CN111394555A - GCr15 bearing steel with low decarburization depth and preparation method thereof - Google Patents
GCr15 bearing steel with low decarburization depth and preparation method thereof Download PDFInfo
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- CN111394555A CN111394555A CN202010454830.7A CN202010454830A CN111394555A CN 111394555 A CN111394555 A CN 111394555A CN 202010454830 A CN202010454830 A CN 202010454830A CN 111394555 A CN111394555 A CN 111394555A
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/68—Temporary coatings or embedding materials applied before or during heat treatment
- C21D1/70—Temporary coatings or embedding materials applied before or during heat treatment while heating or quenching
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/84—Controlled slow cooling
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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
- C21D6/002—Heat treatment of ferrous alloys containing Cr
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/005—Modifying the physical properties by deformation combined with, or followed by, heat treatment of ferrous alloys
Abstract
The invention provides GCr15 bearing steel with low decarburization depth and a preparation method thereof, belonging to the technical field of metal smelting processing.A billet surface is uniformly coated with two layers of high-temperature anti-oxidation coatings as protective layers and then is sent into a heating furnace for sectional heating, so that the bearing steel can be effectively prevented from reacting with oxidizing gas in the heating furnace, the generation of an oxide skin and a decarburization layer is reduced, and meanwhile, the oxidation burning loss of the steel can be reduced; the coating takes the attapulgite as a main body, has good and stable performance and better effect; after the billet steel is sent into the heating furnace for heating, the effective control of the depth of the decarburized layer can be further realized by controlling parameters such as residual oxygen amount, excess air coefficient, furnace pressure and the like in the heating furnace, and the heating furnace can carry out automatic combustion control by setting a target temperature and is convenient to use; after rolling, the billet is quickly cooled to below 600 ℃ and then slowly cooled, so that the oxidation of the billet is slow, the diffusion of carbon can be effectively prevented, and the quality of the billet is improved.
Description
Technical Field
The invention belongs to the technical field of metal smelting and processing, and particularly relates to GCr15 bearing steel with a low decarburization layer depth and a preparation method thereof.
Background
The GCr15 bearing steel is high-carbon chromium bearing steel with less alloy content, good performance and wide application, and is mainly used for manufacturing rolling elements of rolling bearings, and the quality of the rolling elements directly influences the service life of the bearings. The surface quality, dimensional accuracy, depth of decarburized layer, and uniformity of carbide of the bearing steel must be controlled, and it is difficult to control the depth of decarburized layer and the uniformity of carbide. The GCr15 bearing steel billet needs to be subjected to high-temperature diffusion for a long time in a heating furnace, the temperature can be homogenized, segregation elements can be homogenized, but oxidation and decarburization phenomena appear on the surface of the steel billet along with the extension of the heating temperature and the heating time, so that the mechanical property of the surface layer of the bearing steel is reduced, and the use requirement cannot be met. The heating time and the heating temperature can be controlled to a certain extent by adopting a method for controlling the heating time and the heating temperature, but the comprehensive mechanical property of a final finished product is possibly poor due to insufficient heating time, so that how to more effectively control the decarburization of the GCr15 bearing steel is very important.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides the GCr15 bearing steel with low decarburization depth and the preparation method thereof, and the protection layer is coated on the surface of the billet before heating, and the parameters of the heating furnace are controlled, so that the billet can be effectively prevented from reacting with oxidizing gas in the furnace to generate an oxide skin and a decarburized layer in the high-temperature heat treatment process, and the quality of a workpiece is improved.
The present invention achieves the above-described object by the following technical means.
A preparation method of GCr15 bearing steel with low decarburized layer depth comprises the following steps:
step 1: coating a protective layer on the surface of the billet and waiting for drying;
step 2: feeding the steel billet coated with the protective layer into a heating furnace for segmented heating, controlling parameters of the heating furnace to realize weak oxidizing atmosphere heating, discharging and preserving heat for 30min after heating;
and step 3: feeding the heated steel billets into a rough rolling mill group, a medium rolling mill group and a finishing rolling mill group in sequence for rolling;
and 4, step 4: rapidly cooling the rolled steel billet to below 600 ℃ through a water cooling box;
and 5: feeding the steel billet subjected to rapid cooling into a cooling bed heat-insulating cover to be slowly cooled to 400-450 ℃;
step 6: and air-cooling the slowly cooled steel billet to room temperature, and grinding the surface of the air-cooled steel billet by using a grinding wheel.
Further, the protective layer is high-temperature anti-oxidation coating which mainly comprises attapulgite and Al2O3、Cr2O3、SiC、Na2SiO3The composition comprises the following components in percentage by weight: 2.21g/cm3、3.96g/cm3、5.20g/cm3、3.23g/cm3、1.42g/cm3。
Further, the temperatures of the sectional heating are respectively as follows: the preheating section is less than or equal to 850 ℃, the first heating section is 1100-1150 ℃, the second heating section is 1210-1250 ℃, the soaking section is 1190-1230 ℃, and the tapping temperature is 1150-1230 ℃.
Further, when the steel billet enters each heating section in the heating furnace, target temperature values are respectively set to realize automatic combustion control of the heating furnace, and the target temperature values are respectively: the preheating section is 800 ℃, the first section is heated to 1120 ℃, the second section is heated to 1230 ℃, and the soaking section is 1210 ℃.
Further, the process of controlling the parameters of the heating furnace specifically comprises the following steps: controlling the residual oxygen amount in the heating furnace to be 2% -5%, the air excess coefficient to be 0.9-1.2 and the furnace pressure to be 8-15 Pa.
Furthermore, the heating time of the sectional heating is more than or equal to 4 hours, and the total time of the second heating section and the soaking section is more than or equal to 2 hours.
Further, the finishing temperature of the steel billet is more than or equal to 900 ℃.
Further, the rapid cooling rate is 10 ℃/S.
Further, the slow cooling rate is 0.3 ℃/S, and the temperature of the heat preservation cover is 400-450 ℃.
Further, the GCr15 bearing steel is prepared by the preparation method.
The invention has the following beneficial effects
Compared with the prior art, in the preparation process, before entering a heating furnace, two layers of high-temperature anti-oxidation coatings are uniformly coated on the surface of the billet to serve as protective layers, so that the bearing steel can be effectively prevented from reacting with oxidizing gas in the heating furnace, the generation of an oxide skin and a decarburized layer can be reduced, the oxidation burning loss of the steel can be reduced, and the coating taking attapulgite as a main body has good and stable performance, better effect and easy removal; after the billet steel is sent into the heating furnace for heating, the effective control of the depth of the bearing steel decarburized layer is further realized by controlling parameters such as residual oxygen amount, excess air coefficient, furnace pressure and the like in the heating furnace, and the heating furnace can carry out automatic combustion control by setting a target temperature and is convenient to use; after rolling, the billet is quickly cooled to below 600 ℃ and then slowly cooled, so that the oxidation of the billet is slow, the diffusion of carbon can be effectively prevented, and the quality of the billet is improved. The preparation method provided by the invention is simple and convenient, and saves the working procedures of additional annealing, drawing pass and the like, thereby saving the cost; the GCr15 bearing steel prepared by the method has low decarburization layer depth and good comprehensive mechanical property.
Drawings
FIG. 1 is a flow chart of a method for preparing low decarburized layer depth GCr15 bearing steel according to the invention.
Detailed Description
The invention will be further described with reference to the following figures and specific examples, but the scope of the invention is not limited thereto.
The flow chart of the preparation method of the GCr15 bearing steel with the low decarburization depth is shown in figure 1, wherein the billet adopted by the invention is a GCr15 continuous casting billet with the specification of 220mm, and the specific process is as follows:
step 1: coating a protective layer, namely uniformly coating a layer of high-temperature anti-oxidation coating on the surface of the billet to serve as the protective layer, waiting for the coating to be dried after uniform coating, and then continuously and uniformly coating a second layer of coating to wait for the coating to be dried; the coating used in this example was composed mainly of attapulgite and Al2O3、Cr2O3、SiC、Na2SiO3The composition comprises the following components in percentage by weight: 2.21g/cm3、3.96g/cm3、5.20g/cm3、3.23g/cm3、1.42g/cm3；
Step 2: and (3) heating in sections, namely sending the steel billet with the surface coated with the coating into a heating furnace for heating in sections, wherein the temperature requirements of each heating section are as follows: the preheating section is less than or equal to 850 ℃, the first heating section is 1100-1150 ℃, the second heating section is 1210-1250 ℃, and the soaking section is 1190-1230 ℃; the discharging temperature is 1150-1230 ℃, and discharging and heat preservation are carried out for 30min after heating; the total heating time is more than or equal to 4 hours, wherein the total time of the heating second section and the soaking section is more than or equal to 2 hours; in the heating process, the residual oxygen content in the heating furnace is kept to be 2% -5%, the excess air coefficient is 0.9-1.2, the furnace pressure is 8-15 Pa, and the weak oxidizing atmosphere heating is realized; when the steel billet enters each heating section in the heating furnace, each heating section is set according to a target temperature value respectively to realize automatic combustion control, and the target temperature values of each heating section are respectively as follows: preheating section 800 deg.C, heating section 1120 deg.C, heating section 1230 deg.C, soaking section 1210 deg.C;
and step 3: rolling, wherein the heated steel billet is subjected to high-pressure water dephosphorization, and then is sequentially sent to a rough rolling unit, a medium rolling unit and a finishing rolling unit for rolling, and the final rolling temperature is more than or equal to 900 ℃;
and 4, step 4: rapidly cooling, namely rapidly cooling the rolled steel billet to below 600 ℃ through a water cooling box at a cooling rate of 10 ℃/S;
and 5: slowly cooling, namely conveying the rapidly cooled steel billets into a cooling bed heat-insulating cover for slow cooling, wherein the cooling rate is 0.3 ℃/S, and the temperature of the steel billets discharged from the heat-insulating cover is 400-450 ℃;
step 6: air cooling, namely air cooling the slowly cooled steel billet to room temperature;
and 7: and grinding by using a grinding wheel, namely performing grinding operation on the surface of the air-cooled billet to remove a billet surface protective layer, a small amount of surface oxide scale and a decarburized layer.
The heating furnace in the embodiment is a high-efficiency walking beam heating furnace; the rolling units are arranged in a flat-crossed alternative mode, all the rolling units are continuous non-twisting rolling, and the rough rolling unit and the middle rolling unit adopt a micro-tension rolling mode.
The preparation method can more effectively control the decarburization depth of the GCr15 bearing steel, and simultaneously ensures that the final finished product has good comprehensive mechanical properties.
The present invention is not limited to the above-described embodiments, and any obvious improvements, substitutions or modifications can be made by those skilled in the art without departing from the spirit of the present invention.
Claims (10)
1. A preparation method of GCr15 bearing steel with low decarburized layer depth is characterized by comprising the following steps:
step 1: coating a protective layer on the surface of the billet and waiting for drying;
step 2: feeding the steel billet coated with the protective layer into a heating furnace for segmented heating, controlling parameters of the heating furnace to realize weak oxidizing atmosphere heating, discharging and preserving heat for 30min after heating;
and step 3: feeding the heated steel billets into a rough rolling mill group, a medium rolling mill group and a finishing rolling mill group in sequence for rolling;
and 4, step 4: rapidly cooling the rolled steel billet to below 600 ℃ through a water cooling box;
and 5: feeding the steel billet subjected to rapid cooling into a cooling bed heat-insulating cover to be slowly cooled to 400-450 ℃;
step 6: and air-cooling the slowly cooled steel billet to room temperature, and grinding the surface of the air-cooled steel billet by using a grinding wheel.
2. The method for preparing bearing steel according to claim 1, wherein the protective layer is a high temperature oxidation-resistant coating mainly composed of attapulgite, Al2O3、Cr2O3、SiC、Na2SiO3The composition comprises the following components in percentage by weight: 2.21g/cm3、3.96g/cm3、5.20g/cm3、3.23g/cm3、1.42g/cm3。
3. The method for preparing bearing steel according to claim 1, wherein the temperatures of the sectional heating are respectively as follows: the preheating section is less than or equal to 850 ℃, the first heating section is 1100-1150 ℃, the second heating section is 1210-1250 ℃, the soaking section is 1190-1230 ℃, and the tapping temperature is 1150-1230 ℃.
4. The method of manufacturing a bearing steel according to claim 3, wherein the automatic combustion control of the heating furnace is performed by setting target temperature values when the steel slab enters each heating zone in the heating furnace, the target temperature values being: the preheating section is 800 ℃, the first section is heated to 1120 ℃, the second section is heated to 1230 ℃, and the soaking section is 1210 ℃.
5. The bearing steel preparation method according to claim 3, wherein the process of controlling the furnace parameters specifically comprises: controlling the residual oxygen amount in the heating furnace to be 2% -5%, the air excess coefficient to be 0.9-1.2 and the furnace pressure to be 8-15 Pa.
6. A method for preparing bearing steel according to claim 3, wherein the heating time of the sectional heating is not less than 4 hours, and the total time of the heating two sections and the soaking section is not less than 2 hours.
7. The method for producing a bearing steel according to claim 1, wherein the finish rolling temperature of the steel slab is 900 ℃ or higher.
8. Method for producing a bearing steel according to claim 1, characterised in that the rapid cooling rate is 10 ℃/S.
9. The method for preparing the bearing steel according to claim 1, wherein the slow cooling rate is 0.3 ℃/S, and the temperature of the bearing steel out of the heat-preserving cover is 400-450 ℃.
10. GCr15 bearing steel produced by the production method according to any one of claims 1 to 9.
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| CN202010454830.7A CN111394555A (en) | 2020-05-26 | 2020-05-26 | GCr15 bearing steel with low decarburization depth and preparation method thereof |
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Citations (6)
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| JPS5672120A (en) * | 1979-11-14 | 1981-06-16 | Nippon Steel Corp | Prevention method of decarburization of steel product |
| CN102312065A (en) * | 2011-09-21 | 2012-01-11 | 镇江忆诺唯记忆合金有限公司 | Method for preventing GCr 15 steel surface oxidation |
| CN103451396A (en) * | 2013-09-13 | 2013-12-18 | 湖州市银鑫轧辊有限公司 | Processing method for preventing decarbonization of high-carbon steel billet |
| CN108396128A (en) * | 2017-11-28 | 2018-08-14 | 江苏省沙钢钢铁研究院有限公司 | A kind of control method of bloom alloy tool steel wire surface decarburization |
| CN109112280A (en) * | 2018-08-07 | 2019-01-01 | 南京钢铁股份有限公司 | A kind of control method of bearing steel wire rod decarburized depth |
| CN110016541A (en) * | 2019-05-24 | 2019-07-16 | 东北大学 | A method of the GCr15 bearing ball annealing time is shortened by cooling controlling and rolling controlling process |
-
2020
- 2020-05-26 CN CN202010454830.7A patent/CN111394555A/en active Pending
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5672120A (en) * | 1979-11-14 | 1981-06-16 | Nippon Steel Corp | Prevention method of decarburization of steel product |
| CN102312065A (en) * | 2011-09-21 | 2012-01-11 | 镇江忆诺唯记忆合金有限公司 | Method for preventing GCr 15 steel surface oxidation |
| CN103451396A (en) * | 2013-09-13 | 2013-12-18 | 湖州市银鑫轧辊有限公司 | Processing method for preventing decarbonization of high-carbon steel billet |
| CN108396128A (en) * | 2017-11-28 | 2018-08-14 | 江苏省沙钢钢铁研究院有限公司 | A kind of control method of bloom alloy tool steel wire surface decarburization |
| CN109112280A (en) * | 2018-08-07 | 2019-01-01 | 南京钢铁股份有限公司 | A kind of control method of bearing steel wire rod decarburized depth |
| CN110016541A (en) * | 2019-05-24 | 2019-07-16 | 东北大学 | A method of the GCr15 bearing ball annealing time is shortened by cooling controlling and rolling controlling process |
Non-Patent Citations (2)
| Title |
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| 宋进英等: "《板带钢质量缺陷特征与控制》", 30 June 2017 * |
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