JP2001259708A - Method for manufacturing hot-rolled stainless steel sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a hot-rolled stainless steel sheet by which the concentration of distortion in the corner parts of a slab in the early stage of rolling after width press is prevented and the wraparound amount of edge seams is furthermore reduceable performing the width press. SOLUTION: The length of notches in the width direction in the upper and lower corner parts of the slab which is formed by the width press is taken as 2.5-15% of the thickness of the slab before the width press and the length of notches in the thickness direction as 5-15% of the thickness of the slab before the width press.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a hot-rolled stainless steel sheet, and more particularly to a method for manufacturing a hot-rolled stainless steel sheet for preventing surface defects near the edge extending in the rolling direction (hereinafter referred to as edge seam flaws). About.

[0002]

2. Description of the Related Art Hot-rolled stainless steel sheets are continuously cast from molten steel adjusted to a predetermined composition to form slabs, heated in a heating furnace, width-pressed by a press die, and then reduced in width by vertical rolls and horizontally rolled. And the thickness reduction by a plurality of passes. This hot-rolled steel sheet is usually subjected to annealing, pickling, cold rolling, etc., to obtain a cold-rolled steel sheet. The stainless steel sheet used as a cold-rolled steel sheet is mainly used for a product that emphasizes surface properties.

As shown in FIG. 6, a width press applied to a hot-rolled stainless steel sheet presses the slab 100 from the width direction with press dies 230A and 230B to reduce the width of the slab 100 over its entire length. It is generally used because the slab width to be cast can be integrated and the cost reduction effect is large. The press molds 230A and 230B used for the width press include a flat mold 230A shown in FIG. 7 and a press mold having a caliber groove shown in FIG.
Although 230A is used, a press mold 230A having a caliber groove can be used to produce a stainless steel sheet because the width reduction amount can be larger than that of the flat mold 230A.

As shown in FIG. 9, a hot rolled stainless steel sheet produced by performing a width pressing may have an edge seam flaw that extends around d _ES from the edge on the surface near the edge. The edge seam flaws that have turned around d _{ES on} this surface have irregularities between the crystal grains that are coarsened during heating in the initial stage of hot rolling in which thickness reduction and width reduction are repeated, and these irregularities are rolled by hot rolling. It is extended in the direction and wraps around the front and back surfaces near the edge.

[0005] Edge seam on the surface of stainless steel hot rolled steel sheet
When flaws occur, surface grinding by coil gland inder
Or re-pickling, trimming the edge trim around edge seam flaws
Quantity d _ESTo remove edge seam flaws.
And the yield is greatly reduced. Therefore, the amount of width reduction is large.
Width press with a press die having a sharp caliber groove
When producing hot-rolled hot-rolled steel sheets,
Inset d_ESThere is a strong demand for a reduction.

For example, JP-A-5-146807 discloses that
As shown in FIG. 8, using a press die having a projection between the upper and lower caliber grooves along the direction of travel of the slab, and setting the inclination angle θ of the upper and lower side walls 231a and 231b to 8 to 45 °. Anvils for width pressing of interslab slabs are disclosed. Also, JP-A-7-
No. 290137 discloses that hot rolling of stainless steel characterized by cooling both side surfaces of a material to be rolled from before the roll bite to the roll bite outlet under thickness reduction by the horizontal roll of the rough rolling. A method is disclosed.

However, in the width press described in JP-A-5-146807, as shown in FIG.
Since the upper and lower corners of the slab 100 are abutted only at the bottom of the lower caliber groove and the width is pressed, strain concentrates at the corners of the slab in the initial stage of rolling after the width press, and edge seam flaws go around There was a problem that the amount could not be reduced sufficiently.

In the hot rolling method disclosed in Japanese Patent Application Laid-Open No. 7-290137, the edges of the slab are not formed into a predetermined shape by a width press before hot rolling. At the stage, there is a problem that strain concentrates at the corners of the slab, and the amount of edge seam flaw wraparound cannot be reduced sufficiently.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned problems of the prior art. By performing width pressing, distortion occurs at corners of a slab in an initial stage of rolling after width pressing. It is an object of the present invention to provide a method of manufacturing a hot-rolled stainless steel sheet which can be prevented from being concentrated and can further reduce the amount of edge seam flaw wraparound.

[0010]

SUMMARY OF THE INVENTION According to the present invention, a stainless steel slab which has been continuously cast is heated and then width-pressed by a press die having a projection between upper and lower caliber grooves along the traveling direction of the slab. Then, in a method for producing a stainless hot rolled steel sheet which is subjected to a plurality of passes of width reduction by a vertical roll and thickness reduction by a horizontal roll to form a hot rolled steel sheet, in advance, the upper and lower corners of the slab before the width press are formed. The press die is provided with the upper and lower caliber grooves so as to contact the upper and lower caliber grooves, respectively, with the lower side wall, and the upper and lower slabs after the width press formed by the width press are formed. The notch length in the width direction at the corner portion is 2.5 to 15% of the slab thickness before the width pressing, and the notch length in the thickness direction is 5 to 15% of the slab thickness before the width pressing. Stainless This is a method for producing a hot-rolled steel sheet.

[0011] Preferably, the depth of the concave portion at the center of the side surface of the slab after the width pressing formed by the projections is 5.0 to 15% of the slab thickness before the width pressing. It is a manufacturing method. Further, the slab thickness after the thickness reduction is the slab thickness before the width pressing.
Above 1/2, the width reduction is not performed, and the slab thickness after the thickness reduction is preferably less than の of the slab thickness before the width pressing, and then the width reduction is preferably performed on the stainless hot rolled steel sheet. It is a manufacturing method.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method for producing a hot-rolled stainless steel sheet according to the present invention will be described in detail with reference to FIGS. FIG. 1 is a layout diagram of one example of a hot rolling facility suitable for use in the present invention, wherein 21 is a heating furnace, 22 is a descaling device, 23 is a width press device (only a plan view), and 24 is a rough press. A rolling mill row, 25 is a finishing rolling mill row, and 26 is a coiler. Also,
The rough rolling mill row 24 includes four rough rolling mills having vertical rolls 27 (E1, E2, E3, E4) and horizontal rolls 28 (R1, R2, R3, R4). Equipped with a finishing mill.

FIGS. 2A and 2B are a perspective view and a partial sectional view showing the edge shape of the slab after the width pressing in the present invention. 3 (a) and 3 (b) are a plan view showing an example of a press die shape used in the present invention and a partial sectional view taken along the line YY of FIG. 3 (a). FIG. 4 is a plan view illustrating a width press according to the present invention.
(A), FIG. 5 (a) shows the top of the slab with respect to the lower caliber groove before and during the width pressing in the present invention,
It is sectional drawing which shows the position of a lower corner part.

[0014] Here, 10 is a slab, the recess in the central portion of the slab side 11, 10a, 10b is on the slab, notch lower corners, L ₁ is the width direction notch length, L ₂ is the thickness direction notch length, L ₃ is concave in the central portion of the slab side surface
The depth 11 and H ₀ are the slab thickness before the width pressing. In addition, 23A and 23B are press dies, 41 is an entrance side inclined portion, 42 is a parallel portion, 43 is an exit side inclined portion, 30a and 30b are upper and lower caliber grooves, 31a and 31b are upper and lower side walls, 32 projections, C ₁ on a groove bottom interval of the lower caliber groove, theta is the angle of inclination of the side walls, D
Is the depth of the caliber groove, M ₃ is the height of the projection, and M ₄ is the notch length at the tip of the projection.

The hot-rolled stainless steel sheet of the present invention is made by continuously casting molten steel adjusted to a predetermined component to form a slab, and as shown in FIG. The upper and lower caliber grooves provided in the apparatus 23 are width-pressed with a press die having a lower caliber groove, and then subjected to width reduction by a vertical roll 27 and thickness reduction by a horizontal roll 28 a plurality of times, and are subjected to finish rolling in a finishing mill row 25. Then, it is rolled up by the coiler 26 and manufactured.

The heated slab is descaled by the descaling device 22 and then width-pressed by the width pressing device 23. Here, in the method for manufacturing a hot-rolled stainless steel sheet according to the present invention, the width is pressed by a press die having a projection between upper and lower caliber grooves along the traveling direction of the slab, and FIG. It is characterized in that it has a slab edge shape as shown in FIG.

First, a press mold used in the present invention and having a projection between lower caliber grooves will be described. As shown in FIG. 3 (a), when the press dies 23A and 23B are mounted on the width press device 23 and arranged in a line, the press die used in the present invention is viewed from the plane with respect to the pass line center. It is line symmetric. Each of the press dies 23A and 23B is provided with an entrance-side inclined portion 41, a parallel portion 42 having a press surface parallel to the pass line center, and an exit-side inclined portion 43.

The press die used in the present invention includes:
As shown in FIG. 3B, upper and lower caliber grooves 30a and 30b are provided in at least the parallel portion 42 of the entrance-side inclined portion 41, the parallel portion 42, and the exit-side inclined portion 43, along the traveling direction of the slab. Between the upper and lower caliber grooves 30a and 30b.
Is provided. Note that the tip of the projection portion 32, is provided with a flat portion of the notch length M _4, is set to M ₃ the height of the flat portion from the groove bottom of the protrusion 32. Also, upper and lower caliber grooves
As shown in FIG. 3B, the upper and lower side walls 31a and 31b are formed as V-shaped grooves whose upper and lower spaces are narrowed toward the groove bottom. The depth of the upper and lower caliber grooves 30a and 30b is D, the inclination angle of the upper and lower side walls 31a and 31b with respect to the groove bottom is θ, and the upper and lower caliber grooves 30a and 30b are
The groove bottom interval b is set to C _1.

Then, in the width press of the present invention, as shown in FIG.
, 23B, while repeatedly moving the slab 10 from right to left in the drawing and pressing the slab 10 in the width direction with the entry-side inclined portion 32 and the parallel portion 33, reducing the width of the slab 10 over its entire length. I have. Here, the press dies 23A and 23B used in the present invention described above are provided in FIG.
As shown in (b), the entrance side inclined part 41, the parallel part 42 and the exit side inclined part 43 are so arranged that the upper and lower side walls 31a and 31b respectively contact the upper and lower corners of the slab 10 before the width pressing. Of these, it is important to provide the upper and lower caliber grooves 30a and 30b at least on the pressing surface of the parallel portion 42. Thus, on, C ₁ lower caliber groove 30a, the groove bottom interval 30b is
It is smaller than the thickness H ₀ of the slab 10 before wide press.

FIGS. 3B, 5A, and 5
FIG. 2B shows one of the press dies 23A and 23B sandwiching the slab 10, but the other press dies 23B are in a plane view and the press dies 23A and the pass line 23B. Since it is symmetrical with respect to the center and the edge shape of the slab 10 is the same, the illustration is omitted and the detailed description is omitted.

In the width press of the present invention, FIG.
The pressing dies 23A and 23B are arranged in a line so that the upper and lower side walls 31a and 31b abut on the upper and lower corners of the slab 10 as shown in FIG. Then, as shown in FIG. 5B, the upper and lower corners of the slab 10 are deformed by contacting the upper and lower side walls 31a and 31b. Therefore, in the present invention, the width pressing, FIG. 2 (a), the notch of FIG. 2 (b), the length-out widthwise notch L ₁ a and-out thickness direction notch length L ₂ 10a, 10b is formed in the upper and lower corners of the slab 10.

In the width press of the present invention, FIG.
(A) and upper and lower caliber grooves 30 as shown in FIG.
2A and 2B, the protrusion 32 abuts against the center of the side surface of the slab 10, and the side surface of the slab 10 is deformed. As shown in FIGS. The concave portion 11 continuous in the length direction is formed in the portion. The shape of the lower caliber grooves 30a and 30b used in the present invention is shown in FIG.
As can be seen by comparing the vertical sectional views shown in FIG. 5B and FIG. 5A, the notches 10a, 10b at the upper and lower corners are shown.
And when the appropriate width pressing amount capable of forming a concave portion 11, the length L _1-out width direction notches with a length L _2-out thickness direction notch
tan θ, and the notch length L ₂ in the thickness direction is (H
Equal to ₀ -C ₁₎ / 2.

From this, the upper and lower caliber grooves 30a, 30
groove bottom interval C ₁ of b (1), upper, lower wall 31a, the inclination angle θ of 31b (2) below, upper, lower caliber groove 30a, the depth D of the grooves of 30b as more than L ₁ It is. C ₁ = (1-2 × L ₂ / H ₀ ) × H ₀ (1) θ = tan ⁻¹ (L ₁ / L ₂ ) (2) in width press on, limiting the notch 10a in the lower corner portion, and the length of 10b, and the ratio of the slab thickness H ₀ of the front width press, or in addition, the depth of the recess 11 in the slab side surface center portion of the slab 10 Sato, in order to limit the ratio of the slab thickness H ₀ of the front width press is was able reduce more Ejjishimu flaw wraparound amount.

Hereinafter, the notch length L ₁ in the width direction at the upper and lower corners of the slab 10 is defined as the slab thickness H ₀ before the width pressing.
2.5 and 15%, and the thickness direction notch length L ₂ is 5 to 15% of the width before pressing the slab thickness H _0, or in addition, the width press depth L ₃ of the recess 11 in the central portion of the slab side surface reasons for 5 15% before the slab thickness H _0, is described by experiments 1-3. (Experiment 1) Continuously cast 200 mm thick ferritic stainless steel (C: 0.07 mass%, Si: 0.3 mass%, Mn: 0.1 m
A slab of ass%, Cr: 16.5 mass%) was heated in a heating furnace 21 shown in FIG. The heated slab was extracted on the hot rolling equipment line shown in FIG. 1 and descaled by the descaling device 22.

Then, in the width pressing device 23, it is possible to perform the width pressing to the corner shape of the slab shown in Table 1 (1).
The groove bottom interval C ₁ obtained by the equation (2), the upper and lower side walls 31a,
The width of L ₃ / H ₀ is pressed to 10% by a press die with the inclination angle θ of 31b and M _{3 set} to predetermined values and M _{4 set} to 0, and fed to the row 24 of rough rolling mills. Rolled to sheet bar. The edge seam flaw penetration amount was measured at 10 points on each of the upper and lower surfaces in the stationary portion of the sheet bar, and the average value was obtained. The amount of edge seam flaw wraparound was evaluated as shown in the lower column of Table 1, and the results are shown in Table 1.

The width reduction in E1 was 20 mm.

[0027]

[Table 1]

(Experiment 2) A ferrite stainless steel slab having the same thickness and composition as the slab used in Experiment 1 was heated under the same conditions as in Experiment 1, and then subjected to width pressing with the press dies used in Experiment 1. A sheet bar was obtained in the same manner as in Experiment 1 except that width reduction with the vertical roll E1 was not performed, and the amount of edge seam flaws penetrated was evaluated.

Table 2 shows the evaluation results of the edge seam flaws penetrating amount together with the slab corner shapes.

[0030]

[Table 2]

(Experiment 3) A ferrite stainless steel slab having the same thickness and composition as the slab used in Experiment 1 was heated under the same conditions as in Experiment 1, and then, in a width press 23, the corner shapes of the slab shown in Table 3 were used. Groove bottom distance C ₁ , upper and lower wall 3 determined by the above formulas (1) and (2)
1a, 31b inclination angle θ of, and M ₃ a predetermined value, the L ₃ / H ₀ respectively width press to 10% by a press die having a M ₄ 0, was not subjected to width reduction in vertical rolls E1 Except for the above, a sheet bar was obtained in the same manner as in Experiment 1, and the amount of edge seam flaws penetrated was evaluated.

Table 3 also shows the evaluation results of the amount of edge seam flaws penetrating.

[0033]

[Table 3]

As can be seen from the evaluation results of the edge seam flaw infiltration amount shown in Tables 1 and 2, the width is pressed by a press die having a projection between the upper and lower caliber grooves.
The length L _1-out widthwise notch before widths press the slab thickness H ₀
2.5 to 15%, and in the case where the thickness direction notch length L ₂ was 5 to 15% of the width before pressing the slab thickness H ₀ is the slab at the initial stage of rolling after the deformation amount width press at the corner portion Can be prevented from concentrating on the corners of the above, and the evaluation of the edge seam flaw is better than that in the case where the distortion is out of this range.

[0035] Thus, the width of the press, and the length L _1-out widthwise notch 2.5 15% width before pressing the slab thickness H _0, and the front width press in the thickness direction notch length L ₂ slab thickness H _It is 5-15% of ₀ . Tables 1 and 2
As can be seen from the evaluation results, the slab thickness after the thickness reduction is 1/2 or more of the slab thickness before the width press, the case where the width reduction is not performed on the vertical roll is better than the case where the width reduction on the vertical roll is performed. Also, the range in which the evaluation of the edge seam flaw is good is wide. This is because the predetermined notches formed at the corners of the slab are not pressed down by the vertical rolls, so that the effect of uniformizing the strain due to the predetermined notches formed at the edges of the slab in the initial stage of rolling after width pressing is large. Conceivable.

Therefore, when the slab thickness after the thickness reduction is more than 1/2 of the slab thickness before the width pressing, it is better not to perform the width reduction on the vertical roll, and to secure the width accuracy,
It is preferable to apply width reduction after the slab thickness becomes less than 1/2 of the slab thickness before width pressing. Also, from the evaluation results of Ejjishimu flaws shown in Table 3, it can be seen that preferably the depth L ₃ of the recess 11 in the central portion of the slab side surface 5 15% width before pressing the slab thickness H _0.

If the ratio L ₃ / H ₀ of the depth L _{3 of the} concave portion 11 to the slab thickness H ₀ before the width pressing is less than 5.0%, the predetermined cut formed at the corner of the slab in the initial stage of rolling after the width pressing. The effect of equalizing distortion due to chipping is small, and L ₃ / H ₀
Is more than 15%, the recesses remain after finish rolling and become internal defects. In the above experiments, although the notch length M ₄ at the tip of the protrusion 32 and 0, in the width press of the present invention, to the tip of the protrusion 32 may be flat, the tip of the protrusion 32 May be a curved surface.

Although not shown in the above experiment, in the width press of the present invention, the ratio M ₄ / C of the notch length M ₄ at the tip of the projection 32 to the slab thickness H ₀ before the width press is performed.
H ₀ can be reduced to 10% or less. M ₄ / H ₀ is 10%
This is because if the width exceeds the above range, the concave portion may be difficult to transfer to the slab depending on the width reduction amount. As described above, edge seam flaws, in the initial stage of hot rolling repeating thickness reduction and width reduction, strain is concentrated at the corners of the slab, and the strain becomes uneven in the thickness direction of the edge portion, It is considered that irregularities are generated between crystal grains, and the irregularities are generated by being extended in the rolling direction by hot rolling.In the present invention, a predetermined width of the slab is formed at a corner of the slab by hot pressing before hot rolling. Notch, or, furthermore, because a predetermined recess was formed in the center of the side surface of the slab, in the initial stage of hot rolling, strain was not concentrated at the corner of the slab,
It is considered that the distortion becomes uniform in the thickness direction of the edge portion, and the edge seam flaw wraparound amount is further reduced.

In the above experiment, a specific component of ferritic stainless steel was used. However, in the present invention, since the amount of edge seam flaw wrap around is reduced by the above mechanism, the above-mentioned effect is not attained by components other than the specific component. The same is true for ferritic stainless steels.Also, in the case of austenitic and martensitic stainless steels in which the amount of edge seam flaws is smaller than that of ferritic stainless steel, the amount of edge seam flaws can be further reduced than in the case of ferritic stainless steel. is there.

[0040]

[Example] Continuously cast ferritic stainless steel with a thickness of 200 mm and a width of 1300 mm (C: 0.07 mass%, Si: 0.3 mass
s%, Mn: 0.1mass%, Cr: 16.5mass%)
It was charged into the heating furnace 21 shown in FIG. 1 and was soaked at 1200 ° C. for 2 hours.
The soaked slab is extracted on the line of the hot rolling equipment line shown in FIG. 1 and descaled by the descaling device 22. In the width pressing device 23, the slab is pressed into different edge shapes shown in Table 5 by a press die. Each is subjected to width pressing, and the rough rolling mill row 24
R1 reverse rolling of rough rolling (1, 2, 3 passes)
Then, unidirectional rolling (4, 5, and 6 passes) was performed on R2, R3, and R4 to obtain a 30 mm sheet bar according to the thickness reduction schedule shown in Table 4.

[0041]

[Table 4]

In the invention examples A11 to A25, the width pressing amount by the width pressing device 23 was 50 mm, and the width reduction amount by the vertical roll was as shown in Table 4. This sheet bar is fed to a finishing mill row 25 and finish-rolled to a thickness of 4 mm.
It was wound around 26 to obtain a hot-rolled coil. The obtained hot-rolled coil was annealed and pickled, and the amount of edge seam flaws on the upper and lower surfaces at the longitudinal center of the coil was measured. The edge seam flaw wrap-around amount d _ES was obtained by measuring the edge seam flaws of both edges shown in FIG. 9 at 10 locations at a pitch of 10 m and taking the average value of the upper and lower surfaces.

In the conventional examples B11 and B12, the width was pressed as shown in Table 5 using a flat die having no groove on the press surface, and the width was reduced by a vertical roll. In Comparative Examples C11 and C12,
According to the method described in JP-A-5-146807, as shown in Table 5, notches were not formed in the corners of the slabs, but the slabs were width-pressed and reduced in width by vertical rolls.

Table 5 shows the edge seam flaws of Invention Examples A11 to A25, Conventional Examples B11 and B12, and Comparative Examples C11 and C12.

[0045]

[Table 5]

From the results of the edge seam flaw wraparound amounts shown in Table 5, in the invention example, a predetermined notch was formed at the corner of the slab and a recess was formed at the center of the side surface of the slab. Comparative Examples C11 and C12 in which notches cannot be formed and Conventional Example B1 in which width pressing was performed with a flat mold
1, it can be seen that the amount of edge seam flaw wraparound is reduced as compared with B12.

In the invention examples A21 to A25, when the slab thickness after the thickness reduction is more than 1/2 of the slab thickness before the width pressing, the width reduction is not performed, and the slab thickness before the width pressing is 1/2.
Since the width reduction was performed after the width became less than the above, the amount of edge seam flaw wraparound can be reduced as compared with the invention examples A11 to A15 in which the width reduction was performed after the width pressing.

[0048]

According to the present invention, the edge of the slab is formed into a predetermined shape by the width pressing, so that the strain is not concentrated on the corner of the slab in the initial stage of hot rolling, and the edge of the slab is not deformed. The strain becomes uniform in the thickness direction, and the edge seam flaw wraparound amount can be further reduced.

As a result, there is an industrially beneficial effect that the yield of the hot-rolled stainless steel sheet can be improved.

[Brief description of the drawings]

FIG. 1 is a layout diagram of an example of a hot rolling facility suitable for use in the present invention.

FIGS. 2 (a) and 2 (b) are a perspective view and a partial cross-sectional view showing an edge shape of a slab after width pressing in the present invention.

FIGS. 3 (a) and 3 (b) are a plan view and a partial cross-sectional view showing an example of a press die shape used in the present invention.

FIG. 4 is a plan view illustrating a width press according to the present invention.

FIGS. 5A and 5B are cross-sectional views showing positions of slab corners with respect to caliber grooves before and during width pressing in the present invention.

FIG. 6 is a plan view illustrating a conventional width press.

FIG. 7 is a longitudinal sectional view showing a shape of a slab edge when a width is pressed by a conventional flat die.

FIG. 8 is a vertical cross-sectional view showing the shape of a slab edge when the width is pressed by a conventional mold having a caliber groove.

FIG. 9 is a plan view of a steel sheet surface schematically showing edge seam flaws.

[Explanation of symbols]

21 Heating furnace 22 Descaling device 23 Width pressing device 24 Rough rolling mill row 25 Finish rolling mill row 26 Coils 27 Vertical rolls (width rolling mills) 28 Horizontal rolls (horizontal rolling mills) 10 Slabs 11 Recesses at the center of the side of the slab 10a , on the 10b slab, cutout L ₁ widthwise notch length L _2-out thickness direction notch length of L ₃ recess depth H ₀ width before pressing the slab thickness 23A of the lower corner portion, 23B press die 41 entering side inclined portion 42 parallel portion 43 exit side inclined portion 30a, on 30b, the lower caliber groove 31a, on 31b, on the lower side wall 32 projections C _1, the inclination angle D caliber grooves of the groove bottom interval θ sidewalls of the lower caliber groove depth is M ₃ notch length d _ES Ejjishimu flaws wraparound amount of height M ₄ protruding tip of the protruding portion

Continuing from the front page (72) Inventor Shinzo Uchimaki 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Prefecture Inside the Chiba Works, Ltd. (72) Inventor Hideya Furusawa 1 Kawasaki-cho, Chuo-ku, Chiba City, Chiba Prefecture F-term (reference) 4E002 AA07 AB04 BD01 CA01

Claims (3)

[Claims] After heating a continuously cast stainless steel slab, it is width-pressed by a press die having projections between upper and lower caliber grooves along the traveling direction of the slab, and then width-reduced by a vertical roll. In the method of manufacturing a stainless hot rolled steel sheet to be subjected to a plurality of passes and a thickness reduction by a horizontal roll to form a hot rolled steel sheet, in advance, on the slab before the width pressing,
The upper and lower caliber grooves are provided in the press die so that the lower corner portions abut on the upper and lower caliber grooves, respectively, on the lower side wall, and after the width press formed by the width press. The width of the notch in the upper and lower corners of the slab is 2.5 to less than the slab thickness before the width pressing.
A method for manufacturing a hot-rolled stainless steel sheet, wherein the cut-out length in the thickness direction is 15 to 15% of the slab thickness before the width pressing. 2. The method according to claim 1, wherein the depth of the recess formed at the center of the side surface of the slab after the width pressing formed by the projections is 5.0 to 15% of the slab thickness before the width pressing. 3. The method for producing a hot-rolled stainless steel sheet according to item 1. 3. When the slab thickness after the thickness reduction is at least 1/2 of the slab thickness before the width pressing, the width reduction is not performed, and the slab thickness after the thickness reduction is the slab thickness before the width pressing. The method for producing a hot-rolled stainless steel sheet according to claim 1 or 2, wherein the width reduction is performed after the width becomes less than 1/2.