CN114507775A - Heating method for improving primary carbide of ultrahigh-carbon martensitic stainless steel continuous casting billet - Google Patents
Heating method for improving primary carbide of ultrahigh-carbon martensitic stainless steel continuous casting billet Download PDFInfo
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- CN114507775A CN114507775A CN202111384142.9A CN202111384142A CN114507775A CN 114507775 A CN114507775 A CN 114507775A CN 202111384142 A CN202111384142 A CN 202111384142A CN 114507775 A CN114507775 A CN 114507775A
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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
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/70—Furnaces for ingots, i.e. soaking pits
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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
- C21D6/004—Heat treatment of ferrous alloys containing Cr and Ni
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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
- C21D6/005—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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- 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
- C22C38/001—Ferrous alloys, e.g. steel alloys containing N
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—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
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
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Abstract
The invention discloses a heating method for improving primary carbide of an ultra-high carbon martensitic stainless steel continuous casting billet, which comprises the following steps: 1) a preheating section: placing the ultra-high carbon martensitic stainless steel continuous casting blank into a preheating furnace to be heated to 650-700 ℃; 2) a heating section: placing the preheated ultrahigh carbon martensitic stainless steel continuous casting blank into a heating furnace to be heated to a preset temperature; through a reasonable heating process system, the continuous casting billet obtains the maximum high-temperature diffusion kinetic energy in the heating process, after being discharged from a furnace and rolled by a steckel mill, the black coil structure has no undissolved primary carbide with the diameter of more than 4 microns, the carbide is fine and uniformly distributed, and has no structural defects such as chain-shaped segregation zone, hidden crack and the like.
Description
Technical Field
The invention belongs to the technical field of metal smelting, and particularly relates to a heating method for improving primary carbide of an ultrahigh-carbon martensitic stainless steel continuous casting billet.
Background
The martensitic stainless steel is stainless steel with the performance adjusted by adjusting the contents of components such as carbon, chromium and the like in steel grades and a heat treatment process. The main structure of the steel after annealing treatment is ferrite + carbide; after high-temperature austenitization, the steel is cooled down by air, and the main structure is martensite. During the process, carbon which is dissolved in a high-temperature austenite phase mainly exists in the form of (Fe, Cr) carbide, the higher the carbon content is, the higher the hardness of martensite is, the smaller the size of the carbide is, the more dispersed the distribution is, C is easier to diffuse in the process of solution heat treatment, the higher the hardness of steel is, the better the subsequent processing performance is, and the improvement of the sharpness and the wear resistance of the material is facilitated.
The super-high carbon martensitic stainless steel is mainly used for manufacturing high-end hand-shaving razor blades, medical scalpels and the like, and is manufactured into the razor blades or the scalpels through a series of processes of hot rolling, cold rolling, multi-pass rolling, heat treatment, punching, quenching-tempering treatment, blade edge processing (sharpening), surface coating (protecting the blade edge and reducing the friction force between skin and the blade edge) and the like. In addition to high hardness, wear resistance and sharpness, the steel sheet is required to have high corrosion resistance due to frequent contact with water, blood and the like during use.
The ultra-high carbon martensitic stainless steel contains higher alloy elements such as carbon, chromium and the like, segregation is easy to occur between dendritic crystals in the solidification process, large-size primary carbides with the size of more than 10 mu m are separated out, and if the high-temperature diffusion and dissolution are not good in the heating process, the re-dissolution is not easy in the subsequent rolling and heat treatment processes, and the ultra-high carbon martensitic stainless steel is finally inherited to a finished product. On one hand, the sharpness, the corrosion resistance and the quenching hardness of a finished product are influenced, on the other hand, brittle fracture, edge breakage and even edge falling of the finished product material can occur in the process of processing and thinning the subsequent material or in the using process, the service life and the experience comfort degree of the product are seriously influenced, and human body injuries such as skin injury and the like can be caused.
Disclosure of Invention
The invention provides a heating method for improving primary carbide of an ultrahigh-carbon martensitic stainless steel continuous casting billet, and aims to solve the technical problem.
Therefore, the invention adopts the following technical scheme:
a heating method for improving primary carbides of ultra-high carbon martensitic stainless steel continuous casting billets comprises the following steps:
1) a preheating section: placing the ultra-high carbon martensitic stainless steel continuous casting blank into a preheating furnace to be heated to 650-700 ℃;
the preheating furnace adopts three-section heating: a first heating section, a second heating section and a third heating section, wherein the total heating time is not less than 200 minutes; wherein the heating time of the first heating section and the second heating section is not less than 130min, the temperature of the continuous casting billet discharged from the second heating section is not more than 500 ℃, and the heating rate is not more than 4 ℃/min; the heating time of the three heating sections is not less than 70 minutes, the heating rate is not more than 3 ℃/min, the continuous casting billet is extracted out of the preheating furnace after the heating of the three heating sections is finished, and the extraction temperature of the continuous casting billet after preheating is 650-700 ℃;
in the cooling process, the ultrahigh-carbon martensite continuous casting billet is easy to form large residual structural stress due to large temperature difference between the inside and the outside of the casting billet, if the temperature rise rate is too fast in the low-temperature stage, internal cracks of the casting billet are easy to break even, and the internal stress of the martensite continuous casting billet is effectively prevented from being uniformly released through reasonable heating rate control in a preheating furnace.
2) A heating section: placing the preheated ultrahigh carbon martensitic stainless steel continuous casting blank into a heating furnace to be heated to a preset temperature;
the heating furnace adopts three-section heating: a preheating section, a heating section and a soaking section; the temperature of a hearth of the preheating section is 1000-1200 ℃, and the heating time is not less than 50 min; the temperature of a hearth of the heating section is 1250-1290 ℃, and the heating time is not less than 70 min; the temperature of the soaking section is 1250-1280 ℃, and the heating time is not less than 80 min.
Through reasonable matching of the heat load and the heating time of the preheating section and the heating section, on one hand, the temperature difference between the head, the tail and the core surface of a casting blank is less than or equal to 20 ℃ when the casting blank is discharged, and the minimum deformation resistance of the rolling requirement is met; on the other hand, the heating time of the preheating section is shortened, the temperature of the hearth of the preheating section is reduced, the heating time of the heating section, namely the heating time of the high-temperature section, is properly prolonged, and the temperature of the hearth of the heating section is increased, so that the casting blank obtains the maximum diffusion driving force, and primary carbides and component segregation generated in the continuous casting process are homogenized and dissolved to the maximum extent through high-temperature diffusion.
Further, the chemical element composition and the mass percentage of the ultra-high carbon martensitic stainless steel are as follows: carbon: 0.60 to 0.70%, silicon: less than or equal to 1.0 percent, manganese: less than or equal to 1.0 percent, phosphorus: less than or equal to 0.040, sulfur: less than or equal to 0.005%, chromium: 12.00-15.00%, molybdenum: less than or equal to 0.10 percent, nickel: less than or equal to 1.0 percent, vanadium: less than or equal to 0.30 percent, nitrogen: less than or equal to 0.1 percent, and the balance of iron and residual elements.
Further, the preheating furnace and the heating furnace are both walking beam type slab heating furnaces.
Through a reasonable heating process system, the continuous casting billet obtains the maximum high-temperature diffusion kinetic energy in the heating process, after being discharged from a furnace and rolled by a steckel mill, the black coil structure has no undissolved primary carbide with the diameter of more than 4 microns, the carbide is fine and uniformly distributed, and has no structural defects such as chain-shaped segregation zone, hidden crack and the like.
The invention has the beneficial effects that:
1. on the premise of eliminating the structure stress and the structure segregation without a continuous casting billet soft reduction device, the hot working and the quality control of the ultra-high carbon martensitic stainless steel continuous casting billet are realized by optimizing a heating process system;
2. the advantage of low-temperature long-time heating of the preheating furnace is utilized, the heating rate control of the ultra-high carbon martensitic stainless steel continuous casting billet in a low-temperature section is realized, and the condition that the alloy element segregation of the continuous casting billet is aggravated by low-temperature rapid heating is avoided;
3. by reasonably controlling the heating rate of each temperature section in the preheating furnace and the temperature and the heating time of each section of the hearth of the heating furnace, the segregation degree of the alloy elements in the continuous casting billet is successfully improved;
4. by optimizing the heating process, the continuity of the ultrahigh-carbon martensitic stainless steel continuous casting → heating → hot rolling is realized, the process flow is shortened, and the production cost is reduced;
5. by optimizing the heating process of the continuous casting billet, the size and the uniform distribution of primary carbides in the product are greatly improved, the problems of brittle fracture, edge breakage and even edge falling of finished products in the subsequent material processing thinning process are solved, and the product quality is greatly improved.
Drawings
FIG. 1 is a gold phase diagram of a microscope for manufacturing by the prior art;
FIG. 2 is a gold phase diagram of a microscope produced by the process of the present invention.
Detailed Description
The invention will be further illustrated with reference to specific examples:
in this embodiment, an ultra-high carbon martensitic stainless steel continuous casting slab with a specification of 220mm 1250mm 10100mm is adopted, and the steel grade comprises the following chemical elements in percentage by mass: carbon: 0.60 to 0.70%, silicon: less than or equal to 1.0 percent, manganese: less than or equal to 1.0 percent, phosphorus: less than or equal to 0.040, sulfur: less than or equal to 0.005%, chromium: 12.00-15.00%, molybdenum: less than or equal to 0.10 percent, nickel: less than or equal to 1.0 percent, vanadium: less than or equal to 0.30 percent, nitrogen: less than or equal to 0.1 percent, and the balance of iron and residual elements. And rolling the heated black coil into a hot-rolled black coil with the thickness of 4.5mm by a steckel mill.
Firstly, placing an ultra-high carbon martensite stainless steel continuous casting billet with the specification of 220mm 1250mm 10100mm into a preheating furnace to be heated to 680 ℃, and then placing the continuous casting billet into a heating furnace to be continuously heated, wherein the preheating furnace and the heating furnace are both conventional walking beam type slab heating furnaces.
1) A preheating section: the heating mode of the preheating furnace is as follows: heating in a first heating section, a second heating section and a third heating section in a three-section manner, wherein the total heating time is 215 minutes; wherein the heating time of the first heating section and the second heating section is 142 minutes, the temperature of the continuous casting billet leaving the second heating section is 495 ℃, and the heating rate is 3.5 ℃/min; the heating time of the three heating sections is 73 minutes, the heating rate is 2.53 ℃/min, the continuous casting slab is drawn out of the preheating furnace after the heating of the three heating sections is finished, and the drawing temperature is 680 ℃.
2) A heating section: the heating mode of the heating furnace is as follows: the preheating section, the heating section and the soaking section are heated in three sections;
after preheating, enabling the continuous casting blank to enter a heat recovery section of the heating furnace, wherein the length of the heat recovery section is 10.7 meters, and before the continuous casting blank enters a preheating section, opening 8 nozzle thinning valves of the preheating section to ensure that the heating temperature of the preheating section is controllable, the temperature of a hearth of the preheating section is 1080-1160 ℃, and the heating time is 56 minutes; the temperature of the heating section is 1250-; the temperature of the soaking section is 1280 ℃, and the heating time is more than or equal to 82 minutes.
And immediately entering a roughing mill and a steckel mill after heating to be rolled into black rolls with the thickness of 4.5mm, wherein the average size of carbides is 1.7 mu m according to a metallographic structure picture, and large-size carbides with the size of more than 4.0 mu m are not generated.
Claims (3)
1. A heating method for improving primary carbide of an ultra-high carbon martensitic stainless steel continuous casting billet is characterized by comprising the following steps:
1) a preheating section: placing the ultra-high carbon martensitic stainless steel continuous casting blank into a preheating furnace to be heated to 650-700 ℃;
the preheating furnace adopts three-section heating: a first heating section, a second heating section and a third heating section, wherein the total heating time is not less than 200 minutes; wherein the heating time of the first heating section and the second heating section is not less than 130min, the temperature of the continuous casting billet discharged from the second heating section is not more than 500 ℃, and the heating rate is not more than 4 ℃/min; the heating time of the three heating sections is not less than 70 minutes, the heating rate is not more than 3 ℃/min, the continuous casting slab is extracted out of the preheating furnace after the heating of the three heating sections is finished, and the extraction temperature of the preheated continuous casting slab is 650-700 ℃;
2) a heating section: placing the preheated ultra-high carbon martensitic stainless steel continuous casting blank into a heating furnace to be heated to a preset temperature;
the heating furnace adopts three-section heating: a preheating section, a heating section and a soaking section; the temperature of a hearth of the preheating section is 1000-1200 ℃, and the heating time is not less than 50 min; the temperature of a hearth of the heating section is 1250-1290 ℃, and the heating time is not less than 70 min; the temperature of the soaking section is 1250-1280 ℃, and the heating time is not less than 80 min.
2. The heating method for improving the primary carbide of the ultra-high carbon martensitic stainless steel continuous casting billet according to claim 1, wherein the chemical element composition and the mass percentage of the ultra-high carbon martensitic stainless steel are as follows: carbon: 0.60 to 0.70%, silicon: less than or equal to 1.0 percent, manganese: less than or equal to 1.0 percent, phosphorus: less than or equal to 0.040, sulfur: less than or equal to 0.005%, chromium: 12.00-15.00%, molybdenum: less than or equal to 0.10 percent, nickel: less than or equal to 1.0 percent, vanadium: less than or equal to 0.30 percent, nitrogen: less than or equal to 0.1 percent, and the balance of iron and residual elements.
3. The method for improving the heating of the primary carbide of the ultra-high carbon martensitic stainless steel continuous casting billet as claimed in claim 1, wherein the preheating furnace and the heating furnace are walking beam type slab heating furnaces.
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| CN202111384142.9A CN114507775B (en) | 2021-11-19 | 2021-11-19 | Heating method for improving primary carbide of ultra-high carbon martensitic stainless steel continuous casting billet |
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| CN202111384142.9A CN114507775B (en) | 2021-11-19 | 2021-11-19 | Heating method for improving primary carbide of ultra-high carbon martensitic stainless steel continuous casting billet |
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101195853A (en) * | 2007-12-19 | 2008-06-11 | 莱芜钢铁集团有限公司 | Heating method for preventing high carbon belt steel bloom decarburization |
| CN103343201A (en) * | 2013-07-08 | 2013-10-09 | 山西太钢不锈钢股份有限公司 | Method for improving high-carbon martensitic stainless steel carbide |
| CN104313298A (en) * | 2014-09-30 | 2015-01-28 | 山东钢铁股份有限公司 | Cold-charge heating method of bearing steel continuous casting billet |
| CN113118398A (en) * | 2021-04-19 | 2021-07-16 | 山西太钢不锈钢股份有限公司 | Production method for eliminating large-grain carbide of high-carbon martensitic stainless steel continuous casting slab |
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- 2021-11-19 CN CN202111384142.9A patent/CN114507775B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101195853A (en) * | 2007-12-19 | 2008-06-11 | 莱芜钢铁集团有限公司 | Heating method for preventing high carbon belt steel bloom decarburization |
| CN103343201A (en) * | 2013-07-08 | 2013-10-09 | 山西太钢不锈钢股份有限公司 | Method for improving high-carbon martensitic stainless steel carbide |
| CN104313298A (en) * | 2014-09-30 | 2015-01-28 | 山东钢铁股份有限公司 | Cold-charge heating method of bearing steel continuous casting billet |
| CN113118398A (en) * | 2021-04-19 | 2021-07-16 | 山西太钢不锈钢股份有限公司 | Production method for eliminating large-grain carbide of high-carbon martensitic stainless steel continuous casting slab |
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