CN103602775A - Method for effectively controlling generation of central cracks in medium-carbon steel plate - Google Patents
Method for effectively controlling generation of central cracks in medium-carbon steel plate Download PDFInfo
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- CN103602775A CN103602775A CN201310657750.1A CN201310657750A CN103602775A CN 103602775 A CN103602775 A CN 103602775A CN 201310657750 A CN201310657750 A CN 201310657750A CN 103602775 A CN103602775 A CN 103602775A
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Abstract
The invention discloses a method for effectively controlling generation of central cracks in a medium-carbon steel plate. Molten iron pretreatment, converter tapping pure aluminum block deoxidation, LF (ladle furnace) white slag refinement, RH vacuum treatment and other techniques are mainly utilized to control the molten steel purity and the continuous casting frequency, so that the tundish molten steel superheating temperature is controlled at 5-20 DEG C, the casting blank stacking slow cooling time is controlled to at least 45 hours, and the cooling speed of the rolled steel plate is controlled by an ultra-fast cooling system and a head/tail masking technique, thereby effectively controlling the generation of central cracks in the steel plate. The method improves the internal quality of the steel plate, enhances the performance qualification rate and the flaw detection qualification rate of flaw detection steel, and has favorable economical and social benefits.
Description
Technical field
The invention belongs to field of metallurgy, relate to a kind of method that steel plate centre burst produces of controlling, is specifically a kind of method that effective control medium carbon steel steel plate centre burst produces.
Technical background
Middle carbon series (mainly comprise Q345 series, S355 is serial and A709Gr50 serial etc.) steel plate is because of having favorable comprehensive mechanical property and processing performance, relate at present boiler and pressurized vessel, engineering structure and engineering machinery field purposes the most extensively, one of maximum Grades Series of consumption.Yet, production practice are found, middle carbon the series steel plate defective and mechanical property instability problem that very easily occurs detecting a flaw, metallographic detects with scanning electron microscope-energy spectrum analysis and finds, the major defect that causes problems is serious steel plate centre burst, between cracks or have category-A or category-B to be mingled with, there is serious bainite or martensite segregation in crackle both sides.Therefore, for carbon series steel plate quality in improving, solve the defective and mechanical property instability problem of flaw detection, must control effectively to the generation of steel plate centre burst.
Summary of the invention
For overcoming the subsurface defect in existing middle carbon series steel plate production, a kind of method that main purpose of the present invention provides effective control medium carbon steel steel plate centre burst to produce, the middle carbon series steel plate of producing under the method is controlled effectively avoided rolling after the generation that produces of steel plate centre burst, improved interiors of products quality, improve properties percent of pass and the flaw detection steel grade flaw detection qualification rate of steel plate, obtained good economic and social benefit.
The object of the invention is to be achieved through the following technical solutions:
A kind of method that effective control medium carbon steel steel plate centre burst produces, it is characterized in that: the method is rolled rear speed of cooling by controlling Molten Steel Cleanliness, Metal in Tundish superheating temperature, casting blank stacking slow cooling time and steel plate, effectively controlled the generation of steel plate centre burst, specific requirement is as follows:
(1) Molten Steel Cleanliness is controlled.Molten iron need be processed through pre-desulfurization, controls into converter molten steel sulfur content≤0.015%, and fully skims; Top bottom blowing converter smelting, guarantees tapping phosphorus content≤0.015%, strictly avoids slag under converter, and tapping adopts the deoxidation of fine aluminium piece, guarantees that refined aluminum content is at 0.010-0.050%; LF refining furnace is made white slag, adopts the deoxidation of aluminum shot/powder/silk, and add-on is determined according to deoxidation and slag making situation, added in batches.It is 10-12kg/t steel that slag charge (containing the slag charge adding in converter tapping process) adds total amount, guarantees smelting endpoint sulphur content≤50ppm; Liquid steel refining process is all passed through vacuum-treat, requires vacuum tightness≤5.0mbar, hold-time >=12min; In addition be effectively to reduce hydrogen richness in molten steel, require all alloys of smelting process, slag material and the refractory materials that uses all need fully toast at the bakery of >=40 ℃.
(2) Metal in Tundish superheating temperature is controlled.Control the ladle turnover time, strengthen rhythm of production and control, the company of assurance waters heat of molten steel superheating temperature and is controlled at 5 ~ 20 ℃, open water heat can corresponding raising 10 ℃;
(3) steel billet stacking slow cooling is controlled.The refinement steel billet stacking slow cooling time, centering carbon steel series strand rolls off the production line and reenters heater for rolling steel after stacking slow cooling time requirement >=48h and reheat.
(4) steel plate rolls rear cooling control.Steel plate roll rear speed of cooling be controlled at 10 ℃/below min, steel plate enters after ultrafast cooling system, depending on steel plate end to end with middle temperature difference situation to dodging end to end, shielding function end to end comes into operation, reduce steel plate end to end with the middle temperature difference, guarantee the homogeneity of steel plate length direction temperature.Non-on-line shearing steel plate require at temperature >=350 ℃ of rolling off the production line stacking slow cooling after 72 hours again row shear.
The present invention, by controlling Molten Steel Cleanliness and molten steel tundish superheating temperature, has effectively controlled the inner white-spot defects of center segregation of casting blank and steel plate, has reduced formation of crack generation.In addition by strengthening steel plate, roll rear cooling control, guarantee the evenly cooling of steel plate, and non-on-line shearing plate is with to warm stacking slow cooling, effectively make formation of crack up, and then effectively suppress the development of crackle, finally by above measure Comprehensive Control steel plate centre burst, produce.
The present invention has successfully solved the problem of middle carbon series steel plate centre burst, has improved internal quality of steel plate, has improved the flaw detection qualification rate of properties percent of pass and flaw detection steel grade, has obtained good economic and social benefit.
Embodiment
Embodiment 1
A kind of method that effective control medium carbon steel steel plate centre burst produces, the method is rolled rear speed of cooling by controlling Molten Steel Cleanliness, Metal in Tundish superheating temperature, casting blank stacking slow cooling time and steel plate, effectively controlled the generation of steel plate centre burst, select one group of 11 stove Q345R container steel of steel-making, strand size 220mm*2060mm* is long, strand gross weight 1666.296t, and the rolling steel grade trade mark is Q345R, steel plate thickness is 16 ~ 50mm, steel plate gross weight 1501.881t.Specific requirement is as follows:
Control Molten Steel Cleanliness.By molten iron, need process through pre-desulfurization, control into converter molten steel sulfur content≤0.015%, and fully skim; Top bottom blowing converter smelting, guarantees tapping phosphorus content≤0.015%, strictly avoids slag under converter, and tapping adopts the deoxidation of fine aluminium piece, guarantees that refined aluminum content is 0.080%; LF refining furnace is made white slag, adopts aluminum shot to carry out deoxidation to slag, by 40 ~ 60kg/ stove, adds in batches, and every batch of 10 ~ 15kg, adds 5min slag removing sample, the color of observation slag, and the color for the treatment of slag becomes canescence and stops adding.It is 10kg/t steel that slag charge (containing the slag charge adding in converter tapping process) adds total amount, guarantees smelting endpoint sulphur content≤50ppm; Liquid steel refining process is all passed through vacuum-treat, requires vacuum tightness≤5.0mbar, hold-time >=12min; In addition be effectively to reduce hydrogen richness in molten steel, require all alloys of smelting process, slag material and the refractory materials that uses all need fully toast at the bakery of >=40 ℃.
Metal in Tundish superheating temperature is controlled.Control the ladle turnover time, strengthen rhythm of production and control, the company of assurance waters heat of molten steel superheating temperature and is controlled at 15 ℃, open water heat can corresponding raising 10 ℃, be 25 ℃.
The refinement steel billet stacking slow cooling time, centering carbon steel series strand rolls off the production line and reenters heater for rolling steel after stacking slow cooling time requirement >=48h and reheat.
Steel plate roll rear speed of cooling be controlled at 10 ℃/below min, steel plate enters after ultrafast cooling system, depending on steel plate end to end with middle temperature difference situation to dodging end to end, shielding function end to end comes into operation, reduce steel plate end to end with the middle temperature difference, guarantee the homogeneity of steel plate length direction temperature.Non-on-line shearing steel plate require at temperature >=350 ℃ of rolling off the production line stacking slow cooling after 72 hours again row shear.
To all carrying out automatic ultrasonic flaw-detecting by JB4730/2005 II level non-destructive testing standard after this group steel plate shearing, flaw detection 1501.881t, flaw detection qualification rate is 100%.And it is sampled and carries out Performance Detection, performance is qualified reaches 100%.At random this group steel plate head afterbody is sampled, carry out metallurgical analysis, also all do not find centre burst.By above Comprehensive Assessment, steel plate centre burst incidence is effectively controlled.
Embodiment 2
A kind of method that effective control medium carbon steel steel plate centre burst produces, the present embodiment is selected one group of 10 stove S355J-2 medium carbon alloy steel of steel-making, strand size 260mm*2260mm* is long, strand gross weight 1535.518t, the rolling trade mark is Q345BZ15, Q345BZ25 and Q345R, steel plate thickness is 16 ~ 45mm, steel plate gross weight 1375.142t.Specific requirement is as follows:
Mainly by molten iron, need process through pre-desulfurization, control into converter molten steel sulfur content≤0.015%, and fully skim; Top bottom blowing converter smelting, guarantees tapping phosphorus content≤0.015%, strictly avoids slag under converter, and tapping adopts the deoxidation of fine aluminium piece, guarantees that refined aluminum content is at 0.010-0.050%; LF refining furnace is made white slag, adopts aluminium wire to carry out deoxidation to slag, by 20 ~ 30kg/ stove, adds in batches, and every batch of 5 ~ 10kg, adds 5min slag removing sample, the color of observation slag, and the color for the treatment of slag becomes canescence and stops adding.It is 10-12kg/t steel that slag charge (containing the slag charge adding in converter tapping process) adds total amount, guarantees smelting endpoint sulphur content≤50ppm; Liquid steel refining process is all passed through vacuum-treat, vacuum tightness≤5.0mbar, hold-time >=12min; The all alloys of smelting process, slag material and the refractory materials using all need fully toast at the bakery of >=40 ℃.
Metal in Tundish superheating temperature is controlled.Connect and to water heat of molten steel superheating temperature and be controlled at 20 ℃ (open water heat can corresponding raising 10 ℃); Middle carbon steel series strand rolls off the production line and reenters heater for rolling steel after stacking slow cooling time requirement >=48h and reheat.
Steel plate roll rear speed of cooling be controlled at 10 ℃/below min, steel plate enters after ultrafast cooling system, depending on steel plate end to end with middle temperature difference situation to dodging end to end, shielding function end to end comes into operation, reduce steel plate end to end with the middle temperature difference, guarantee the homogeneity of steel plate length direction temperature.Thickness be greater than the requirement of 22mm steel plate at temperature >=350 ℃ of rolling off the production line stacking slow cooling after 72 hours again row shear.
To all carrying out automatic ultrasonic flaw-detecting by JB4730/2005 II level non-destructive testing standard after this group steel plate shearing, flaw detection 1375.142t, flaw detection qualification rate is 100%.And it is sampled and carries out Performance Detection, performance is qualified reaches 100%.At random this group steel plate head afterbody is sampled, carry out metallurgical analysis, also all do not find centre burst.By above Comprehensive Assessment, steel plate centre burst incidence is effectively controlled.
Claims (4)
1. effectively control the method that medium carbon steel steel plate centre burst produces for one kind, it is characterized in that: the method is rolled rear speed of cooling by controlling Molten Steel Cleanliness, Metal in Tundish superheating temperature, casting blank stacking slow cooling time and steel plate, effectively controlled the generation of steel plate centre burst, specific requirement is as follows:
(1) Molten Steel Cleanliness is controlled; Molten iron is processed through pre-desulfurization, controls into converter molten steel sulfur content≤0.015%; Top bottom blowing converter smelting, guarantees tapping phosphorus content≤0.015%, avoids slag under converter, and tapping adopts the deoxidation of fine aluminium piece, guarantees that refined aluminum content is at 0.010-0.050%; LF refining furnace is made white slag, adopts the deoxidation of aluminum shot/powder/silk, adds in batches; It is 10-12kg/t steel that slag charge adds total amount, guarantees smelting endpoint sulphur content≤50ppm; Liquid steel refining process is all passed through vacuum-treat, requires vacuum tightness≤5.0mbar, hold-time >=12min;
(2) Metal in Tundish superheating temperature is controlled; Control the ladle turnover time, strengthen rhythm of production and control, the company of assurance waters heat of molten steel superheating temperature and is controlled at 5 ~ 20 ℃;
(3) steel billet stacking slow cooling is controlled; The refinement steel billet stacking slow cooling time, centering carbon steel series strand rolls off the production line and reenters heater for rolling steel after stacking slow cooling time requirement >=48h and reheat;
(4) steel plate rolls rear cooling control; Steel plate roll rear speed of cooling be controlled at 10 ℃/below min; Non-on-line shearing steel plate require at temperature >=350 ℃ of rolling off the production line stacking slow cooling after 72 hours again row shear.
2. the method that effective control medium carbon steel steel plate centre burst according to claim 1 produces, is characterized in that: the alloy adding in smelting process, slag material and the refractory materials using all need fully toast at the bakery of >=40 ℃.
3. the method that effective control medium carbon steel steel plate centre burst according to claim 1 produces, it is characterized in that: steel plate enters after ultrafast cooling system, depending on steel plate end to end with middle temperature difference situation to dodging end to end, shielding function end to end comes into operation, reduce steel plate end to end with the middle temperature difference, guarantee the homogeneity of steel plate length direction temperature.
4. the method that effective control medium carbon steel steel plate centre burst according to claim 1 produces, is characterized in that: in step (2), open and water heat of molten steel superheating temperature than even watering 10 ℃ of heat raisings.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN112410653A (en) * | 2020-11-06 | 2021-02-26 | 安阳钢铁股份有限公司 | Method for effectively preventing 40Cr cold thin slab slitting cracks from being generated |
| CN115255302A (en) * | 2022-08-29 | 2022-11-01 | 山东钢铁集团日照有限公司 | Full-process crack control method for high-carbon high-alloy steel |
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Patent Citations (4)
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| CN101713009A (en) * | 2009-11-27 | 2010-05-26 | 天津钢铁集团有限公司 | Method for improving pass percent of medium plate flaw detection |
| CN101899613A (en) * | 2010-07-15 | 2010-12-01 | 南京钢铁股份有限公司 | Method for reducing surface cracks of medium carbon niobium-containing steel |
| CN103276293A (en) * | 2013-06-07 | 2013-09-04 | 南京钢铁股份有限公司 | Production method of excellent hydrogen induced cracking resistant pipeline steel plate |
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Cited By (3)
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|---|---|---|---|---|
| CN112410653A (en) * | 2020-11-06 | 2021-02-26 | 安阳钢铁股份有限公司 | Method for effectively preventing 40Cr cold thin slab slitting cracks from being generated |
| CN112410653B (en) * | 2020-11-06 | 2022-05-24 | 安阳钢铁股份有限公司 | Method for effectively preventing 40Cr cold thin slab slitting cracks from being generated |
| CN115255302A (en) * | 2022-08-29 | 2022-11-01 | 山东钢铁集团日照有限公司 | Full-process crack control method for high-carbon high-alloy steel |
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Application publication date: 20140226 |