-01-26 CN CN202210091574.9A patent/CN114410947B/en active Active
Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20080210352A1 (en) * | 2005-03-16 | 2008-09-04 | Honda Motor Co., Ltd. | Method for Heat-Treating Steel Material |
| CN103352173A (en) * | 2013-06-30 | 2013-10-16 | 贵州安大航空锻造有限责任公司 | Preheat treatment method for 18CrNiMo7-6 alloy steel forged pieces |
| CN105969949A (en) * | 2016-06-02 | 2016-09-28 | 溧阳市金昆锻压有限公司 | 18CrNiMo7-6 gear shaft forging preheating isothermal annealing process |
| CN108453202A (en) * | 2018-02-13 | 2018-08-28 | 无锡宏达重工股份有限公司 | A kind of manufacturing process of large marine shafting forging manufacture |
| EP3591081A1 (en) * | 2018-07-05 | 2020-01-08 | Deutsche Edelstahlwerke Specialty Steel GmbH & Co. KG | Use of a steel for producing a steel component, namely for a gearwheel, a shaft, an axle or a tool holder to a thermochemically cured edge layer and such steel component having a thermochemically cured edge layer |
| CN109082628A (en) * | 2018-08-17 | 2018-12-25 | 中车戚墅堰机车车辆工艺研究所有限公司 | A kind of Gear Carbonization Process and its application |
| CN111518996A (en) * | 2020-04-15 | 2020-08-11 | 大冶特殊钢有限公司 | Heat treatment method of 18CrNiMo7-6 steel |
| CN111485085A (en) * | 2020-05-22 | 2020-08-04 | 无锡派克新材料科技股份有限公司 | Method for improving grain growth resistance of 18CrNiMo7-6 alloy at 930-950 DEG C |
Also Published As
| Publication number | Publication date |
|---|---|
| CN114410947B (en) | 2024-01-16 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN101652494B (en) | Carbonitrided induction-hardened steel part with excellent rolling contact fatigue strength at high temperature and process for producing the same | |
| CN108277449B (en) | Heat treatment method for carburizing and quenching low-carbon alloy steel workpiece | |
| CN110951943A (en) | Baimamu multiphase steel rail and heat treatment method thereof | |
| CN109536689B (en) | Hot working process method of bearing steel part | |
| CN114107626A (en) | Continuous spheroidizing annealing method for high-carbon chromium bearing steel round steel | |
| CN111485086A (en) | Controlled rolling and cooling process for reducing decarburized layer depth of high-carbon alloy tool steel wire rod | |
| CN105886717A (en) | Normalizing method for forging waste heat of steel | |
| CN110760653B (en) | Control method for preventing bearing steel from decarbonizing | |
| CN114134399B (en) | Energy-saving steel wire rod with high bainite content for high alloy tool and manufacturing method thereof | |
| CN104745787B (en) | Production method of tool steel capable of being directly cold rolled | |
| CN102286655A (en) | Device and method for isothermal normalizing utilizing forging waste heat | |
| CN114410947B (en) | Efficient heat treatment process for carburized driven gear blank for railway locomotive | |
| CN113680820B (en) | Rolling control and cooling control process for improving cold heading performance of wire rod for medium carbon alloy cold extrusion sleeve | |
| JPS63238217A (en) | Production of seamless steel pipe of martensitic stainless steel having excellent low-temperature toughness and stress corrosion cracking resistance | |
| CN111876677B (en) | Forming process of hexagonal alloy tool steel S2 | |
| RU2612101C1 (en) | Method of hot-rolled stock preparation for production of hardware fasteners | |
| JP2001181791A (en) | Bar stock and wire rod for cold forging, excellent in induction hardenability and cold forgeability | |
| JP2614653B2 (en) | Manufacturing method of carburized parts with little heat treatment distortion | |
| CN111842485A (en) | Heating method for reducing decarburization layer depth of aluminum alloy-containing structural steel wire rod | |
| CN106148881B (en) | Carburized austempered slider for linear slide rails and method for manufacturing same | |
| JPS5980715A (en) | Production of spheroidal graphite cast iron having high resistance to fatigue | |
| CN114990292B (en) | Heat treatment method for hot work die steel | |
| CN109055701B (en) | Heat treatment method of extrusion needle | |
| CN112080697B (en) | Steel for clutch driven disc, preparation method of steel and clutch driven disc | |
| CN107419175A (en) | Fatigue life good economical tool steel and its production method |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |