阅读说明：本技术 一种热轧x型钢及其热轧成型工艺 (Hot-rolled X-shaped steel and hot-rolling forming process thereof ) 是由 陈辉 吴保桥 夏勐 张卫斌 张文满 吴湄庄 沈千成 邢军 黄琦 于 2021-07-29 设计创作，主要内容包括：一种热轧X型钢及其热轧成型工艺,属于X型钢成型工艺技术领域,其中的热轧X型钢由圆坯、矩形坯或异形坯热轧成型,包括相互交叉后形成的4个支撑腿,上部或下部的两个支撑腿之间的夹角设置为30°～150°,且同一延伸方向的两个支撑腿长度之和设置为300mm～1500mm,该热轧成型工艺包括坯料浇注成型-坯料加热、除磷-开坯机轧制-四辊往复精轧机轧制-空冷,本发明的有益效果是,本发明对X型钢的外形尺寸进行限定,满足了实际市场需要和工程装配要求,将不同类型的坯形通过开坯和四辊往复精轧一次成形,结构稳定,荷载承受力较强,可广泛应用于大型的建筑结构领域。(A hot-rolled X-shaped steel and a hot-rolling forming process thereof belong to the technical field of X-shaped steel forming processes, wherein the hot-rolled X-shaped steel is formed by hot rolling a round billet, a rectangular billet or a special-shaped billet and comprises 4 supporting legs formed after mutual intersection, the included angle between two supporting legs at the upper part or the lower part is set to be 30-150 degrees, and the sum of the lengths of the two supporting legs in the same extension direction is set to be 300-1500 mm, the hot rolling forming process comprises the steps of blank casting forming, blank heating, dephosphorization, cogging mill rolling, four-roller reciprocating finish rolling mill rolling and air cooling.)

1. A hot-rolled X-shaped steel is characterized by being formed by hot rolling of a round billet, a rectangular billet or a special-shaped billet and comprising 4 supporting legs formed after mutual intersection, wherein the included angle between two upper or lower supporting legs is set to be 30-150 degrees, and the sum of the lengths of the two supporting legs in the same extension direction is set to be 300-1500 mm.

2. The hot rolled X-steel according to claim 1, characterized in that: the thickness of 4 supporting legs sets up to 15 ~ 80mm, and the crossing department between 4 supporting legs is provided with the transition fillet, and the tip rounding off of 4 supporting legs.

3. A hot-roll forming process of a hot-rolled X-section steel according to claim 1 or 2, comprising the steps of:

1) and (3) casting and molding a blank: carrying out ladle pouring after molten iron pretreatment, converter smelting and argon blowing refining in sequence to obtain a required blank;

2) heating the blank and removing phosphorus: heating the blank at a set temperature for a period of time, and then conveying the blank to a high-pressure water phosphorus removal machine for phosphorus removal, so that the temperature of the phosphorus-removed blank is not lower than 1150 ℃;

3) rolling by a cogging mill: conveying the blanks subjected to high-pressure dephosphorization to a cogging mill, deforming the blanks one by one to form an X shape, and performing multi-pass rolling to finish primary rolling through extension distribution of each pass;

4) rolling by a four-roller reciprocating finishing mill: the blank which is primarily rolled is sent to a four-roller reciprocating finishing mill for rolling, the roll gap axis between a horizontal rolling mill and a vertical rolling mill is adjusted, and the shape required by the product is obtained after multi-pass rolling is carried out within the set cogging temperature range;

5) air cooling: and the rolled finished product is air-cooled to room temperature on a cooling bed, so that the transformation of ferrite and pearlite is realized in the cooling process.

4. A hot rolling forming process of hot rolled X-shaped steel according to claim 3, wherein in the step 1), a slag removing machine is used to remove slag from the molten iron during the pretreatment of the molten iron, and oxygen is blown to reduce the S content in the molten iron after the slag removal is finished.

5. The hot roll forming process of hot rolled X-shaped steel according to claim 3, wherein in the step 1), the argon blowing refining is performed by continuously blowing argon into the molten steel smelted in the ladle, and controlling the content of Als in the argon blowing station according to the oxygen content in the oxygen determination result by feeding an aluminum wire; and (3) putting the ladle into a refining furnace, continuously introducing argon into the ladle, and adjusting the content of Als in a mode of adding aluminum particles.

6. A hot roll forming process of hot rolled X-shaped steel according to claim 3, wherein the outer edges of the rolls of the horizontal or vertical rolling mill are provided with smooth grooves which are matched with the ends of four supporting legs of the X-shaped steel to be rolled; the smooth groove is formed by connecting two fillets into a section of transition arc.

7. The hot rolling forming process of the hot rolling X-shaped steel according to claim 3, wherein when the blank is a beam blank, the heating temperature in a heating furnace is set to 1180-1220 ℃, the heating time is 90-180 min, the pressure of high-pressure dephosphorization is more than or equal to 10MPa, and the temperature of the steel billet after dephosphorization is more than or equal to 1150 ℃;

when rolling is carried out in a cogging mill, the cogging temperature is 1100-1140 ℃, the finishing temperature is more than or equal to 1020 ℃, 5-11 passes of rolling are carried out, the special-shaped blank is deformed one by one to form an X shape preliminarily, and the total section deformation compression ratio in the whole deformation stage is more than or equal to 20 percent;

when the four-roller reciprocating finishing mill rolls, the initial rolling temperature is 950-1050 ℃, the final rolling temperature is less than or equal to 960 ℃, the rolling is carried out for 7-13 times, and the total section deformation compression ratio in the whole deformation stage is more than or equal to 30%; and after rolling, the finished product enters a cooling bed at the temperature of 550-680 ℃, and then is subjected to air cooling.

8. The hot rolling forming process of hot rolled X-shaped steel according to claim 3, wherein when the blank is a round or rectangular blank, a single stand finish rolling is performed between the step 4) and the step 5), and the product rolled by the four-roll reciprocating finish rolling mill passes through a single stand rolling mill to ensure that the external dimension of the product meets the requirement of machining precision.

9. The hot rolling forming process of the hot rolling X-shaped steel according to claim 8, wherein when the blank is a round blank or a rectangular blank, the heating temperature in a heating furnace is 1180-1250 ℃, the heating time is 100-180 min, and the pressure of high-pressure dephosphorization is more than or equal to 12 MPa;

when rolling is carried out in a cogging mill, the cogging temperature is 1100-1150 ℃, the finishing temperature is more than or equal to 1050 ℃, rolling is carried out for 7-11 times, the blank is deformed one by one to form an X shape preliminarily, and the total section deformation compression ratio in the whole deformation stage is more than or equal to 25%;

when the four-roller reciprocating finishing mill rolls, the initial rolling temperature is 980-1050 ℃, the final rolling temperature is less than or equal to 980 ℃, rolling is carried out for 9-13 times, and the total section deformation compression ratio in the whole deformation stage is more than or equal to 35%; when the single stand is used for finish rolling, the initial rolling temperature is more than or equal to 920 ℃; and after rolling, the finished product enters a cooling bed at the temperature of 620-700 ℃, and then is subjected to air cooling.

Technical Field

The invention relates to the technical field of X-shaped steel forming processes, in particular to hot-rolled X-shaped steel and a hot-rolled forming process thereof.

Background

The column beam member of the X-shaped section steel is a common and important structural component in a building structure, and the common X-shaped section steel mostly uses the cross-shaped section steel as a main product member, but for beam column structures with special structures, if the cross-shaped section steel is adopted for structural design, serious material waste is caused for adopting bending-resistant tensile stress rod members at different positions.

The X-shaped steel widely adopted in the market at present is mainly of a cross structure, and the other parts are formed by butt welding steel plates or two same angle steels. However, for some high-rise buildings, especially for the part of the component carrying the very large bending load, the thickness is required to meet certain dimensional requirements under the condition of meeting the structural strength, and in addition, for the X-shaped structure, the thickness requirements for the different parts carrying the bending resistance and the tensile strength are different. Therefore, the existing product system is difficult to be used for matching X-shaped steel for high-rise buildings and other large structures.

At present, X-shaped steel, particularly cross-shaped steel, is mainly produced by welding, wherein one method is to weld a T-shaped steel and a steel plate, and the other method is to weld a large steel plate and two small steel plates to finally form a required X-shaped structure. However, the welding heat affected zone of the welded X-shaped steel has great influence on the overall mechanical property of the product, and the welding process greatly increases the labor cost and the equipment investment cost, thereby indirectly affecting the construction cost and the installation time of the engineering structure.

Disclosure of Invention

In order to solve the technical problems, the invention provides hot-rolled X-shaped steel and a hot-rolled forming process thereof according to the application of an X-shaped column beam component commonly used for a large building structure and the design of an actual rolling process, limits the overall dimension of the X-shaped steel, meets the actual market requirements and engineering assembly requirements, forms different types of blank shapes at one time through cogging and four-roller reciprocating finish rolling, has stable structure and strong load bearing capacity, and can be widely applied to the field of large building structures.

In order to achieve the purpose, the technical scheme adopted by the invention for solving the technical problems is as follows: the hot-rolled X-shaped steel is characterized by being formed by hot rolling a round billet, a rectangular billet or a special-shaped billet and comprising 4 supporting legs formed after mutual intersection, wherein the included angle between the two supporting legs at the upper part or the lower part is set to be 30-150 degrees, and the sum of the lengths of the two supporting legs in the same extension direction is set to be 300-1500 mm.

The thickness of 4 supporting legs sets up to 15 ~ 80mm, and the crossing department between 4 supporting legs is provided with the transition fillet, and the tip rounding off of 4 supporting legs.

The hot rolling forming process of the hot rolling X-shaped steel comprises the following steps:

1) and (3) casting and molding a blank: carrying out ladle pouring after molten iron pretreatment, converter smelting and argon blowing refining in sequence to obtain a required blank;

2) heating the blank and removing phosphorus: heating the blank at a set temperature for a period of time, and then conveying the blank to a high-pressure water phosphorus removal machine for phosphorus removal, so that the temperature of the phosphorus-removed blank is not lower than 1150 ℃;

3) rolling by a cogging mill: conveying the blanks subjected to high-pressure dephosphorization to a cogging mill, deforming the blanks one by one to form an X shape, and performing multi-pass rolling to finish primary rolling through extension distribution of each pass;

4) rolling by a four-roller reciprocating finishing mill: the blank which is primarily rolled is sent to a four-roller reciprocating finishing mill for rolling, the roll gap axis between a horizontal rolling mill and a vertical rolling mill is adjusted, and the shape required by the product is obtained after multi-pass rolling is carried out within the set cogging temperature range;

5) air cooling: and the rolled finished product is air-cooled to room temperature on a cooling bed, so that the transformation of ferrite and pearlite is realized in the cooling process.

In the step 1), in the molten iron pretreatment process, a slag removing machine is used for removing slag from the molten iron in the molten iron pretreatment process, and oxygen is blown after slag removal is finished to reduce the S content in the molten iron.

In the step 1), the argon blowing refining process is to continuously blow argon into molten steel smelted in a ladle, feed an aluminum wire according to the oxygen content in the oxygen determination result and control the content of Als in an argon blowing station; and (3) putting the ladle into a refining furnace, continuously introducing argon into the ladle, and adjusting the content of Als in a mode of adding aluminum particles.

Smooth grooves are formed in the outer edge of a roller of the horizontal rolling mill or the vertical rolling mill and matched with the end parts of four supporting legs of the X-shaped steel to be rolled; the smooth groove is formed by connecting two fillets into a section of transition arc.

When the blank is a special-shaped blank, the heating temperature in a heating furnace is set to be 1180-1220 ℃, the heating time is 90-120 min, the pressure of high-pressure dephosphorization is more than or equal to 10MPa, and the temperature of the steel blank after dephosphorization is more than or equal to 1150 ℃;

when rolling is carried out in a cogging mill, the cogging temperature is 1100-1140 ℃, the finishing temperature is more than or equal to 1020 ℃, 5-11 passes of rolling are carried out, the special-shaped blank is deformed one by one to form an X shape preliminarily, and the total section deformation compression ratio in the whole deformation stage is more than or equal to 20 percent;

when the four-roller reciprocating finishing mill rolls, the initial rolling temperature is 950-1050 ℃, the final rolling temperature is less than or equal to 960 ℃, the rolling is carried out for 7-13 times, and the total section deformation compression ratio in the whole deformation stage is more than or equal to 30%; and after rolling, the finished product enters a cooling bed at the temperature of 550-680 ℃, and then is subjected to air cooling.

And when the blank is a round blank or a rectangular blank, performing single-stand finish rolling between the step 4) and the step 5), and enabling the product rolled by the four-roller reciprocating finish rolling mill to pass through a single-stand rolling mill so as to ensure that the overall dimension of the product meets the requirement of machining precision.

When the blank is a round blank or a rectangular blank, the heating temperature in a heating furnace is set to 1180-1250 ℃, the heating time is 100-180 min, and the pressure of high-pressure dephosphorization is more than or equal to 12 MPa;

when rolling is carried out in a cogging mill, the cogging temperature is 1100-1150 ℃, the finishing temperature is more than or equal to 1050 ℃, rolling is carried out for 7-11 times, the blank is deformed one by one to form an X shape preliminarily, and the total section deformation compression ratio in the whole deformation stage is more than or equal to 25%;

when the four-roller reciprocating finishing mill rolls, the initial rolling temperature is 980-1050 ℃, the final rolling temperature is less than or equal to 980 ℃, rolling is carried out for 9-13 times, and the total section deformation compression ratio in the whole deformation stage is more than or equal to 35%; when the single stand is used for finish rolling, the initial rolling temperature is more than or equal to 920 ℃; and after rolling, the finished product enters a cooling bed at the temperature of 620-700 ℃, and then is subjected to air cooling.

The invention has the beneficial effects that:

1. the invention provides a hot-rolled X-shaped steel formed by hot rolling a round billet, a rectangular billet or a special-shaped billet, and according to the common application of an X-shaped column beam member and the actual rolling process design of a large building structure, the included angle between supporting legs of the X-shaped steel formed by rolling is 30-150 degrees, which accords with the connection and installation in the application of the current large building; the sum of the lengths of the two supporting legs in the same extension direction is 300-1500 mm, so that the common requirements of beam columns in large buildings are met, and the pressing distribution in the existing rolling process is met; and the intersection of the four supporting legs and the end parts of the supporting legs are in smooth transition, so that the cracking caused by stress concentration or collision in the assembling and using processes is avoided, and the service life of the supporting legs is prolonged.

2. The invention designs the shape of the box-shaped hole of the cogging mill and the elongation of each pass according to different shapes of blanks, can ensure that the size of an intermediate blank required by a finish rolling process is obtained in the rolling process, then the four-roller reciprocating finish rolling mill is used for rolling, the overall dimension, the thickness and the included angle between supporting legs of hot-rolled X-shaped steel can be jointly controlled by an upper roller, a lower roller, a left roller and a right roller of the four-roller reciprocating finish rolling mill, the rolling precision of products can be improved, and the groove-carving smooth processing can be carried out on the outer edge of the roller according to the structural characteristics of specific products by considering the production control of the X-shaped steel with different supporting leg lengths, supporting leg thicknesses and different included angles.

3. According to the invention, after the round billet and the rectangular billet are rolled by the cogging mill, the difference between the external dimension and the final finished product dimension is larger, single-pass finish rolling can be added after the four-roller finish rolling mill performs reciprocating rolling, and the control of the final accurate dimension can be realized.

In conclusion, the invention limits the external dimension of the X-shaped steel according to the application of the X-shaped column beam component commonly used in the large building structure and the actual rolling process design, meets the actual market requirement and the engineering assembly requirement, forms different types of blank shapes at one time through cogging and four-roller reciprocating finish rolling, has stable structure and stronger load bearing capacity, and can be widely applied to the field of large building structures.

Drawings

The contents of the expressions in the various figures of the present specification and the labels in the figures are briefly described as follows:

FIG. 1 is a schematic drawing showing the dimension of X-shaped steel;

FIG. 2 is a schematic view showing a structure of rolling an X-shaped steel on a four-roll reciprocating finishing mill;

FIG. 3 is a schematic view showing another structure of rolling an X-shaped steel on a four-roll reciprocating finishing mill;

FIG. 4 is a flow chart of the hot rolling process of X-shaped steel;

FIG. 5 is a schematic view of the configuration of the cogging rolling passes of the cogging mill in example 1;

FIG. 6 is a schematic view showing the configuration of the cogging rolling passes of the cogging mill in example 2;

FIG. 7 is a schematic structural view of rolling passes of a four-high reciprocating finishing mill in example 2;

FIG. 8 is a schematic view showing the rolling pass configuration of the single stand finishing mill in example 2;

the labels in the above figures are: 1. support legs, 2 transition fillets, 3 smooth grooves, 4 horizontal rolling mills and 5 vertical rolling mills.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and the following embodiments are used for illustrating the present invention and are not intended to limit the scope of the present invention.

In the description of the present invention, it should be noted that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "inner", "outer", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; may be directly connected or indirectly connected through an intermediate. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

The specific implementation scheme of the invention is as follows: as shown in fig. 1 to 3, a hot-rolled X-shaped steel is formed by hot-rolling a round billet, a rectangular billet or a beam blank, and comprises 4 supporting legs 1 formed after being intersected with each other, an included angle between two supporting legs 1 at the upper part or the lower part is set to be 30 to 150 degrees, in large-scale building application, two sides of a commonly used column beam are generally provided with supporting pieces such as a rod piece and the like and generally need to be connected by bolts or welding, so that the minimum included angle between the two legs is set to be not less than 30 degrees for facilitating secondary processing or installation of a structural part, and in order to improve the bearing capacity, the included angle between the two supporting legs 1 is less than 180 degrees. The length sum of the two supporting legs 1 in the same extending direction is set to be 300-1500 mm, the main basis is that the existing X-shaped steel is usually formed by welding angle steel or plates, the width of the plate surface is not less than 300 and the thickness is not less than 15mm in general requirements of beam columns of some large buildings, and therefore the length sum of the two legs in the same extending direction of the hot-rolled X-shaped steel is not less than 300 mm; in addition, for the current domestic section steel rolling mill, the maximum reduction extension of a rolled piece is limited by the blank thickness and the rolling capacity, the reduction distribution in the width direction can be properly carried out on the X-shaped steel by adopting a single-side skew rolling method, and the reduction is small for the thicker rolled piece, so that the maximum extension of a single supporting leg 1 in the same extension direction is not more than 800mm (the maximum width of the current domestic section steel rolling can reach 1000mm), and the maximum extension of two supporting legs 1 in the same extension direction is not more than 1500 mm.

Specifically, the thickness of 4 supporting legs 1 is set to be 15-80 mm, and the largest thickness of the flange of the domestic largest heavy H-shaped steel production line is about 100mm, so that the largest thickness of a single supporting leg 1 is limited to be smaller than 80mm according to the actual market requirement of hot-rolled X-shaped steel for a building structure. Moreover, the intersection between 4 supporting legs 1 is provided with transition fillet 2, and 4 supporting legs 1's tip rounding off, has avoided the fracture that produces because stress concentration or collide with in the assembly use, has prolonged its life.

As shown in fig. 4, the hot rolling forming process of the hot rolled X-shaped steel includes the following steps:

1) and (3) casting and molding a blank: carrying out ladle pouring after molten iron pretreatment, converter or electric furnace smelting, argon blowing refining, external refining and vacuum refining in sequence to obtain a required blank, wherein the blank can be a round blank, a rectangular blank or a special-shaped blank; in the molten iron pretreatment process, a slag removing machine is used for removing slag from the molten iron in the molten iron pretreatment process, and oxygen is blown after the slag removal is finished, so that the S content in the molten iron is reduced, and the molten iron desulfurization treatment is realized; the argon blowing refining process includes continuously blowing argon into molten steel smelted in a ladle, feeding an aluminum wire according to the oxygen content in the oxygen determination result, controlling the content of Als in an argon blowing station, ensuring that gas and impurities in the molten steel can be well removed in the argon blowing stage, ensuring the purity of the molten steel, continuously introducing argon into the ladle after the ladle enters a refining furnace, adjusting the content of Als in a mode of adding aluminum particles, fully realizing deoxidation and microalloy reaction, and ensuring the subsequent continuous pouring quality.

2) Heating the blank and removing phosphorus: heating the blank at a set temperature for a period of time, and then conveying the heated blank to a high-pressure water dephosphorization machine for dephosphorization, so that the temperature of the dephosphorized blank is not lower than 1150 ℃, and the blank is ensured to obtain relatively small deformation resistance in the rolling stage of the cogging stage, thereby being beneficial to the deformation flow of metal.

3) Rolling by a cogging mill: the method comprises the steps of conveying a blank subjected to high-pressure dephosphorization to a cogging mill, deforming the blank one by one to form an X shape, performing multi-pass rolling to finish primary rolling through extension distribution of each pass, ensuring that the size of an intermediate blank required in a finish rolling process is obtained in the rolling process, ensuring that the total section deformation compression ratio in the whole deformation stage is more than or equal to 20% when the blank is a special-shaped blank, and ensuring that the total section deformation compression ratio in the whole deformation stage is more than or equal to 25% when the blank is a round blank or a rectangular blank.

4) Rolling by a four-roller reciprocating finishing mill: the blank primarily rolled is sent to a four-roller reciprocating finishing mill for rolling, and the roll gap axis between the horizontal rolling mill 4 and the vertical rolling mill 5 is adjusted according to the shape and the size of the X-shaped steel to be processed. Considering the production control of X-shaped steel with different lengths of the supporting legs 1, the thicknesses of the supporting legs 1 and different included angles, the outer edges of the rollers can be subjected to groove-carving smooth treatment according to the structural characteristics of specific products, namely, smooth grooves 3 are formed in the outer edges of the rollers of the horizontal rolling mill 4 or the vertical rolling mill 5, the smooth grooves 3 are formed by connecting two round corners into a section of transition arc, and the smooth grooves 3 are matched with the end parts of four supporting legs 1 of the X-shaped steel to be rolled. For the X-shaped steel with a larger angle theta between the two upper supporting legs 1 and a longer length of the lower supporting leg 1(L3 or L4), in order to limit the short supporting leg 1 to have a larger extension in the rolling process, convex angle notching can be carried out on the upper roller and the lower roller of the vertical roller mill 5 to form a smooth groove 3, which is particularly shown in FIG. 2; for the X-shaped steel with smaller theta value (30 degrees to 45 degrees), considering the abundance of metal flowing under the condition of single supporting leg 1 and considering the leg length control of the finished product, the smooth grooves 3 can be formed by carrying out convex angle notching on the horizontal roller of the horizontal rolling mill 4, which is shown in detail in figure 3. The grooving of the roller is controlled and selected according to the actual product size requirement and the actual rolling process, and is not limited to the two grooving selection modes, and the smooth grooves 3 can be arranged on the horizontal roller and the vertical roller to achieve the effect of the figure 1 or the figure 2.

The shape required by the product is obtained after the blank subjected to primary rolling is subjected to multi-pass rolling within a set cogging temperature range, the temperature of a cogging rolling section is required to be higher than the austenite complete recrystallization temperature in the process, and fine original austenite grains can be obtained. The process mainly ensures rolling large deformation to realize original grain refinement in the reciprocating stage. When the blank is a special-shaped blank, the total section deformation compression ratio of the whole deformation stage is ensured to be more than or equal to 30 percent, and when the blank is a round blank or a rectangular blank, the total section deformation compression ratio of the whole deformation stage is ensured to be more than or equal to 35 percent.

5) Air cooling: the rolled finished product is air-cooled to room temperature on a cooling bed, so that the transformation of ferrite and pearlite is realized in the cooling process, and good mechanical properties are obtained.

When the blank is a special-shaped blank, the blank is rolled by a cogging mill, the difference between the external dimension and the final finished product dimension is not large, the dimension precision after the four-roll finishing mill rolls back and forth can meet the requirement, and further processing is not needed; when the blank is a round blank or a rectangular blank, the difference between the external dimension and the final finished product dimension is larger after the blank is rolled by a cogging mill, single-pass finish rolling can be added after the four-roll finishing mill performs reciprocating rolling, and the control of the final precise dimension can be realized.

Example 1

As shown in fig. 1, in this embodiment, in order to produce a hot-rolled X-shaped steel having two identical support legs 1, i.e., L1, L2, L3 and L4, and 4 identical support legs 1, i.e., T1, T2, T3 and T4, the specification of the hot-rolled X-shaped steel is XS500 × 300 20, i.e., L1 and L2 are 500mm, L3 and L4 are 300mm, T1, T2, T3 and T4 are 20mm, θ is 30 ° and R1 is R2 is 20 mm. And is roll formed using a beam blank.

The hot rolling production process of the hot rolling X-shaped steel comprises the following steps:

pretreating molten iron: the time of the molten iron pretreatment procedure is less than or equal to 30 minutes; the visual slag removal bright surface is more than or equal to 70 percent; and (4) blowing after slagging-off is finished, wherein [ S ] discharged from the station is less than or equal to 0.015%.

Smelting in a converter: the dosage of the molten iron is 75-85 tons; the steelmaking reference process time is 25-35 minutes; the final point pressure gun is more than 20 seconds, and the tapping time is more than 1 minute.

Argon blowing (alloy trimming): the time of the argon blowing station is less than or equal to 10 minutes; and (3) oxygen determination, feeding aluminum wires, and controlling the content of Als discharged from the station to be in the range of 0.005-0.025 percent according to the oxygen determination result.

LF refining: the LF slagging time is less than or equal to 25 minutes; controlling argon flow while blowing with large argon flow; the content of Als is adjusted to be 0.010-0.020% by adding aluminum particles.

Pouring a steel ladle: adopting whole-process protective casting; the open pouring time is not more than 30 seconds when each furnace is continuously poured; the tundish adopts argon micro-positive pressure protection, and the depth of the working liquid level of the tundish is more than or equal to 500 mm. The tundish adopts a water gap and a stopper rod; the crystallizer is automatically controlled by an external submerged nozzle stopper.

Heating the blank and removing phosphorus: heating a deformed blank of 750 multiplied by 450 multiplied by 120mm (the deformed blank is a near-net-shape H-shaped blank, the section length of the deformed blank is 750mm, the width of the deformed blank is 450mm, the flange thickness of the deformed blank is 120mm) in a heating furnace, the heating temperature is 1180-1220 ℃, the heating time is 90-120 min, then carrying out high-pressure water descaling, the descaling needs to be ensured to be clean, the descaling pressure is more than or equal to 10MPa, and the temperature of the descaled blank is not lower than 1150 ℃ before the discharged blank of the heating furnace is sent to a cogging mill for rolling.

Rolling by a cogging mill: conveying the blanks subjected to high-pressure dephosphorization to a cogging mill, wherein the cogging temperature is 1100-1140 ℃, the finish rolling temperature is not lower than 1020 ℃, the temperature of a rolling section of the cogging mill is ensured to be higher than the austenite complete recrystallization temperature, the rolling is carried out for 5 passes in the whole BD rolling stage, the cogging stage mainly comprises the step of rolling and deforming the upper and lower support legs of the special-shaped blank into an X shape, and the total section deformation compression ratio of the whole deformation stage is 42%.

Rolling by a four-roller reciprocating finishing mill: adjusting the roll gap axis between the horizontal rolling mill 4 and the vertical rolling mill 5 to be 30 degrees, the starting rolling temperature to be 950-1050 ℃, rolling for 7 passes, the final rolling temperature is not higher than 960 ℃, the process mainly ensures rolling large deformation to realize grain refinement in the back-and-forth stage, and the total section deformation compression ratio in the whole deformation stage is 66 percent.

The rolling parameters in the cogging rolling stage and the four-high finishing rolling stage are shown in table 1.

Table 1 rolling parameters of example 1

Wherein the content of the first and second substances,

as can be seen from table 1, in the cogging stage, as the multiple rolling passes proceed, the flanges of the original blank are deformed into two adjacent support legs in an X shape. Meanwhile, in consideration of the size of the four-roll finish rolling stage, the subsequent deformation reduction is fully considered in the cogging stage, the pass thickness of the upper supporting leg is set to be larger than that of the lower supporting leg by adjusting the rolling pass, so that the upper supporting leg is subjected to compression upsetting deformation on the lower supporting leg in the cogging rolling process, the 'elongation' deformation of the upper and lower supporting legs of the special-shaped blank is realized in the last cogging pass, and the pass of cogging rolling is shown in fig. 5; in the four-roller finish rolling stage, the section deformation compression ratio is gradually reduced along with the multi-pass rolling, the roll gap axis between the horizontal rolling mill 4 and the vertical rolling mill 5 is unchanged, the included angle between two support legs of a product is ensured to be 30 degrees, metal is enabled to flow in a limited mode through groove pass of an upper horizontal roller and a lower horizontal roller, the extension deformation of the support legs of the finished product is realized, and the pass of the four-roller reciprocating finish rolling mill is shown in figures 2 and 3. And pressing is carried out between each pass along the roll gap axis, so that the thickness of the two supporting legs is ensured to be gradually reduced, and the specification and thickness of a finished product are finally realized. The X-shaped blank is formed preliminarily in the cogging rolling stage, and the grain refinement is realized after the blank is subjected to large deformation in the four-roll finish rolling stage, so that the performance of a finished product can be improved.

Air cooling: and after rolling, the steel is air-cooled and cooled to room temperature in an upper cooling bed, wherein the temperature of the upper cooling bed is 550-680 ℃, so that the transformation of ferrite and pearlite is realized in the cooling process, and good mechanical properties are obtained.

By sampling the hot-rolled X-shaped steel long supporting legs with the specifications of XS 500X 300X 20 along the rolling direction, the room-temperature tensile yield strength can reach 392MPa to 488MPa, the tensile strength can reach 512MPa to 622MPa, and the cold bending D is 3T₃(the cold bending diameter is 3 times the thickness T of the support leg₃) And (4) passing.

Example 2

As shown in fig. 1, this example is intended to produce hot-rolled X-shaped steel of L1, L3, L2 and L4, the specifications of which are XD900 × 450 × 35 × 50, indicating that L1 and L2 are 900mm, L3 and L4 are 450mm, T1 and T2 are 35mm, T3 and T4 are 50mm, θ is 90 °, R1 is 25 and R2 is 30, with two support legs 1 of different lengths and thicknesses. And is formed by rolling a rectangular blank.

The hot rolling production process of the hot rolling X-shaped steel comprises the following steps:

pretreating molten iron: the time of the molten iron pretreatment procedure is less than or equal to 30 minutes; the visual slag removal bright surface is more than or equal to 70 percent; and (4) blowing after slagging-off is finished, wherein [ S ] discharged from the station is less than or equal to 0.015%.

Smelting in a converter: the dosage of the molten iron is 55-65 tons; the steelmaking reference process time is 25-35 minutes; the final point pressure gun is more than 20 seconds, and the tapping time is more than 1 minute.

Argon blowing (alloy trimming): the time of the argon blowing station is less than or equal to 10 minutes; and (3) oxygen determination, feeding aluminum wires, and controlling the content of Als discharged from the station to be 0.005-0.020% according to the oxygen determination result.

LF refining: the LF slagging time is less than or equal to 25 minutes; controlling argon flow while blowing with large argon flow; the Als component is adjusted to 0.010-0.020% by adding aluminum particles.

Pouring a steel ladle: the whole-process protection casting is adopted, and the tundish adopts a water gap and stopper rod form.

Heating the blank: heating the rectangular billet with the diameter of 600 multiplied by 450mm in a heating furnace, wherein the heating temperature is 1180-1240 ℃, the heating time is 100-150 min, and then carrying out high-pressure water descaling, wherein the descaling needs to be ensured to be clean, the descaling pressure is more than or equal to 10MPa, and the temperature of the steel billet after descaling is not lower than 1150 ℃ before the billet discharged from the heating furnace is sent to a cogging mill for rolling.

Rolling by a cogging mill: and conveying the high-pressure dephosphorized blank to a cogging mill, wherein the cogging temperature is 1100-1150 ℃, the finish rolling temperature is not lower than 1050 ℃, the temperature of a rolling section of the cogging mill is ensured to be higher than the austenite complete recrystallization temperature, the whole cogging rolling stage is rolled for 7 passes in total, and the total section deformation compression ratio of the whole deformation stage is 28%.

Rolling by a four-roller reciprocating finishing mill: adjusting the roll gap axis between a horizontal rolling mill 4 and a vertical rolling mill 5 to be 90 degrees, the start rolling temperature to be 980-1050 ℃, rolling for 9 passes, the final rolling temperature is not higher than 980 ℃, the process mainly ensures rolling large deformation to realize grain refinement in the round-trip stage, and the total section deformation compression ratio in the whole deformation stage is 45 percent.

Finish rolling with a single frame: the initial rolling temperature is not lower than 920-960 ℃, the procedure mainly ensures the external dimension of the product and accurately controls the length and the R angle of the support leg 1 with the specification of the final product.

The rolling parameters in the cogging rolling stage, the four-high finishing rolling stage and the single stand finishing rolling stage are shown in table 2.

Table 2 rolling parameters for example 2

As can be seen from table 1, in the cogging stage, as the multi-pass rolling is performed, the upper and lower cogging mills are used to roll the billet into an X shape (90 °) with the upper and lower supporting legs perpendicular to each other, and two intermediate billets with different leg lengths are rolled by cogging heavy reduction, and the pass of the cogging mills is shown in fig. 6; in the four-high finishing stage, as the multi-pass rolling is carried out, the roll gap axis between the horizontal rolling mill 4 and the vertical rolling mill 5 is unchanged (90 degrees), the length of the shorter supporting leg of the final product is controlled by the vertical horizontal pass (L3/L4), the extending width of the longer supporting leg is controlled by the left and right vertical rolling, so that the length of the supporting leg of the finished product is controlled (L1/L2), and the pass of the four-high reciprocating finishing mill is shown in FIG. 7. In the single-stand finish rolling stage, finish rolling forming is performed on the final size through setting of the size and the shape and the fillet parameters of a single pass, and the pass of the single-stand finish rolling mill is shown in FIG. 8. The round billet or the rectangular billet is preliminarily formed into an X shape (90 degrees) in the cogging rolling stage, and the billet is subjected to large deformation in the four-roller finish rolling stage to realize grain refinement, so that the performance of a finished product can be improved.

Air cooling: after rolling, the steel is put on a cooling bed for air cooling and is cooled to room temperature, the temperature of the cooling bed is 600-700 ℃, the transformation of ferrite and pearlite is ensured to be realized in the cooling process, and good mechanical properties are obtained.

By sampling the hot-rolled X-shaped steel long supporting legs with the specification of XD900, 450, 35 and 50 along the rolling direction, the room-temperature tensile yield strength can reach 344-427 MPa, the tensile strength can reach 471-585 MPa, and the cold bending D is 3T₃(the cold bending diameter is 3 times the thickness T of the supporting leg₃) And (4) passing.

In conclusion, the invention limits the external dimension of the X-shaped steel according to the application of the X-shaped column beam component commonly used in the large building structure and the actual rolling process design, meets the actual market requirement and the engineering assembly requirement, forms different types of blank shapes at one time through cogging and four-roller reciprocating finish rolling, has stable structure and stronger load bearing capacity, and can be widely applied to the field of large building structures.

While the foregoing is directed to the principles of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.