Method for producing checkered plate from phosphorus-containing steel, and checkered plate from phosphorus-containing steel

Abstract

The present invention provides a method for producing checkered plate from phosphorus-containing steel and a phosphorus-containing steel checkered plate. The phosphorus-containing steel comprises the following composition by mass: C: ≤0.005%, Si: ≤0.15%, Mn: 0.3%-0.6%, P: ≤0.060%, S: ≤0.015%, with the remainder being Fe and impurities. Compared to the prior art, the present invention addresses the difficult-to-handle phosphorus-containing steel slabs by modifying the heating, rolling, and cooling processes during production to produce hot-rolled checkered plate products, thereby improving the economic benefits of the enterprise and addressing the problem of outer diameter overruns that can occur with checkered plate rolled from downgraded slabs. The resulting hot-rolled checkered plate product reduces costs.

Description

Technical Field

[0001] The present invention relates to the technical field of metallurgy and steel plate manufacturing, in particular to a method for producing a checkered plate from phosphorus-containing steel and a checkered plate made of phosphorus-containing steel. Background Art

[0002] Hot-rolled patterned steel plates, also known as checkered plates, offer numerous advantages, including aesthetic appeal, excellent anti-slip properties, and ease of cleaning. They are widely used in machinery, shipbuilding, transportation, construction, and other fields. Generally speaking, checkered plates enjoy high market demand, and customers have low requirements for mechanical and mechanical properties, making them a cost-effective product for steel companies.

[0003] During the steelmaking and continuous casting process, phosphorus-containing steel can be subject to production anomalies, resulting in surface quality failures that fail to meet product grading standards, resulting in downgraded slabs. If these downgraded slabs are used to produce the original cold-rolled grades, there is a risk of cracking during stamping. Consequently, these downgraded slabs are often not used for original orders, resulting in an inventory backlog. Due to the unique composition of these slabs, steelmakers often process them by rolling them into hot-rolled coils for spot trading, which results in significant cost losses.

[0004] Chinese patent publication number CN 110893414 A, published on March 20, 2020, discloses a method for rolling checkered plate from abnormal billets. The abnormal billets produced during steelmaking are cut to standard checkered plate billet dimensions, then heated and rough rolled. The finishing rolling process uses a checkered roller on the upper roll of the final stand. Rolling is performed using different final stand fixed reduction ratio modes depending on the thickness specification of the finished checkered plate coil. High-pressure air blowing is used at the end of laminar cooling. The coiling thickness coefficient is set based on the pattern height calculated from the final stand reduction ratio, ultimately resulting in a finished checkered plate coil. This method effectively utilizes abnormal billets from steelmaking to produce finished checkered plate, minimizing scrap losses. However, the process is not suitable for the production of phosphorus-containing steels with high phosphorus content. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for producing checkered plates from phosphorus-containing steel and phosphorus-containing steel checkered plates. For phosphorus-containing steel slabs that are difficult to handle, by changing their production process, they are manufactured into hot-rolled checkered plate products, thereby improving the economic benefits of the enterprise. At the same time, it also solves the problem of outer diameter exceeding the limit that exists in checkered plates rolled from downgraded slabs.

[0006] A method for producing a checkered plate from phosphorus-containing steel comprises the following steps:

[0007] 1) heating;

[0008] 2) rolling;

[0009] 3) cooling;

[0010] 4) Coiling.

[0011] In step 1), the casting is heated in a heating furnace at a temperature of 1210-1250° C. The casting is a downgraded casting formed because the surface quality of the phosphorus-containing steel does not meet the requirements of the product grading standard.

[0012] Furthermore, the heating time in the furnace is: hot billet ≥ 180 minutes, cold billet ≥ 210 minutes.

[0013] The heating adopts a four-stage heating method with temperatures of: preheating section 800-1000°C, first heating section 1000-1150°C, second heating section 1150-1300°C, and soaking section temperature 1200-1250°C.

[0014] In step 2), the rolling process includes controlling the start temperature of the finishing rolling to be 900-1070°C and the final rolling temperature to be 890-930°C.

[0015] The rolling is performed after heating by a high-pressure water descaling process to break the iron oxide scale on the surface of the slab, and then rolling;

[0016] The rolling includes rough rolling, wherein the thickness is reduced to 35-60 mm by back and forth rolling;

[0017] The rolling process includes finishing rolling, controlling the starting temperature of finishing rolling in the range of 900-1070°C, thinning to the target thickness through 7 stands of finishing rolling, and controlling the final rolling outlet temperature in the range of 890-930°C by cooling water between stands;

[0018] The finishing rolling adopts a high-load 100% reduction ratio rolling method and an F7 load of 17%-23% to ensure that the steel coil is in full contact with the roller groove so that the groove height meets the use requirements; 3.0mm≤finished product thickness<6.0mm, groove height≥0.6mm; 6.0mm≤finished product thickness≤10.0mm, groove height≥0.9mm.

[0019] During rolling, the slab length is 7000-10500mm, the width is 1250-1700mm, the thickness is 200-250mm, the hot rolling side pressure is 0-200mm, and the slab is produced according to the following thickness, side pressure, and slab length rules to solve the problem of the outer diameter exceeding the limit of the rolled patterned plate.

[0020] Specifically:

[0021] For side pressure 150mm<W≤200mm, finished product thickness 3.0-10.0mm, billet length ≤9.5m;

[0022] For side pressure 100mm<W≤150mm, finished product thickness 3.0-6.0mm, billet length ≤9.5m; finished product thickness 6.0-10.0mm, billet length ≤10.0m;

[0023] For side pressure 10mm<W≤100mm, finished product thickness 3.0-5.0mm, billet length ≤9.5m; finished product thickness 5.0-10.0mm, billet length ≤10.0m;

[0024] For side pressure W<10mm, finished product thickness is 3.0-5.0mm, and billet length is ≤9.5m; for finished product thickness is 5.0-10.0mm, and billet length is ≤10.5m.

[0025] In step 3), the cooling adopts a front-end centralized cooling method; laminar cooling water is used for centralized cooling at the front end to ensure that the hot coil winding inlet temperature is controlled at 620-680°C.

[0026] In step 4), the coiling temperature is controlled at 620-680°C.

[0027] A phosphorus-containing steel checkered plate is produced by the above method. The phosphorus-containing steel comprises the following components in mass percentage: C: ≤0.005%, Si: ≤0.15%, Mn: 0.3%-0.6%, P: ≤0.060%, S: ≤0.015%, and the balance is Fe and impurities.

[0028] Compared to existing technologies, this invention controls the heating, rolling, cooling, and coiling processes for steel slabs with high phosphorus content (P ≤ 0.060%) to produce hot-rolled checkered plate products, reducing costs and improving economic benefits. The invention also produces slabs with standardized thickness, side pressure, and length, resolving the problem of exceeding outer diameter limits in rolled checkered plate. DETAILED DESCRIPTION

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0030] Example 1

[0031] A method for producing patterned plates from phosphorus-containing steel comprises hot rolling with a thickness of 2250 mm. The chemical composition and mass percentage of the phosphorus-containing steel slab are as follows: C: 0.0045%, Si: 0.14%, Mn: 0.4%, P: 0.060%, S: 0.013%, and the balance being Fe and impurities.

[0032] The production method specifically comprises the following steps

[0033] 1) The downgraded slabs, whose surface quality does not meet the product grading standards, are heated in a heating furnace at 1220°C. The cold slab heating step lasts for 210 minutes. The four-stage heating method uses a preheating stage of 800-1000°C, a first heating stage of 1000-1150°C, a second heating stage of 1150-1300°C, and a soaking stage of 1220°C.

[0034] 2) After heating, the slab undergoes a high-pressure water descaling process to remove surface oxide scale. The slab undergoes rough rolling, reducing it to 60mm via a round trip process. The start temperature of the finishing roll is controlled at 930°C. The slab undergoes finishing rolling on seven stands, reducing it to the target thickness. Inter-stand cooling is used to control the final rolling exit temperature at 910°C. The finishing rolling process utilizes a high-load, 100% reduction rolling method, with an F7 load of 18.2%, ensuring full contact between the coil and the roll notch, resulting in a groove height of 0.62mm, meeting operational requirements.

[0035] The slab length is 9000mm, the slab width is 1259mm, the thickness is 230mm, the hot rolling side pressure is 5mm, and the order thickness is 3.0mm.

[0036] 3) The slab is cooled centrally at the front end by laminar cooling water to ensure that the inlet temperature of the hot coil is controlled at 640℃.

[0037] Through the above production process, qualified hot-rolled checkered plate products can be produced.

[0038] Example 2

[0039] A method for producing patterned plates from phosphorus-containing steel, comprising hot rolling with a thickness of 2250 mm. The chemical composition and mass percentage of the phosphorus-containing steel slab are as follows: C: 0.0040%, Si: 0.12%, Mn: 0.55%, P: 0.055%, S: 0.010%, and the balance being Fe and impurities.

[0040] The specific steps include:

[0041] 1) The downgraded slabs, whose surface quality does not meet the product grading standards, are heated in a heating furnace at 1230°C. The cold slabs are heated in the furnace for 210 minutes. The four-stage heating method has a preheating stage of 800-1000°C, a first heating stage of 1000-1150°C, a second heating stage of 1150-1300°C, and a soaking stage of 1230°C.

[0042] 2) After heating, the slab undergoes a high-pressure water descaling process to remove surface oxide scale. The slab is then roughed and rolled back and forth to a thickness of 50mm, with the start temperature of the finishing roll controlled at 980°C. The slab is then finished by seven stands, thinning it to the target thickness. Cooling water between the stands controls the final exit temperature at 920°C. The finishing process utilizes a high-load, 100% reduction rolling method, with an F7 load of 19.6%, ensuring full contact between the coil and the roll notch, resulting in a groove height of 0.67mm, meeting operational requirements.

[0043] The slab length is 9400mm, width is 1400mm, thickness is 230mm, hot rolling side pressure W=110mm, and order thickness is 4.0mm.

[0044] 3) The slab is cooled centrally at the front end by laminar cooling water to ensure that the inlet temperature of the hot coil is controlled at 650℃.

[0045] Through the above production process, qualified hot-rolled checkered plate products can be produced.

[0046] Example 3

[0047] A method for producing patterned plates from phosphorus-containing steel, comprising hot rolling with a thickness of 2250 mm. The chemical composition and mass percentage of the phosphorus-containing steel slab are as follows: C: 0.0045%, Si: 0.10%, Mn: 0.45%, P: 0.055%, S: 0.011%, and the balance being Fe and impurities.

[0048] The specific production method comprises the following steps:

[0049] 1) The downgraded slab, whose surface quality does not meet the product grading standards, is heated in a heating furnace at 1240°C. The cold slab heating step lasts for 210 minutes. A four-stage heating method is used: a preheating stage of 800-1000°C, a first heating stage of 1000-1150°C, a second heating stage of 1150-1300°C, and a soaking stage of 1240°C.

[0050] 2) After heating, the slab undergoes a high-pressure water descaling process to remove surface oxide scale. The slab undergoes rough rolling, reducing it to 50mm via a round trip process. The start temperature of the finishing roll is controlled at 970°C. The slab undergoes finishing rolling on seven stands, reducing it to the target thickness. Inter-stand cooling water is used to control the final rolling exit temperature at 910°C. The finishing rolling process utilizes a high-load, 100% reduction ratio rolling method. The F7 load is 20.2% to ensure full contact between the coil and the roll notch, resulting in a groove height of 0.63mm, meeting operational requirements.

[0051] The slab length is 9500mm, width is 1509mm, thickness is 230mm, hot rolling side pressure is 8mm, and the order thickness is 4.5mm.

[0052] 3) The slabs are centrally cooled at the front end by laminar cooling water to ensure that the inlet temperature of the hot coil is controlled at 640°C.

[0053] Through the above production process, qualified hot-rolled checkered plate products can be produced.

[0054] Example 4 (as a comparison)

[0055] A method for producing patterned plates from phosphorus-containing steel, comprising hot rolling with a thickness of 2250 mm. The chemical composition and mass percentage of the phosphorus-containing steel slab are as follows: C: 0.0047%, Si: 0.13%, Mn: 0.55%, P: 0.050%, S: 0.013%, and the balance being Fe and impurities.

[0056] The specific production method steps include:

[0057] 1) The downgraded slab, whose surface quality does not meet the product grading standards, is heated in a heating furnace at 1230°C. The furnace time for this cold slab heating step is 210 minutes. The four-stage heating method uses a preheating stage of 800-1000°C, a first heating stage of 1000-1150°C, a second heating stage of 1150-1300°C, and a soaking stage of 1225°C.

[0058] 2) After heating, the slab undergoes a high-pressure water descaling process to remove surface oxide scale. The slab undergoes rough rolling, reducing it to 45mm via a round trip process. The start temperature of the finishing roll is controlled at 960°C. The slab undergoes finishing rolling on seven stands, reducing it to the target thickness. The final exit temperature is controlled at 920°C using inter-stand cooling water. The finishing rolling process utilizes a high-load, 100% reduction rolling method, with an F7 load of 19.8%, ensuring full contact between the coil and the roll notch, resulting in a groove height of 0.65mm, meeting operational requirements.

[0059] The slab length is 9800mm, width is 1390mm, thickness is 230mm, hot rolling side pressure is 140mm, and order thickness is 3.8mm.

[0060] 3) The slabs are centrally cooled at the front end by laminar cooling water to ensure that the inlet temperature of the hot coil is controlled at 650°C.

[0061] After the above production process, the hot-rolled patterned plate product produced has an outer diameter of 2240mm, which exceeds the designed coiling capacity of the coiler of 2150mm, resulting in difficulty in unloading the steel coil and causing production to stop for 15 minutes.

[0062] The above embodiments are described to facilitate understanding and use of the invention by those skilled in the art. It will be apparent that those skilled in the art can readily make various modifications to these embodiments and apply the general principles described herein to other embodiments without requiring inventive effort. Therefore, the present invention is not limited to the above embodiments. Improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A method for producing a checkered plate from phosphorus-containing steel, characterized in that: The method for producing a checkered plate from phosphorus-containing steel comprises the following steps: 1) Heating; 2) rolling; 3) Cooling; 4) Coiling; The phosphorus-containing steel comprises the following components by mass percentage: C: ≤0.005%, Si: ≤0.15%, Mn: 0.3%-0.6%, P: 0.060%, S: ≤0.015%, and the balance is Fe and impurities; The heating adopts a four-stage heating method with the temperatures being: preheating stage 800-1000°C, first heating stage 1000-1150°C, second heating stage 1150-1300°C, and soaking stage temperature 1200-1250°C; After heating, the slab is descaled using high-pressure water to remove the iron oxide scale on the surface before rolling. In the rolling process, the start rolling temperature is controlled at 900-1070°C; the final rolling temperature is controlled at 890-930°C; The rolling includes rough rolling, wherein the thickness is reduced to 35-60 mm by back and forth rolling; In step 3), the cooling adopts a front-stage centralized cooling method, and the coiling inlet temperature is controlled at 620-680°C.

2. The method for producing a checkered plate from phosphorus-containing steel according to claim 1, characterized in that: The heating time in the furnace is ≥180min for hot billets and ≥210min for cold billets.

3. A phosphorus-containing steel checkered plate produced by the method according to claim 1 or 2.