JPH07108406B2 - Pack rolling method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a layered rolling (pack rolling) method for producing a wide and thin material of non-ferrous metal such as alloy Ti and high alloy steel by hot rolling. It is about.

[Conventional technology]

Generally, in non-ferrous metals such as alloy Ti and high alloy steels,
There are many so-called difficult-to-process materials such as insufficient cold rolling and high deformation resistance, and it is often very difficult to manufacture thin sheets by cold rolling due to problems such as cracking, milling capacity and rolling efficiency. .

Further, even in hot rolling these metals, in order to adjust the structure of the product, to keep the hot rolling temperature within a certain range, in order to eliminate the rolling anisotropy as seen in alloy Ti Although there are demands such as wanting to carry out cross rolling, the usual tandem strip mill often cannot satisfy this demand. Therefore, it is difficult to manufacture a thin plate even in hot rolling.

Therefore, in order to solve these problems, stack rolling (pack rolling) has been conventionally performed.

The pack rolling method described here uses a desired material as a core material, and covers the upper and lower and four corners of the core material with a cover material and spacers and welds the surroundings to assemble the packed material and hot-roll it, and then disassemble the packed material. Then, it is a method of manufacturing a thin plate of the core material.

FIG. 1 schematically shows the shape of the pack.

In the figure, 1: core material, 2: cover material, 3: spacer, 4: welded part.

However, there is no systematic research on this method,
There is no knowledge about the dimensions of the cover material and the core material and the selection method of the material, and it is the current situation that the manufacturers rely on their cans, and the following problems occur.

(1) As a selection method of the cover material and the core material, in order to select a material and a rolling temperature range in which the deformation resistances of both are as close as possible,
The combination is limited. For this reason, the materials to which this method can be applied are limited, and it is not possible to manufacture thin plates of arbitrary materials.

(2) When the selection or combination of the cover material and the core material is inappropriate, the core material is corrugated inside the pack, and in some cases, the core material is folded and overlapped, and a product cannot be obtained. In addition, a step for correcting the corrugation is required, which is inefficient and causes a cost increase.

[Problems to be solved by the invention]

The present invention is a non-ferrous metal such as alloy Ti and a wide width of high alloy steel, in producing a thin material by hot rolling, to prevent the occurrence of shape defects due to the rolling of the core material and improve the efficiency of thin plate production, It is an object of the present invention to provide a pack rolling method for achieving a reduction.

[Means for solving problems]

The present invention is a thin material in which one or more core materials coated with a release agent on the surface are laminated, the upper and lower parts thereof are covered with a cover material, and the surroundings are surrounded by a spacer and welded to assemble a laminated rolling material, which is hot rolled. In the manufacturing method, the material and the rolling temperature of the core material and the cover material are selected so that the deformation resistance value of the core material is equal to or more than the deformation resistance value of the cover material.

[Action]

As described above, FIG. 1 schematically shows the structure of the laminated rolled material in cross section.

Here, the core material 1 is a plate made of a material to be thinned, and one or more sheets each having a surface coated with a release agent are stacked.

The release agent is for preventing the core materials and the core material and the cover material from adhering to each other by rolling, and any release agent may be used as long as it satisfies this requirement.

The top and bottom of the core material 1 are sandwiched by the cover material 2, and the periphery thereof is surrounded by the spacer 3. The cover material 2 and the spacer 3 are welded over the entire circumference to prevent the cover material 2 from peeling off during rolling and breaking of the laminated rolling material. The laminated rolled material is filled with air or other gas, or in a vacuum atmosphere.

Here, the cover material deformation resistance value; k _s core material deformation resistance value; k _i laminated plate thickness ratio core material thickness / total plate thickness The inventors have conducted research on laminated rolling, and as a result, constructed as described above. When the laminated rolled material is hot-rolled, the deformation resistance values k _s and k _{i of} the cover material 2 and the core material 1 are different, so the respective reduction amounts are different and the laminated plate thickness ratio before and after rolling is different. It was confirmed experimentally that such a phenomenon occurs.

When k _s > k _i The core material 1 is crushed from the cover material 2 by rolling, and the core material 1
Is longer than that of the cover material 2, the core material 1
Is replaced by spacer 3 and there is no place for core material 1,
The phenomenon shown in FIGS. 2A and 2B occurs. That is, (a) if the welded portion 4 of the cover material 2 is weak, the core material 1 pushes the spacers 3 and the laminated rolling material is destroyed. In this case, it is impossible to continue rolling thereafter. .. (a) and (b) If the core material 1 is thin and easy to buckle, the core material 1 will buckle to the spacers 3 and a wavy shape defect will result. If the rolling is further continued, the core material is folded and overlapped, resulting in a defective product. Therefore, it is difficult to obtain a flat plate. ...... Fig. 2 (b) When k _s <k _{i Since} the cover material 2 has a smaller deformation resistance than the core material 1, rolling reduces the cover material 2 more than the core material 1 in the rolling direction. Since the core material 1 does not stick to the spacer 3 because of the large elongation, no shape defect occurs. This state is shown in FIG.

Therefore, a flat plate can be obtained.

The above phenomenon is experimentally shown.

The combination of SS41 and pure Ti as cover material and core material respectively, and SS4
With the combination of 1, Ti-6Al-4V, rolling experiments were carried out while hot by varying the laminated plate thickness ratio and the total plate thickness.

After rolling, the pack was disassembled, the core material was taken out, and the steepness thereof was measured. The results are shown in FIG.

Rolling was performed in a temperature range where the deformation resistance of pure Ti <SS41, deformation resistance of Ti-6Al-4V> SS41.

From these results, the one using pure Ti as the core material tends to have a large corrugation, while the one using Ti-6Al-4V is flat in any pack structure and no shape defect occurs at all. I understand. In Fig. 3, pack break (1), waveform generation (2), and shape defect (3) are the results when pure Ti is used as the core material.

From the above, it can be seen that in pack rolling, the shape defect of the core material is prevented by setting the cover material and rolling temperature so that k _s <k _i .

Next, examples of the present invention will be described.

〔Example〕

For Example 1 ...... k _s> k _i (Comparative Example) cover material 2 to SS41 (25.4 × 1435 × 1884mm) , the core material 1
Using 3 sheets of Ti-6Al-4V (15.2 × 1270 × 1727mm), coated with alumina powder as a release agent, overlapped, and spacers 3 welded around to create a laminated rolling material of 96.7 × 1463 × 1864mm at 950 ° C. After heating up to 28.9 mm, it was rolled in a thick plate mill.

The temperature during rolling is about 850 ° C and about 900 for the cover material and core material, respectively.
At ° C., deformation resistance of each of the temperature as shown in Table 1 following a respective ^{20kgf / mm 2, 15kgf / mm} 2.

The thickness of the core material after rolling was 4.6 mm, and it was observed that waves with a maximum height of 14 mm and a pitch of 500 mm were generated in the core material.

Example 2 ... When k _s > k _i (Example of the present invention) Rolling conditions Assembly slab dimensions Thickness 71.5 mm, width 1456 mm Length 1960 mm Cover material (mild steel C equivalent 0.1%) 22.4t × 1456W × 1960Lmm (Upper and lower) Core material (Ti-6Al-4V) 8.6t × 1315W × 1815Lmm × 3 Laminated plate thickness ratio (core material thickness / total thickness): 0.37 Heating temperature… 920 ℃ Rolling was performed at a lower temperature than in the case of Example 1 in order to increase the size.

In this case, the temperatures of the cover material and core material are 750 ℃ and 800 ℃, respectively.
The deformation resistance values corresponding to these temperatures are 23 kgf / mm, respectively.
² and 33 kgf / mm ² . (Table 1) Rolling results Product dimensions: thickness 2.44 mm, width 1219 mm, length 2438 mm Shape: Good shape in both longitudinal and width directions.

Surface flaws: Good with no material flaws and no flaws.

Crop loss: The maximum length of the core material (Ti-6Al-4V) was about 60 mm / one side.

〔The invention's effect〕

The pack rolling method of the present invention has the following effects.

(1) The shape of the core material by lamination rolling is good.

(2) Since the method of selecting the cover material and the core material can be freely selected, the pack rolling method can be applied to any material and thin plate manufacturing can be performed.

(3) Shape defects such as corrugation of the core material are eliminated, the efficiency of thin plate production is improved, and the cost is reduced.

(4) As long as the conditions shown in the present invention are satisfied, any number of core materials may be used.
Ultra thin sheet of alloy can be manufactured.

(5) Basically, the constitution of the laminated rolled material shown in the present invention is
Since it is determined by the deformation resistance of the core material and the cover material, not only the Ti alloy but also other metals can be applied.

[Brief description of drawings]

FIG. 1 is a cross-sectional explanatory view showing a laminated rolling material structure of the present invention,
Figure 2 is an explanatory view of the laminate roll in k _s> k _i of the present invention, FIG. 3 is an explanatory diagram showing a relation between steepness and combined thickness ratio, Fig. 4 of the present invention k _s < It is explanatory drawing by the lamination rolling in k _i . In the figure, 1: core material, 2: cover material, 3: spacer, 4: weld, 5: clearance. In the drawings, the same reference numerals indicate the same or corresponding parts.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takashi Arizumi 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Toshinori Matsuo 1-2-1 Marunouchi, Chiyoda-ku, Tokyo Nihon Steel Pipe Co., Ltd. (72) Inventor Junzo Tamai 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Steel Pipe Co., Ltd. (56) Reference JP-A-48-86762 (JP, A) JP-A-59 -42102 (JP, A)

Claims (1)

[Claims] 1. A thin material obtained by hot-rolling a laminated rolling material obtained by laminating one or more core materials each having a release agent applied on the surface thereof, covering the upper and lower sides thereof with a cover material, surrounding the periphery with spacers, and welding and assembling them. A method of manufacturing a material, wherein a material and a rolling temperature of the core material and the cover material are selected so that the deformation resistance value of the core material is equal to or more than the deformation resistance value of the cover material.