阅读说明：本技术 一种新型钢结构专用钢及其制备方法 (Novel steel special for steel structure and preparation method thereof ) 是由 吴刚 文小明 韩宇 陈红远 薛文辉 徐勇 于 2020-03-24 设计创作，主要内容包括：本发明提供了一种新型钢结构专用钢及其制备方法,其中,在加热制度上,采用较高的加热温度,保温在炉时间缩短。经实验室模拟试验,加热温度控制在1230-1260℃,保温时间控制在25分钟,保证了合金元素的充分融入,以及低合金钢在轧制时有较好的塑性以及良好的板形,满足轧制工艺要求,根据用户所要求的成品厚度,调整粗轧中间坯厚度,保证精轧压缩比达到以上,改善成品的金相组织和物理性能,提高产品质量,中温卷取,获得细小均匀的组织和合适的氧化铁皮结构。这种钢材制造成本比镀锌板节省,应用于钢结构上,可以满足技术性能要求,可以降低原材料制造成本,提高相关产业经济效益,促进了环保行业发展和科学技术进步。(The invention provides novel steel special for a steel structure and a preparation method thereof, wherein a higher heating temperature is adopted in a heating system, and the heat preservation furnace-in time is shortened. Through a laboratory simulation test, the heating temperature is controlled to 1230-. Compared with a galvanized plate, the steel has the advantages that the manufacturing cost is saved, the steel is applied to a steel structure, the technical performance requirement can be met, the manufacturing cost of raw materials can be reduced, the economic benefit of related industries is improved, and the development of the environmental protection industry and the scientific and technical progress are promoted.)

1. The novel steel special for the steel structure is characterized by comprising the following chemical components in percentage by mass: c: 0.05-0.20%, Si: 0.07-0.27%, Mn: 0.15-0.55%, S: 0.001-0.008%, P: 0.003-0.015%, Al: 0.015 to 0.055%, Ni: 0.001-0.10%, Cr: 0.03-0.25%, N: 0.0010-0.0060% and the balance of Fe and other inevitable impurities.

2. The preparation method of the novel steel structure special steel as claimed in claim 1, characterized by comprising the following steps:

1) pre-desulphurisation of molten iron

Heavy scrap steel is adopted, the slag is required to be completely removed, and S in molten iron fed into a furnace is less than or equal to 0.005 percent;

2) converter steelmaking

The converter steelmaking process requires that the carbon drawing is hit once and the spot blowing is avoided, the tapping adopts high manganese and ferrosilicon, the tapping hole is controlled before the tapping to avoid the free flow, the argon blowing is carried out on a steel ladle, Als in the steel ladle is controlled according to 0.015-0.050%, and the N of the steel ladle is required to be less than or equal to 20 ppm;

3) refining procedure

The LF ladle furnace is adopted for treatment, the contents of nitrogen and oxygen in the steel are strictly controlled, and the calcium-silicon line treatment is adopted, so that impurities in the steel are fully denatured, and the isotropic performance of the product is improved;

4) continuous casting procedure

Before continuous casting, argon is adopted to purge a tundish, protective casting is carried out in the whole process, no molten steel is exposed in the casting process, the increase of N is controlled to be less than or equal to 5ppm, high-alkalinity tundish slag is adopted, upward floating of inclusions in steel is facilitated, the control target of the superheat degree of continuous casting is not more than 30 ℃, hot overheating of slabs is carried out, and the rest slabs are placed in a slow cooling area in a warehouse;

5) heating furnace section

The heating temperature is 1230-;

6) rolling and coiling part

And (3) selecting a 3+3 mode for rolling control, well distributing the load of a finish rolling model, ensuring the stability of the rolling process and the finish rolling temperature: more than or equal to 860 ℃, coiling temperature: and the temperature is 520-620 ℃, the front section is immediately cooled, and the front section is cooled in a mode, so that the accurate control of the final rolling and coiling temperature is fully ensured.

3. The novel steel structure special for the steel structure as claimed in claim 2, wherein in the step 3), the CaSi wire is fed for 450 meters.

4. The novel steel special for the steel structure as claimed in claim 2, wherein the soft reduction function is used in the steel casting process in the step 4), and the constant drawing speed is kept at 1.0-1.2 m/min in the steel casting process.

Technical Field

The invention relates to the field of steel manufacturing, in particular to novel steel special for a steel structure and a preparation method thereof.

Background

In recent years, with the continuous increase of infrastructure construction and factory building, steel structure buildings are popularized and continuously developed, steel structures are widely applied to the aspects of buildings, railways, bridges, houses and the like, and the grades comprise plain carbon steels Q235B, Q235C, Q345B, low-alloy high-strength steel and the like, and the thickness specification is as follows: 3.0-16.0 mm and the like, generally, steel structures made of common materials remove iron scales on the surfaces through acid washing and shot blasting processes, and because the waste acid liquid has great harm to the environment and human bodies, steel structure factories seek new production technologies and processes to replace the original processes.

In order to solve the problems, users sometimes adopt galvanized plates as raw materials, the cost is 1.5-2 times that of common carbon steel under common conditions, the practicability and uniformity of the surface of a steel structure are solved, the manufacturing cost rises, the production profit is reduced, particularly, the market competition at home and abroad is very fierce at present, the enterprise profit is greatly compressed, the survival crisis is faced in many times, the research and development of alternative materials capable of meeting the actual production and manufacturing and performance requirements of the steel structure are urgently needed, and the production cost of enterprises is reduced.

Disclosure of Invention

In order to solve the problems, the invention provides novel steel special for a steel structure and a preparation method thereof.

The invention provides a novel steel structure special steel, which comprises the following chemical components in percentage by mass: c: 0.05-0.20%, Si: 0.07-0.27%, Mn: 0.15-0.55%, S: 0.001-0.008%, P: 0.003-0.015%, Al: 0.015 to 0.055%, Ni: 0.001-0.10%, Cr: 0.03-0.25%, N: 0.0010-0.0060% and the balance of Fe and other inevitable impurities.

The invention also provides a preparation method of the novel steel structure special steel, which comprises the following steps: 1) pre-desulphurisation of molten iron

Heavy scrap steel is adopted, the slag is required to be completely removed, and S in molten iron fed into a furnace is less than or equal to 0.005 percent;

2) converter steelmaking

The converter steelmaking process requires that the carbon drawing is hit once and the spot blowing is avoided, the tapping adopts high manganese and ferrosilicon, the tapping hole is controlled before the tapping to avoid the free flow, the argon blowing is carried out on a steel ladle, Als in the steel ladle is controlled according to 0.015-0.050%, and the N of the steel ladle is required to be less than or equal to 20 ppm;

3) refining procedure

The LF ladle furnace is adopted for treatment, the contents of nitrogen and oxygen in the steel are strictly controlled, and the calcium-silicon line treatment is adopted, so that impurities in the steel are fully denatured, and the isotropic performance of the product is improved;

4) continuous casting procedure

Before continuous casting, argon is adopted to purge a tundish, protective casting is carried out in the whole process, no molten steel is exposed in the casting process, the increase of N is controlled to be less than or equal to 5ppm, high-alkalinity tundish slag is adopted, upward floating of inclusions in steel is facilitated, the control target of the superheat degree of continuous casting is not more than 30 ℃, hot overheating of slabs is carried out, and the rest slabs are placed in a slow cooling area in a warehouse;

5) heating furnace section

The heating temperature is 1230-;

6) rolling and coiling part

And (3) selecting a 3+3 mode for rolling control, well distributing the load of a finish rolling model, ensuring the stability of the rolling process and the finish rolling temperature: more than or equal to 860 ℃, coiling temperature: and the temperature is 520-620 ℃, the front section is immediately cooled, and the front section is cooled in a mode, so that the accurate control of the final rolling and coiling temperature is fully ensured.

Preferably, in the step 3), the CaSi wire is fed for 450 meters.

Preferably, the steel casting process in the step 4) has a soft reduction function, and the constant drawing speed is kept at 1.0-1.2 m/min in the steel casting process.

The special steel for the steel structure has good oxidation resistance and stripping resistance, wherein the alloy elements play a decisive role, and the method comprises the following steps:

(1) the adhesiveness of the iron scale is increased;

(2) the phase structure and the variety of the iron scale are influenced, and the growth of a rust layer is hindered;

(3) the anti-stripping capability of the steel plate is increased;

(4) the oxidation resistance of the steel plate is increased;

(5) the alloying elements and their compounds hinder the generation of cracks and defects.

The content ranges and functions of the chemical element components forming the steel are as follows:

c: 0.05 to 0.20% by weight, C is required to significantly improve the strength of the steel, and the C content is preferably 0.05 to 0.20% by weight because the C content is required to be high to achieve a certain rigidity of the steel, but if the C content exceeds 0.20% by weight, the C content is not preferable because the C content adversely affects the spalling resistance of the steel and also affects the weldability, cold brittleness, cold stamping property, etc. of the steel.

P: 0.003 to 0.015 wt% of P exerts a harmful effect in steel, and is high in P content, which tends to cause cold embrittlement in steel, and if it exceeds 0.015 wt%, the toughness is greatly lowered, so that the P content is preferably 0.003 to 0.015 wt%.

Cr: 0.03-0.25 wt%. The addition of Cr to steel can form dense Cr2O3 oxide film on the surface of steel to raise the passivating capacity of steel, and can raise the corrosion resistance of steel. The preferable Cr content in the present invention is in the range of 0.03 to 0.25 wt%.

Ni: 0.001-0.10 wt%. Ni is a relatively stable element, the addition of Ni can improve the mechanical strength of steel, change the self-corrosion potential of steel to the positive direction, increase the stability of steel, and the addition of a proper amount of Ni in steel can also improve the adhesiveness of iron scales on the surface of steel and avoid the phenomenon of iron scale falling off in the cold forming process. The Ni content is preferably 0.001 to 0.10 wt% in the present invention.

Si: 0.07-0.27 wt%. Si is a common deoxidizer and also an element that improves the strength of the steel, and the Si content is preferably 0.07 to 0.27% because Si is low and can improve the cold-roll formability of the steel and the toughness of the steel.

Mn: 0.15-0.55 wt%. Mn, which increases the yield strength and tensile strength of steel, is one of the most commonly used elements in steel, and also increases the corrosion resistance of steel to some extent, but an excessive amount of Mn reduces the toughness and weldability of steel, and thus the content is preferably 0.15 to 0.55 wt%.

S: 0.001-0.008 wt% S is one of harmful elements in steel, the S content is easy to play a hot brittleness role in the steel, and the S content is controlled to be 0.001-0.008 wt%.

Al: 0.015-0.055 wt%. Al is the most commonly used deoxidizing element in killed steel, a certain amount of aluminum is added into molten steel, the aluminum and oxygen react at high temperature to form aluminum oxide, the aluminum oxide exists on the surface of the molten steel in the form of residues, the oxygen content in the molten steel is controlled by removing the residues, the impurity content in the steel is reduced, and the quality of the steel is improved, so that the method plays an important role. The preferred content range is 0.015 to 0.055 wt%.

N: 0.0010-0.0050 Wt%. In the smelting process, N is beneficial to removing harmful gas impurities and mechanical impurities generated in the smelting process, the quality of steel is improved, and the performance of the steel is improved. Therefore, the N content is preferably 0.0010 to 0.0050 Wt%.

The balance consisting of Fe and other impurities.

The invention has the following beneficial effects:

(1) in the aspect of chemical composition design, the content of the added alloy is low, the steel quality is pure, and the cost is saved on the basis of ensuring excellent performance.

(2) The anti-oxidation iron sheet on the surface of the steel plate has the stripping performance, and the use requirement of a user is met.

(3) The mechanical property is small, various indexes meet the requirements, and the elongation after fracture is large.

(4) In the aspect of controlling the structure of the iron scale, the process is ensured by adopting measures such as reasonable higher heating temperature, proper finish rolling temperature, moderate temperature coiling temperature and the like, and the plate shape is excellent.

(5) The steel special for the steel structure produced by the process completely meets the use requirements of users through excellent performance and good iron scale structure and plate shape.

(6) The steel product and the surface special for the steel structure produced by the technology reduce the cost of enterprises, show higher finished product quality and yield, have good economic benefit and social benefit and have good popularization value.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

This embodiment provides a novel special steel of steel construction, and chemical composition and mass percent are: c: 0.05-0.20%, Si: 0.07-0.27%, Mn: 0.15-0.55%, S: 0.001-0.008%, P: 0.003-0.015%, Al: 0.015 to 0.055%, Ni: 0.001-0.10%, Cr: 0.03-0.25%, N: 0.0010-0.0060% and the balance of Fe and other inevitable impurities.

The invention also provides a preparation method of the novel steel structure special steel, which comprises the following steps:

1) pre-desulphurisation of molten iron

Heavy scrap steel is adopted, the slag is required to be completely removed, and S in molten iron fed into a furnace is less than or equal to 0.005 percent;

2) converter steelmaking

The converter steelmaking process requires that the carbon drawing is hit once and the spot blowing is avoided, the tapping adopts high manganese and ferrosilicon, the tapping hole is controlled before the tapping to avoid the free flow, the argon blowing is carried out on a steel ladle, Als in the steel ladle is controlled according to 0.015-0.050%, and the N of the steel ladle is required to be less than or equal to 20 ppm;

3) refining procedure

The LF ladle furnace is adopted for treatment, the contents of nitrogen and oxygen in steel are strictly controlled, calcium-silicon wires are adopted for calcium treatment, and CaSi wires are fed for 450 meters, so that impurities in the steel are fully denatured, and the isotropic performance of the product is improved;

4) continuous casting procedure

Before continuous casting, argon is adopted to purge a tundish, protective casting is carried out in the whole process, no molten steel is exposed in the casting process, the control of the increase of N is less than or equal to 5ppm, high-alkalinity tundish slag is adopted, the upward floating of inclusions in steel is facilitated, the steel casting process is put into a soft reduction function, the constant drawing speed is kept at 1.0-1.2 m/min, the continuous casting superheat degree is controlled to be not more than 30 ℃, the slab is subjected to hot overheating loading, and the rest slab is placed in a slow cooling area in a warehouse;

5) heating furnace section

The heating temperature is 1230-;

6) rolling and coiling part

And (3) selecting a 3+3 mode for rolling control, well distributing the load of a finish rolling model, ensuring the stability of the rolling process and the finish rolling temperature: more than or equal to 860 ℃, coiling temperature: and the temperature is 520-620 ℃, the front section is immediately cooled, and the front section is cooled in a mode, so that the accurate control of the final rolling and coiling temperature is fully ensured.

The following performance tests were performed on the steels produced by the methods provided in the above examples and on steels produced by other processes, and the results are shown in table 1:

table 1 results of performance testing

Number plate	Yield strength Rt0.5	Tensile strength Rm	Elongation% A50
				BG350-Z	≥350	≥490	≥22
The process	420	540	36
				Other processes	380	520	29

And (4) conclusion: from experimental results of examples and comparative examples, the steel special for the steel structure provided by the application has a reinforcing effect obviously superior to that of other processes.

Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice within the art to which the invention pertains. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.