A production method for thin-gauge medium-high carbon steel

Abstract

The present invention relates to the technical field of rolling medium-high carbon thin materials, specifically a method for producing thin-gauge medium-high carbon steel. 1) Control the slab charging temperature, preheating section heating temperature, and heating furnace exit temperature; 2) Rough rolling is performed using two or more rolling mills, with the first rolling mill being R1 and the second rolling mill being R2, to control the rolling speed; 3) Control the rough rolling load; 4) Control the load of the seven finishing rolling mills; 5) Control the plate shape by the bending roll force; 6) Set the guide gauge opening of each finishing rolling mill to K, mm; the plate and strip width to D, mm; then △SG=K-D, △SG is the guide gauge allowance value, mm. The present invention can improve the rolling stability of medium-high carbon thin gauges, reduce the accidents of folding and jamming steel and tail swinging during the rolling of medium-high carbon thin gauges, and improve the quality of medium-high carbon products and the comprehensive yield rate.

Description

Technical Field

[0001] The present invention relates to the technical field of medium-high carbon thin material rolling, in particular to a method for producing thin-gauge medium-high carbon steel. Background Art

[0002] Currently, hot-rolled strip production lines face significant challenges rolling thin-gauge medium- and high-carbon steel products due to limitations in equipment capacity and rolling process conditions, as well as the high carbon content of medium- and high-carbon steel. Accidents such as head strip folding and tail strip swinging are common during the rolling process. More significantly, strip drift within the mill, deviating from the rolling centerline and scraping against the guide gauge, causing steel jams. This not only impacts rolling stability but also reduces product quality and overall yield. Summary of the Invention

[0003] In order to overcome the shortcomings of the existing technology, the present invention provides a production method for thin-gauge medium-high carbon steel, which can improve the rolling stability of thin-gauge medium-high carbon steel, reduce the accidents of steel bending and jamming and tail swinging during the rolling of thin-gauge medium-high carbon steel, and improve the quality of medium-high carbon products and the comprehensive yield rate.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions:

[0005] A method for producing thin-gauge medium-high carbon steel, wherein the thin-gauge refers to a hot-rolled strip steel with a thickness of 1.5 to 3.5 mm, and the medium-high carbon steel refers to a carbon steel with a carbon mass content of 0.25% to 0.6%, specifically comprising the following steps:

[0006] 1) The slab charging temperature is controlled at 350-700℃, the preheating temperature is controlled at 700-850℃; the heating temperature out of the furnace is controlled at 1240-1260℃;

[0007] 2) Rough rolling is carried out using two or more rolling mills, the first rolling mill is R1, the second rolling mill is R2, the first pass rolling speed of R1 is 1.8-2.2 m / s, the second pass rolling speed is 2.2-2.5 m / s, and the third pass rolling speed is 2.3-2.6 m / s;

[0008] The first pass rolling speed of R2 is 3.1~3.5m / s, the second pass rolling speed is 4.0~4.5m / s, and the third pass rolling speed is 4.1~4.6m / s;

[0009] 3) The first pass load of R1 is 20% to 22%, the second pass load is 17% to 22%, and the third pass load is 13% to 16%;

[0010] 4) Finish rolling is carried out using more than seven rolling mills, the first rolling mill is F1, the second rolling mill is F2, the third rolling mill is F3, the fourth rolling mill is F4, the fifth rolling mill is F5, the sixth rolling mill is F6, and the seventh rolling mill is F7;

[0011] Load distribution: F1 is 30% to 42%, F2 is 30% to 41%, F3 is 10% to 18%, F4 is 5% to 10%, F5 is 2% to 6%, F6 is 1.5% to 5%, and F7 is 1.2% to 1.8%;

[0012] 5) Control the plate shape by bending roller force, control the F1 bending roller force to 750~1000KN, the F2 bending roller force to 700~950KN, the F3 bending roller force to 600~900KN, the F4 bending roller force to 500~800KN, the F5 bending roller force to 440~750KN, the F6 bending roller force to 400~700KN, and the F7 bending roller force to 330~650KN;

[0013] 6) Set the guide gauge opening of each finishing mill to K, mm; the strip width to D, mm;

[0014] Then △SG=KD, △SG is the guide ruler allowance value, mm.

[0015] Furthermore, in step 1), the thickness of the raw material slab is 170 to 230 mm.

[0016] Furthermore, in step 1), the preheating time of the heating furnace is greater than 40 minutes.

[0017] Furthermore, in step 1), the total time the slab is in the furnace is greater than 185 minutes.

[0018] Furthermore, in step 1), the soaking period is greater than 30 minutes.

[0019] Furthermore, in step 2), the temperature of the rough rolling intermediate billet is controlled at 1090-1120°C.

[0020] Furthermore, in step 2), the thickness of the rough rolling intermediate billet is controlled to be 32 to 38 mm.

[0021] Furthermore, in step 4), the finishing rolling outlet temperature is controlled at 910-930°C.

[0022] Furthermore, in step 6), F1 to F4, ΔSG is 35-55 mm; F5 to F7, ΔSG is 55-90 mm.

[0023] Compared with the existing method, the present invention has the following beneficial effects:

[0024] The present invention ensures the uniformity of the temperature of thin-gauge medium- and high-carbon slabs by optimizing the heating and steel-burning system, and at the same time improves the parameters of the load and rolling speed of each rough rolling pass, improves the plate shape of the rough rolling intermediate billet, increases the temperature of the thin-gauge medium- and high-carbon intermediate billet, reduces the guide gauge margin of each rolling mill stand of the finishing mill, reduces the probability of strip deviation during head threading, improves threading stability, and finally optimizes the load distribution of each stand of the finishing rolling mill group and the coordinated use of the bending roll force, improves the flatness of the plate shape during rolling, systematically solves the instability problem of medium- and high-carbon rolling, and effectively solves the accidents of folding and jamming steel and tail swinging during medium- and high-carbon thin-gauge rolling, thereby improving the rolling stability of medium- and high-carbon thin-gauges, reducing and improving the quality of medium- and high-carbon products and the comprehensive yield rate.

[0025] By adopting the method of the present invention, the rolling stability of thin-gauge medium-high carbon steel is greatly improved, and the rolling success rate of thin-gauge medium-high carbon steel is increased from 58.13% to 95.35%; at the same time, the quality defects caused by production accidents are reduced, and the quality defect rate is reduced from 12.32% to 2.65%; the yield rate of thin-gauge medium-high carbon steel is increased from 94.36% to 98.32%. DETAILED DESCRIPTION

[0026] The present invention discloses a method for producing thin-gauge medium-high carbon steel. Those skilled in the art can refer to the contents of this article and appropriately improve the process parameters to achieve the desired results. It should be noted that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included in the present invention. The methods and applications of the present invention have been described through preferred embodiments, and relevant personnel can obviously modify or appropriately change and combine the methods and applications described herein without departing from the content, spirit, and scope of the present invention to implement and apply the technology of the present invention.

[0027] A method for producing thin-gauge medium-high carbon steel comprises the following steps:

[0028] 1. Control the slab charging temperature to 350℃~700℃, the slab preheating time in the heating furnace is more than 40 minutes, and the heating temperature in the preheating section is 700℃~850℃; the total slab in the furnace time is more than 185 minutes, the soaking period time is more than 30 minutes, and the heating out of the furnace temperature is controlled at 1240℃~1260℃.

[0029] 2. Rough rolling is performed using two rolling mills, with the front and rear mills designated R1 and R2, respectively. The rolling speeds for each pass of the R1 mill are set at 1.8-2.2 m / s, 2.2-2.5 m / s, and 2.3-2.6 m / s, respectively; the rolling speeds for each pass of the R2 mill are set at 3.1-3.5 m / s, 4.0-4.5 m / s, and 4.1-4.6 m / s, respectively. The temperature of the intermediate bar during rough rolling is controlled at 1090°C to 1120°C.

[0030] 3. For raw slabs with a thickness of 170mm to 230mm, the load distribution for the three R1 passes is 20% to 22%, 17% to 22%, and 13% to 16%, respectively; the load distribution for the three R2 passes is 15% to 18%, 13% to 17%, and 10% to 13%, respectively. The thickness of the intermediate slab during rough rolling is controlled at 32 to 38mm.

[0031] 4. The finishing rolling outlet temperature is controlled at 910℃~930℃. The finishing rolling adopts seven rolling mills, denoted by F1 to F7, with the load distribution as follows: F1 is 30%~42%, F2 is 30%~41%, F3 is 10%~18%, F4 is 5%~10%, F5 is 2%~6%, F6 is 1.5%~5%, and F7 is 1.2%~1.8%.

[0032] 5. The plate shape between each stand of finishing rolling mill is controlled to be straight or slightly double-sided. The plate shape of each stand is controlled by bending roll force. The use range of bending roll force of each stand F1-F7 is:

[0033] The bending roller force of F1 frame is 750KN~1000KN, the bending roller force of F2 frame is 700KN~950KN, the bending roller force of F3 frame is 600KN~900KN, the bending roller force of F4 frame is 500KN~800KN, the bending roller force of F5 frame is 440KN~750KN, the bending roller force of F6 frame is 400KN~700KN, and the bending roller force of F7 frame is 330KN~650KN.

[0034] 6. The guide gauge opening of each stand of finishing rolling mill is set to be △SG more than the strip width, as follows:

[0035] △SG n =35mm~55mm;△SG p =55mm~90mm;

[0036] Where △SG represents the guide gauge allowance value;

[0037] n represents racks 1-4, and p represents racks 5-7.

[0038] Example 1:

[0039] A method for producing medium-high carbon No. 50 steel with a thickness of 1.8 mm and a width of 1250 mm, comprising the following steps:

[0040] 1. The charging temperature of the slab is 450℃. The preheating time of the slab in the heating furnace is 45 minutes, and the heating temperature of the preheating section is 800℃. The total time of the slab in the furnace is 186 minutes, the soaking time is 35 minutes, and the heating out of the furnace temperature is controlled at 1245℃.

[0041] 2. The rough rolling mill adopts two rolling mills. The front and rear rolling mills are represented by R1 and R2 respectively. R1 and R2 have different rolling passes. The rolling speed of each pass of R1 is set to 2.0 m / s, 2.5 m / s and 2.6 m / s respectively; the rolling speed of each pass of R2 rolling mill is set to 3.3 m / s, 4.3 m / s and 4.5 m / s respectively. The temperature of the rough rolling intermediate billet is controlled at 1100℃; the finishing rolling outlet temperature is controlled at 920℃.

[0042] 3. The raw material used is 230mm thick slab. The load distribution of the three passes of R1 is 20%, 17%, and 14%, respectively; the load distribution of the three passes of R2 is 16%, 15%, and 12%, respectively. The thickness of the intermediate bar in roughing rolling is controlled at 35mm. The load distribution of the seven finishing stands F1-F7 is: F1 is 30%, F2 is 36%, F3 is 16%, F4 is 7%, F5 is 6%, F6 is 3.5%, and F7 is 1.5%.

[0043] 4. The plate shape between each rolling mill in the finishing rolling is controlled to be straight or slightly double-sided. The plate shape is controlled by the bending roll force. The bending roll force of the F1 stand is 900KN, the bending roll force of the F2 stand is 850KN, the bending roll force of the F3 stand is 830KN, the bending roll force of the F4 stand is 650KN, the bending roll force of the F5 stand is 600KN, the bending roll force of the F6 stand is 5500KN, and the bending roll force of the F7 stand is 5000KN.

[0044] 5. The guide gauge opening allowances of each rolling mill F1-F7 are:

[0045] △SG1=35mm; △SG2=35mm; △SG3=35mm; △SG4=35mm; △SG5=55mm; △SG6=55mm; △SG7=55mm;

[0046] The guide gauge widths of rolling mills F1 to F7 are 1285mm, 1285mm, 1285mm, 1285mm, 1305mm, 1305mm, and 1305mm respectively.

[0047] Example 2:

[0048] A method for producing medium-high carbon 65Mn steel with a thickness of 2.0 mm and a width of 1200 mm comprises the following steps:

[0049] 1. The charging temperature of the slab is 550℃. The preheating time of the slab in the heating furnace is 50 minutes, and the heating temperature of the preheating section is 850℃. The total time of the slab in the furnace is about 195 minutes, the soaking time is 40 minutes, and the heating temperature out of the furnace is controlled at 1250℃.

[0050] 2. The rough rolling mill adopts two rolling mills. The front and rear rolling mills are represented by R1 and R2 respectively. R1 and R2 have different rolling passes. The rolling speed of each pass of R1 is set to 2.2m / s, 2.5m / s and 2.6m / s respectively; the rolling speed of each pass of R2 is set to 3.5m / s, 4.5m / s and 4.6m / s respectively. The temperature of the rough rolling intermediate billet is controlled at 1120℃; the finishing rolling outlet temperature is controlled at 930℃.

[0051] 3. The raw material used is 170mm thick slab. The load distribution of the three passes of the roughing mill R1 is 20%, 22%, and 16%, respectively; the load distribution of the three passes of the R2 mill is 15%, 17%, and 13%, respectively. The thickness of the roughing intermediate bar is controlled at 38mm. The load distribution of the seven finishing mills F1-F7 is as follows: F1 is 33%, F2 is 35%, F3 is 16%, F4 is 6%, F5 is 5.4%, F6 is 3%, and F7 is 1.6%.

[0052] 4. The plate shape of each rolling mill in the finishing rolling mill is controlled to be straight or slightly double-sided. The plate shape of each stand is controlled by the bending roll force. The use range of the bending roll force of each stand F1-F7 is: the bending roll force of F1 stand is 900KN, the bending roll force of F2 stand is 880KN, the bending roll force of F3 stand is 800KN, the bending roll force of F4 stand is 750KN, the bending roll force of F5 stand is 6800KN, the bending roll force of F6 stand is 6500KN, and the bending roll force of F7 stand is 600KN.

[0053] 5. The guide gauge opening allowances of each rolling mill F1-F7 are:

[0054] △SG1=40mm; △SG2=40mm; △SG3=40mm; △SG4=40mm; △SG5=60mm; △SG6=60mm; △SG7=60mm;

[0055] The guide gauge widths of rolling mills F1 to F7 are 1240mm, 1240mm, 1240mm, 1240mm, 1260mm, 1260mm, and 1260mm respectively.

[0056] The present invention can improve the rolling stability of thin-gauge medium-high carbon steel, reduce folding, jamming, and tail-swinging accidents during rolling, and improve the quality and overall yield rate of medium-high carbon products. Using the method described in the present invention, the rolling stability of thin-gauge medium-high carbon steel is significantly improved, and the success rate of rolling thin-gauge medium-high carbon steel is increased from 58.13% to 95.35%. At the same time, quality defects caused by production accidents are reduced, with the quality defect rate dropping from 12.32% to 2.65%. The yield rate of thin-gauge medium-high carbon steel is increased from 94.36% to 98.32%.

[0057] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A method for producing thin-gauge medium-high carbon steel, characterized in that: The thin gauge refers to hot-rolled strip steel with a thickness of 1.5 to 3.5 mm, and the medium-high carbon steel refers to carbon steel with a carbon content of 0.25% to 0.6%. The process specifically includes the following steps: 1) The slab charging temperature is controlled at 350-700℃, the preheating temperature is controlled at 700-850℃; the heating temperature out of the furnace is controlled at 1240-1260℃; 2) Rough rolling is carried out using two or more rolling mills, the first rolling mill is R1, the second rolling mill is R2, the first pass rolling speed of R1 is 1.8-2.2 m / s, the second pass rolling speed is 2.2-2.5 m / s, and the third pass rolling speed is 2.3-2.6 m / s; The first pass rolling speed of R2 is 3.1~3.5m / s, the second pass rolling speed is 4.0~4.5m / s, and the third pass rolling speed is 4.1~4.6m / s; 3) The first pass load of R1 is 20% to 22%, the second pass load is 17% to 22%, and the third pass load is 13% to 16%; 4) Finish rolling is carried out using more than seven rolling mills, the first rolling mill is F1, the second rolling mill is F2, the third rolling mill is F3, the fourth rolling mill is F4, the fifth rolling mill is F5, the sixth rolling mill is F6, and the seventh rolling mill is F7; Load distribution: F1 is 30% to 42%, F2 is 30% to 41%, F3 is 10% to 18%, F4 is 5% to 10%, F5 is 2% to 6%, F6 is 1.5% to 5%, and F7 is 1.2% to 1.8%; 5) Control the plate shape by bending roller force, control the F1 bending roller force to 750~1000KN, the F2 bending roller force to 700~950KN, the F3 bending roller force to 600~900KN, the F4 bending roller force to 500~800KN, the F5 bending roller force to 440~750KN, the F6 bending roller force to 400~700KN, and the F7 bending roller force to 330~650KN; 6) Set the guide gauge opening of each finishing mill to K, mm; the strip width to D, mm; Then △SG=KD, △SG is the guide ruler allowance value, mm.

2. The method for producing thin-gauge medium-high carbon steel according to claim 1, characterized in that: In step 1), the thickness of the raw material slab is 170 to 230 mm.

3. The method for producing thin-gauge medium-high carbon steel according to claim 1, characterized in that: In step 1), the preheating time of the heating furnace is greater than 40 minutes.

4. The method for producing thin-gauge medium-high carbon steel according to claim 1, characterized in that: In step 1), the total time the slab is in the furnace is greater than 185 minutes.

5. The method for producing thin-gauge medium-high carbon steel according to claim 1, characterized in that: In step 1), the soaking period is greater than 30 minutes.

6. The method for producing thin-gauge medium-high carbon steel according to claim 1, characterized in that: In step 2), the temperature of the rough rolling intermediate billet is controlled at 1090-1120°C.

7. The method for producing thin-gauge medium-high carbon steel according to claim 1, characterized in that: In step 2), the thickness of the rough rolling intermediate billet is controlled at 32 to 38 mm.

8. The method for producing thin-gauge medium-high carbon steel according to claim 1, characterized in that: In step 4), the finishing rolling outlet temperature is controlled at 910-930°C.

9. The method for producing thin-gauge medium-high carbon steel according to claim 1, characterized in that: In step 6), from F1 to F4, ΔSG is 35 to 55 mm; from F5 to F7, ΔSG is 55 to 90 mm.