JPS5976601A - Rolling method of plate material - 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 The present invention relates to a rolling method for producing grain-oriented electrical steel sheets having excellent magnetic properties.

Conventionally, in the production of grain-oriented electrical steel sheets, Mn8゜At
1300℃ to sufficiently dissolve inhibitors such as N.
Hot rolling is performed after heating the slab at a high temperature above, but the extremely high heating temperature causes the crystal grains to become coarse, and even after hot rolling, the coarse grains are not broken down sufficiently, resulting in As a result, secondary recrystallization during final annealing is insufficient and remains in the product as linear fine grains, resulting in a problem in that magnetic properties are significantly impaired.

As a countermeasure to this problem, a so-called different circumferential speed rolling technique was developed in JP-A-55-152123, in which the upper and lower work rolls are rolled at different speeds during hot rolling in order to sufficiently destroy coarse grains during heating.
However, it is not yet a sufficiently established technique because a predetermined speed difference cannot be stably achieved.

As a result of various studies on a simpler rolling method for breaking coarse grains, the present inventors noticed that the ease of elongation in the longitudinal direction during rolling differs significantly depending on the surface roughness of the roll. The present invention was made based on the discovery that coarse grains can be broken by creating a number of zones with different degrees of ease. 2 in direction
A method of rolling a plate material, characterized in that the sheet material is rolled in a layered state with more than one layer.

The roll surface roughness of conventional rolling rolls is usually almost uniform in the longitudinal direction of the roll body, but the rolling roll of the present invention has a large roughness in the longitudinal direction of the roll body, as shown in Fig. 1. The zones and the zones with small roughness are alternately arranged in layers, and the zone where the roughness of the lower work roll is also large is located at the position in the body length direction of the zone where the roughness of the upper work roll is large.

The degree of roughness unevenness is determined by, for example, using a power loe so that the roughness of the part G with large roughness is 160 μmRa1, the width of the clear area is 10 m, the roughness of the part with small roughness is 40 μtnRa, and the width of the band is 10 m. Hold a meeting.

The hot-rolled slab S is rolled using these work rolls 1 and 2, but at this time, it is difficult to stretch in the longitudinal direction in the areas where the roughness of the rolls is large because the fourth grandchild coefficient during rolling is large. In areas where the roll roughness is small, the coefficient of friction during rolling is small, making it easy to elongate in the longitudinal direction. As a result, a shearing force acts on the material rolled in the vicinity of the boundary between both zones in the longitudinal direction.

In the above-mentioned different circumferential speed rolling, shearing force acts within the plane in the thickness direction of the plate, whereas in the method according to the present invention, shearing force equal to the number of layers in the band acts within the plane of the plate width. There is no change in the fact that it has the effect of effectively destroying coarse grains.

The following is a description based on all embodiments of the present invention.

1 suitable for hot rolling continuously cast slabs for unidirectional electrical steel sheets containing CQ, 05%, Si 3.0%, At 0.03%.
After rough rolling, finish rolling was performed in a 6-stand finishing mill under the following conditions.

(B) The work roll of the fourth stand and the fifth stand is the roll of the present invention (the degree of roughness unevenness is the same as the above value)
Rolling incorporating.

(b) Rolling in which the roll of the present invention is incorporated only in the work roll of the fifth stand.

(c) Rolling with normal work rolls.

After cold rolling, decarburization annealing, and recrystallization annealing of each of the obtained hot-rolled coils in the usual manner, the iron loss values of the unidirectional electrical steel sheets were all measured, and the results are shown in Figure 2. It is clear that the condition b) results in an excellent iron loss value.

As described above, by using the rolling method according to the present invention, grain-oriented electrical steel sheets having excellent magnetic properties can be easily and inexpensively produced.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the rolling of a hot slab using rolls with layered surface roughnesses, and FIG. 2 is a diagram showing the relationship between hot rolling conditions and product iron loss value. 1.2...Work roll, 3,4...Reinforcement roll, S
... Rolled material, G... Band with large surface roughness, T.
... Band with small optical surface roughness. No./Required

Claims (1)

[Claims] A method for rolling a plate material, characterized in that the bottom surface roughness of the roll used is changed in a layered manner into two or more layers in the longitudinal direction of the roll body.