JPH04284901A - Method for rolling clad steel plate - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of rolling a clad steel plate made of bonded dissimilar metals.

0002

[Prior Art] Conventionally, when clad steel plates are manufactured by roll rolling, in order to keep the cladding ratio constant, reduction in the width direction of the plate is not applied, and as shown in Fig. 3, reduction in the thickness direction (
The rolled material (cladding material) is rolled by performing only the so-called thickness reduction), and the rolled material is rolled by 180° for each pass.
It was turned horizontally to keep the elongation of the base material and cladding material constant.

[0003] In this method, as the plate is rolled down in the thickness direction, spreading occurs not only in the rolling direction but also in the lateral direction (width direction). Rolling was performed only in the thickness direction, ignoring the spread in the width direction.

0004

[Problems to be Solved by the Invention] However, the rolling force in the thickness direction alone cannot control the rate of spread in the width direction, and in reality, as shown in the equation below, the rolling force in the thickness direction gradually As shown in FIG. 4, the metal flow is expanded and peeling (internal defects) at the cladding interface is induced at the ends of the rolled material in the width direction. For this reason, a large number of defective products were produced in which the cladding interface peeled off during post-rolling ultrasonic inspection, resulting in a poor finishing yield.

[0005]

[Math 1]

However, ΔB: Amount of plate width expansion ΔH: Amount of reduction in the plate thickness direction H1: Plate thickness before rolling R: Roll radius In addition, in order to avoid reduction in the plate width direction, the plate width dimension is adjusted for each rolled material. There were variations, and there was waste in the assortment of products.

The present invention has been made to solve the above-mentioned problems, and improves the shape of the edge portion in the width direction of a rolled material and prevents peeling of the cladding interface at the edge portion, thereby improving the yield and The purpose is to improve product quality.

[0008]

[Means for Solving the Problems] The method for rolling a clad steel plate according to the present invention involves rolling down the sheet in the width direction in addition to rolling in the sheet thickness direction. Rolling is performed while suppressing metal flow in the sheet width direction.

[0009]

[Function] Metal flow in the width direction that occurs due to reduction in the thickness direction is suppressed by reduction in the width direction of the plate, so the ends of the rolled material in the width direction have a flat cross-sectional shape, and the ends have a cladding interface. No peeling occurs.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to FIG.

The rolled material is a cast clad material having a thickness of 650 mm and a width of 1000 mm, with the base material 1 as the inner material and the laminate material 2 as the outer material.

A pair of upper and lower work rolls 3 and a pair of left and right work rolls 4 are combined and arranged in the rolling mill.

While passing the rolled material through this rolling mill, according to the rolling pass schedule described below, the rolled material is rolled in the thickness direction by a pair of upper and lower work rolls 3, and a pair of left and right work rolls is used to reduce the rolled material in the thickness direction. 4, the rolling material was rolled in the width direction of the sheet, and the rolled material was turned horizontally by 180 degrees for each pass, and rolling was repeated for 12 passes.

*Rolling pass schedule 1 pass: Rolling is performed only in the thickness direction, and the amount of reduction in the thickness direction is 50 mm (at this time, the amount of spread in the width direction ΔB of the sheet is approximately 1
5mm).

2nd to 11th passes: Rolling down in the thickness direction and rolling down in the width direction are performed in parallel as follows. In other words, 2 to 9 passes: Reduction amount in the plate thickness direction 50 mm Reduction amount in the plate width direction Approx. 1
5mm (=expansion in the width direction of the plate when the reduction amount in the plate thickness direction is 50mm)
10th and 11th passes: Amount of reduction in the thickness direction: 20 mm Amount of reduction in the width direction of the plate: Approximately 6 mm (= Amount of spread in the width direction of the plate when the amount of reduction in the thickness direction is 20 mm)
12 passes: Only the reduction in the thickness direction is performed, and the amount of reduction in the thickness direction is 9 mm.

In short, in the above rolling, the width of the plate is increased by 1000 mm + approximately 15 mm in one pass (=expansion amount ΔB in the width direction of the plate).
Then, rolling down in the board width direction is performed by a pair of left and right work rolls 4 that maintains the board width until the 11th pass (suppression of metal flow in the board width direction), and in the final 12 passes, rolling down in the board width direction is not performed. A slight reduction in the thickness direction is carried out, so the width of the plate is maintained at approximately 1000 mm + approximately 15 mm, and the thickness is reduced to 151 mm by 12 passes of reduction in the thickness direction.

Comparing the edge in the width direction of the product W of the present invention obtained by such rolling with the edge in the width direction of the conventional product W' obtained only by rolling in the thickness direction, As shown in FIG. 3, the end of the conventional product W' in the board width direction has a cross-sectional shape in which the end surface protrudes at the height of the laminate and retracts between the positions. The ends of the product W in the board width direction had a flat cross-sectional shape as shown in FIG. Furthermore, when comparing the ultrasonic test results of the product W of the present invention with the ultrasonic test results of the conventional product W', it was found that internal defects (peeling at the cladding interface) were found in the conventional product W' as shown in FIG. It is widely distributed from the center in the width direction to the edges,
The occurrence is particularly noticeable at the ends in the width direction of the board, whereas in product W of the present invention, the occurrence stops at the center in the width direction as shown in Figure 2, and there is no occurrence at the ends in the width direction of the board. It became.

[0018]

[Effects of the Invention] As described above, the present invention performs a reduction in the width direction in addition to the reduction in the thickness direction, and by this reduction in the width direction, the expansion in the width direction of the plate that occurs due to reduction in the thickness direction is suppressed. However, since the clad steel plate is rolled, the cross-sectional shape of the edge in the width direction of the plate can be improved, and separation of the clad interface at the edge can be reliably prevented. Therefore, the finishing yield can be greatly improved compared to the conventional method, and at the same time, product quality can be improved.

[Brief explanation of the drawing]

FIG. 1 is a conceptual diagram showing a method of the present invention and a product manufactured by the method.

FIG. 2 is a plan view showing the results of an ultrasonic test of the end portion in the board width direction of the product shown in FIG. 1;

FIG. 3 is a conceptual diagram showing a conventional method and a product manufactured by the method.

4 is a plan view showing the results of an ultrasonic test of the end portion in the board width direction of the product shown in FIG. 3; FIG.

[Explanation of symbols]

1... Base material, 2... Laminated material, 3, 4... Work roll, W... Product.

Claims (1)

[Claims] [Claim 1] In addition to rolling in the plate thickness direction, rolling is performed in the plate width direction, and rolling is performed while suppressing metal flow in the plate width direction that occurs when rolling in the plate thickness direction. Method of rolling clad steel plate.