CN101704026B - Method for controlling pitting on surface of medium steel plate - Google Patents
Method for controlling pitting on surface of medium steel plate Download PDFInfo
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- CN101704026B CN101704026B CN2009102326086A CN200910232608A CN101704026B CN 101704026 B CN101704026 B CN 101704026B CN 2009102326086 A CN2009102326086 A CN 2009102326086A CN 200910232608 A CN200910232608 A CN 200910232608A CN 101704026 B CN101704026 B CN 101704026B
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Abstract
The invention discloses a method for controlling pitting on the surface of a medium steel plate, which prevents the surface of the medium steel plate from generating the pitting by controlling the components of a billet and adopting different heating and descaling processes according to different components, wherein the billet comprises the following chemical components in percentage by mass: 0.08 to 0.20 percent of C, 0.13 to 0.20 percent of Si, 0.90 to 1.60 percent of Mn, less than or equal to 0.02 percent of P, less than or equal to 0.02 percent of S, 0 to 0.04 percent of Nb, 0 to 0.018 percent of Ti, 0.02 to 0.05 percent of Alt and the balance of Fe and impurities; for a steel grade containing microalloy, a method for reducing Si content, heating the steel at a high temperature, descaling at the high temperature and fast cooling the steel after rolling the steel is adopted; and for a steel grade containing no microalloy, a method for reducing Si content, heating the steel at a low temperature, descaling at the low temperature and fast cooling the steel after rolling the steel is adopted. The method of the invention can substantially clear off primary scales on the surface of the medium steel plate, thereby greatly reducing the occurrence of the pitting on the surface of the medium steel plate, and reducing the energy consumption and production cost and improving the production efficiency and the economic benefit of enterprises while guaranteeing the properties of the steel plate. The method is suitable to be popularized on a national scale.
Description
Technical field
We are bright to relate to a kind of surface of steel plate processing method, specifically be a kind of medium plate surface pit control method that prevents to produce in the surface of steel plate operation of rolling pit.
Background technology
Along with the development of steel and iron industry, the user is also more and more higher to the requirement of steel plate.Steel plate is except will satisfying necessary mechanical performance index, and the user is also more and more higher to the requirement of plate surface quality.The steel plate pit is the recurrent a kind of defective of surface of steel plate.It is pressed people's surface of steel plate because slab iron scale in heating or production process is removed totally, comes off in subsequently processing or transportation, forms pit, makes surface of steel plate rough matsurface occur, is called pitted skin again.Pit influences the surface quality of steel plate greatly, and it is useless that serious meeting formation pockmark causes steel plate to declare.Thereby, domestic many producers control technology of pit that all begins one's study, and take measures to be solved.
The pit that the surface produces in the steel plate heating and the operation of rolling mainly contains two kinds: the once oxidation iron sheet that produces in (1) strand heating process is not removed totally, is pressed into surface of steel plate and produces pit in the operation of rolling.This class pit is often deep, and is bigger to steel plate harm; (2) rolled piece generally can be avoided if this class pit is noted the de-scaling in operation of rolling rolling or treat that the iron scale that generates in the warm process does not have to remove the pit totally be pressed into surface of steel plate and produce.
At present, though more about the research of iron scale, focus mostly on aspect the band steel, the research of cut deal is less, and many solutions all are to adopt physical method, such as high-pressure water descaling, rolling de-scaling and Mechanical Method dephosphorization etc.Introduced " medium thin slab continuous casting hot-strip surface iron scale control method " as number of patent application 200710010183.5, the thickness of strand that adopts is 100 ~ 170mm, adopt direct hot charging technology when rolling, the product of producing is the band steel, will curl after the cooling of band steel, this method is suitable for producing the band steel.The thickness of strand that adopts during Heavy Plate Production often will surpass 180mm, and most steel grade can not adopt direct hot charging technology to be rolled, and also can't curl behind rolling the finishing.Application number 02137851 has been introduced " processing method and the isolated plant on a kind of hot-strip surface ", " the band steel enters the loose part of iron scale; make the flexural deformation of band steel by depress roller and carrying roller; destroy the physical arrangement of iron scale, reaches the loose and part of iron scale is come off from the band steel matrix " proposed.This method need use special equipment to improve cost, and is difficult to be fit to Heavy Plate Production.
It should be noted that the difference owing to the continuous casting billet composition, the complexity that its scale on surface is removed also is different.At the steel grade more than 0.2%, slab matrix and iron scale can generate sharp brilliant olivine (Fe at the interface for Si content
2SiO
4), Fe
2SiO
4Can become liquid phase from solid phase, Fe in time more than 1175 ℃
2SiO
4Can assemble change greatly by significant accelerating oxidation iron sheet pore after the fusion, quicken the oxidation on steel surface.In addition, work as Fe
2SiO
4After fusing is solidified, FeO crystal grain can be surrounded, form FeO/Fe
2SiO
4The eutectoid product.FeO layer pinning can be lived after these eutectoid things solidify, the FeO that pinning is lived is difficult in the de-scaling and is removed fully, and these iron scales of not removing are easy to be pressed into surface of steel plate and form the pit defective in the operation of rolling subsequently.In addition, its heating process of the strand of heterogeneity is different, and its heating of generation and the rolling mill practice that control the surface of steel plate pit also are not quite similar.
Summary of the invention
The bright purpose of we provides a kind of medium plate surface pit control method, and this control method becomes to assign to eliminate surface of steel plate pit defective by improving production technology with the optimization steel billet under the existing processes equipment condition.
The objective of the invention is to be achieved through the following technical solutions:
A kind of medium plate surface pit control method is characterized in that this method takes to control the steel billet composition and adopt different heating and descaling process to prevent that surface of steel plate from producing pit according to heterogeneity, and concrete steps are as follows:
1) strand chemical composition mass percent is: C 0.08 ~ 0.20, Si 0.13 ~ 0.20, Mn 0.90 ~ 1.60, P≤0.02, S≤0.02, Nb 0 ~ 0.04, Ti 0 ~ 0.018, Alt 0.02 ~ 0.05, and all the other are Fe and impurity;
2), take to reduce Si content, high temperature heating, high temperature de-scaling and roll the back fast cooling method for the steel grade that contains microalloy; Be specially: the strand tapping temperature is controlled at 1230 ~ 1245 ℃, and strand adopts high-pressure water descaling in thick de-scaling place, and de-scaling pressure is not less than and is 18MPa, and strand is not less than 1175 ℃ in thick de-scaling place temperature; Adopt two stage rolling when rolling, adopt high-pressure water descaling before the finish rolling, the de-scaling water pressure is not less than 17MPa; The laminar flow cooling is adopted in rolling back, returns red temperature and is controlled at 690 ~ 750 ℃, and control medium plate surface produces pit;
3), take to reduce Si content, low-temperature heat, low temperature de-scaling and roll the back fast cooling method for the steel grade that does not contain microalloy; Be specially: the strand tapping temperature is controlled at 1145 ~ 1165 ℃, and strand adopts high-pressure water descaling in thick de-scaling place, and de-scaling pressure is not less than and is 18MPa; Adopt two stage rolling when rolling, adopt high-pressure water descaling before the finish rolling, the de-scaling water pressure is not less than 17MPa; The laminar flow cooling is adopted in rolling back, and steel plate returns red temperature and is controlled at 740 ~ 780 ℃, and control medium plate product surface produces pit.
Slab thickness of the present invention is 180 ~ 260mm, and medium plate product thickness specification is 10 ~ 50mm.
The present invention, takes to reduce Si content, high temperature heating, high temperature de-scaling and rolls processes such as afterwards fast cold for micro alloyed steel in conjunction with the heating process of the thick different chemical composition continuous casting billet of 180-260mm; For the steel grade that does not contain microalloy, take to reduce Si content, low-temperature heat, low temperature de-scaling and roll processes such as afterwards fast cold, eliminate surface of steel plate pit defective.
Main production process route is: molten iron preliminary treatment → converter smelting → refining → continuous casting → steel billet check → cooling in heap → steel billet examination → strand heating → thick de-scaling → roughing → smart de-scaling → finish rolling → laminar flow cooling → aligning → air cooling → cutting to length (→ flaw detection) → sampling → spray printed mark → check → warehouse-in.
Concrete technical measures are:
1, continuous casting billet metallurgically control
Continuous casting billet Composition Control scope (mass percent) is: C 0.08 ~ 0.20, Si 0.13 ~ 0.20, Mn0.90 ~ 1.60, P≤0.02, S≤0.02, Nb 0 ~ 0.04, Ti 0 ~ 0.018, Alt 0.02 ~ 0.05, all the other compositions are iron and impurity.Si is a kind of oxidation resistant element, but works as si content more than 0.2%, and its oxidation rate increased sharply when the steel temperature surpassed more than 1175 ℃, and higher Si content can cause generating Fe between slab matrix and iron scale interface
2SiO
4, Fe
2SiO
4Can make that with combining of FeO iron scale is difficult to remove.Therefore, under the situation that performance allows, the Si content that should control in the steel is no more than 0.2%.
2, continuous casting billet heating
According to the difference of chemical composition, continuous casting billet is divided into high temperature and two kinds of different process of low-temperature heat.For micro alloyed steel, for guaranteeing microalloy fully solid solution and the Fe in the steel
2SiO
4Everywhere in molten condition, furnace temp should guarantee that strand is not less than 1175 ℃ in the thick de-scaling place temperature of arrival in thick de-scaling; For not containing micro alloyed steel, for reducing cost, simultaneously for preventing that the original austenite grains of strand from too growing up, its surface temperature is no more than 1170 ℃ in the time of should guaranteeing that strand heats in heating furnace.Heat time heating time 1min/mm, soaking time is 20 ~ 50min.Steel plate guarantees better with the temperature homogeneity of block plate in heating process as far as possible, should be no more than 15 ℃ as the temperature deviation of piece slab as far as possible.
3, de-scaling
Thick de-scaling place system water pressure should be not less than 18MPa as far as possible, and smart descaling system water pressure should be not less than 17MPa as far as possible.The slab that contains microalloy should be not less than 1175 ℃ in thick de-scaling place temperature, and its start rolling temperature preferably is no more than 1170 ℃.
4. laminar flow cooling
For guaranteeing plate property and prevent steel plate rolling its surface oxidation of back that finishes, should be behind steel plate rolling rapidly with its cooling, the red temperature of returning of steel plate is controlled at 750 ± 30 ℃.
The present invention produces the problem of pit according to the removing mechanism of iron scale at the surface of steel plate of heterogeneity, has proposed concrete enforcement and solution.The present invention is simple, practical, has important and practical meanings for the surface quality of improving steel plate.
The invention has the advantages that: by to the continuous casting billet Composition Control, formulate reasonably heating and descaling process, the once oxidation iron sheet of surface of steel plate can be removed totally substantially, greatly reduce the incidence of surface of steel plate pit; Formulate heating process according to different chemical compositions, when guaranteeing plate property, reduced energy consumption, reduced production cost, improved production efficiency and economic benefit of enterprises; The present invention does not need to change for the technological equipment at scene substantially, be very suitable for applying in China, but the present invention gathers around and has broad application prospects.
The specific embodiment
A kind of medium plate surface pit control method, this method is taked to control the steel billet composition and is adopted different heating and descaling process to prevent that surface of steel plate from producing pit according to heterogeneity, the present invention takes different control measure to prevent that surface of steel plate from producing the pit defective, has very important significance for the surface quality of improving cut deal according to different chemical composition.
The technological process of steel plate rolling is: molten iron preliminary treatment → converter smelting → RH+LF (or LF+RH) refining → continuous casting → steel billet check → cooling in heap → steel billet examination → strand heating → thick de-scaling → roughing → smart de-scaling → finish rolling → laminar flow cooling → aligning → air cooling → cutting to length (→ flaw detection) → sampling (→ ball blast → normalizing heat treatment → aligning → sampling) → spray printed mark → check → warehouse-in.
The thickness range of continuous casting billet: 180 ~ 260mm.
Steel plate thickness specification: 10 ~ 50mm.
The steel billet main chemical compositions is as shown in table 1, and the ingredients listed, all the other are Fe and trace impurity in table.
The suitable steel grade chemical composition of table 1 the present invention
| Composition | C | Si | Mn | P | S | Nb | Ti | Alt |
| Embodiment 1 | 0.15 | 0.15 | 1.17 | 0.0056 | 0.0047 | 0.0288 | ||
| Embodiment 2 | 0.16 | 0.14 | 1.20 | 0.0058 | 0.0046 | 0.025 | 0.01 | 0.0291 |
Continuous casting billet is taked the type of cooling of cooling in heap, to reduce the hydrogen content in the strand, the internal stress that produces when reducing cooling simultaneously as far as possible.
After the strand slow cooling 48 hours, enter heating furnace and heat.
Embodiment 1
According to the composition of embodiment in the table 11, its embodiment is:
The slab thickness that example 1 adopts is 220mm, and finished product thickness is 30mm.
Cause forming the pit defective in the operation of rolling for the once oxidation iron sheet that prevents the steel slab surface generation is difficult to remove, consider that the strand that present embodiment adopts does not add microalloy element, need not to consider microalloy solid solution again.For cutting down the consumption of energy, save production cost simultaneously, low-temperature heat technology is adopted in decision.Strand 1min/mm heat time heating time, strand are heated to 1145 ~ 1170 ℃ in heating furnace, the soaking zone temperature is lower 10 ~ 15 ℃ than bringing-up section temperature, insulation 40min.
The strand tapping temperature is 1145 ~ 1165 ℃, and strand adopts high-pressure water descaling in thick de-scaling place, and de-scaling pressure is 18MPa.
Adopt two stage rolling when rolling, the phase I start rolling temperature is 1115 ~ 1140 ℃, temperature control plate blank thickness 50mm.De-scaling before the finish rolling, de-scaling pressure is not less than 17MP, and the finish rolling start rolling temperature is 870 ~ 910 ℃, rolls the back and adopts the laminar flow cooling, returns red temperature and is controlled at 740 ~ 780 ℃.Obtain not having the medium plate of surperficial pit.
Embodiment 2
According to the composition of case study on implementation in the table 12, its embodiment is:
The slab thickness that example 2 adopts is 220mm, and finished product thickness is 35mm.
Different with example 1 is that strand contains microalloy element in the example 2, for making the abundant solid solution of microalloy, guarantees that simultaneously the once oxidation iron sheet that generates in the heating process removes easily, prevents that the surface from producing the pit defective, and example 2 needs to adopt the high temperature heating processes.Strand 1min/mm heat time heating time, strand are heated to 1230 ~ 1250 ℃ in heating furnace, the soaking zone temperature is lower 10 ~ 15 ℃ than bringing-up section temperature, samming 50min.
The strand tapping temperature is 1230 ~ 1245 ℃, and strand adopts high-pressure water descaling in thick de-scaling place, and de-scaling pressure is 18MPa, and strand is about 1200 ℃ in de-scaling point temperature.
Adopt two stage rolling when rolling, the phase I start rolling temperature is 1170 ~ 1190 ℃, temperature control plate blank thickness 63mm.De-scaling before the finish rolling, de-scaling pressure is not less than 17MP, and the finish rolling start rolling temperature is 920 ~ 950 ℃, rolls the back and adopts the laminar flow cooling, returns red temperature and is controlled at 700 ~ 740 ℃.Obtain not having the medium plate of surperficial pit.
The present invention formulates reasonably heating and descaling process by to the continuous casting billet Composition Control, and the once oxidation iron sheet of surface of steel plate can be removed totally substantially, greatly reduces the incidence of surface of steel plate pit; And, when guaranteeing plate property, reduced energy consumption according to different chemical composition formulation heating processes, and reduced production cost, improved production efficiency and economic benefit of enterprises.
Claims (1)
1. medium plate surface pit control method is characterized in that this method takes to control the steel billet composition and adopt different heating and descaling process to prevent that surface of steel plate from producing pit according to heterogeneity, and concrete steps are as follows:
1) strand chemical composition mass percent is: C 0.08～0.20, Si 0.13～0.20, Mn 0.90～1.60, P≤0.02, S≤0.02, Nb 0～0.04, Ti 0～0.018, Alt 0.02～0.05, and all the other are Fe and impurity; Slab thickness is 180～260mm;
2), take to reduce Si content, high temperature heating, high temperature de-scaling and roll the back fast cooling method for the steel grade that contains microalloy; Be specially: the strand tapping temperature is controlled at 1230～1245 ℃, and strand adopts high-pressure water descaling in thick de-scaling place, and de-scaling pressure is not less than and is 18MPa, and strand is not less than 1175 ℃ in thick de-scaling place temperature; Adopt two stage rolling when rolling, adopt high-pressure water descaling before the finish rolling, the de-scaling water pressure is not less than 17MPa; The laminar flow cooling is adopted in rolling back, returns red temperature and is controlled at 690～750 ℃, and control medium plate surface produces pit;
3), take to reduce Si content, low-temperature heat, low temperature de-scaling and roll the back fast cooling method for the steel grade that does not contain microalloy; Be specially: the strand tapping temperature is controlled at 1145～1165 ℃, and strand adopts high-pressure water descaling in thick de-scaling place, and de-scaling pressure is not less than and is 18MPa; Adopt two stage rolling when rolling, adopt high-pressure water descaling before the finish rolling, the de-scaling water pressure is not less than 17MPa; The laminar flow cooling is adopted in rolling back, and steel plate returns red temperature and is controlled at 740～780 ℃, and control medium plate product surface produces pit; Medium plate product thickness specification is 10～50mm.
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| CN2009102326086A CN101704026B (en) | 2009-12-03 | 2009-12-03 | Method for controlling pitting on surface of medium steel plate |
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| CN2009102326086A CN101704026B (en) | 2009-12-03 | 2009-12-03 | Method for controlling pitting on surface of medium steel plate |
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| CN101856669B (en) * | 2010-06-02 | 2012-01-04 | 东北大学 | Control method of softness of oxide scales on surface of hot-rolling strip steel |
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| CN103611728A (en) * | 2013-12-06 | 2014-03-05 | 东北大学 | Method for improving surface quality of hot-rolling high-strength medium plate |
| CN103769424B (en) * | 2014-01-08 | 2015-11-25 | 南京钢铁股份有限公司 | The control method of steekle mill surface of steel plate red scale |
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| CN106216392B (en) * | 2016-07-19 | 2017-12-29 | 东北大学 | One kind eliminates cut deal piebald defects controlling method |
| CN109794516B (en) * | 2019-01-28 | 2021-04-20 | 东北大学 | Control method for eliminating pit defect of medium plate |
| CN110180904B (en) * | 2019-05-29 | 2021-04-27 | 北京首钢股份有限公司 | Control method for surface pitting defects of ultra-low carbon phosphorus-containing BH steel hot-rolled strip steel |
| CN110976534B (en) * | 2019-10-15 | 2021-11-19 | 邯郸钢铁集团有限责任公司 | Method for reducing steel surface mottling of single-stand wide and thick plate rolling mill engineering machinery |
| CN111822528A (en) * | 2020-04-17 | 2020-10-27 | 广东韶钢松山股份有限公司 | Medium plate and production method thereof |
| CN112676344A (en) * | 2020-11-27 | 2021-04-20 | 南京钢铁股份有限公司 | Method for producing medium-thickness steel for engineering machinery by using single-stand steckel mill |
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| CN1396011A (en) * | 2002-06-25 | 2003-02-12 | 倪法根 | Surface treating method and apparatus for hot-rolled steel band |
| CN101209456A (en) * | 2006-12-27 | 2008-07-02 | 鞍钢股份有限公司 | High-strength medium plate production process |
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