阅读说明：本技术 焊接结构用钢板sm490b的制造方法 (Method for manufacturing steel plate SM490B for welded structure ) 是由 李宗强 阮志勇 樊雷 吴铠 陈小龙 李显 陈盛淋 朱鹏宇 于 2020-12-01 设计创作，主要内容包括：本发明提供了一种焊接结构用钢板SM490B的制造方法,所述焊接结构用钢板SM490B化学成分重量百分比为C：0.05～0.09wt％,Si≤0.47wt％,Mn：0.80～1.40wt％,P≤0.030wt％,S≤0.015wt％,Alt：0.020～0.040wt％,N≤0.006wt％,Nb+Ti≤0.10wt％；余量为Fe和不可避免的微量元素。所述制造方法,工艺路线依次为：高炉铁水冶炼、铁水脱硫预处理、转炉钢水冶炼、LF钢水精炼处理、RH钢水精炼处理、板坯连铸、热板坯加热、除鳞、粗轧、精轧、矫直。本发明的焊接结构用钢板SM490B达到了SM490C的性能水平,而且成本较低。(The invention provides a manufacturing method of a steel plate SM490B for a welding structure, wherein the steel plate SM490B for the welding structure comprises the following chemical components in percentage by weight: 0.05-0.09 wt%, Si is less than or equal to 0.47 wt%, Mn: 0.80-1.40 wt%, P is less than or equal to 0.030 wt%, S is less than or equal to 0.015 wt%, Alt: 0.020-0.040 wt%, N is less than or equal to 0.006 wt%, and Nb and Ti are less than or equal to 0.10 wt%; the balance of Fe and inevitable trace elements. The manufacturing method comprises the following process routes in sequence: blast furnace molten iron smelting, molten iron desulphurization pretreatment, converter molten steel smelting, LF molten steel refining treatment, RH molten steel refining treatment, plate blank continuous casting, hot plate blank heating, descaling, rough rolling, finish rolling and straightening. The steel plate SM490B for the welded structure of the invention reaches the performance level of SM490C and has lower cost.)

1. The manufacturing method of the steel plate SM490B for the welding structure is characterized in that the steel plate SM490B for the welding structure comprises the following chemical components in percentage by weight: 0.05-0.09 wt%, Si is less than or equal to 0.47 wt%, Mn: 0.80-1.40 wt%, P is less than or equal to 0.030 wt%, S is less than or equal to 0.015 wt%, Alt: 0.020-0.040 wt%, N is less than or equal to 0.006 wt%, and Nb and Ti are less than or equal to 0.10 wt%; the balance of Fe and inevitable trace elements;

the manufacturing method comprises the following process routes in sequence: the method comprises the steps of molten iron desulphurization pretreatment, converter molten steel smelting, LF molten steel refining treatment, RH molten steel refining treatment, slab continuous casting, hot slab heating, descaling, rough rolling, finish rolling and straightening.

2. The method for manufacturing a steel plate SM490B for welded structures according to claim 1, wherein in the converter steel smelting step: the S of the molten iron fed into the furnace is required to be less than or equal to 0.010 wt%; argon is blown from bottom in the whole smelting process; the end point control of the converter is that C is less than or equal to 0.06wt percent and P is less than or equal to 0.025wt percent.

3. The method for manufacturing a steel plate SM490B for welded structures according to claim 1, wherein in the RH molten steel refining process: the total vacuum circulation time is 15-20 min, and the ultimate vacuum retention time is more than 10 min; net cycle time is more than 3 min; after calcium treatment, soft argon blowing time is 8-10 min; the molten steel sedation time is more than or equal to 20 min.

4. The method for producing a steel plate SM490B for a welded structure according to claim 1, wherein in the slab continuous casting step: and (3) steel ladle slag discharging detection control is adopted, the pouring temperature of the tundish is 1530-1560 ℃, the tundish uses an alkaline covering agent and low-carbon steel covering slag, and the casting blank drawing speed is 0.90-1.21 m/min.

5. The method for manufacturing a steel plate SM490B for a welded structure according to claim 1, wherein in the hot slab heating step: controlling the heating temperature of the casting blank to be 1160-1240 ℃, and ensuring that the heating time of the casting blank in the furnace is more than or equal to 180min and the soaking time is more than or equal to 30 min.

6. The method for producing a steel plate SM490B for welded structures according to claim 1, wherein the finish rolling start target temperature is 890 to 930 ℃ and the finish rolling target temperature is

Technical Field

The invention relates to the field of metallurgy, in particular to a method for manufacturing a steel plate for a welding structure, and especially relates to a method for manufacturing a steel plate SM490B for a welding structure or a method for manufacturing a steel plate for an SM490B welding structure.

Background

The steel plate SM490B for welded structures is suitable for structural members of buildings, bridges, ships, vehicles, engineering machinery, etc. which require excellent welding performance.

Japanese Industrial Standard JIS G3106, two designations SM490B and SM490C, tensile test thickness>No. 1A sample is adopted for 16-40mm, the yield strength is required to be more than or equal to 315MPa, the tensile strength range is 490-610 MPa, and the elongation rate is scaled by a fixed length and a scaling distance A₂₀₀The requirement is more than or equal to 21 percent, and the control difficulty of the elongation index is high. The two marks correspond to the respective requirements of low-temperature impact energy at 0 DEG C>27J、>And 47J. But at presentThe conventional steel plate for welded structures SM490B (steel plate for SM490B welded structures) has unsatisfactory performance.

In summary, the following problems exist in the prior art: the performance index of the existing steel plate SM490B for the welding structure (the steel plate for the SM490B welding structure) is not high, the actual stamping resistance of the product in the using process is not enough, and the safety is poor.

Disclosure of Invention

The invention provides a manufacturing method of a steel plate SM490B for a welding structure, which aims to solve the problems that the performance index of the existing steel plate SM490B for the welding structure (the steel plate for the SM490B welding structure) is not high, the actual stamping resistance of the product in the using process is not enough, and the safety is poor.

Therefore, the invention provides a manufacturing method of a steel plate SM490B for a welding structure, wherein the steel plate SM490B for the welding structure comprises the following chemical components in percentage by weight: 0.05-0.09 wt%, Si is less than or equal to 0.47 wt%, Mn: 0.80-1.40 wt%, P is less than or equal to 0.030 wt%, S is less than or equal to 0.015 wt%, Alt: 0.020-0.040 wt%, N is less than or equal to 0.006 wt%, and Nb and Ti are less than or equal to 0.10 wt%; the balance of Fe and inevitable trace elements;

the manufacturing method comprises the following process routes in sequence: blast furnace molten iron smelting, molten iron desulphurization pretreatment, converter molten steel smelting, LF molten steel refining treatment, RH molten steel refining treatment, plate blank continuous casting, hot plate blank heating, descaling, rough rolling, finish rolling and straightening.

Further, in the converter molten steel smelting process: the S of the molten iron fed into the furnace is required to be less than or equal to 0.010 wt%; argon is blown from bottom in the whole smelting process; the end point control of the converter is that C is less than or equal to 0.06wt percent and P is less than or equal to 0.025wt percent.

Further, in the RH molten steel refining process: the total vacuum circulation time is 15-20 min, and the ultimate vacuum retention time is more than 10 min; net cycle time is more than 3 min; after calcium treatment, soft argon blowing time is 8-10 min; the molten steel sedation time is more than or equal to 20 min.

Further, in the slab continuous casting process: and (3) steel ladle slag discharging detection control is adopted, the pouring temperature of the tundish is 1530-1560 ℃, the tundish uses an alkaline covering agent and low-carbon steel covering slag, and the casting blank drawing speed is 0.90-1.21 m/min.

Further, in the hot slab heating step: controlling the heating temperature of the casting blank to be 1160-1240 ℃, and ensuring that the heating time of the casting blank in the furnace is more than or equal to 180min and the soaking time is more than or equal to 30 min.

Further, the finish rolling initial rolling target temperature range is 890-930 ℃, and the finish rolling target temperature is

According to the invention, through the design of low-carbon components in steel, a proper amount of Nb + Ti microalloy is added, the N content in the steel is strictly controlled, and a reasonable smelting-continuous casting-rolling process is formulated, so that the stable production of the product is realized, and the steel plate SM490B for the welding structure with stable mechanical property and good impact toughness is obtained. The steel plate SM490B mechanical property R for the welding structure obtained by the invention_eHNot less than 315MPa, tensile strength R_m490 to 610MPa, elongation A₂₀₀Not less than 23 percent and low-temperature impact energy A at 0 DEG C_kv>120J; the control range of the steel plate welding crack sensitivity index Pcm is 0.12-0.16, which is far lower than the Japanese industrial standard JIS G3106, the required index is less than or equal to 0.28, and the steel plate welding crack sensitivity is low. The metallographic structure is mainly F + P, and the grain size is 9.5 grade.

Drawings

FIG. 1 is a photograph of a metallographic structure at a magnification of 500 times in example 2 of the present invention.

Detailed Description

The present invention will now be described in order to more clearly understand the technical features, objects, and effects of the present invention.

The invention provides a manufacturing method of a steel plate SM490B for a welding structure, which comprises the following chemical components in percentage by weight: 0.05-0.09 wt%, Si is less than or equal to 0.47 wt%, Mn: 0.80-1.40 wt%, P is less than or equal to 0.030 wt%, S is less than or equal to 0.015 wt%, Alt: 0.020-0.040 wt%, N is less than or equal to 0.006 wt%, and Nb and Ti are less than or equal to 0.10 wt%; the balance of Fe and inevitable trace elements. The steel plate SM490B for the welding structure with excellent mechanical properties has the product yield strength R_eLNot less than 315MPa, tensile strength R_m490 to 610MPa, elongation A₂₀₀Not less than 23%, and low temperature impact energy at 0 deg.C>120J。

The manufacturing method of the steel plate SM490B for the welding structure comprises the following process routes in sequence: the method comprises the steps of molten iron desulphurization pretreatment, converter molten steel smelting, LF molten steel refining treatment, RH molten steel refining treatment, slab continuous casting, hot slab heating, descaling, rough rolling, finish rolling, straightening, sampling, steel plate inspection, marking and warehousing.

Smelting molten steel in a converter: the S of the molten iron fed into the furnace is required to be less than or equal to 0.010 wt%; argon is blown from bottom in the whole smelting process; the end point control of the converter comprises C less than or equal to 0.06 wt% and P less than or equal to 0.025 wt%;

LF molten steel refining treatment: removing impurities, balancing temperature and alloying the molten steel in an LF furnace;

RH molten steel refining treatment: the total vacuum circulation time is 15-20 min, and the ultimate vacuum retention time is more than 10 min; net cycle time is more than 3 min; after calcium treatment, soft argon blowing time is 8-10 min; the molten steel sedation time is more than or equal to 20 min;

slab continuous casting: and (3) steel ladle slag discharging detection control is adopted, the pouring temperature of the tundish is 1530-1560 ℃, the tundish uses an alkaline covering agent and low-carbon steel covering slag, and the casting blank drawing speed is 0.90-1.21 m/min.

The high-precision continuous casting control process comprises the following steps: the casting process of 'weak cooling, low superheat degree, constant drawing speed and high straightening temperature' is adopted, and the generation of surface cracks of the plate blank is reduced.

Rolling a medium plate: controlling the heating temperature of the casting blank to be 1160-1240 ℃, ensuring that the heating time of the casting blank in the furnace is more than or equal to 180min, and the soaking time is more than or equal to 30min, so that the microalloying elements are dissolved in solid solution, and the austenite grain size is controlled; the rough rolling is carried out for 8 times, and the last time of the rough rolling adopts manual large-reduction rolling to uniformly hot-roll the structure and improve the shape of the steel plate and the stamping performance after rolling; the finish rolling initial rolling target temperature range is 890-930 ℃, and the finish rolling target temperature

The invention has the technical characteristics that:

1) the low-carbon composition design is adopted, the control range of C in the steel is 0.05-0.09 wt%, the impact toughness of the steel plate can be effectively improved, and the steel plate has low welding crack sensitivity. The N in the molten steel is controlled to be less than or equal to 0.006 wt%, the precipitation of Ti and N in the liquid molten steel in the slab continuous casting process is reduced, and the destructive effect of the TiN precipitate with coarse size on the toughness of the steel plate for the welding structure can be reduced.

2) A small amount of Ti is added into the steel to reduce the content of N reacting with Al element, so that the precipitation of AlN is inhibited, and the surface cracks of the casting blank are effectively reduced.

3) The high-precision continuous casting control process comprises the following steps: the production of surface cracks of the plate blank is reduced by adopting a casting process of 'weak cooling, low superheat degree, constant pulling speed and high straightening temperature' and a casting process of 'weak cooling, low superheat degree, constant pulling speed and high straightening temperature'.

4) The medium plate rolling process comprises the following steps: controlling the heating temperature of the casting blank to be 1160-1240 ℃, ensuring that the heating time of the casting blank in the furnace is more than or equal to 180min, and the soaking time is more than or equal to 30min, so that the microalloying elements are dissolved in solid solution, and the austenite grain size is controlled; the rough rolling is carried out for 8 times, and the last time of the rough rolling adopts manual large-reduction rolling to uniformly hot-roll the structure and improve the shape of the steel plate and the stamping performance after rolling; the finish rolling initial rolling target temperature range is 890-930 ℃, and the finish rolling target temperature

The manufacturing method of the steel plate SM490B for the welding structure with excellent mechanical properties adopts the following component proportions and specific processes. Wherein, Table 1 shows the compositions (in weight%) of the steels of the respective examples. Table 2 shows the process parameters corresponding to the example steels described in table 1. Table 3 shows the mechanical properties of the steel compositions described in the examples of Table 1.

Table 1: chemical composition (wt%) of product

Table 2: specific process parameters of the examples

Table 3: mechanical properties of Steel plate SM490B for welded Structure obtained in examples

The metallographic structure of the above example is mainly F + P, and the grain size is class 9.5, wherein fig. 1 is the metallographic structure of example 2.

It can be seen from the above examples that the present invention achieves higher performance at lower cost (less noble metal is added), and has higher cost performance. The steel plate SM490B for the welding structure has the mechanical property reaching the level of SM490C high-quality grade, and is low in cost.

The above description is only an exemplary embodiment of the present invention, and is not intended to limit the scope of the present invention. In order that the components of the present invention may be combined without conflict, it is intended that all equivalent changes and modifications made by those skilled in the art without departing from the spirit and principles of the present invention shall fall within the protection scope of the present invention.