Manufacturing method of hot-rolled section steel

Abstract

The invention discloses a method for manufacturing hot-rolled section steel. The method comprises the following steps that a blank is heated through a heating furnace, after the temperature reaches 1150-1250 DEG C, steel is discharged and enters a first cogging mill to be rolled and reciprocated for 3-7 passes, then the steel is rolled through a second cogging mill and reciprocated for 3-7 passes, and then the steel is continuously rolled through 3-9 universal rolling mills. And after rolling is finished, sawing to be 6-24m by a hot saw, cooling to be below 80 DEG C on a cooling bed, straightening under the cooling bed, finishing, stacking, collecting and storing in a finished product warehouse. The method has the characteristics of flexible and changeable process, high production efficiency, convenient organization and wide application range of profile steel products.

Description

Technical Field

[0001] The invention relates to a method for manufacturing hot-rolled steel sections. Background Art

[0003] As the central government continues to clarify its policies on the development of prefabricated buildings, local governments are also implementing supporting policies intensively. While some provinces and cities have issued special guidance opinions and related supporting measures on prefabricated buildings, they have also proposed development plans for steel structure buildings, clarifying the scope of promotion and implementation of steel structure building forms and the proportion of steel structures used in various types of new buildings.

[0004] Steel pipes, steel sections and plates jointly replace rebar to reduce volume, and steel sections compete with plates and steel pipes.

[0005] Hot-rolled steel competitive threat: According to data from the China Steel Structure Association, hot-rolled steel accounts for 14.3%, and substitutes - cold-formed steel, welded H-steel, and main plate steel for steel structures (66.5%) are the main threats to steel.

[0006] In 2023, the international new shipbuilding market will continue to maintain strong demand, and orders for traditional mainstream ship types, bulk carriers and oil tankers, will grow rapidly. On the other hand, benefiting from the continued stable and substantial growth in my country's new energy vehicle exports, freight rates in the global car carrier operating market are high, and demand for new ship orders continues to be hot. my country's shipbuilders have seized the historic opportunity of the shortage in the car carrier market and are taking on orders for various large-scale car carriers in batches.

[0007] my country's backbone shipbuilding companies have obvious competitive advantages, with new orders of 71.2 million deadweight tons, a significant year-on-year increase of 56.4%, accounting for 66.6% of the global total. For three consecutive years, the volume of new orders has been above 40 million deadweight tons, driving a steady recovery in demand for shipbuilding steel. Statistics show that in 2023, the total amount of shipbuilding steel in my country will exceed 14 million tons, continuing to grow by 16.7% year-on-year, maintaining rapid growth for two consecutive years. In terms of varieties, plates are 12 million tons, a year-on-year increase of 17.6%, profiles are 1.15 million tons, a year-on-year increase of 15%, and other varieties are 850,000 tons, a year-on-year increase of 6.3%.

[0008] It is expected that in 2024, the shipbuilding industry will maintain steady growth, thereby driving steady growth in the consumption of ship steel; at the same time, the demand for ship repair, marine ranching, offshore wind power, etc. is expected to maintain a certain growth. It is estimated that the annual steel consumption of my country's shipbuilding industry will be about 17.8 million tons, an increase of about 3% year-on-year. Summary of the invention

[0009] In order to overcome the above-mentioned defects, the present invention aims to provide a convenient and flexible method for hot rolling steel sections, which has simple process, energy saving and high efficiency.

[0010] To achieve the above object, the method for manufacturing hot-rolled steel sections of the present invention comprises the following steps:

[0011] 1) The raw materials are smelted and continuously cast by a steelmaking process to obtain a casting billet;

[0012] 2) heating the ingot at 1150-1250° C. for 1.0-3.0 hours;

[0013] 3) Above 1100℃, the steel is rolled through 3-7 passes on the first frame, and then above 1000℃, the steel is rolled through 3-7 passes on the second frame, and finally rolled through 3-9 universal rolling mills; then it is cut into 6-24m fixed length or double length by hot saw, and then cooled to below 80℃ on the cooling bed, and after being taken off the cooling bed and passed through the straightening machine, it is stacked and collected and stored in the finished product warehouse.

[0014] Furthermore, the steel sections include but are not limited to: bulb flat steel, L-shaped steel, track steel, elevator guide rail steel, and H-shaped steel.

[0015] Furthermore, the steel sections include but are not limited to: carbon structural steel, low alloy high strength structural steel, structural steel for ships and marine engineering, and weather resistant structural steel.

[0016] Furthermore, the method also includes a step of controlling the rolling temperature during the rolling process to improve product performance and quality stability.

[0017] Furthermore, the method also includes a step of controlling the rolling cooling environment during the rolling process to improve product performance and quality stability.

[0018] The process of the present invention is advanced and flexible, the rolling pass and rhythm are easy to control, green and environmentally friendly, energy-saving and efficient, and in line with the development trend. The manufactured products range is relatively wide, including marine ship steel, building bridge steel, crawler steel, etc. According to the requirements of the use environment, the product can have excellent properties such as high strength, high toughness, cold resistance, and weather resistance, and can be used in the manufacture of ocean-going shipbuilding, bridge and building steel. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0020] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0021] In the description of the present invention, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0022] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0023] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0024] Example 1

[0025] In this embodiment, the L-shaped steel hot working process is controlled by the following chemical composition and content: silicon content (Si) 0.10-0.50, manganese content (Mn) 0.70-1.60, phosphorus content (P) ≤ 0.04, sulfur content (S) ≤ 0.04, vanadium (V) 0.03-0.1, niobium (Nb) 0.015-0.05, and the rest are small amounts of alloy elements, Fe and unavoidable impurities.

[0026] After steelmaking and refining, the molten iron is continuously cast, hot rolled and heat treated in rectangular billets. The process is to heat the billet at 1200-1250℃ for 2.0-2.5 hours, then roll it on the first billet stand for 5 passes at 1150℃, then roll it on the second billet stand for 5 passes at 1100℃, and finally roll it on 7 universal rolling mills or two-roller rolling mills, and configure a cooling section at the mill outlet. Then it is cut to a fixed length of 12m by a hot saw, and then cooled to below 80℃ by a cooling bed. After passing through a straightener on the lower cooling bed, it is stacked and collected and stored in the finished product warehouse.

[0027] The L-shaped steel manufactured in this embodiment has a yield strength ReL (MPa) ≥ 315, a tensile strength Rm (MPa) of 440-570, a transverse impact (0°C) Ak ≥ 31J, and a longitudinal impact (0°C): Ak ≥ 22J.

[0028] Example 2

[0029] In this embodiment, the track steel hot working process is controlled to have the following chemical compositions and contents: carbon (C) content ranges from 0.22% to 0.29%, manganese (Mn) content ranges from 1.1% to 1.4%, silicon (Si) content ranges from 0.17% to 0.37%, and boron (B) content ranges from 0.0005% to 0.0035%. The rest are small amounts of alloying elements, Fe, and unavoidable impurities.

[0030] After steelmaking and refining, the molten iron is continuously cast, hot rolled and heat treated in rectangular billets. The process is to heat the billet at 1200-1250℃ for 1.5-2.0 hours, then roll it on the first billet stand at 1180℃ for 7 passes, then roll it on the second billet stand at 1150℃ for 7 passes, and finally roll it on 7 universal rolling mills or two-roller mills. Then it is cut to a fixed length of 12m by hot saw, and a heat preservation cover is set at the entrance of the cooling bed. Then it is cooled to below 80℃ by the cooling bed, and after passing through the straightening machine on the lower cooling bed, it is stacked and collected and stored in the finished product warehouse.

[0031] The track steel manufactured in this embodiment has a yield strength ReL (MPa) ≥ 635, a tensile strength Rm (MPa) ≥ 835, and an impact KV ≥ 47J.

[0032] The present invention is described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge of ordinary technicians in the field without departing from the purpose of the present invention. Many other changes and modifications that do not depart from the concept and scope of the present invention should be regarded as the protection scope of the present invention.

[0033] In the description of this specification, specific features, structures, materials or characteristics may be combined in an appropriate manner in any one or more embodiments or examples.

[0034] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for manufacturing hot-rolled steel, characterized in that: The method comprises the following steps: 1) The raw materials are smelted and continuously cast by a steelmaking process to obtain a casting billet; 2) heating the ingot at 1150-1250° C. for 1.0-3.0 hours; 3) The product is rolled at 1100℃ or above through 3-7 passes on the first frame, and then rolled at 1000℃ or above through 3-7 passes on the second frame, and finally rolled on 3-9 universal rolling mills; then it is cut to a fixed length of 6-24m or double length by hot saw, and then cooled to below 80℃ on a cooling bed, and after being taken off the cooling bed and passed through a straightening machine, it is stacked and collected and stored in the finished product warehouse.

2. The method for manufacturing hot-rolled steel according to claim 1, characterized in that: The steel sections include but are not limited to: bulb flat steel, L-shaped steel, track steel, elevator guide rail steel, and H-shaped steel.

3. The method for manufacturing hot-rolled steel according to claim 1, characterized in that: The steel sections include, but are not limited to: carbon structural steel, low alloy high strength structural steel, structural steel for ships and marine engineering, and weather resistant structural steel.

4. The method for manufacturing hot-rolled steel according to claim 1, characterized in that: It also includes the step of controlling the rolling temperature during the rolling process to improve product performance and quality stability.

5. The method for manufacturing hot-rolled steel according to claim 1, characterized in that: It also includes the steps of controlling the rolling cooling environment during the rolling process to improve product performance and quality stability.

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