JP2001047102A - Manufacture of h-shape steel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method without necessitating a stage for straightening strain in the manufacture of an H-shape steel in which accelerating cooling is executed in order to imparting high strength and high toughness after finish rolling. SOLUTION: In a stage in which the H-shape steel is formed by finish rolling after rolling a bloom into a base stock having the shape of the H-shape steel with a break down mill and roughly rolling the dimensions of each part, before the finish rolling stage, cooling for unifying the temperature distribution on the outside surface of flanges or lowering the temperature in fillet parts at this temperature distribution is executed and, after that, the finish rolling by which the opening angle of the flanges becomes zero is executed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an H-section steel which performs cooling after hot rolling, and more particularly to a method for efficiently manufacturing an H-section steel without cooling using a straightening machine or press after cooling.

[0002]

2. Description of the Related Art In recent years, there has been an increasing demand for seismic resistance of architectural members, and H-section steels having excellent strength and toughness have been demanded for columns and beams, and controlled rolling and controlled cooling have been applied as manufacturing methods. Have been.

[0003] Control rolling and controlled cooling are general methods for high-strength and high-toughness steel materials, and controlled rolling is used for slabs and CCBBs (continuous cousins) heated to 1000 ° C or more.
Asting beam blank) The material is subjected to rough rolling once to a medium thickness, and then the final finish rolling is performed in the temperature range where the temperature of the steel sheet is at or near the non-recrystallization temperature range, and controlled cooling is accelerated after rolling. Ar by cooling
It cools from three temperatures or more to about 500 ° C. to secure the strength.

[0004] As a method of performing controlled cooling of an H-section steel flange by an accelerated cooling device at the rear of a finish rolling mill,
Simultaneous cooling from inside and outside of flange (Japanese Patent Publication 5-7)
No. 3806, hereinafter referred to as prior art 1), a method in which spray nozzles are arranged in multiple stages and the outer surface of a flange of an H-section steel is cooled from behind a guide through a slit provided in the guide (Japanese Patent Laid-Open No. 5-317948, hereinafter referred to as prior art 2). ).

In the case of the prior art 1, the H-section steel itself is, as shown in FIG. 1, a flange 1, a flange width (H), a flange thickness (t2), a web 2, a web height (B), and a web thickness (t1). In order to efficiently manufacture various types of H-section steel, the width, position, height, etc. of the cooling device on the inner surface of the flange must be changed to a complicated structure that can be easily changed, or the cooling must be performed. A mechanism that allows the position of the device to be freely adjusted is required. Further, since a cooling device is provided on the inner surface, there is a risk of collision with the H-shaped steel, and there is a problem in terms of stable operation.

In prior art 2, the spray nozzles are arranged in multiple stages to cool the outer surface of the flange. In the case of strong cooling such as accelerated cooling, the outer surface of the flange is cooled during accelerated cooling because the flange is cooled only from the outer surface. (Fig. 2)
(1)) occurs. After cooling, as the overall temperature decreases on the cooling floor, the flange outer surface becomes bent (FIG. 2).
When (2)) occurred and the H-section steel was at room temperature, a bend having a convex flange outer surface remained, and after that, straightening work by a straightening machine or a press occurred. In particular, it is difficult to perform a straightening operation for a bending in which the remaining bending makes the outer surface of the flange convex, resulting in an increase in cost.

[0007]

As described above, in the method of performing controlled cooling by the accelerated cooling device at the rear of the finishing mill, the method of cooling from the inner and outer surfaces becomes complicated, and the method of cooling from the outer surface is performed after cooling. , A straightening process was indispensable. The present invention provides a method for producing an H-section steel having a small thermal strain by only cooling from the outer surface without using a complicated apparatus.

[0008]

Means for Solving the Problems The present inventors studied in detail the effect of the temperature distribution of each part of the H-section steel on the shape of the H-section steel after the cooling step, and found that the temperature distribution of the flange outer surface before finish rolling was reduced. I understood what was important. That is, the temperature distribution on the outer surface of the flange is substantially uniform or the fillet portion 3
(FIG. 1, in FIG. 1, the base of the flange 1 and the base of the web 2) is made to have a low temperature, and then the finish angle is set to zero by finish rolling. , It was possible to maintain vertical.

The gist of the present invention is as follows.

[0010] 1. After the finish rolling, the cooling water is sprayed on the outer surface of the flange to cool the H-shaped steel.
Before the finish rolling step, the outer surface temperature distribution of the flange is uniform, or a step of performing cooling to make only the fillet part lower than the peripheral part, and after the rolling, a finish rolling step is provided such that the opening angle of the flange becomes zero. A method for producing an H-beam.

[0011]

FIG. 4 is a schematic view showing an embodiment of the production of the present invention. After heating the slab with the heating furnace 7,
The material is rolled into an H-shaped steel material by a breakdown mill 8, and the respective parts are roll-formed by reverse rolling in a first rough rolling mill group 9 and a second rough rolling mill group 11. Thereafter, finish rolling is performed. In the present invention, the fillet portion is cooled from the outside before the finish rolling, so that the temperature distribution on the outer surface of the flange is uniform, or the fillet portion is set at a low temperature in the temperature distribution. The term “uniform” in the present invention means that the temperature of the fillet portion is + 30 ° C. to −50 ° C. in comparison with the temperature of the flange portion, as long as the object of the present invention can be achieved.
The temperature may be within the range of ° C. Here, the temperature of the fillet portion is the outer surface reheating temperature at 1/2 B from the upper or lower end of the flange, and the flange temperature is the outer surface reheating temperature at 1/4 B from the upper or lower end of the flange.

The fillet portion has a large thermal capacity and is not easily cooled, and becomes high in the temperature distribution of the flange outer surface before the finish rolling, which causes deformation due to thermal strain after the cooling step, so that the fillet portion is cooled. Cooling may be performed after the rough rolling step and before the finish rolling, and the timing and method are not particularly specified,
In this embodiment, in consideration of equipment costs, the side guides 10a and 10b provided before and after the rough rolling mill are spray nozzles capable of changing the nozzle height and spray width to selectively cool the fillet portion on the outer surface of the flange. The fillet was cooled from the outer surface of the flange.

After cooling, the vertical roll 5 of the finishing mill 12
a, 5b, the gap between the horizontal rolls 6a, 6bAdjustment
After finishing the opening angle of the flange after rolling to zero,
The outer surface of the flange is accelerated and cooled by the cooling device 13, and thereafter,
After cutting to a predetermined length with a hot cutting machine, the cooling floor 14 is cooled to room temperature.
Left.

[0014]

EXAMPLES The effects of the present invention will be described with reference to examples. Hereinafter, using the equipment arrangement row shown in FIG. 4, the web height H at the end of the finish rolling is 572 mm, and the flange width B is 510 m.
An example in which an H-section steel having a thickness of 13 mm, a web thickness of 60 mm, a flange thickness of 80 mm, and a length of 13 m will be described.

In this embodiment, a slab having a thickness of 250 mm is heated to 1250 ° C. by a heating furnace 7, and then rolled into an H-shaped steel material by a breakdown mill 8. Are roll-formed by reverse rolling in the rough rolling mill group 11 described above. Reverse rolling was controlled rolling. After the rough rolling, reverse rolling is performed by a universal roughing mill 11, the fillet portion is cooled, finish rolling is performed, and then the flange is accelerated and cooled.

The cooling of the fillet portion is performed by the second rough rolling mill 1
Side guides 10a, 10b each having a length of about 10 m each around 1
The cooling device provided in the above section fillets the outer surface of the flange with a water density of 1500 l / min over a width of 70 mm.
At 2, it was cooled. As a result, only the fillet portion is at a low temperature of about 850 ° C. at the outer peripheral portion of the flange at about 900 ° C., which is about 15 ° C. lower than when the fillet portion is not cooled.
The temperature had dropped by 0 ° C.

Immediately before the finishing mill 12, the heat is recovered and the temperature rises by about 20 to 30 ° C. The temperature of the outer surface of the flange was the reheat temperature of the outer surface at a position 1 / 4B from the upper or lower end of the flange, and the temperature of the fillet portion was the temperature at 1 / 2B.

In the finish rolling, at the end of the rough rolling, the shape in which the opening angle α of the flange is opened outward at 0.46 degrees is rolled so that the opening angle α becomes zero, and the flange is made vertical. Thereafter, the H-shaped steel was carried into the cooling device 13, and at the same time as the rear end entered the device, the cooling water was discharged at a water density of 1500 l / m.
Inject with inm2 and oscillate 120
Cooled for seconds. After cooling and reheating, the above-mentioned flange outer surface temperature was 500 ° C. and was uniform in the longitudinal direction.

After cooling, the sample was measured and cut by a hot cutting machine, transported to a cooling floor, and allowed to cool naturally. Even at room temperature, the opening angle α of the flange was zero, and there was no need for correction.

Next, as Comparative Examples 1 to 3, H-shaped steels were manufactured by changing the temperature distribution on the outer surface of the flange depending on whether or not the outer surface of the flange was cooled and the time of cooling. Each comparative example was manufactured using the equipment arrangement row shown in FIG. 4 as in the example of the present invention.

In Comparative Example 1, finish rolling is performed at the stage of rough rolling without cooling the outer surface of the flange. After the rough rolling, the temperature distribution of the flange outer surface before the finish rolling is 1000 ° C. in the fillet portion and the flange is The fillet portion has a middle and high shape with a high temperature of 900 ° C.

In Comparative Example 2, at the stage of rough rolling, the entire width of the flange was cooled by a cooling device incorporated in the side guide of the second rough rolling mill. The fillet portion was 850 ° C. and the flange was 800 ° C.

In Comparative Example 3, the outer surface of the flange was not cooled before the finish rolling, and only the fillet portion was cooled immediately before the accelerated cooling after the finish rolling. The cooling was performed under the same conditions as the fillet cooling conditions during rough rolling in the above-described embodiment of the present invention. As described above, in any of the comparative examples, the finish angle was such that the opening angle of the flange was zero and the flange was raised. After that, accelerated cooling for improving the strength was performed, and after measuring and cutting with a hot cutting machine, the wafer was conveyed to a cooling floor and allowed to cool naturally.

When the temperature reached room temperature, the outer dimension Hc of the toe of the flange and the center Ht of the flange shown in FIG. 5 were measured. Table 1 shows the measurement results of the examples of the present invention. In any of the comparative examples, it was necessary to correct the opening angle of the flange by repeated bending of the straightener. In the case of Comparative Example 1, it was difficult to make the opening angle of the flange zero, because the inward fall of the flange was large. Comparative Examples 2 and 3
In Comparative Example 1, although the inward fall of the flange was smaller than that in Comparative Example 1, a correction operation was required.

Further, the strength of the flange portion of the H-section steel according to Comparative Example 2 was reduced at 1/4 and 3/4 from the top of the flange portion.
It is considered that the cooling start temperature in the accelerated cooling after the finish rolling was lower than the temperature required for securing the strength except for the fillet portion.

[0026]

[Table 1]

[0027]

As described above, according to the present invention, when an H-section steel excellent in strength and toughness is manufactured by accelerated cooling, the deformation of the flange due to cooling does not occur. Becomes unnecessary, and high-efficiency production at low cost becomes possible.

[Brief description of the drawings]

FIG. 1 is a diagram showing names of respective parts of an H-section steel.

FIG. 2 is a view showing the shape of an H-section steel in a cooling process after finish rolling, wherein (1) shows a state of deformation after accelerated cooling, and (2) shows a deformed state after cooling on a cooling floor.

FIG. 3 shows the state of finish rolling. (1) is the opening angle α of the flange before rolling, (2) is the shape after rolling,
(3) shows the situation during rolling

FIG. 4 is a diagram showing an arrangement of equipment for manufacturing an H-section steel.

FIG. 5 is a view showing deformation of a flange in an H-section steel.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Flange 2 ... Web 3 ... Fillet 4 ... Flange opening angle 5a, 5b ... Vertical roll 6a, 6b ... Horizontal roll 7 ... Heating furnace 8 ... Breakdown rolling mill 9 ... First rough rolling mill group 10a, 10b ... Side Guide (cooling device) 11 ... second rough rolling mill group 12 ... finishing rolling mill 13 ... cooling device 14 ... cooling floor

Continued on the front page (72) Inventor Tsuruwa Arimura 1-2-1 Marunouchi, Chiyoda-ku, Tokyo F-term (reference) 4E002 AC03 BB05 BB07 BC07 BD07 CB01 CB08

Claims (1)

[Claims] 1. A method for producing an H-section steel, in which cooling water is injected onto a flange outer surface after finish rolling to cool the flange, wherein the temperature distribution of the flange outer surface is made uniform or only the fillet portion is removed from the peripheral portion before the finish rolling step. A method for producing an H-section steel, comprising: a cooling step of reducing the temperature to a low temperature; and a finish rolling step of reducing the opening angle of the flange to zero after rolling.