Method for manufacturing hot-rolled stainless steel coil through direct rolling, annealing and pickling

Abstract

The invention provides a manufacturing method for a hot-rolled stainless steel coil through direct rolling, annealing and acid pickling. The manufacturing method comprises a hot rolling procedure and a cold rolling procedure. The hot rolling procedure comprises the following steps of continuous casting steel billet heating, rough rolling through a vertical roll scale breaker, rough rolling through a descaling machine, rough rolling through a four-rack two-roll rough rolling machine and a vertical rolling machine, rolling through an E3 vertical rolling machine, finish rolling through a nine-rack four-roll finish rolling machine and black skin coil coiling. The cold rolling process comprises the following steps of hot rolling black skin coil uncoiling, laser welding, cold rolling through a three-rack eighteen-roller mill, degreasing, annealing, pulling, straightening and scale breaking, shot blasting, acid pickling, drying and white skin coil coiling. Compared with a traditional production and manufacturing process, one annealing and acid pickling process is omitted, and the white-skin roll with the good plate shape and surface quality is obtained.

Description

Technical Field

[0001] This invention relates to the field of stainless steel rolling, and more specifically to a manufacturing method for hot-rolled stainless steel coils that undergoes direct rolling, annealing, and pickling. Background Technology

[0002] The traditional process for obtaining white stainless steel coils after hot rolling and cooling involves solution annealing and pickling, followed by cold rolling to the target thickness. This process is lengthy, energy-intensive, and has high production costs.

[0003] In summary, the existing technology has the following problems: the existing process of producing white stainless steel rolls from black rolls after hot rolling and cooling is long, consumes a lot of energy, and has high production costs. Summary of the Invention

[0004] This invention provides a manufacturing method for hot-rolled stainless steel coils through direct rolling, annealing, and pickling, which solves the problem that producing white-skinned coils from hot-rolled and cooled black-skinned coils requires traditional annealing and pickling processes, resulting in long process flow, high energy consumption, and high production costs.

[0005] Therefore, this invention proposes a manufacturing method for hot-rolled stainless steel coils by direct rolling, annealing, and pickling, comprising a hot rolling process and a cold rolling process. The composition of the hot-rolled stainless steel coils by weight percentage is: C: 0.10-0.17%, Si: 0.3-0.6%, Mn: 10.4-10.7%, P: ≤0.055%, S: ≤0.005%, Ni: 0.9-2%, Cr: 12.5-13.3%, N: 0.18-0.20%, with the remainder being Fe and unavoidable residual elements.

[0006] The hot rolling process includes the following steps: heating of continuously cast steel billets, vertical roll descaling mill, descaling mill, roughing on a four-stand two-high roughing mill and vertical roll mill, rolling on an E3 vertical roll mill, finishing on a nine-stand four-high finishing mill, and coiling of black steel coils.

[0007] The cold rolling process includes the following steps: uncoiling of hot-rolled black sheet coils, laser welding, cold rolling on a three-stand eighteen-roll mill, degreasing, annealing, tension straightening to remove scale, shot blasting, pickling, drying, and coiling of white sheet coils;

[0008] In the uncoiling step of hot-rolled black steel coils: the selected steel coils have a crown value of 10-40μm and a camber of ≤5mm / m;

[0009] In the laser welding process: the front and rear strips are welded using a laser welding machine protected by argon-nitrogen inert gas. The welding gap is 0-0.1mm, the power is 1.5-3.9Kw, the welding speed is 1-4min / m, and the defocusing amount is -11 to 16mm. The weld should be full, smooth, and free of defects. After rolling, the height of the weld should be slightly lower than the thickness of the base strip.

[0010] In the cold rolling process of the three-stand 18-roll mill: hot-rolled black coils are directly rolled by the three-stand 18-roll cold rolling mill F1-F3. The reduction rate of the F1 cold rolling mill is 14% to 20%, the reduction rate of the F2 cold rolling mill is 9% to 15%, and the reduction rate of the F3 cold rolling mill is 8% to 12%. The tension between the stands is controlled at 180-240KN, and the tension at the mill exit is controlled at 170-220KN.

[0011] This invention directly cold-rolls and rolls hot-rolled stainless steel black coils. Traditional manufacturing processes require annealing and pickling to obtain stainless steel white coils, which are then cold-rolled. This invention's direct rolling process eliminates the annealing and pickling steps, utilizing the ductility and toughness of the hot-rolled black coil after cooling. The black coil performance requirements are: yield strength 581-709 MPa, tensile strength 987-1085 MPa, elongation A50 > 40%, and hardness 105-110 HRB. The material has high yield and tensile strength, high hardness, and low elongation. Direct rolling of black coils results in a high work hardening rate, and cold rolling easily leads to edge breakage, brittle fracture, and other risks, causing significant economic losses and safety risks. Direct rolling reduces annealing and pickling steps, lowering production costs. Meanwhile, the finished products produced have low surface roughness and good plate shape. In some application scenarios, they do not need to undergo cold rolling again and can be used directly, which has great economic value.

[0012] Compared to traditional manufacturing processes, this invention eliminates one annealing and pickling step. Utilizing the inherent plastic deformation capacity of cooled stainless steel hot-rolled coils, it directly rolls them using a high-strength, high-rigidity, and high-precision 18-roll cold rolling mill. The thinnest specification can be produced at 1.0mm thickness, yielding white-coated coils with excellent sheet shape and surface quality, fully meeting the downstream cold-rolling performance and surface quality requirements. Some thicker specifications can be directly processed into industrial pipes, replacing the original cold-rolled sheets and broadening the applications of white-coated coils. Simultaneously, it saves energy and reduces production costs. Thick-specification cold-rolled finished products eliminate the need for annealing and pickling processes by directly cold-rolling hot-rolled black-coated coils to the target thickness, replacing the original method of annealing and pickling white-coated coils before cold-rolling to the target thickness. This reduces the cost per ton of steel for thick-specification finished white-coated coils by approximately 160 yuan / ton.

[0013] The present invention also provides a hot-rolled stainless steel direct-rolled annealed pickled white sheet coil (2E white sheet coil), which is manufactured by a hot-rolled stainless steel coil direct-rolled annealed pickled manufacturing method. The hot-rolled stainless steel direct-rolled annealed pickled white sheet coil (2E) has a yield strength of 400-650 MPa, a tensile strength of 750-935 MPa, an elongation of >40%, a hardness of 85-100 HRB, and a grain size of 7.5-10.0.

[0014] This invention utilizes the fact that hot-rolled black steel coils still retain about 50% of their plastic deformation capacity after cooling. By directly rolling them using a high-rigidity, high-rolling-force cold rolling mill to a certain target thickness, followed by annealing, shot blasting, and pickling, 2E white steel coils with good surface quality and plate shape can be obtained. This surface condition can replace some cold-rolled products, further reducing the cost of stainless steel rolling processing. Detailed Implementation

[0015] To provide a clearer understanding of the technical features, objectives, and effects of this invention, the invention is now described.

[0016] The purpose of this invention is to provide a manufacturing method for hot-rolled stainless steel coils that undergoes direct rolling, annealing, and pickling. Compared with traditional processes, this method reduces the steps of solution annealing and pickling, allows for direct rolling to achieve a minimum thickness of 1.0 mm, and lowers energy consumption and production costs per ton of steel. It has significant market potential.

[0017] This invention proposes a manufacturing method for hot-rolled stainless steel coils through direct rolling, annealing, and pickling, comprising: a hot rolling process and a cold rolling process.

[0018] The hot rolling process includes the following steps: heating of continuously cast steel billets, vertical roll descaling mill, descaling mill, roughing on a four-stand two-high roughing mill and vertical roll mill, rolling on an E3 vertical roll mill, finishing on a nine-stand four-high finishing mill, and coiling of black steel coils.

[0019] The cold rolling process includes the following steps: uncoiling of hot-rolled black sheets, laser welding, cold rolling on a three-stand eighteen-roll mill, degreasing, annealing, tension straightening to remove scale, shot blasting, pickling, drying, and winding of white sheets.

[0020] I. Hot Rolling Process

[0021] 1) Stainless steel hot rolling manufacturing process steps: continuous casting billet heating — vertical roll descaling machine — descaling machine — 4-stand two-roll roughing mill and vertical roll mill (R1 flat roll - E1 vertical roll - R2 flat roll - R3 flat roll - E2 vertical roll - R4 flat roll) — E3 vertical roll mill — 9-stand four-roll finishing mill (F1-F9) — coiling (black coil);

[0022] 2) The initial rolling temperature of the billet roughing is ≥1200℃, the target temperature of finishing rolling is controlled at 1100±20℃, the target temperature of final rolling is 1030±20℃, laminar flow cooling is adopted for coiling, and the head and tail are not cooled in order to ensure the plate shape. The target temperature for coiling is 800±50℃.

[0023] 3) The roughing mill work rolls adopt a negative crown roll type, the finishing mill support rolls adopt a flat roll type, and the finishing mill work rolls adopt a negative crown roll type. The negative crown value of the rolls is designed in a gradient from front to back, with the negative crown value decreasing from large to small. That is, the negative crown value of the roughing mill work rolls R1-R4 decreases from -0.6mm to -0.5mm, and the negative crown value of the finishing mill work rolls F1-F9 decreases from -0.4mm to -0.08mm in a gradient. Make good roll type matching for all stands to ensure that the final crown value of hot-rolled stainless steel coils is controlled at 0-50μm.

[0024] 4) Hot-rolled stainless steel black coils with thicknesses of 1.6-2.4mm and widths of 600-810mm;

[0025] 5) Hot-rolled stainless steel black coils have a yield strength of 581-709 MPa, a tensile strength of 987-1085 MPa, an elongation of 40-45%, a hardness of 105-110 HRB, and a grain size of 11.5-13.0.

[0026] 6) Hot-rolled stainless steel coils are not allowed to have quality defects such as broken edges, scratches, or peeling that affect cold rolling. The overflow edge of the steel coil is <3mm and the camber is <5mm / m.

[0027] II. Cold Rolling Process

[0028] 1) Cold rolling manufacturing steps: hot-rolled black coil uncoiling—laser welding—3-stand 18-roll mill (F1-F3)—degreasing—annealing—tension straightening and descaling—shot blasting—pickling—drying—coiling (2E white coil)

[0029] 2) Strictly control the quality of hot-rolled stainless steel black strip raw materials, select steel coils within the stable cycle of hot rolling production process, with a crown value of 10-40μm, camber ≤5mm / m, and no broken edges or dents on the edges, and no peeling, scratches, pits, etc. on the surface, to ensure that no strip breakage or other accidents occur during the rolling process.

[0030] 3) The front and rear strips are welded using a laser welding machine with argon-nitrogen inert gas protection. The welding gap is 0-0.1mm, the power is 1.5-3.9Kw, the welding speed is 1-4min / m, and the defocusing amount is -11 to 16mm. The weld should be full, smooth, and free of defects. After rolling, the height of the weld should be slightly lower than the thickness of the base strip.

[0031] 4) Hot-rolled black coils are directly rolled by 3-stand 18-roll cold rolling mills F1-F3. The reduction rate of F1 is 14% to 20%, F2 is 9% to 15%, and F3 is 8% to 12%. The tension between stands is controlled at 180-240KN, and the tension at the mill exit is controlled at 170-220KN. The reduction rate of the 3 stands is reasonably selected and allocated according to the thickness of the raw material, the target thickness of the rolling, and the quality of the rolled plate.

[0032] 5) Hot-rolled black coils are rolled using an emulsion cooling and lubrication process. The emulsion temperature is controlled at 50±5℃. The emulsion system consists of a main system and a vacuum filtration system. The emulsion flow rate is 9000L / min, and the main oil tank has a capacity of 110m³. 3 Magnetic filter box 30m 3 The vacuum filtration system has a filtration capacity of 10,000 L / min and a filtration accuracy of 80 μm. The emulsion recovered from the rolling mill is transported by gravity through the return oil pipeline to the magnetic filtration system with an oil tank. It then flows through the magnetic filter tank, overflows into the vacuum filter, and is finally pumped to the main oil tank via a booster pump. The emulsion is heated using saturated steam at 160–170℃, with automatic control based on the temperature of the liquid in the circulating tank. The emulsion concentration is 3–6%, pH value is 6.5–7.5, iron powder content is ≤500 ppm, ash content is ≤1000 ppm, conductivity is ≤350 μS / cm, saponification value is ≥145 mg KOH / g, impurity oil content is ≤10%, and acid value is ≤25 mg KOH / g.

[0033] 6) After the stainless steel hot-rolled coil is rolled, it is subjected to surface degreasing treatment to improve the surface quality of the strip. The concentration of degreasing agent is ≤2.5%, the degreasing temperature is 60-80℃, and the strip is washed with desalinated water at a temperature of 80-100℃. After washing, it is dried at a temperature of 90-100℃.

[0034] 7) Annealing is performed using a horizontal suspended furnace with a process speed ≤120m / min, furnace section tension 4-8N / mm², TV value ≤180m / min (strip thickness mm * annealing rate m / min), annealing furnace gas temperature ≤1250℃, and strip temperature detection is provided. For the direct rolling process, strip temperature control is intelligently implemented according to the process requirements of each zone, with temperature controlled between 1000-1080℃ and an accuracy of ±15℃. The process speed is 30-120m / min, and the air-fuel ratio is controlled at 9-12 based on the natural gas calorific value, with residual oxygen content after combustion controlled at 1-5%.

[0035] 8) After annealing, the strip is tensioned and leveled to break up the scale, which promotes the loosening and cracking of the iron oxide scale on the surface. The elongation is controlled at 1-3%. Then, it is sprayed with pressure controlled at ≤0.65Mpa.

[0036] 9) The strip steel, after being stretched, straightened, and descaled, passes through the unit's guide rollers, changing its position from horizontal to vertical. It then undergoes shot blasting and descaling treatment by four vertical shot blasting machines. After shot blasting and descaling, it passes through another set of guide rollers to change its position from vertical to horizontal. The vertical shot blasting machines effectively reduce residual or indented iron oxide scale on the strip surface. Depending on the surface roughness requirements, the steel shot diameter is Φ0.3~Φ0.4mm, the hardness is 50.5-55.2HRC, the shot blasting motor speed is 1500-2100RPM, and the current is 50-110A.

[0037] 10) The pickling process is divided into mixed acid pickling (section I and section II), nitric acid passivation (section I and section II), and drying process sections. In mixed acid pickling section I, the nitric acid content is 10-50 g / L, the hydrofluoric acid content is 1-8 g / L, the metal ion concentration is <55 g / L, and the temperature of the mixed acid solution is 55±3℃; in mixed acid pickling section II, the nitric acid content is 20-80 g / L, the hydrofluoric acid content is 2-15 g / L, the metal ion concentration is <55 g / L, and the temperature of the mixed acid solution is 55±3℃; in nitric acid passivation section I, the nitric acid content is 40-80 g / L, the hydrofluoric acid content is 1-5 g / L, the metal ion concentration is <55 g / L, and the temperature of the mixed acid solution is 48±2℃; in nitric acid passivation section II, the nitric acid content is 60-90 g / L, the hydrofluoric acid content is 0-3 g / L, the metal ion concentration is <50 g / L, and the temperature of the mixed acid solution is <50℃.

[0038] 11) After pickling, the strip steel is rinsed and dried to improve its corrosion resistance. The rinsing is done with demineralized water at a temperature of 80°C. Then, it is dried with hot air at a temperature of 90°C-150°C.

[0039] 12) The winding machine adopts belt-assisted winding, with a winding speed ≤200m / min and winding tension ≤60KN;

[0040] 13) Hot-rolled stainless steel direct-rolled annealed pickled white skin coil (2E) yield strength 400-650Mpa, tensile strength 750-935Mpa, elongation >40%, hardness value 85-100HRB, grain size 7.5-10.0.

[0041] Compared to traditional manufacturing processes, this invention eliminates one annealing and pickling step. Rapid cooling after hot-rolled stainless steel black coils reduces carbide precipitation, improving the plasticity and toughness of the coils. By rationally designing the percentages of stabilizing austenite elements such as C, Si, and Mn, the stability of austenite during cold rolling is enhanced, reducing the volume fraction of deformation-induced martensite transformation and mitigating work hardening. Ultimate rolling is achieved through high-strength, high-rigidity, and high-precision three-stand eighteen-roll cold continuous rolling, with the total deformation rate controlled to less than 50%. Through these hot-rolling controls, black coils with suitable plasticity and toughness are obtained, exhibiting the following properties: yield strength 581-709 MPa, tensile strength 987-1085 MPa, elongation A50 > 40%, and hardness 105-110 HRB. This avoids the strip breakage phenomenon (rapid work hardening during cold rolling) that can occur when directly cold-rolling hot-rolled black coils due to their high yield strength, high tensile strength, and low elongation. This invention utilizes the inherent plastic deformation capacity of hot-rolled stainless steel coils after cooling, directly rolling them using a high-strength, high-rigidity, and high-precision 18-roll cold rolling mill. It can produce coils with a minimum thickness of 1.0 mm, yielding white-skinned coils with excellent shape and surface quality, fully meeting the downstream cold-rolling performance and surface quality requirements. Some thicker specifications can be directly processed into industrial pipes, replacing traditional cold-rolled sheets and broadening the applications of white-skinned coils. Simultaneously, it saves energy and reduces production costs, possessing significant economic and market promotion value.

[0042] Example 1

[0043] Hot-rolled stainless steel black coils with dimensions of 1.6mm*600mm*C (thickness*width*length) or 1.6mm*600mm (thickness*width) were directly rolled, annealed, and pickled. They were then rolled to a thickness of 1.1mm using a three-stand eighteen-roll mill, with a total reduction of 31.25%. The finished pickled white coil had a yield strength of 404 MPa, a tensile strength of 835 MPa, an elongation after fracture (A50) of 52.9%, a Rockwell hardness of 89.8 HRB, a microstructure of austenitic A with a grain size of 7.83, and a surface roughness of 1.89. The product performance and surface quality met the technical requirements. The composition of the hot-rolled stainless steel coil in this example, by weight percentage, is: C: 0.14%, Si: 0.45%, Mn: 10.45%, P: 0.045%, S: 0.004%, Ni: 1.01%, Cr: 13.1%, N: 0.195%.

[0044] Example 2

[0045] Hot-rolled stainless steel black coils with dimensions of 2.2mm*690mm*C (thickness*width*length) or 1.6mm*600mm (thickness*width) were directly rolled, annealed, and pickled. They were then rolled to a thickness of 1.2mm using a three-stand eighteen-roll mill, with a total reduction of 45.45%. The finished pickled white coils had a yield strength of 415 MPa, a tensile strength of 823 MPa, an elongation after fracture (A50) of 55.8%, a Rockwell hardness of 97.6 HRB, a microstructure of austenitic A with a grain size of 8.45, and a surface roughness of 1.7. The product performance and surface quality met the technical requirements. The composition of the hot-rolled stainless steel coil in this example, by weight percentage, is: C: 0.17%, Si: 0.4%, Mn: 10.5%, P: 0.040%, S: 0.0035%, Ni: 1.02%, Cr: 12.6%, N: 0.185%.

[0046] The above description is merely an illustrative embodiment of the present invention and is not intended to limit the scope of the invention. The various components of the present invention can be combined with each other without conflict. Any equivalent changes and modifications made by those skilled in the art without departing from the concept and principles of the present invention should fall within the scope of protection of the present invention.

Claims

1. A manufacturing method for hot-rolled stainless steel coils after direct rolling, annealing, and pickling, characterized in that, The manufacturing method of a hot-rolled stainless steel coil with direct rolling, annealing, and pickling includes: a hot rolling process and a cold rolling process. The hot rolling process includes the following steps: heating of continuously cast steel billets, vertical roll descaling mill, descaling mill, roughing on a four-stand two-high roughing mill and vertical roll mill, rolling on an E3 vertical roll mill, finishing on a nine-stand four-high finishing mill, and coiling of black steel coils. The cold rolling process includes the following steps: uncoiling of hot-rolled black sheet coils, laser welding, cold rolling on a three-stand eighteen-roll mill, degreasing, annealing, tension straightening to remove scale, shot blasting, pickling, drying, and coiling of white sheet coils; In the uncoiling step of hot-rolled black steel coils: the selected steel coils have a crown value of 10-40μm and a camber of ≤5mm / m; In the laser welding process: the front and rear strips are welded using a laser welding machine protected by argon-nitrogen inert gas. The welding gap is 0-0.1mm, the power is 1.5-3.9Kw, the welding speed is 1-4min / m, and the defocusing amount is -11 to 16mm. The weld should be full, smooth, and free of defects. After rolling, the height of the weld should be slightly lower than the thickness of the base strip. In the cold rolling process of the three-stand 18-roll mill: hot-rolled black coils are directly rolled by the three-stand 18-roll cold rolling mill F1-F3. The reduction rate of the F1 cold rolling mill is 14% to 20%, the reduction rate of the F2 cold rolling mill is 9% to 15%, and the reduction rate of the F3 cold rolling mill is 8% to 12%. The tension between the stands is controlled at 180-240KN, and the tension at the mill exit is controlled at 170-220KN.

2. The manufacturing method of hot-rolled stainless steel coil by direct rolling, annealing, and pickling as described in claim 1, characterized in that, The initial rolling temperature of the billet roughing is ≥1200℃, the target temperature for finishing rolling is controlled at 1100±20℃, and the target temperature for final rolling is 1030±20℃. Laminar flow cooling is adopted for coiling. To ensure the plate shape and prevent the head and tail from cooling, the target coiling temperature is 800±50℃.

3. The manufacturing method of hot-rolled stainless steel coil by direct rolling, annealing, and pickling as described in claim 1, characterized in that, The roughing mill work rolls adopt a negative crown roll type, the finishing mill support rolls adopt a flat roll type, and the finishing mill work rolls adopt a negative crown roll type. The negative crown value of the rolls is designed in a gradient from front to back, with the negative crown value decreasing from large to small. That is, the negative crown value of the roughing mill work rolls R1-R4 decreases from -0.6mm to -0.5mm, and the negative crown value of the finishing mill work rolls F1-F9 decreases from -0.4mm to -0.08mm in a gradient. The roll type ratio of all stands is well matched to ensure that the final crown value of the hot-rolled stainless steel coil is controlled at 0-50μm.

4. The manufacturing method of hot-rolled stainless steel coil by direct rolling, annealing, and pickling as described in claim 1, characterized in that, Hot-rolled black coils are produced using an emulsion cooling and lubrication process. The emulsion temperature is controlled at 50±5℃. The emulsion system consists of a main system and a vacuum filtration system. The emulsion flow rate is 9000 L / min, and the main oil tank has a capacity of 110 m³. 3 Magnetic filter box 30m 3 The vacuum filtration system has a filtration capacity of 10,000 L / min and a filtration accuracy of 80 μm.

5. The manufacturing method of hot-rolled stainless steel coil by direct rolling, annealing, and pickling as described in claim 1, characterized in that, The emulsion is heated using saturated steam at 160–170℃, with automatic temperature control based on the liquid temperature within the circulating tank. The emulsion concentration is 3–6%, pH value is 6.5–7.5, iron powder content is ≤500ppm, ash content is ≤1000ppm, conductivity is ≤350μS / cm, saponification value is ≥145mgKOH / g, impurity oil content is ≤10%, and acid value is ≤25mgKOH / g.

6. The manufacturing method of hot-rolled stainless steel coil by direct rolling, annealing, and pickling as described in claim 1, characterized in that, In the degreasing process: After the stainless steel hot-rolled coil is rolled, it undergoes surface degreasing treatment to improve the surface quality of the strip. The concentration of the degreasing agent is ≤2.5%, and the degreasing temperature is 60-80℃. After degreasing, the strip is washed with desalinated water at a temperature of 80-100℃. After washing, it is dried at a temperature of 90-100℃.

7. The manufacturing method of hot-rolled stainless steel coil by direct rolling, annealing, and pickling as described in claim 1, characterized in that, Annealing is performed in a horizontal suspended furnace with a process speed of ≤120m / min, furnace section tension of 4-8N / mm2, TV value of ≤180, and annealing furnace gas temperature of ≤1250℃.

8. The manufacturing method of hot-rolled stainless steel coil by direct rolling, annealing, and pickling as described in claim 1, characterized in that, After the strip is heated, it is stretched and leveled to break up the scale, which causes the iron oxide scale on the surface to loosen and crack. The elongation is controlled at 1-3%. Then it is sprayed with pressure controlled at ≤0.65Mpa.

9. The manufacturing method of hot-rolled stainless steel coil by direct rolling, annealing, and pickling as described in claim 1, characterized in that, The strip steel after stretching, straightening, and descaling passes through the unit's guide rollers, which change the strip steel from a horizontal position to a vertical position. Then, it passes through four vertical shot blasting machines for shot blasting and descaling treatment. The use of vertical shot blasting machines can effectively reduce the residual or indented iron oxide scale on the surface of the strip steel. After shot blasting and descaling, the strip steel passes through another set of guide rollers to change the strip steel from a vertical position to a horizontal position.

10. The manufacturing method of hot-rolled stainless steel coil by direct rolling, annealing, and pickling as described in claim 1, characterized in that, The winding machine uses belt-assisted winding, with a winding speed ≤200m / min and winding tension ≤60KN.