Method for eliminating shape defects of hot-rolled thin-gauge high-strength weather-proof steel plate

Abstract

The invention belongs to the technical field of steel rolling, and relates to a method for eliminating shape defects of a hot-rolled thin-gauge high-strength weather-proof steel plate, which adopts a six-roller reversible cold rolling unit for cold rolling and flattening, and specifically comprises the steps of uncoiling, threading, pinch roll I pinch, six-roller reversible cold rolling unit cold rolling and flattening, pinch roll II pinch and coiling by a coiling machine. And cold rolling leveling is conducted according to set technological parameters, and finally the hot-rolled high-strength weather-resistant thin-gauge steel strip which is excellent in comprehensive performance, flat and smooth in plate face and standard in flatness is produced. The surface of the high-strength weather-resistant steel plate treated by the method is flat and smooth, and the straightness is less than or equal to 4mm / 1000mm; compared with an original steel strip, the steel plate structure property is basically unchanged.

Description

Technical Field

[0001] The invention belongs to the technical field of steel rolling, and relates to eliminating shape defects of thin-gauge weathering steel plates, and specifically is a method for eliminating shape defects of hot-rolled thin-gauge high-strength weathering steel plates. Background Art

[0002] High-strength weathering steel is a new type of material that is environmentally friendly, corrosion-resistant, high-strength, low-cost, paint-free, and maintenance-free. It is the trend of future development. Photovoltaic brackets are important supporting and protective accessories for solar photovoltaic power generation equipment. Paint-free and maintenance-free photovoltaic brackets mainly use hot-rolled high-strength weathering steel coils with a yield strength of 620MPa or above and a thickness of 1.5-2.0mm. After striping, roll forming or high-frequency induction welding into C-type and O-type brackets, in addition to physical and chemical performance requirements, the plate shape quality requirements of hot-rolled coils are very high. The plate surface should be flat and smooth, without visible defects, and the straightness should be ≤4mm / 1000mm. In order to meet the user's plate shape requirements, hot-rolled thin-gauge high-strength steel is generally traditionally required to go through a straightening and flattening process to effectively improve the flatness, surface quality and thickness accuracy of the hot-rolled coils.

[0003] In Chinese patent literature represented by application numbers 201711307007.8, 201210107921.9, 201810375462.X, 201410176710.X, and 200910093663.1, existing hot-rolled high-strength plate shape control methods are disclosed, all of which are to eliminate plate shape defects by adjusting the straightening and flattening process, including two-pass combined flattening, straightening and flattening combined with straightening, annealing combined with straightening and flattening, etc. The process is relatively complicated and requires a special high-strength flattening, pickling and flattening or hood annealing production line. Summary of the invention

[0004] The purpose of the present invention is to provide a method for eliminating the shape defects of hot-rolled thin-gauge high-strength weathering steel plates, using a six-roller reversible cold rolling unit for cold rolling and flattening to produce hot-rolled high-strength weathering thin-gauge steel strips with excellent comprehensive performance and a flat and smooth plate surface that meets the straightness standards.

[0005] The technical solution adopted by the present invention to achieve the above-mentioned purpose is: A method for eliminating the shape defects of hot-rolled thin-gauge high-strength weathering steel strip, comprising cold rolling and leveling a hot-rolled high-strength weathering steel strip having a thickness of 1.5 mm to 2.0 mm and a yield strength of ≥620 MPa using a six-roller reversible cold rolling unit, the steps comprising: S1. The hot-rolled high-strength weathering steel strip is uncoiled, straightened by nine rollers, pickled, rinsed, rolled by three rollers, and coiled to obtain a pickled steel strip; S2. At the end of the cold rolling process, the pickled steel strip with a temperature of ≤45°C is sent to the six-roller reversible cold rolling unit, unrolled by the uncoiler, threaded, clamped by the first pinch roller, cold-rolled and leveled by the six-roller reversible cold rolling unit, clamped by the second pinch roller, and coiled by the coiler, and then cold-rolled and leveled according to the set process parameters.

[0006] Furthermore, the process parameters of cold rolling and leveling are set in S2 as follows: the working rolls of the six-roller reversible cold rolling unit are hot rolls that have reached the end of the cold rolling process; the rolling force is 4000 to 8000KN; the elongation is 2.2-5.0%; the leveling speed is the starting speed of 15-30m / min, and after the adjusted plate shape is stable, it is gradually increased to 120m / min; the tension control is that the front tension setting value is 160KN, and the rear tension setting value is 60KN.

[0007] The beneficial effects of the present invention are as follows: the surface of the high-strength weathering steel plate treated by the method of the present invention is flat and smooth, with a flatness of ≤4mm / 1000mmm; and the structure and properties of the steel plate are basically unchanged compared with the original steel strip. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 Schematic diagram of the cold rolling and leveling system of the method of the present invention; In the figure, 1 is the uncoiler; 2 is the pinch roll one; 3 is the six-roller reversible cold rolling mill; 4 is the pinch roll two; 5 is the coiler; 6 is the hydraulic roll gap controller; 7 is the hydraulic pressing cylinder; 8 is the front tension meter; 9 is the rear tension meter. DETAILED DESCRIPTION

[0009] The present invention will be further described below in conjunction with the accompanying drawings and embodiments: A method for eliminating the shape defects of hot-rolled thin-gauge high-strength weathering steel strip, comprising cold rolling and leveling a hot-rolled high-strength weathering steel strip having a thickness of 1.5 mm to 2.0 mm and a yield strength of ≥620 MPa using a six-roller reversible cold rolling unit; the steps comprising: 1. After the hot-rolled high-strength weathering steel strip is uncoiled by the uncoiler, the strip is corrected in shape by a nine-roll straightener, and then pickled and rinsed, and then coiled by a three-roll tension roller into a coiler to obtain a pickled hot-rolled high-strength weathering steel strip; 2. Cold rolling and leveling of pickled hot-rolled high-strength weathering steel strip: At the end of the cold rolling process, the pickled steel strip with a temperature of ≤45°C is sent to the six-roller reversible cold rolling unit for cold rolling and leveling according to the set process flow and parameters. The specific process is as follows: Figure 1As shown, the uncoiler 1 uncoils and passes the strip to the pinch roller 1 2 to enter the six-roller reversible cold rolling unit 3, and then passes through the pinch roller 2 4 to enter the coiler 5 for coiling; the six-roller reversible cold rolling unit 3 is controlled by the hydraulic roll gap controller 6 to control the position and rolling force of the hydraulic pressing cylinder 7, and set the elongation and the roll leveling speed V1; the front tension value F0 is set, and the speed and torque of the uncoiler 1 are controlled according to the feedback of the front tension meter 8 to control the front tension; the rear tension value F1 is set, and the speed and torque of the coiler 5 are controlled according to the feedback of the rear tension meter 9 to control the rear tension.

[0010] Example 1: A hot-rolled high-strength weathering steel strip with a thickness of 1.8 mm is cold-rolled and leveled by a six-roll reversible cold rolling unit. The hot-rolled high-strength weathering steel strip is uncoiled → nine-roll straightening → pickling → rinsing → three-roll tension roller → coiling to obtain the pickled steel strip; at the end of the cold rolling process, the steel strip with a temperature of ≤45°C is sent to the six-roll reversible cold rolling unit, uncoiled → threaded → pinch roller pinching → six-roll reversible cold rolling unit cold rolling flat → pinch roller pinching → coiling by the coiler, and cold rolled according to the set process parameters; the rolling force is 8000KN, the elongation is 5.0%, the starting speed is 15-30m / min, and after the plate shape is adjusted to be stable, it is gradually increased to 120m / min, the front tension setting value is 160KN, and the rear tension setting value is 60KN, so as to obtain a hot-rolled high-strength weathering steel strip with a thickness of 1.8mm and good plate shape.

[0011] Yield strength of steel plate: 740MPa before cold rolling, 760MPa after cold rolling; tensile strength: 830MPa before cold rolling, 850MPa after cold rolling; elongation: 22% before cold rolling, 18% after cold rolling; 180° bending test d=2a: intact before and after cold rolling; organization: ferrite plus a small amount of bainite, grain size 12, no obvious elongated deformed grains after cold rolling; plate shape: the plate surface is flat and smooth, with a straightness of 2mm / 1000mm.

[0012] Example 2: A hot-rolled high-strength weathering steel strip with a thickness of 1.5 mm is cold-rolled and leveled by a six-roll reversible cold rolling unit. The hot-rolled high-strength weathering steel strip is uncoiled → nine-roll straightening → pickling → rinsing → three-roll tension roller → coiling to obtain the pickled steel strip; at the end of the cold rolling process, the hot-rolled high-strength weathering steel strip with a temperature of ≤45°C is sent to the six-roll reversible cold rolling unit, uncoiled → threaded → pinch roller pinching → six-roll reversible cold rolling unit cold rolling flat → pinch roller pinching → coiling by the coiler, and cold rolled according to the set process parameters; the rolling force is 4000KN, the elongation is 2.2%, the starting speed is 15-30m / min, and after the plate shape is adjusted to be stable, it is gradually increased to 120m / min, the front tension setting value is 160KN, and the rear tension setting value is 60KN, so as to obtain a hot-rolled high-strength weathering steel strip with a thickness of 1.5mm and good plate shape.

[0013] Yield strength of steel plate: 710MPa before cold rolling, 715MPa after cold rolling; tensile strength: 765MPa before cold rolling, 770MPa after cold rolling; elongation: 23% before cold rolling, 23% after cold rolling; 180° bending test d=2a: intact before and after cold rolling; organization: ferrite plus a small amount of bainite, grain size 12.5, obvious elongated deformed grains after cold rolling; plate shape: the plate surface is flat and smooth, with a straightness of 3mm / 1000mm.

[0014] The above examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention. Unless otherwise specified, the embodiments are all based on conventional experimental conditions. In addition, for those skilled in the art, without departing from the essence and scope of the present invention, any modifications, equivalent changes, improvements made, all belong to the scope of protection claimed in the present invention.

Claims

1. A method for eliminating the shape defects of hot-rolled thin-gauge high-strength weathering steel strip, comprising cold rolling and leveling a hot-rolled high-strength weathering steel strip with a thickness of 1.5 mm to 2.0 mm and a yield strength of ≥ 620 MPa using a six-roller reversible cold rolling unit, characterized in that: include: S1. The hot-rolled high-strength weathering steel strip is uncoiled, straightened by nine rollers, pickled, rinsed, rolled by three rollers, and coiled to obtain a pickled steel strip; S2. At the end of the cold rolling process, the pickled steel strip with a temperature of ≤45°C is sent to the six-roller reversible cold rolling unit, unrolled by the uncoiler, threaded, clamped by the first pinch roller, cold-rolled and leveled by the six-roller reversible cold rolling unit, clamped by the second pinch roller, and coiled by the coiler, and then cold-rolled and leveled according to the set process parameters.

2. A method for eliminating shape defects of hot-rolled thin-gauge high-strength weathering steel according to claim 1, characterized in that: The process parameters of cold rolling and leveling set in S2 are: the working rolls of the six-roller reversible cold rolling unit are hot rolls that have reached the end of the cold rolling process; the rolling force is 4000 to 8000KN; the elongation is 2.2-5.0%; the leveling speed is the starting speed of 15-30m / min, and after the plate shape is adjusted to be stable, it is gradually increased to 120m / min; the tension control is that the front tension setting value is 160KN, and the rear tension setting value is 60KN.

Images