CN113817967A - Hot-delivery hot-charging production method for reducing depth of decarburized layer of bearing steel round steel - Google Patents
Hot-delivery hot-charging production method for reducing depth of decarburized layer of bearing steel round steel Download PDFInfo
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
- B21B1/16—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling wire rods, bars, merchant bars, rounds wire or material of like small cross-section
- B21B1/18—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling wire rods, bars, merchant bars, rounds wire or material of like small cross-section in a continuous process
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B37/00—Control devices or methods specially adapted for metal-rolling mills or the work produced thereby
- B21B37/74—Temperature control, e.g. by cooling or heating the rolls or the product
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- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/004—Heat treatment of ferrous alloys containing Cr and Ni
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- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/005—Heat treatment of ferrous alloys containing Mn
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- 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
- C21D6/008—Heat treatment of ferrous alloys containing Si
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- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/06—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires
- C21D8/065—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires of ferrous alloys
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22C33/00—Making ferrous alloys
- C22C33/04—Making ferrous alloys by melting
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/008—Ferrous alloys, e.g. steel alloys containing tin
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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
- 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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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—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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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—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
Abstract
The invention belongs to the technical field of steel rolling production, and relates to a hot-conveying hot-charging production method for reducing the depth of a decarburized layer of bearing steel round steel. The method comprises the following steps: obtaining a continuous casting billet through converter smelting, LF refining, VD vacuum treatment and continuous casting operation; then, a continuous casting billet is subjected to hot conveying and hot charging by using a heat preservation vehicle or a heat preservation conveying roller path; after the hot materials are loaded into a heating furnace, the continuous casting billet is heated in the heating furnace, the temperature of the preheating and heating section is 700-980 ℃, and the total holding time is not more than 90 minutes; the temperature of the heating second section and the soaking section is 1180-1220 ℃, the total holding time is not less than 120 minutes, and the total in-furnace time is not less than 200 minutes; simultaneously controlling the ratio of air to coal gas in the heating furnace; after heating, the continuous casting billet is taken out of the heating furnace for high-pressure water dephosphorization, and after dephosphorization, controlled rolling and controlled cooling are carried out; the scheme of the invention can effectively utilize the waste heat of the continuous casting billet, reduce the gas consumption, save the energy consumption, improve the yield and improve the steel performance.
Description
Technical Field
The invention belongs to the technical field of steel rolling production, and particularly relates to a hot-feeding hot-charging production method for reducing the depth of a decarburized layer of bearing steel round steel.
Background
The heating furnace is a main production device in a hot rolling procedure in the steel industry and is also a main energy consumption device. It not only affects the yield and performance quality of round steel, but also affects the life and energy consumption of the rolling mill. Traditionally, bearing steel round steel is produced by heating and rolling after cold charging, and the process is that a continuous casting billet which is taken out of a continuous casting machine is directly connected into a heat preservation pit for slow cooling or cold stacking, and after the continuous casting billet is cooled to normal temperature and qualified by finishing inspection, the charging, heating and rolling processes of the continuous casting billet are carried out. The advantages of this process are: wide adaptability, flexible production arrangement and strong product quality assurance.
However, the waste heat of the continuous casting billet can not be effectively utilized, so that the energy is wasted, the carbon emission is increased, and meanwhile, the oxidation burning loss and decarburization of the continuous casting billet are increased in the slow cooling and heating processes of the continuous casting billet. Therefore, by using the novel bearing steel round steel production method, the decarburized layer depth of the hot-rolled round steel is reduced on the premise of ensuring the uniformity of carbides, and the aims of energy conservation and emission reduction are fulfilled.
Disclosure of Invention
The invention aims to overcome the technical defects in the prior art, and provides a hot-delivery hot-charging production method for reducing the decarburized layer depth of bearing steel round steel, which has the advantages that: the waste heat of the continuous casting billet can be effectively utilized, and the purposes of energy conservation and emission reduction are achieved; secondly, the oxidation burning loss of the continuous casting billet is small, and the yield is improved; thirdly, the consumption of gas in a preheating section and a heating section is reduced, and the energy consumption is saved; fourthly, the production period is short, and the production efficiency is high; and fifthly, improving key performance indexes such as carbide uniformity and decarburized layer.
In order to achieve the purpose, the invention firstly provides bearing steel round steel which comprises the following components in percentage by weight: c: 0.96-1.03%, Mn: 0.30-0.40%, Si: 0.20-0.30%, Cr: 1.42-1.50%, P is less than or equal to 0.015%, S is less than or equal to 0.012%, Ni is less than or equal to 0.10%, Cu: 0.04-0.10%, Mo is less than or equal to 0.08%, Al: 0.005-0.015 percent of Ti, less than or equal to 0.0030 percent of Ti, less than or equal to 0.0009 percent of O, less than or equal to 0.0010 percent of Ca, less than or equal to 0.04 percent of As, less than or equal to 0.002 percent of Pb, and less than or equal to 0.03 percent of Sn; the balance being Fe and unavoidable impurities.
The invention also provides a hot-delivery hot-charging production method for reducing the depth of the decarburized layer of the bearing steel round steel, which comprises the following steps:
the method comprises the steps of converter smelting, LF refining, VD vacuum treatment and continuous casting operation to obtain a continuous casting billet; then hot charging, heating in a heating furnace, dephosphorization by high-pressure water, controlled rolling and controlled cooling, shearing, collecting and packaging, finishing and inspecting.
The specific operation steps and parameter settings are as follows:
(1) performing converter smelting, LF refining, VD vacuum treatment and continuous casting operation on the raw materials to obtain a continuous casting billet (220 square);
(2) based on the continuous casting billet obtained in the step (1), utilizing a thermal insulation vehicle or a thermal insulation conveying raceway to carry out hot charging on the continuous casting billet, and keeping a certain temperature interval for hot charging into a heating furnace;
(3) after the hot material is loaded into the heating furnace based on the step (2), heating the continuous casting billet in the heating furnace, and simultaneously controlling the ratio of air to coal gas in the heating furnace to be 1.15-1.35; the specific procedure of heating in the heating furnace is as follows: the temperature of the preheating section is less than or equal to 800 ℃, the retention time is less than 50 minutes, the heating source is closed, and heat is transferred through the heating section; heating to a temperature of 900 ℃ and 1100 ℃, and keeping the time less than 50 minutes; the temperature of the heating second section is 1160-; the temperature of the soaking section is 1180 ℃ and 1250 ℃, the retention time is less than 80 minutes, and the total in-furnace time is not less than 200 minutes; firstly, the decarburization on the surface of the continuous casting billet is reduced by rapidly passing through a decarburization sensitive temperature range (preheating + heating for one section). Secondly, the depth of the decarburization layer is reduced again by utilizing the characteristic that oxidation is larger than decarburization in a high-temperature (heating two-stage + soaking stage) stage. Meanwhile, the high-temperature diffusion effect is ensured to control the uniformity of carbide.
(4) After heating in the heating furnace based on the step (3), taking the continuous casting slab out of the heating furnace, and carrying out high-pressure water dephosphorization at the pressure of 20-26MPa to thoroughly remove the iron oxide scales on the surface of the continuous casting slab;
(5) performing controlled rolling and controlled cooling on the continuous casting billet subjected to the high-pressure water dephosphorization in the step (4), wherein the specific conditions are as follows: the initial rolling temperature is 1040-1120 ℃, the continuous casting slab is rolled at the finished product speed of 1.2-4.2m/s, and the continuous casting slab is sequentially subjected to rough rolling, intermediate rolling, (pre) finish rolling and rolling by a KOCKS rolling mill, the final rolling temperature is controlled to be 750-850 ℃, and the temperature of an upper cooling bed is controlled to be 650-750 ℃. By controlling rolling and cooling, the increase of a decarburized layer and the generation of net-shaped carbides in the rolling and cooling processes are reduced.
(6) And (5) after rolling and cooling are controlled based on the step (5), carrying out surface quality inspection, shearing, collecting and packaging, finishing and inspection on the round steel on the cooling bed.
Preferably, the temperature range of the continuous casting slab in the step (2) is 500-700 ℃.
Preferably, the ratio of the air to the coal gas in the step (3) is controlled to be 1.2-1.28.
Preferably, the preheating and heating section in the step (3) is recorded as a low temperature section, the temperature range of the low temperature section is 700-980 ℃, and the holding time of the low temperature section is not more than 90 minutes.
Preferably, the heating second section and the soaking section in the step (3) are marked as a high-temperature section, the temperature interval of the high-temperature section is 1180-1220 ℃, and the holding time of the high-temperature section is not less than 120 minutes.
Preferably, the pressure of the high-pressure water dephosphorization in the step (4) is 22-25 MPa.
Preferably, the initial rolling temperature in the step (5) is 1050-; the temperature of the upper cooling bed is 680-740 ℃.
Preferably, the rolling speed in the step (5) is 1.4-4 m/s.
The invention has the advantages and technical effects that:
compared with the bearing steel round steel indexes of the conventional control method, the invention has the following advantages:
(1) the method skips the slow cooling process of the continuous casting billet heat preservation pit, and the production cycle is reduced by 3 days; meanwhile, the production efficiency is improved, and the occupied site is reduced.
(2) The residence time in the heating furnace is shortened by 30 minutes, the fuel (coal gas) consumption is reduced by more than 12 percent, and the production capacity of each ton of steel is improved by more than 30 percent. And the decarburization on the surface of the continuous casting billet is reduced by rapidly passing through a decarburization sensitive temperature range (preheating and heating for one section) in the heating furnace. Secondly, by utilizing the characteristic that oxidation is larger than decarburization in a high-temperature (heating two-stage + soaking stage) stage, the depth of a decarburized layer is reduced again, and the high-temperature diffusion effect is ensured so as to control the uniformity of carbide.
(3) By using the hot-delivery hot-loading controlled-rolling controlled-cooling technology, the decarburized layer depth of the bearing steel hot-rolled round steel is reduced, and the average total decarburized layer depth is reduced by not less than 0.03 percent of the nominal diameter.
(4) The surface oxidation burning loss of the continuous casting billet is reduced, so that the finished product yield is improved by 0.7 percent.
(5) The carbide uniformity of the bearing steel round steel is improved; in the hot charging state, the band-shaped nonuniformity of the carbide is reduced by 0.5 level.
Detailed Description
The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.
Comparative example 1:
rolling bearing steel round steel with the diameter of 70mm to produce;
the invention comprises the following components: c: 1.0%, Mn: 0.36%, Si: 0.25%, Cr: 1.46%, P: 0.008%, S: 0.003%, Ni: 0.02%, Cu: 0.07%, Mo: 0.01%, Al: 0.011%, Ti: 0.0013%, [ O ]: 0.0005%, Ca: 0.0001%, As: 0.004%, Pb: 0.0002%, Sn: 0.003%; the balance being Fe and unavoidable impurities.
The method comprises the following steps: performing VD vacuum treatment and continuous casting operation to obtain a continuous casting billet; slow cooling, heating in a heating furnace, removing phosphorus by high-pressure water, controlled rolling and controlled cooling, shearing, collecting and packaging, finishing and inspecting.
(1) The raw materials are subjected to converter smelting, LF refining, VD vacuum treatment and continuous casting operation to obtain a 220-square continuous casting billet.
(2) And (3) directly putting the continuous casting slab into a heat preservation pit for slow cooling for 72 hours, cooling the continuous casting slab to the temperature below 200 ℃ at the highest temperature, conveying the continuous casting slab to a storage yard, and rolling in a furnace.
(3) Cold charging of the continuous casting billet, heating in a heating furnace, wherein the ratio of air to coal gas is 1.3; the temperature of the preheating section is 800 ℃, the retention time is 80 minutes, and the heating is normally carried out; heating for a period of time, namely 980 ℃, and keeping for 80 minutes; heating the second stage to 1210 deg.c for 90 min; the temperature of the soaking section is 1220 ℃, and the retention time is 90 minutes;
(4) taking the continuous casting slab out of the heating furnace, and carrying out high-pressure water dephosphorization at the dephosphorization pressure of 21 MPa;
(5) the initial rolling temperature is-1100 ℃, the rolling speed of the finished product is 3.0m/s, the rough rolling, the middle rolling, (pre) finish rolling and the rolling of a KOCKS rolling mill are carried out in sequence, the final rolling temperature is 850 ℃, and the temperature of an upper cooling bed is 750 ℃.
(6) And (4) carrying out surface quality inspection, shearing, collecting and packaging, finishing and inspection on the round steel on the cooling bed.
The test is carried out according to the GB/T18254-2016 high-carbon chromium bearing steel standard, the qualification rate is 100 percent, and the statistics of the total decarburized layer and the band shape of the carbide are shown in the table 1.
TABLE 1 Cold-mounted rolled decarburized layer and strip
Example 1:
hot feeding, hot loading and rolling production are carried out on bearing steel round steel with the diameter of 40 mm;
the invention comprises the following components: c: 0.97%, Mn: 0.35%, Si: 0.24%, Cr: 1.46%, P: 0.012%, S: 0.003%, Ni: 0.02%, Cu: 0.07%, Mo: 0.01%, Al: 0.012%, Ti: 0.0012%, [ O ]: 0.0005%, Ca: 0.0001%, As: 0.004%, Pb: 0.0002%, Sn: 0.003%; the balance being Fe and unavoidable impurities. The method comprises the following steps: performing VD vacuum treatment and continuous casting operation to obtain a continuous casting billet; then hot charging, heating in a heating furnace, dephosphorization by high-pressure water, controlled rolling and controlled cooling, shearing, collecting and packaging, finishing and inspecting.
(1) The raw materials are subjected to converter smelting, LF refining, VD vacuum treatment and continuous casting operation to obtain a 220-square continuous casting billet.
(2) A220-square continuous casting billet with the temperature of about 550 ℃ is hot-charged into a heating furnace by using a thermal insulation trolley.
(3) Heating the continuous casting billet in a heating furnace, wherein the ratio of air to coal gas is 1.2; the temperature of the preheating section is 650 ℃, the retention time is 40 minutes, the heating source is closed, and heat is transferred through the heating section; heating for a period of time at 980 ℃ and keeping for 45 minutes; heating the second section at 1180 deg.c for 65 min; the temperature of the soaking section is 1210 ℃, and the retention time is 70 minutes. The total oven time is about 220 minutes.
(4) And (4) taking the continuous casting slab out of the heating furnace, and carrying out high-pressure water dephosphorization, wherein the dephosphorization pressure is 22 MPa.
(5) The initial rolling temperature is 1100 ℃, the rolling speed of the finished product is 4.0m/s, the rough rolling, the middle rolling, (pre) finish rolling and the rolling of a KOCKS rolling mill are carried out in sequence, the final rolling temperature is 835 ℃, and the temperature of an upper cooling bed is 740 ℃.
(6) And (4) carrying out surface quality inspection, shearing, collecting and packaging, finishing and inspection on the round steel on the cooling bed.
The test is carried out according to the GB/T18254-2016 high-carbon chromium bearing steel standard, the qualification rate is 100 percent, and the statistics of the total decarburized layer and the band shape of the carbide are shown in the table 2.
TABLE 2 phi 40mm hot-delivery hot-assembly rolled decarburized layer and band
Example 2:
hot feeding, hot loading and rolling production are carried out on bearing steel round steel with the diameter of 60 mm;
the invention comprises the following components: c: 0.99%, Mn: 0.34%, Si: 0.25%, Cr: 1.46%, P: 0.014%, S: 0.004%, Ni: 0.02%, Cu: 0.07%, Mo: 0.01%, Al: 0.012%, Ti: 0.0014%, [ O ]: 0.0006%, Ca: 0.0001%, As: 0.004%, Pb: 0.0002%, Sn: 0.003%; the balance being Fe and unavoidable impurities.
The method comprises the following steps: performing VD vacuum treatment and continuous casting operation to obtain a continuous casting billet; then hot charging, heating in a heating furnace, dephosphorization by high-pressure water, controlled rolling and controlled cooling, shearing, collecting and packaging, finishing and inspecting.
(1) The raw materials are subjected to converter smelting, LF refining, VD vacuum treatment and continuous casting operation to obtain a 220-square continuous casting billet.
(2) A220-square continuous casting billet with the temperature of about 595 ℃ is hot-charged into a heating furnace by using a thermal insulation trolley.
(3) Heating the continuous casting billet in a heating furnace, wherein the ratio of air to coal gas is 1.28; the temperature of the preheating section is 700 ℃, the retention time is 40 minutes, the heating source is closed, and heat is transferred through the heating section; heating to 990 deg.C for 40 min; heating the second section at 1190 deg.c for 70 min; the temperature of the soaking section is 1200 ℃, and the retention time is 75 minutes. The total oven time is about 225 minutes.
(4) And (4) taking the continuous casting slab out of the heating furnace, and carrying out high-pressure water dephosphorization, wherein the dephosphorization pressure is 24 MPa.
(5) The initial rolling temperature is 1080 ℃, the finished product rolling speed is 1.8m/s, the rough rolling, the middle rolling, (pre) finish rolling and the rolling of a KOCKS rolling mill are carried out in sequence, the final rolling temperature is 800 ℃, and the temperature of an upper cooling bed is 710 ℃.
(6) And (4) carrying out surface quality inspection, shearing, collecting and packaging, finishing and inspection on the round steel on the cooling bed.
The test is carried out according to the GB/T18254-2016 high-carbon chromium bearing steel standard, the qualification rate is 100 percent, and the statistics of the total decarburized layer and the band shape of the carbide are shown in the table 3.
TABLE 3 phi 60mm hot-delivery hot-charging rolling decarburized layer and band
Example 3:
hot feeding, hot loading and rolling production are carried out on bearing steel round steel with the diameter of 70 mm;
the invention comprises the following components: c: 1.0%, Mn: 0.36%, Si: 0.25%, Cr: 1.46%, P: 0.008%, S: 0.003%, Ni: 0.02%, Cu: 0.07%, Mo: 0.01%, Al: 0.011%, Ti: 0.0013%, [ O ]: 0.0005%, Ca: 0.0001%, As: 0.004%, Pb: 0.0002%, Sn: 0.003%; the balance being Fe and unavoidable impurities.
The method comprises the following steps: performing VD vacuum treatment and continuous casting operation to obtain a continuous casting billet; then hot charging, heating in a heating furnace, dephosphorization by high-pressure water, controlled rolling and controlled cooling, shearing, collecting and packaging, finishing and inspecting.
(1) The raw materials are subjected to converter smelting, LF refining, VD vacuum treatment and continuous casting operation to obtain a 220-square continuous casting billet.
(2) A220-square continuous casting billet with the temperature of about 645 ℃ is hot-charged into a heating furnace by using a thermal insulation vehicle.
(3) Heating the continuous casting billet in a heating furnace, wherein the ratio of air to coal gas is 1.25; the temperature of the preheating section is 670 ℃, the retention time is 42 minutes, the heating source is closed, and heat is transferred through the heating section; heating to 1050 ℃ for a period of time, and keeping for 45 minutes; the temperature of the second stage of heating is 1200 ℃, and the retention time is 70 minutes; the temperature of the soaking section is 1220 ℃, and the retention time is 70 minutes. The total oven time is about 227 minutes.
(4) And (4) taking the continuous casting slab out of the heating furnace, and carrying out high-pressure water dephosphorization, wherein the dephosphorization pressure is 25 MPa.
(5) The initial rolling temperature is 1050 ℃, the rolling speed of the finished product is 1.4m/s, the rough rolling, the middle rolling, (pre) finish rolling and the rolling of a KOCKS rolling mill are carried out in sequence, the final rolling temperature is 785 ℃, and the temperature of the finished product on a cooling bed is 680 ℃.
(6) And (4) carrying out surface quality inspection, shearing, collecting and packaging, finishing and inspection on the round steel on the cooling bed.
The test is carried out according to the GB/T18254-2016 high-carbon chromium bearing steel standard, the qualification rate is 100 percent, and the statistics of the total decarburized layer and the band shape of the carbide are shown in the table 4.
TABLE 4 phi 70mm hot-delivery hot-assembly rolling decarburized layer and band
Compared with cold-rolled bearing steel, the invention shortens the furnace time, reduces the energy consumption, reduces the production period and the inventory turnover, and achieves the benefits of saving the cost and the cost.
The invention has excellent performance, and the average total decarburized layer depth is reduced by 0.07 percent of the nominal diameter; meanwhile, the band shape of the carbide is reduced by 0.5 level. As can be seen from Table 5, the average depth of decarburized layer of the hot-transfer furnace was 0.24% of the nominal diameter, and the average carbide band reached 2.0.
TABLE 5 comparison of Cold Loading with Hot Loading
Description of the drawings: the above embodiments are only used to illustrate the present invention and do not limit the technical solutions described in the present invention; thus, while the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted; all such modifications and variations are intended to be included herein within the scope of this disclosure and the present invention and protected by the following claims.
Claims (8)
1. A hot-delivery hot-charging production method for reducing the depth of a decarburized layer of bearing steel round steel is characterized by comprising the following steps of:
(1) carrying out converter smelting, LF refining, VD vacuum treatment and continuous casting operation on the raw materials to obtain a continuous casting billet;
(2) based on the continuous casting billet obtained in the step (1), utilizing a thermal insulation vehicle or a thermal insulation conveying raceway to carry out hot charging on the continuous casting billet, and keeping a certain temperature interval for hot charging into a heating furnace;
(3) after the hot material is loaded into the heating furnace based on the step (2), heating the continuous casting billet in the heating furnace, and simultaneously controlling the ratio of air to coal gas in the heating furnace to be 1.15-1.35; the specific procedure of heating in the heating furnace is as follows: the temperature of the preheating section is less than or equal to 800 ℃, the retention time is less than 50 minutes, the heating source is closed, and heat is transferred through the heating section; heating to a temperature of 900 ℃ and 1100 ℃, and keeping the time less than 50 minutes; the temperature of the heating second section is 1160-; the temperature of the soaking section is 1180 ℃ and 1250 ℃, the retention time is less than 80 minutes, and the total in-furnace time is not less than 200 minutes;
(4) after heating in the heating furnace based on the step (3), taking the continuous casting slab out of the heating furnace, and carrying out high-pressure water dephosphorization at the pressure of 20-26 MPa;
(5) performing controlled rolling and controlled cooling on the continuous casting billet subjected to the high-pressure water dephosphorization in the step (4), wherein the specific conditions are as follows: the initial rolling temperature is 1040-750 ℃ plus 1120 ℃, the continuous casting slab is rolled at the finished product speed of 1.2-4.2m/s, and the continuous casting slab is sequentially subjected to rough rolling, intermediate rolling, finish rolling and rolling by a KOCKS rolling mill, the final rolling temperature is controlled at 750-850 ℃, and the temperature of an upper cooling bed is controlled at 650-750 ℃;
(6) after rolling and cooling are controlled based on the step (5), surface quality inspection, shearing, collection and packaging, finishing and inspection are carried out on the round steel on the cooling bed;
the bearing steel round steel comprises the following components in percentage by weight: c: 0.96-1.03%, Mn: 0.30-0.40%, Si: 0.20-0.30%, Cr: 1.42-1.50%, P is less than or equal to 0.015%, S is less than or equal to 0.012%, Ni is less than or equal to 0.10%, Cu: 0.04-0.10%, Mo is less than or equal to 0.08%, Al: 0.005-0.015 percent of Ti, less than or equal to 0.0030 percent of Ti, less than or equal to 0.0009 percent of O, less than or equal to 0.0010 percent of Ca, less than or equal to 0.04 percent of As, less than or equal to 0.002 percent of Pb, and less than or equal to 0.03 percent of Sn; the balance being Fe and unavoidable impurities.
2. The hot-delivery hot-fill production method for reducing the decarburized layer depth of round steel for bearing steel as claimed in claim 1, wherein the temperature range of the continuous casting slab in the step (2) is 500-700 ℃.
3. The hot-air hot-fill production method for reducing the decarburized layer depth of round steel for bearing steel as claimed in claim 1, wherein the ratio of air to gas in step (3) is controlled to be 1.2 to 1.28.
4. The hot-delivery hot-fill production method for reducing the decarburized layer depth of round steel of bearing steel as recited in claim 1, wherein the preheating and heating step (3) is a low temperature step, the temperature range of the low temperature step is 700-980 ℃, and the holding time of the low temperature step is not more than 90 minutes.
5. The hot-delivery hot-charging production method for reducing the decarburized layer depth of the round steel of bearing steel as claimed in claim 1, wherein the heating second section and the soaking section in step (3) are marked as high temperature sections, the temperature range of the high temperature section is 1180-1220 ℃, and the holding time of the high temperature section is not less than 120 minutes.
6. The hot-feeding and hot-filling production method for reducing the decarburized layer depth of the round steel of bearing steel according to claim 1, wherein the pressure for removing phosphorus by high-pressure water in the step (4) is 22-25 MPa.
7. The hot-delivery hot-charging production method for reducing the decarburized layer depth of the round steel bar for bearing steel as claimed in claim 1, wherein the initial rolling temperature in the step (5) is 1050-; the temperature of the upper cooling bed is 680-740 ℃.
8. The hot-feeding and hot-filling production method for reducing the decarburized layer depth of round steel for bearing steel according to claim 1, wherein the rolling speed in the step (5) is 1.4 to 4 m/s.
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| CN115612920A (en) * | 2022-08-29 | 2023-01-17 | 江阴兴澄特种钢铁有限公司 | Steel for flexible bearing of harmonic speed reducer of robot and production method thereof |
| CN115612920B (en) * | 2022-08-29 | 2024-03-29 | 江阴兴澄特种钢铁有限公司 | Steel for flexible bearing of robot harmonic reducer and production method of steel |
| CN115747442A (en) * | 2022-10-21 | 2023-03-07 | 南京钢铁股份有限公司 | Preparation method of normalizing-free medium carbon wheel hub bearing steel |
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