CN111872141B - Method for improving descaling quality of nickel-containing steel plate - Google Patents
Method for improving descaling quality of nickel-containing steel plate Download PDFInfo
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- CN111872141B CN111872141B CN202010804595.1A CN202010804595A CN111872141B CN 111872141 B CN111872141 B CN 111872141B CN 202010804595 A CN202010804595 A CN 202010804595A CN 111872141 B CN111872141 B CN 111872141B
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- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
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- B21B45/00—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
- B21B45/04—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills for de-scaling, e.g. by brushing
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Abstract
The invention discloses a method for improving the descaling quality of a nickel-containing steel plate, which comprises the following steps: (1) after the slab is loaded into the heating furnace, the temperature of the soaking section of the heating furnace is controlled to be 20-30 ℃ lower than that of the third soaking section, the soaking time of the slab is not less than 0.1 XH +10min and not more than T and not more than 0.2 XH +10min, the micro-positive pressure state of a hearth is maintained, the furnace pressure is controlled to be 20-30Pa, and the oxidation burning loss of the slab is reduced; (2) arranging a descaling box program automatic control system, automatically and continuously descaling twice by using a descaling box after the slab is discharged, wherein the first descaling speed is 1.4-1.6m/s, the second descaling speed is 1.1-1.4m/s, the initial pressure of the two-time descaling is more than or equal to 19.5MPa, and the final pressure is more than or equal to 18 MPa; (3) descaling water is used once when rolling is carried out at one stage; according to the invention, through process design, on the premise of not using measures such as protective coating, peeling, iron sheet wrapping protection and the like, the scale removing effect is improved by using the existing process equipment, waste products caused by pressing in of the iron sheet are basically eliminated, the enterprise cost is greatly reduced, and the contract cashing rate of the Ni-containing variety steel is obviously improved.
Description
Technical Field
The invention relates to the technical field of production of nickel-containing steel plates, in particular to a method for improving the descaling quality of a nickel-containing steel plate.
Background
Surface quality is the user to the directly perceived embodiment of wide and thick board product quality requirement, because scale that the descaling quality is unstable leads to impresses, the steel sheet surface pit that forms, pitted surface, defects such as mottle can directly influence the pleasing to the eye degree of wide and thick board product, reduce user' S use and experience, especially contain the Ni steel, compare in ordinary steel, its steel billet is at the S emergence reaction in the heating process and the burner gas, the extension of oxygen in the steel has been aggravated, the oxidation aggravation, the iron sheet stickness increases, high pressurized-water descaling is difficult to get rid of, final defect leads to the coping to increase, delivery cycle extension, some steel sheets can only do and scrap the processing, manufacturing cost is showing and is increasing. Before the invention, the produced steel for the tank body containing Ni, the steel for the engineering machinery and the like generally have the defect of scale pressing in surface caused by incomplete descaling, part of the steel plate is polished and then barely meets the delivery requirement of a user, only waste judgment can be carried out seriously, the delivery cycle of the steel plate is severely limited, the cost is increased, and huge waste is caused.
Disclosure of Invention
The invention aims to solve the problems that the scale removal effect of the existing nickel-containing steel plate is not ideal due to the limitation of the existing process, so that various surface defects of the finished steel plate are caused due to incomplete scale removal, even the steel plate cannot be delivered and can only be judged to be useless, and the production cost is obviously increased, and provides a method for improving the scale removal quality of the nickel-containing steel plate; the method can obviously improve the descaling quality of the heated billet, reduce/eliminate the press-in of the primary scale and ensure that the surface quality of the Ni-containing steel plate meets the requirements of delivery technical conditions.
The invention discloses a method for improving the descaling quality of a nickel-containing steel plate, which comprises the following steps:
(1) after the slab raw material is loaded into the heating furnace, controlling the temperature of the soaking section of the heating furnace to be 20-30 ℃ lower than that of the third heating section, controlling the soaking time of the slab to be 0.1 XH +10min or less and T to be less than or equal to 0.2 XH +10min, and controlling the thickness of the H slab raw material; keeping the micro-positive pressure state of the hearth, controlling the furnace pressure to be 20-30Pa, and slightly controlling the furnace pressure to be 2-5 Pa higher than that in normal production if the temperature is kept for a short time within 1h, so that the cold air suction is reduced, and the oxidation burning loss of the blank is reduced;
(2) setting a descaling box program automatic control system, automatically and continuously descaling twice by adopting a descaling box after the plate blank is discharged, namely automatically returning to an inlet of the descaling box after primary descaling is finished, and carrying out secondary descaling; setting the roller way speed of a descaling box, wherein the first descaling speed is 1.4-1.6m/s, the second descaling speed is 1.1-1.4m/s, the initial pressure of two-time descaling is guaranteed to be more than or equal to 19.5MPa, and the final pressure is guaranteed to be more than or equal to 18 MPa;
(3) the descaling water of the machine body is used once during the first-stage rolling, and a first-stage rolling and subsequent rolling processes are carried out after a small amount of residual iron oxide scales and secondary iron oxide scales are sufficiently removed; after descaling according to the process, the rolled finished product Ni-containing steel plate is inspected by a turning plate, and no iron scale is pressed into the upper and lower surfaces of the rolled finished product Ni-containing steel plate, so that the quality standard requirement is met.
The thickness of the plate blank raw material is 200-300mm, and the thickness of the finished steel plate is 10-120 mm.
The invention achieves the aim of the invention by improving the prior art, and the specific process improvement reason is as follows:
(1) the heating process sets the temperature of the soaking section 20-30 ℃ lower than that of the third heating section, and simultaneously ensures that the soaking time is more than or equal to 0.2 XH +10min and more than or equal to T more than or equal to 0.1 XH +10 min: the method aims to ensure that the soaking time and temperature of the plate blank can meet the requirements of tapping temperature and section uniformity, and can avoid the aggravation of blank oxidation caused by long-time soaking and the disadvantage of descaling. The Ni-containing steel is different from other common steel types, Ni is easy to react with S in furnace gas of a heating furnace at the high temperature of more than 1000 ℃ to form an NiS network structure with a lower melting point, a protective film formed by a billet at the lower temperature is damaged after the Ni is melted, S ferrite in the billet is increased in the heating process, the diffusion of oxygen in the steel is accelerated, the oxidation is intensified, the iron sheet viscosity is increased, the iron oxide layer is thicker and the viscosity is larger along with the increase of the heating temperature and the extension of the heat preservation time, so the soaking time of the Ni-containing steel is not too long, and the soaking temperature is slightly lower than the heating section to be beneficial to the improvement of the descaling effect through experimental investigation; the micro-positive pressure state of the hearth is kept to reduce the cold air suction and reduce the oxidation burning loss of the steel plate;
(2) the reason for designing continuous automatic two-time descaling in the descaling process is as follows: for Ni-containing steel, because part of iron sheet is still not removed in one-time descaling, two continuous automatic descaling procedures are designed, a descaling box is utilized to carry out full descaling, and the primary oxide scale formed by heating a plate blank in a furnace is removed; the continuous twice pressure maintaining and the descaling of more than 18MPa by utilizing the descaling box are designed by fully considering the characteristics of pressure change and speed rise of a descaling system in the descaling process and a descaling gap: the method comprises the steps of firstly, removing scale at medium and high speed, wherein the scale is removed at about 1.5m/s, the pressure of the system is reduced to be slightly lower than the set scale removing pump speed-raising pressure (the speed-raising pressure is supplemented at 19.5-20.8 MPa), the speed-raising pressure is supplemented to be set initial pressure (about 23 MPa) by utilizing the clearance time of automatic slab rewinding, and the continuous two-time scale removing pressure guarantee is realized on the premise of not changing the system hardware condition of a scale removing box by adopting the medium and low speed scale removing at about 1.3m/s during the second scale removing;
(3) the reason for using the descaling water once during the first-stage rolling is as follows: in order to fully remove a small amount of residual iron scales and secondary iron scales, the primary iron scales are ensured to be finally and completely removed, and the user requirements are met.
According to the invention, through process design, on the premise of not using measures such as protective coating, peeling, iron sheet wrapping protection and the like, the scale removing effect is improved by using the existing process equipment, waste products caused by pressing in of the iron sheet are basically eliminated, the enterprise cost is greatly reduced, and the contract cashing rate of the Ni-containing variety steel is obviously improved.
Drawings
FIG. 1 is a schematic view of a process for heating a fractured slab in example 1 of the present invention;
FIG. 2 is a state diagram of the discharging timing of a Ni-containing slab in example 1 of the present invention;
FIG. 3 is a view showing a state after first descaling of a Ni-containing slab in example 1 of the present invention;
FIG. 4 is a view showing a state after continuously performing second descaling on a Ni-containing slab according to example 1 of the present invention;
FIG. 5 shows the surface condition of a rolled steel sheet according to example 1 of the present invention.
Detailed Description
In order to better explain the technical solution of the present invention, the technical solution of the present invention is further described below with reference to specific examples, which are only exemplary to illustrate the technical solution of the present invention and do not limit the present invention in any way.
Example 1
Taking the production of a steel plate containing 3.0 percent of Ni0 as an example, the specification of a finished product is 50 multiplied by 2700 multiplied by L mm, a plate blank with the specification of 250 multiplied by 2000 multiplied by 3500mm is adopted, and the specific production process is as follows:
(1) heating the plate blank in a heating furnace, setting soaking time for 40min, controlling the temperature difference between the soaking section and the third heating section according to the target of 25 ℃, wherein the heating setting is schematically shown in figure 1; the actual soaking time is 43min, and the temperature difference fluctuation meets the set requirement.
FIG. 1 is a schematic diagram of a heating process of a slab with a section of 250mm containing Ni3.0% steel.
(2) After the plate blank is taken out of the furnace, the descaling box is selected for automatic continuous descaling twice (namely, the plate blank automatically returns to the inlet of the descaling box after primary descaling is finished and is subjected to secondary descaling), the roller speed of the descaling box is respectively selected to be 1.5m/s and 1.3m/s, the initial pressure of the secondary descaling reaches 23MPa, the pressure after the descaling is respectively 20.1MPa and 19.2MPa, and the requirements of descaling conditions are met;
(3) the first pass of the first stage of the rolling mill is descaled by a machine body once; after descaling according to the process, the rolled finished product Ni-containing steel plate is inspected by a turning plate, and no iron scale is pressed into the upper and lower surfaces of the rolled finished product Ni-containing steel plate, so that the quality standard requirement is met.
FIG. 2 is a state diagram of the discharging timing of a Ni-containing slab in example 1 of the present invention;
FIG. 3 is a view showing a state after first descaling of a Ni-containing slab in example 1 of the present invention;
FIG. 4 is a view showing a state after continuously performing second descaling on a Ni-containing slab according to example 1 of the present invention;
FIG. 5 shows the surface condition of a rolled steel sheet according to example 1 of the present invention.
As can be seen from fig. 2-5: after the plate blank is subjected to primary descaling, part of primary scale on the plate surface is not completely removed, the primary scale on the plate surface is basically removed after continuous secondary descaling, the plate enters a rolling mill and is descaled by a machine body, a secondary thin layer of secondary scale is also removed, and the plate surface quality is good.
Example 2
Taking the production of a steel plate containing 2.8 percent of Ni2 as an example, the specification of a finished product is 10 multiplied by 2660 multiplied by L mm, a plate blank with the specification of 200 multiplied by 1550 multiplied by 2900mm is adopted, and the specific production process is as follows:
(1) heating the plate blank in a heating furnace, setting soaking time for 35min, and controlling the temperature difference between the soaking section and the third heating section according to a target of 20 ℃; the actual soaking time is 37min, and the temperature difference fluctuation meets the set requirement;
(2) after the plate blank is taken out of the furnace, the descaling box is selected for automatic continuous descaling twice (namely, the plate blank automatically returns to the inlet of the descaling box after primary descaling is finished and is subjected to secondary descaling), the roller speed of the descaling box is respectively selected to be 1.5m/s and 1.31m/s, the initial pressure of the secondary descaling reaches 22MPa, the pressure after the descaling is respectively 20.2MPa and 19.4MPa, and the requirements of descaling conditions are met;
(3) the first pass of the first stage of the rolling mill is descaled by a machine body once; after descaling according to the process, the rolled finished product Ni-containing steel plate is inspected by a turning plate, and no iron scale is pressed into the upper and lower surfaces of the rolled finished product Ni-containing steel plate, so that the quality standard requirement is met.
Example 3
Taking the production of a steel plate containing 3.2 percent of NiO as an example, the specification of a finished product is 80 multiplied by 2600 multiplied by L mm, a plate blank with the specification of 300 multiplied by 2000 multiplied by 3650mm is adopted, and the specific production process is as follows:
(1) heating the plate blank in a heating furnace, setting soaking time for 50min, and controlling the temperature difference between the soaking section and the third heating section according to a 23 ℃ target; the actual soaking time is 51min, and the temperature difference fluctuation meets the set requirement;
(2) after the slab is taken out of the furnace, the descaling box is selected for automatic continuous descaling twice (namely, the slab automatically returns to the inlet of the descaling box after primary descaling is finished and is subjected to secondary descaling), the roller speed of the descaling box is respectively selected to be 1.51m/s and 1.3m/s, the initial pressure of the secondary descaling reaches 24MPa, the pressure after the descaling is respectively 21.4MPa and 19.5MPa, and the requirements of descaling conditions are met;
(3) the first pass of the first stage of the rolling mill is descaled by a machine body once; after descaling according to the process, the rolled finished product Ni-containing steel plate is inspected by a turning plate, and no iron scale is pressed into the upper and lower surfaces of the rolled finished product Ni-containing steel plate, so that the quality standard requirement is met.
Example 4
Taking the production of a steel plate containing 3.3 percent of Nis as an example, the specification of a finished product is 100 multiplied by 3020 multiplied by L mm, a plate blank with the specification of 300 multiplied by 2200 multiplied by 3980mm is adopted, and the specific production process is as follows:
(1) heating the plate blank in a heating furnace, setting soaking time for 68min, and controlling the temperature difference between the soaking section and the third heating section according to the target of 30 ℃; the actual soaking time is 69min, and the temperature difference fluctuation meets the set requirement;
(2) after the plate blank is taken out of the furnace, the descaling box is selected for automatic continuous descaling twice (namely, the plate blank automatically returns to the inlet of the descaling box after primary descaling is finished and is subjected to secondary descaling), the roller speed of the descaling box is respectively selected to be 1.50m/s and 1.3m/s, the initial pressure of the secondary descaling is 24.2MPa, the pressure after the descaling is 22.3MPa and 21.4MPa, and the requirements of descaling conditions are met;
(3) the first pass of the first stage of the rolling mill is descaled by a machine body once; after descaling according to the process, the rolled finished product Ni-containing steel plate is inspected by a turning plate, and no iron scale is pressed into the upper and lower surfaces of the rolled finished product Ni-containing steel plate, so that the quality standard requirement is met.
Claims (1)
1. A method for improving the descaling quality of a nickel-containing steel plate is characterized by comprising the following steps:
(1) after the slab raw material is loaded into the heating furnace, controlling the temperature of the soaking section of the heating furnace to be 20-30 ℃ lower than that of the third heating section, wherein the soaking time of the slab is not less than 0.1 XH +10min and not more than T and not more than 0.2 XH +10min, and H is the thickness of the slab raw material; keeping the micro-positive pressure state of the hearth, controlling the furnace pressure to be 20-30Pa, and slightly controlling the furnace pressure to be 2-5 Pa higher than that in normal production if the temperature is kept for a short time within 1h, so that the cold air suction is reduced, and the oxidation burning loss of the blank is reduced;
(2) setting a descaling box program automatic control system, automatically and continuously descaling twice by adopting a descaling box after the plate blank is discharged, namely automatically returning to an inlet of the descaling box after primary descaling is finished, and carrying out secondary descaling; setting the roller way speed of a descaling box, wherein the first descaling speed is 1.4-1.6m/s, the second descaling speed is 1.1-1.4m/s, the initial pressure of two-time descaling is guaranteed to be more than or equal to 19.5MPa, and the final pressure is guaranteed to be more than or equal to 18 MPa;
(3) the descaling water of the machine body is used once during the first-stage rolling, and a small amount of residual iron oxide scales and secondary iron oxide scales are fully removed and then the first-stage rolling is carried out;
the thickness of the plate blank raw material is 200-300mm, and the thickness of the finished steel plate is 10-120 mm.
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| JP2000102813A (en) * | 1998-09-25 | 2000-04-11 | Nkk Corp | Method for manufacturing hot-rolled steel sheet superior in pickling and surface properties |
| CN101144116A (en) * | 2007-11-13 | 2008-03-19 | 攀钢集团攀枝花钢铁研究院 | Casting blank heating method for controlling surface to generate iron scale structure |
| CN101700533A (en) * | 2009-11-27 | 2010-05-05 | 天津钢铁集团有限公司 | Method for increasing scale removal effect of medium and heavy plate |
| CN102247985B (en) * | 2011-07-01 | 2013-06-26 | 河北省首钢迁安钢铁有限责任公司 | Method for producing steel for stirring tank with limit specification through hot rolling |
| CN103212571B (en) * | 2013-04-18 | 2015-06-10 | 湖南华菱湘潭钢铁有限公司 | Method for producing oxide scale capable of preventing steel plate surface from getting rusty |
| CN110961465B (en) * | 2019-11-22 | 2021-08-20 | 首钢京唐钢铁联合有限责任公司 | Method for controlling thickness of hot-rolled pickling base material iron scale |
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