JPS629702A - Production of rough shape billet - Google Patents

Abstract

PURPOSE:To improve the toughness of a fillet part and to decrease the anisotropy of an impact characteristic by rolling a slab obtd. by forging with plural box calibers which are provided with bulging parts in the central part and are successively increased in the caliber width, rolling further the slab with box calibers having a flat bottom then forming the rough billet. CONSTITUTION:The slab 12 is cast from a steel ingot 10 by forging. The slab 12 having the decreased anisotropy of the structure and inclusions is thus obtd. The slab 12 is successively rolled with the plural box calibers which are provided with the bulging parts in the central parts and are successively increased in the caliber width to form an intermediate billet 14 made into a dogbone sectional shape having grooves 14B on the thick surfaces 14A. The intermediate billet 14 are rolled with the box calibers having the flat bottom to form the intermediate billet 15 having the flat thick surface 15A. The billet is rolled by forming calibers to form the rough billet 16 for a wide flange beam. Then the anisotropy of the structure and inclusions in the part to be formed as the fillet part 20A of the shape steel 20 is decreased.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a method for manufacturing a rough-shaped steel billet, and in particular, the production of a rough-shaped steel billet suitable for use in manufacturing a rough-shaped steel billet for rolling a shape steel having a web and seven flange. Concerning improvements in methods.

[Conventional technology]

Conventionally, shaped steel having wear and flanges such as H-shaped W4 or (hereinafter referred to as a beam blank) and a shape steel rolling process to produce a shape steel from the beam blank obtained in the blooming process. In addition, in the above-mentioned blooming rolling process, in order to manufacture high-quality rough-shaped steel pieces with high efficiency and good walking speed, Japanese Patent Application Laid-Open No. 56-4100
As shown in Fig. 2, the continuous casting slab is rolled down in the width direction using a box hole mold with a bulge in the center of the hole, and the width is widened at both ends of the slab in the width direction. A beam blank is produced by obtaining a steel billet and then rolling the intermediate steel billet in a shaped hole die.

[Problems to be solved by the invention]

On the other hand, in recent years, resource development in cold regions has been active in order to deal with energy issues, and with this resource development, demand for steel sections such as H-beams and I-beams has been increasing in cold regions. Furthermore, structures conventionally manufactured by welding 1-III are being replaced by shaped steel such as rolled H-shaped steel from the viewpoint of reducing manufacturing costs. Rolled shaped steel used as a substitute for shaped steel used in such cold regions and shaped steel manufactured by welding has an excellent impact resistance at the joint between the wear part and the flange part (hereinafter referred to as the fillet part). In addition, it is required to have impact characteristics with less directionality. In other words, when using H-shaped steel, etc., gas cutting is usually performed on a part of the wear part or flange part, but at this time, if the mechanical properties of the fillet part are poor, cutting that is similar to gas cutting is usually performed. There is a possibility that cracks may occur along the fillet portion due to the chipping. This cracking is due to the influence of residual stress existing in the fillet, and is more severe in colder working environments and poorer fillet toughness. Therefore, in the shaped steel used in cold regions and the roll shaped steel described above, the fillet portion is required to have approximately the same mechanical properties as other wear portions and flange portions. However, the conventional type W4+! In the tin method, each manufacturing process from the steel ingot to the product is unidirectional rolling extending in the longitudinal direction, and the rolling force is difficult to propagate to the fillet portion, and the material within the cross section of the section steel is web-like. The fillet portion is inferior in strength and toughness compared to the fillet portion and the flange portion. Therefore, there is a problem that it is not possible to add m to the above requirements. Furthermore, steel sections such as H-section steel manufactured by conventional manufacturing methods have a problem in that the impact value of the fillet portion is much smaller than that of other web portions and flange portions. As described above, the fillet portion is inferior in strength and toughness, and its impact value is extremely small. This is due to the fact that the temperature of the fillet part is higher than that of other flange parts and wear parts (and the degree of processing of the fillet part is lower than that of other web parts and flange parts. As one of the solutions to this problem, the present applicant has already reported in Japanese Patent Publication No. 59-21681 that the fillet can be improved by adjusting the hole shape of the universal rolling mill, the number of baths, and the rolling temperature of each bath. We have proposed a method for manufacturing shaped copper that improves the strength and toughness of the fillet section by increasing the amount of strain in the fillet section.However, even in the above method for manufacturing shaped steel, each process from the steel ingot to the product is Since rolling is done in one direction, elongating in the longitudinal direction, there is a large degree of anisotropy in the impact properties in the fillet part, and the strength and toughness of the fillet part have not yet been sufficiently improved, compared to the wear part and flange part. However, the strength and toughness of the fillet portion were poor.

[Purpose of the invention] The present invention has been made to solve the above-mentioned conventional problems, and aims to improve the toughness of the fillet portion, reduce the anisotropy of impact properties, and uniformize the material quality within the cross section of the section steel. The purpose of the present invention is to provide a method for manufacturing rough-shaped steel slabs that can be produced. [Means to solve the problem]

As summarized in FIG. 1, the present invention is a method for manufacturing a coarse copper piece, including a step of manufacturing a slab from a steel ingot by forging, and a step of manufacturing the slab 143i! A first rolling step in which the slab obtained in the first rolling step is rolled in a plurality of box hole molds in which a bulge is provided in the center and the hole width is sequentially widened; A second rolling step in which the obtained intermediate steel slab is rolled in a flat-bottomed box hole die, and the intermediate steel billet obtained in the second rolling step is rolled in a shaping hole die to produce a rough shaped steel billet for H-beam steel. By having the third rolling step, the above object is achieved. (Function) When manufacturing a rough shaped steel piece for rolling a shaped steel having a wear and a flange, such as H-shaped steel or ■-shaped steel, the present invention first starts from a steel ingot 10 as shown in FIG. The slab 12 is manufactured by forging. Therefore, since the slab 12 is manufactured from the steel ingot 10 by forging, it is possible to manufacture the slab 12 with less anisotropy of fibers and inclusions.Thereby, The anisotropy of the structure and inclusions in the fillet portion 2OA of the section steel 20 manufactured from the slab 12 can be reduced. The intermediate steel piece 14 is then rolled in a plurality of box hole molds whose hole widths are sequentially widened to form an intermediate steel piece 14 having a dogbone cross-sectional shape and having a groove 14B corresponding to the bulged portion on the thickness surface 14A. The intermediate steel pieces 1, 15 are rolled in a box hole die to form a dog-bone cross-sectional shape with a flat thickness surface 15A, and the intermediate steel pieces 1, 15 are rolled in a shaping hole die with a dog-bone cross-section shape with a flat thickness surface 16A. It is designed to be a rough shaped steel piece 16 (beam blank) for H-shaped steel.Therefore, the box hole-shaped bulging portion adds strain to the portion that will become the fillet portion 2OA of the shaped steel 20, and furthermore, Since the strain is propagated not only in the rolling direction but also in the flange width direction and flange thickness direction perpendicular to the rolling direction, it is possible to further reduce the anisotropy of II cracks and inclusions in the fillet portion 20A. It is possible to improve the toughness of the fillet portion 2OA when rolled into the shape 1120, reduce the anisotropy of impact properties, and make the material uniform in the cross section of the shape steel.

【Example】

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the method for manufacturing a coarse copper piece according to the present invention will be described in detail below with reference to the drawings. As shown in FIGS. 2 and 3, the manufacturing equipment for the rough-shaped steel billet of this embodiment includes a slab forging machine (not shown) that manufactures a slab 12 from a steel ingot 10 by forging, and a slab forging machine using the slab forging machine. The slab 12 is rolled into an intermediate steel piece 15 having a dogbone cross-sectional shape. A plurality of box hole molds 22 and 24 are provided with the bulging portion 21 in the center and the holes @ W are sequentially widened, and the holes are made from the box hole mold 24 in the previous stage. Box hole type 2 with wide width W and flat bottom
6, and a blooming roll hole mold 3 provided with a plurality of shaping holes 28 for rolling the intermediate steel piece 14.15 obtained by the plurality of box hole molds 22, 24, and 26 into a beam blank 16.
It consists of a rolling mill equipped with 0. Next, the operation of this embodiment will be explained. First, as shown in Figure 2, a steel ingot is
0 is forged into a slab 12 with less anisotropy of structure and inclusions. Next, using the slab 12, as shown in FIG.
．． A beam blank 16 is manufactured by 28. That is, first, as shown in FIG. 3(A), a hole mold 22 is provided in the center thereof with a bulge 21 having approximately the same apex angle as that of the slab 12.
Rolling is performed in the width direction. By this rolling in the width direction, grooves are formed in the thickness surface of the slab 12, resulting in an intermediate steel piece 14 having a dogbone cross-sectional shape and having grooves 14B corresponding to the bulges 21 in the bulging surface 14A of the slab 12. Next, similar rolling in the width direction is performed as shown in FIG. This is done by the mold 24. In this way, the middle MtlJ piece 14 has a thickness surface 14A1, that is,
The flange is formed into a dog-bone cross-sectional shape that becomes wider in sequence. The rolling in these box-hole molds 22 and 24 is performed a plurality of times using the same box-hole mold until the flange width of the intermediate steel piece 14 having a dogbone cross-sectional shape becomes approximately equal to the hole width W of the hole. Therefore, the product form 1120
A strain is applied by the bulging portion 21 to the portion of the intermediate steel slab 14.15 corresponding to the fillet portion 2OA, and the strain is applied not only in the rolling direction but also in the flange width direction and the 7 flange thickness direction perpendicular thereto. propagated, thereby forming copper 2
Tissue and inclusions in fillet portion 2OA of No. 0. The anisotropy can be reduced. Incidentally, the bulging portion 21 also functions to prevent the slab 12 from being deformed into a rhombic shape or twisted when the slab 12 is rolled down in the width direction. As shown in FIG. 3(C), the intermediate steel piece 14 having a dogbone cross-sectional shape obtained in this way is rolled down in the width direction by a box hole die 26 having a flat bottom 25, and the intermediate steel piece 14 has a flat thickness surface 15A. 15 is obtained. In addition, in this box hole mold 26 as well, as in the above-mentioned box hole mold 22.24, a plurality of baths are performed until the flange width of the intermediate steel piece 15 becomes approximately equal to the hole width W of the hole mold 26. . The intermediate steel piece 15 thus obtained is shown in FIG. 3(D).
As shown in FIG. 2, the beam blank 16 is rolled into a dogbone cross-sectional shape of a desired size using the forming hole die 28. The beam blank 16 obtained in this way is sufficiently processed by forging in the slab manufacturing process and rolling using a box hole die 22. @ in 2OA
The anisotropy of ruts and inclusions is reduced. The beam blank 16 thus obtained is rolled into a shaped steel such as an H-shaped steel or a ■-shaped steel by a universal rolling mill (not shown). The results of this example will be explained below with reference to FIG. FIG. 4 shows a method of the present invention for obtaining HFf3tlA20 from a steel ingot 10 through a forged slab 12 and a beam blank 16, a first conventional method for obtaining an H-section steel from a steel ingot through a rolled slab and a beam blank, and It is a diagram showing a comparison of the impact characteristics of the fillet portion of each H-beam manufactured by the second conventional method of obtaining an H-shape from an ingot through a beam blank directly without going through a rolling slab. is the test temperature ('C), and the vertical axis is the absorbed energy (kgf-s).
This is the one taken. In addition, the actual IE in the figure shows the test results obtained from the test piece taken from the H-beam steel obtained by the method of the present invention, and the single-point chain aF shows the test results obtained from the H-beam steel obtained by the first conventional method. The test results obtained from the test piece taken from the section steel are shown, and Fracture IG shows the test result obtained from the test piece taken from the H section steel obtained by the second conventional method. Also, the symbols E, F, G (7) subscripts, C, Z indicating each line.
The test results of impact properties obtained from test pieces taken in the longitudinal direction of Gt and H-section steel, in the flange width direction C1, and in the flange thickness direction 2 are shown. In order to match the conditions for each method, the same steel ingot was used, and the slab was 1500mm wide and 300mm thick.
The beam blank has a wear height of 910 mm.
m5. °The flange width is 435mm, and the H-shaped steel has a wear height of 7001am and a flange width of 300111mm.
, web thickness 13111, 7 langes thickness 25+ea+. In addition, each steel ingot contains C-0°18%, Mn
-1,35%, 5i-0,15% of the same chemical composition. As is clear from FIG. 4, compared to the conventional manufacturing method, the manufacturing method of the present invention was able to improve the absorption energy itself of the fillet portion of the H-section steel. Furthermore, extremely high values of absorbed energy were obtained not only in the longitudinal direction of the H-beam steel, but also in the 7 runte width direction C and the flange plate thickness direction 2. Therefore, the value of absorption energy β in each direction, C, Z, -C1bu-z, c-z, which is the parameter of different direction, becomes smaller, and this causes It can be seen that sexual performance has also been improved.

【Effect of the invention】

As explained above, according to the present invention, the toughness of the fillet portion is improved, and the anisotropy of Ii impact characteristics is reduced,
It has the excellent effect of making the material uniform in the cross section of the section steel and achieving a soaked quality.

[Brief explanation of drawings]

FIG. 1 is a flowchart showing the gist of the method for producing a matched copper piece according to the present invention, FIG. 2 is a sectional view showing the cross-sectional shape of a steel piece obtained in each step in an example of the present invention, and FIG. 4 is a front view showing the first to third rolling steps using the blooming rolls, and FIG. 4 is a comparison showing the impact characteristics of the fillet portion of H-section steel produced by the method of the present invention and the conventional method. It is a line diagram. 10... Steel ingot, 12... Slab, 14.15... Intermediate steel piece, 16... Beam blank, 20... H-shaped tI4゜

Claims (1)

[Claims] (1) A process of manufacturing a slab from a steel ingot by forging, and rolling the slab obtained in the slab manufacturing process with a plurality of box hole dies in which a bulge is provided in the center and the hole width is gradually widened. a first rolling process of rolling the intermediate steel piece obtained in the first rolling process in a flat-bottomed box hole die; and a second rolling process of rolling the intermediate steel piece obtained in the second rolling process. A method for manufacturing a rough-shaped steel billet, comprising: a third rolling step of rolling the steel billet in a shaping hole die to obtain a rough-shaped steel billet.