Method for hot-rolling I16 I-shaped steel by using 200 large-section square billet

Abstract

The invention discloses a method for hot rolling of I16 I-shaped steel by using 200 large-section square billets. The method sequentially comprises the following working procedures of 200 * 200 mm large-section square billet heating, high-pressure water descaling, BD rolling mill reciprocating blooming, 10-rack continuous finish rolling, cooling bed cooling, straightening machine straightening, cold saw sizing, checking, stacking, bundling, weighing, plate hanging and warehousing. Wherein the heating time of the square billet is longer than 120 minutes, the temperature of a first heating section is 960-1150 DEG C, the temperature of a second heating section is 1190-1250 DEG C, and the temperature of a soaking section is 1200-1260 DEG C; the output water pressure of the high-pressure water descaling device is 15-20 Mpa; the straightening temperature is 20-120 DEG C; the initial rolling temperature of a BD rolling mill is 1140-1170 DEG C, the finish rolling temperature is 980-1080 DEG C, and the finish rolling temperature is 870-970 DEG C. According to the method, steel turning is not needed in the rolling process of the BD machine, the production efficiency is improved, and compared with a blank of 230 mm * 230 mm, the method has the advantages that the rolling starting temperature is reduced by 10-20 DEG C, the elongation is increased by 1-2%, and the gas consumption is reduced by 9.8 m < 3 > / t.

Description

Technical Field

[0001] The invention belongs to the technical field of steel rolling, and in particular relates to a method for hot rolling I16 I-beams with 200 large-section square billets. Background Art

[0002] Energy saving and consumption reduction are the directions that must be studied for enterprise development. The existing technology for rolling I16 I-beams mainly adopts the method of full continuous rolling, and the billets used are mainly 165*165mm and 180*180mm cross-section billets. At present, there is no data report on the use of 200*200mm large cross-section square billets to roll I16 I-beams. The main reason is that the use of 200*200mm large cross-section square billets to roll I16 I-beams has the problem of difficult control of mechanical properties due to the reduction of the reduction.

[0003] Kunming Iron and Steel Rolling Mill has been using 160mm×88mm×6mm×9.9mm I-beams (I16 specification) with 230mm×230mm cross-section billets because it does not have a 200*200mm crystallizer for steelmaking and continuous casting. When using 230mm×230mm cross-section billets to roll I16 specification I-beams, the BD machine needs to be turned over twice by 90 degrees for rolling, resulting in low production efficiency.

[0004] The present invention aims to provide a production method for producing I16 specification hot-rolled I-beams by using a 200*200mm large-section square billet BD machine without turning over the steel, so as to improve production efficiency and reduce gas consumption per ton of steel. Summary of the invention

[0005] The object of the present invention is to provide a method for hot rolling I16 I-beam with 200 large-section square billet.

[0006] The object of the present invention is achieved by a method for hot rolling I16 I-beam with 200 large-section square billets, comprising the following steps: heating of 200*200mm large-section square billets, high-pressure water descaling, reciprocating initial rolling by a BD rolling mill, continuous finishing rolling with 10 stands, cooling on a cooling bed, straightening by a straightening machine, sizing by a cold saw, inspection, stacking, bundling, weighing, labeling and storage; Among them, in the heating process of 200*200mm large-section square billet, the heating time of the square billet is greater than 120 minutes, the temperature of the first heating stage is 960-1150°C, the temperature of the second heating stage is 1190-1250°C, and the temperature of the soaking stage is 1200-1260°C; In the high-pressure water descaling process, the output water pressure of the high-pressure water descaling device is 15~20Mpa; the straightening temperature is 20~120℃; The starting rolling temperature of the BD rolling mill is 1140-1170°C, the finishing rolling temperature is 980-1080°C, and the final rolling temperature is 870-970°C; In the reciprocating initial rolling process of the BD rolling mill, the rectangular steel billet is reciprocated and initially rolled for 5 times in the BD rolling mill. During the first rolling, the roll gap is 47mm, the speed of biting into the steel billet is 1m / s, and the acceleration is 3.2m / s. 2 The rolling speed of the steel billet is 2.8m / s, the elongation coefficient of the steel billet is 1.147, and the cross-sectional area of ​​the rolled steel billet is 46106mm 2 The web thickness of the steel billet with a length of 7.94m is 135mm, and the steel billet is pressed down by 65mm by the rolls of the billet mill; The roll gap of the BD rolling mill during the second rolling is 70 mm, the speed of biting into the steel billet is 1 m / s, and the acceleration is 3.8 m / s. 2 The rolling speed of the steel billet is 3m / s, the elongation coefficient of the steel billet is 1.177, and the cross-sectional area of ​​the rolled steel billet is 39163mm 2 , the length is 8.55m, the web thickness of the steel billet is 98mm, and the steel billet is pressed down by the billet mill rolls by 37mm; The roll gap of the BD rolling mill during the third rolling is 52 mm, the speed of biting into the steel billet is 1 m / s, and the acceleration is 4 m / s. 2 The rolling speed of the steel billet is 3.5m / s, the elongation coefficient of the steel billet is 1.076, and the cross-sectional area of ​​the rolled steel billet is 36387mm 22 , the length is 10.11m, the web thickness of the steel billet is 75mm, and the steel billet is pressed down by the billet mill roll by 23mm; When the BD rolling mill performs the fourth pass rolling, the roll gap is 22 mm, the speed of biting into the steel billet is 1 m / s, and the acceleration is 3.5 m / s 2 The rolling speed of the steel billet is 3m / s, the elongation coefficient of the steel billet is 1.067, and the cross-sectional area of ​​the rolled steel billet is 34117mm 2 , the length is 13.8m, the web thickness of the steel billet is 45mm, and the steel billet is pressed down by the billet mill roll by 30mm; The roll gap of the BD rolling mill during the fifth rolling is 22 mm, the speed of biting into the steel billet is 1 m / s, and the acceleration is 5.3 m / s. 2 The rolling speed of the steel billet is 3.8m / s, the elongation coefficient of the steel billet is 1.514, and the cross-sectional area of ​​the rolled steel billet is 22528mm 2 , the length is 23.58m, the web thickness of the steel billet is 38mm, and the steel billet is pressed down by the billet rolling mill rolls by 7mm.

[0007] The beneficial effects of the present invention are as follows: the present invention combines the equipment characteristics of the BD rolling mill and the 10-stand finishing rolling mill of the Kunming Steel profile production line, comprehensively considers factors such as the finished product size, elongation coefficient, and rolling mill capacity, and provides a method for hot rolling I16 I-beams with 200 large-section square billets. The method adopts a BD machine for 5 passes, a finishing mill for 10 passes, and a rolling production system. By controlling the temperatures of heating, rolling, cooling bed, straightening, etc., the production of I16 I-beams with controllable mechanical properties is achieved. The method of the present invention does not require steel turning during the rolling process of the BD mill, thereby improving production efficiency. Compared with the use of 230mm×230mm billets, the rolling start temperature of the method of the present invention is reduced by 10~20℃, the elongation is increased by 1~2%, and the gas consumption is reduced by 9.8m 3 / t. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 The invention discloses a rolling system for I16 I-beam, wherein: 1 is a steel billet; 2 is a heating furnace; 3 is a high-pressure water descaling device; 4 is a roller table (including a heating furnace output roller table, a BD rolling mill front extension roller table, a 5BD rolling mill front working roller table, a BD rolling mill rear working roller table, a BD rolling mill rear extension roller table, a flying shear transport roller table, etc.); 5 is a BD rolling mill front push bed; 6 is a BD rolling mill; 7 is a BD rolling mill rear push bed; 8 is a rolled piece; 9 is a flying shear; 10 is a finishing mill group; 11 is a finished product profile; and 12 is a cooling bed. DETAILED DESCRIPTION

[0009] The present invention is further described below in conjunction with the embodiments, but the present invention is not limited in any way. Any changes or substitutions made based on the teachings of the present invention belong to the protection scope of the present invention.

[0010] The invention discloses a method for hot rolling I16 I-beam with 200mm large-section square billet, comprising the following steps: heating of 200*200mm large-section square billet, high-pressure water descaling, reciprocating initial rolling by BD rolling mill, continuous finishing rolling with 10 stands, cooling by cooling bed, straightening by straightening machine, sizing by cold saw, inspection, stacking, bundling, weighing, hanging and warehousing; Among them, in the heating process of 200*200mm large-section square billet, the heating time of the square billet is greater than 120 minutes, the temperature of the first heating stage is 960-1150°C, the temperature of the second heating stage is 1190-1250°C, and the temperature of the soaking stage is 1200-1260°C; In the high-pressure water descaling process, the output water pressure of the high-pressure water descaling device is 15~20Mpa; the straightening temperature is 20~120℃; The starting rolling temperature of the BD rolling mill is 1140-1170°C, the finishing rolling temperature is 980-1080°C, and the final rolling temperature is 870-970°C; In the reciprocating initial rolling process of the BD rolling mill, the rectangular steel billet is reciprocated and initially rolled for 5 times in the BD rolling mill. During the first rolling, the roll gap is 47mm, the speed of biting into the steel billet is 1m / s, and the acceleration is 3.2m / s. 2 The rolling speed of the steel billet is 2.8m / s, the elongation coefficient of the steel billet is 1.147, and the cross-sectional area of ​​the rolled steel billet is 46106mm 2 The web thickness of the steel billet with a length of 7.94m is 135mm, and the steel billet is pressed down by 65mm by the rolls of the billet mill; The roll gap of the BD rolling mill during the second rolling is 70 mm, the speed of biting into the steel billet is 1 m / s, and the acceleration is 3.8 m / s. 2 The rolling speed of the steel billet is 3m / s, the elongation coefficient of the steel billet is 1.177, and the cross-sectional area of ​​the rolled steel billet is 39163mm 2 , the length is 8.55m, the web thickness of the steel billet is 98mm, and the steel billet is pressed down by the billet mill rolls by 37mm; The roll gap of the BD rolling mill during the third rolling is 52 mm, the speed of biting into the steel billet is 1 m / s, and the acceleration is 4 m / s. 2 The rolling speed of the steel billet is 3.5m / s, the elongation coefficient of the steel billet is 1.076, and the cross-sectional area of ​​the rolled steel billet is 36387mm 22 , the length is 10.11m, the web thickness of the steel billet is 75mm, and the steel billet is pressed down by the billet mill roll by 23mm; When the BD rolling mill performs the fourth pass rolling, the roll gap is 22 mm, the speed of biting into the steel billet is 1 m / s, and the acceleration is 3.5 m / s 2 The rolling speed of the steel billet is 3m / s, the elongation coefficient of the steel billet is 1.067, and the cross-sectional area of ​​the rolled steel billet is 34117mm 2 , the length is 13.8m, the web thickness of the steel billet is 45mm, and the steel billet is pressed down by the billet mill roll by 30mm; The roll gap of the BD rolling mill during the fifth rolling is 22 mm, the speed of biting into the steel billet is 1 m / s, and the acceleration is 5.3 m / s. 2 The rolling speed of the steel billet is 3.8m / s, the elongation coefficient of the steel billet is 1.514, and the cross-sectional area of ​​the rolled steel billet is 22528mm 2 , the length is 23.58m, the web thickness of the steel billet is 38mm, and the steel billet is pressed down by the billet rolling mill rolls by 7mm.

[0011] In the 10-stand continuous finishing rolling process, the finishing mill rolling process parameters are as follows: The horizontal roll gap of the 1# finishing mill is 26 mm, the vertical roll gap on the transmission side is 26.5 mm, the vertical roll gap on the operating side is 26.5 mm, the rolling speed is 0.654 m / s, the front extension coefficient is 1.079, and the rear extension coefficient is 0.927; The horizontal roll gap of the 2# finishing mill is 19.5mm, the vertical roll gap on the transmission side is 22.5mm, the vertical roll gap on the operating side is 22.5mm, the rolling speed is 0.864m / s, the front extension coefficient is 1.321, and the rear extension coefficient is 0.757; The horizontal roll gap of the 3# finishing mill is 14.5mm, the vertical roll gap on the transmission side is 14.5mm, the vertical roll gap on the operating side is 14.5mm, the rolling speed is 1.137m / s, the front extension coefficient is 1.317, and the rear extension coefficient is 0.759; The horizontal roll gap of the 4# finishing mill is 11mm, the vertical roll gap on the transmission side is 7.5mm, the vertical roll gap on the operating side is 7.5mm, the rolling speed is 1.497m / s, the front extension coefficient is 1.317, and the rear extension coefficient is 0.759; The horizontal roll gap of the 5# finishing mill is 8.5mm, the vertical roll gap on the transmission side is 4.5mm, the vertical roll gap on the operating side is 4.5mm, the rolling speed is 1.939m / s, the front extension coefficient is 1.295, and the rear extension coefficient is 0.772; The horizontal roll gap of the 6# finishing mill is 9mm, the vertical roll gap on the transmission side is 0mm, the vertical roll gap on the operating side is 0mm, the rolling speed is 1.987m / s, the front extension coefficient is 1.025, and the rear extension coefficient is 0.976; The horizontal roll gap of the 7# finishing mill is 7mm, the vertical roll gap on the transmission side is 2.7mm, the vertical roll gap on the operating side is 2.7mm, the rolling speed is 2.556m / s, the front extension coefficient is 1.286, and the rear extension coefficient is 0.778; The horizontal roll gap of the 8# finishing mill is 6.2mm, the vertical roll gap on the transmission side is 2.4mm, the vertical roll gap on the operating side is 2.4mm, the rolling speed is 2.965m / s, the front extension coefficient is 1.16, and the rear extension coefficient is 0.862; The horizontal roll gap of the 9# finishing mill is 8mm, the vertical roll gap on the transmission side is 0mm, the vertical roll gap on the operating side is 0mm, the rolling speed is 3.056m / s, the front extension coefficient is 1.031, and the rear extension coefficient is 0.97; The horizontal roll gap of the 10# finishing mill is 5.4mm, the vertical roll gap on the driving side is 2.1mm, the vertical roll gap on the operating side is 2.1mm, the rolling speed is 3.5m / s, the front extension coefficient is 1.045, and the rear extension coefficient is 0.873.

[0012] The inlet opening of each frame guide of the finishing mill is 15mm larger than the material shape of the rolled piece, and the outlet opening is 15mm larger than the material shape of the rolled piece; the maximum outlet speed of the finishing mill unit is 5m / s.

[0013] In the cooling process of the cooling bed, the upper cooling bed adopts the cooling bed moving beam to move four steps to arrange a collection form of I16 specification hot-rolled I-beam rolled pieces.

[0014] In the straightening process of the straightening machine, the straightening temperature is ≤120℃, and the pressure parameters of the straightening machine are controlled as follows: the pressure reduction of the upper roller is 5.0mm, the pressure reduction of the upper two rollers is 7.5mm, the pressure reduction of the upper three rollers is 5.5mm, the pressure reduction of the upper four rollers is 3.0mm, and the pressure reduction of the upper five rollers is 2.0mm.

[0015] The chemical composition of the 200 large-section square billet is as follows: C 0.06-0.14%, Si 0.10-0.25%, Mn 0.35-0.56%, S≤0.040%, P≤0.040%.

[0016] Example 1 1) Billet heating, descaling and conveying A rectangular steel billet 1 with a size of 200mm×200mm×7631mm and a grade of Q235, as shown in Table 1, is fed into a step heating furnace 2 for heating, and then the heated steel billet is fed into a high-pressure water descaling device 3 through a heating furnace output roller table 4 to remove the oxidized iron scale, and then the steel billet 1 is fed to the BD mill front working roller table 4, the BD mill 5 and the BD rolling mill rear working roller table 4 by the BD mill front extension roller table 4, and is heated in a heating furnace for 2 hours after reciprocating rolling in the BD mill 6, with a heating temperature of 1145°C, a heating temperature of 1015°C, a heating temperature of 1209°C in the second heating stage, and a temperature of 1220°C in the soaking stage; the BD mill start rolling temperature is 1145°C, the finishing rolling temperature is 1030°C, and the final rolling temperature is 890°C. The output water pressure of the high-pressure water descaling device is 18.5Mpa.

[0017] Table 1 Chemical composition of rectangular steel billet in Example 1 2) BD mill initial rolling The billet is rolled in five passes by the BD mill 6 to obtain a billet roll 8, and then the billet roll 8 is transported to the rear extension roller table and the flying shear transport roller table 4 of the BD mill. During the billet rolling process of the BD mill, the steel feeding and steel discharge conditions of each pass must be confirmed according to the process requirements, and the front pusher 5 or the rear pusher 7 of the BD mill aligns the roll with the corresponding slot until the five passes of rolling are completed. The rolling parameters of the BD mill are shown in Table 2.

[0018] Table 2 BD rolling mill rolling parameters of Example 1 3) Flying shear head The workpiece 8 that has completed the blank rolling is transported via the flying shear transport roller 4, and the blank workpiece 8 is sheared and the head and tail are removed at the flying shear 9 to make the cross-section shape distribution, total height and web thickness of the workpiece meet the finishing requirements, and finally transported to the finishing mill 10.

[0019] 4) Finishing mill rolling The received open blanks are rolled ten times by ten finishing mills 10 to obtain finished profile rolled products.

[0020] The finishing mill group is equipped with 10 finishing mill stands (numbered: 1#~10#), of which 6# and 9# are edge rolling mills, and the rest of the stands are universal rolling mills. Before rolling, verify that the roll gap of each rolling mill meets the process requirements. The rolled pieces rolled by the BD mill are sheared and transported to the finishing mill for rolling. During the rolling process, the parameters are controlled according to the rolling parameters of the finishing mill (Table 3), and the finished I16 specification hot-rolled I-beam rolled pieces are obtained.

[0021] Table 3 Rolling parameters of finishing mill in Example 1 5. Cooling, straightening, cold sawing, sizing, inspection, stacking and bundling The finished I16 hot-rolled I-beam rolled piece obtained by the finishing mill 10 is conveyed by rollers and enters the cooling bed for cooling. In order to ensure uniform cooling, the cooling bed moving teeth move three steps on the cooling bed, and a rolling piece is arranged. When the rolling piece is cooled to 110°C, it enters the straightening machine for straightening. After the straightened steel is sawed by a saw, it is stacked and packaged in the form of 3 branches and 11 layers. Finally, a qualified I16 hot-rolled I-beam product is obtained. The product size and mechanical properties are shown in Figure 4: Table 4 Dimensional mechanical properties of I16 hot-rolled I-beam produced in Example 1 Example 2 The steel billet with chemical composition shown in Table 5 enters the stepping heating furnace and is heated for 2.5 hours. The temperature of the first heating stage is 1100°C, the temperature of the second heating stage is 1240°C, and the temperature of the soaking stage is 1250°C. The starting temperature of the BD rolling mill is 1169°C, the finishing rolling temperature is 1053°C, and the final rolling temperature is 960°C. The output water pressure of the high-pressure water descaling device is 19Mpa. The other steps are the same as those in Example 1. The mechanical properties of the obtained I16 I-beam are shown in Table 6.

[0022] Table 5 Chemical composition of steel billet in Example 2 Table 6 Dimensional mechanical properties of I16 hot-rolled I-beam produced in Example 2

Claims

1. A method for hot rolling I16 I-beam with 200 large section square billet, characterized in that: The method comprises the following steps in sequence: heating of 200*200mm large-section square billet, high-pressure water descaling, reciprocating initial rolling of BD rolling mill, continuous finishing rolling of 10 stands, cooling of cooling bed, straightening of straightening machine, sizing of cold saw, inspection, stacking, bundling, weighing, hanging and warehousing; Among them, in the heating process of 200*200mm large-section square billet, the heating time of the square billet is greater than 120 minutes, the temperature of the first heating stage is 960-1150°C, the temperature of the second heating stage is 1190-1250°C, and the temperature of the soaking stage is 1200-1260°C; In the high-pressure water descaling process, the output water pressure of the high-pressure water descaling device is 15~20Mpa; the straightening temperature is 20~120℃; The starting rolling temperature of the BD rolling mill is 1140-1170°C, the finishing rolling temperature is 980-1080°C, and the final rolling temperature is 870-970°C; In the reciprocating initial rolling process of the BD rolling mill, the rectangular steel billet is reciprocated and initially rolled for 5 times in the BD rolling mill. During the first rolling, the roll gap is 47mm, the speed of biting into the steel billet is 1m / s, and the acceleration is 3.2m / s. 2 The rolling speed of the steel billet is 2.8m / s, the elongation coefficient of the steel billet is 1.147, and the cross-sectional area of ​​the rolled steel billet is 46106mm 2 The web thickness of the steel billet with a length of 7.94m is 135mm, and the steel billet is pressed down by 65mm by the rolls of the billet mill; The roll gap of the BD rolling mill during the second rolling is 70 mm, the speed of biting into the steel billet is 1 m / s, and the acceleration is 3.8 m / s. 2 The rolling speed of the steel billet is 3m / s, the elongation coefficient of the steel billet is 1.177, and the cross-sectional area of ​​the rolled steel billet is 39163mm 2 , the length is 8.55m, the web thickness of the steel billet is 98mm, and the steel billet is pressed down by the billet mill rolls by 37mm; The roll gap of the BD rolling mill during the third rolling is 52 mm, the speed of biting into the steel billet is 1 m / s, and the acceleration is 4 m / s. 2 The rolling speed of the steel billet is 3.5 m / s, the elongation coefficient of the steel billet is 1.076, and the cross-sectional area of ​​the rolled steel billet is 36387 mm 22 , the length is 10.11m, the web thickness of the steel billet is 75mm, and the steel billet is pressed down by the billet mill roll by 23mm; When the BD rolling mill performs the fourth pass rolling, the roll gap is 22 mm, the speed of biting into the steel billet is 1 m / s, and the acceleration is 3.5 m / s 2 The rolling speed of the steel billet is 3m / s, the elongation coefficient of the steel billet is 1.067, and the cross-sectional area of ​​the rolled steel billet is 34117mm 2 , the length is 13.8m, the web thickness of the steel billet is 45mm, and the steel billet is pressed down by the billet mill roll by 30mm; The roll gap of the BD rolling mill during the fifth rolling is 22 mm, the speed of biting into the steel billet is 1 m / s, and the acceleration is 5.3 m / s. 2 The rolling speed of the steel billet is 3.8m / s, the elongation coefficient of the steel billet is 1.514, and the cross-sectional area of ​​the rolled steel billet is 22528mm 2 , the length is 23.58m, the web thickness of the steel billet is 38mm, and the steel billet is pressed down by the billet rolling mill rolls by 7mm.

2. The method for hot rolling I16 I-beam with 200 large section billet according to claim 1, characterized in that: In the 10-stand continuous finishing rolling process, the finishing mill rolling process parameters are as follows: The horizontal roll gap of the 1# finishing mill is 26 mm, the vertical roll gap on the transmission side is 26.5 mm, the vertical roll gap on the operating side is 26.5 mm, the rolling speed is 0.654 m / s, the front extension coefficient is 1.079, and the rear extension coefficient is 0.927; The horizontal roll gap of the 2# finishing mill is 19.5mm, the vertical roll gap on the transmission side is 22.5mm, the vertical roll gap on the operating side is 22.5mm, the rolling speed is 0.864m / s, the front extension coefficient is 1.321, and the rear extension coefficient is 0.757; The horizontal roll gap of the 3# finishing mill is 14.5mm, the vertical roll gap on the transmission side is 14.5mm, the vertical roll gap on the operating side is 14.5mm, the rolling speed is 1.137m / s, the front extension coefficient is 1.317, and the rear extension coefficient is 0.759; The horizontal roll gap of the 4# finishing mill is 11mm, the vertical roll gap on the transmission side is 7.5mm, the vertical roll gap on the operating side is 7.5mm, the rolling speed is 1.497m / s, the front extension coefficient is 1.317, and the rear extension coefficient is 0.759; The horizontal roll gap of the 5# finishing mill is 8.5mm, the vertical roll gap on the transmission side is 4.5mm, the vertical roll gap on the operating side is 4.5mm, the rolling speed is 1.939m / s, the front extension coefficient is 1.295, and the rear extension coefficient is 0.772; The horizontal roll gap of the 6# finishing mill is 9mm, the vertical roll gap on the transmission side is 0mm, the vertical roll gap on the operating side is 0mm, the rolling speed is 1.987m / s, the front extension coefficient is 1.025, and the rear extension coefficient is 0.976; The horizontal roll gap of the 7# finishing mill is 7mm, the vertical roll gap on the transmission side is 2.7mm, the vertical roll gap on the operating side is 2.7mm, the rolling speed is 2.556m / s, the front extension coefficient is 1.286, and the rear extension coefficient is 0.778; The horizontal roll gap of the 8# finishing mill is 6.2mm, the vertical roll gap on the transmission side is 2.4mm, the vertical roll gap on the operating side is 2.4mm, the rolling speed is 2.965m / s, the front extension coefficient is 1.16, and the rear extension coefficient is 0.862; The horizontal roll gap of the 9# finishing mill is 8mm, the vertical roll gap on the transmission side is 0mm, the vertical roll gap on the operating side is 0mm, the rolling speed is 3.056m / s, the front extension coefficient is 1.031, and the rear extension coefficient is 0.97; The horizontal roll gap of the 10# finishing mill is 5.4mm, the vertical roll gap on the driving side is 2.1mm, the vertical roll gap on the operating side is 2.1mm, the rolling speed is 3.5m / s, the front extension coefficient is 1.045, and the rear extension coefficient is 0.

873.

3. The method for hot rolling I16 I-beam with 200 large section square billet according to claim 1, characterized in that: The inlet opening of each frame guide of the finishing mill is 15mm larger than the material profile of the rolled piece, and the outlet opening is 15mm larger than the material profile of the rolled piece; the maximum outlet speed of the finishing mill unit is 5m / s.

4. The method for hot rolling I16 I-beam with 200 large section billet according to claim 1, characterized in that: In the cooling process of the cooling bed, the upper cooling bed adopts the cooling bed moving beam to move four steps to arrange a collection form of I16 specification hot-rolled I-beam rolled pieces.

5. The method for hot rolling I16 I-beam with 200 large section square billet according to claim 1, characterized in that: In the straightening process of the straightening machine, the straightening temperature is ≤120℃, and the pressure parameters of the straightening machine are controlled as follows: the pressure reduction of the upper roller is 5.0mm, the pressure reduction of the upper two rollers is 7.5mm, the pressure reduction of the upper three rollers is 5.5mm, the pressure reduction of the upper four rollers is 3.0mm, and the pressure reduction of the upper five rollers is 2.0mm.

6. The method for hot rolling I16 I-beam with 200 large section square billet according to claims 1-5, characterized in that: The chemical composition of the 200 large-section square billet is as follows: C 0.06-0.14%, Si 0.10-0.25%, Mn 0.35-0.56%, S≤0.040%, P≤0.040%.

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