JP2991622B2 - Method of manufacturing cold rolled stainless steel strip - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a cold rolled stainless steel strip by a tandem rolling mill, and more particularly to a method for producing a cold rolled stainless steel strip having excellent surface gloss.

[0002]

2. Description of the Related Art A cold rolled stainless steel strip is annealed and pickled from a hot rolled steel strip, and then cold rolled in a multiple rolling mill such as a Sendzimir mill having a work roll diameter of 150 mm or less to finish-anneal pickling or finish brightening. After annealing, rolling reduction 1.2
% Or less.

[0003] The cold-rolled stainless steel strip produced in this way is often used in the state of the surface after production, particularly in the case of ferrite series represented by SUS430, and the product after finish temper rolling is used. Excellent surface gloss is required. On the other hand, in the case of an austenitic material represented by SUS 304, buffing is often performed after finish temper rolling, and it is important that the product after buffing has excellent surface gloss.

[0004] Conventionally, in a cold rolling mill using a small-diameter work roll such as a Sendzimir mill, for example, as described in Japanese Patent Application Laid-Open No. 57-13362, the surface roughness of the roll is devised so as to be excellent. For example, a surface gloss was obtained. However, in this method, the surface roughness of the steel strip at the time of annealing and pickling before cold rolling remains until after cold rolling, so that satisfactory surface gloss has not been obtained.

On the other hand, Japanese Patent Application Laid-Open No. 64-83305 discloses a method for producing a stainless steel strip with a high efficiency by greatly reducing the rolling time.
As described in Japanese Unexamined Patent Publication (Kokai) No. Hei 2-284703 and the like, attempts have been made to perform cold rolling by a tandem rolling mill using a work roll of 150 mm or more. But,
In the rolling by the tandem rolling mill, there is a problem in that concave defects such as oil pits and depression pits on the surface of the steel strip are generated by rolling, and a satisfactory surface gloss cannot be obtained for a product.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and to realize a method of manufacturing a cold-rolled stainless steel strip which is highly efficient and can obtain excellent surface gloss. .

[0007]

[Means for Solving the Problems]

[0008] 請 Motomeko invention described 1, when cold rolled stainless steel strip in a tandem rolling mill, the work roll diameter of the first stand and the following diameter 150 mm, the second and subsequent stand work roll diameter Is a large diameter of 150 mm or more.

[0009]

[Operation] When a SUS 304 stainless steel sheet having no concave defects on its surface is cold-rolled by a tandem rolling mill, almost no concave defects are observed on the surface of the product. On the other hand, when a SUS 430 stainless steel sheet having no concave defects on its surface is cold-rolled by a tandem rolling mill, concave defects are generated on the product surface. Since this difference is considered to be due to the difference in mechanical properties between the two, the surface hardness was measured. The results are shown in FIG. From this, the surface hardness (H _R B) before tandem rolling is approximately 85 for SUS 304 and 430 for SUS 304.
The surface hardness increases as the rolling process proceeds, that is, as the elongation increases, and the SU
It can be seen that S 304 is harder than SUS 430.

Therefore, it is considered that the process of the concave defect generated in the tandem rolling is as follows. First, a large number of concave defects (oil pits) are generated in the first stand of the tandem rolling mill, but are repaired and reduced in the second and subsequent stands. There is no concave defect on the surface of the steel strip before the first stand rolling, and a large amount of the oil is generated after the first stand because a large amount of rolling oil is generated in the rolling of the first stand where the hardness of the surface of the steel strip is insufficient. In the second and subsequent stands, it is considered that no new concave defects are generated by work hardening of the steel strip surface by rolling, but rather these are repaired by rolling. Therefore, by pre-hardening the surface of the material before tandem rolling, only the concave defects are repaired in all stands after the first stand, and a stainless steel strip having excellent surface gloss can be realized. The same result is obtained even if the work roll of the first stand is made small in diameter instead of pre-hardening the surface of the material before tandem rolling, and only a work hardening is caused without a large amount of rolling oil being caught. As a result, the occurrence of concave defects in tandem rolling is prevented, and excellent surface gloss is obtained.

[0011]

【Example】

Embodiment 1 FIG. 1 is a configuration diagram of a rolling mill in a first embodiment, 1 is a steel strip, 2 is a work roll of a temper rolling mill, 3 is a temper rolling mill, 4 is a work roll of a tandem rolling mill. Reference numeral 5 denotes a tandem rolling mill.

When the ferritic stainless steel SUS 430 steel strip 1 which has been hot-rolled, annealed, and pickled is subjected to skin-pass rolling using a lubricating oil by a temper rolling mill 3, work hardening causes a steel sheet having an elongation of, for example, 20%. band of the surface hardness (H _R B)
Rose from 79 before rolling to 94. FIG. 2 shows the relationship between the elongation and the surface hardness. The elongation in skin pass rolling is at most 30% or less, but the effect is recognized at elongation of 5% or more, and the effect is somewhat slowed at 20% or more.

This steel strip is cold-rolled by a five-stand quadruple tandem rolling mill 5 and the gloss of the product (G according to JIS Z 8741).
s (20 °)). When the result is compared with the tandem rolled material (tandem rolled without hardening),
As shown in Fig. 3, when the product thickness is 2.0mm, 12%, 1.5m
The improvement was 9% at m and 8% at 1.2 mm. The installation place of the temper rolling mill 3 is not particularly limited. However, when an in-line skin pass mill is installed in a continuous annealing facility that is a pre-process of cold rolling, it is convenient if the in-line skin pass mill can be used.

The work roll 2 of the temper rolling mill 3 includes:
When the diameter of the work roll 4 is smaller than that of the work roll 4 of the tandem rolling mill 5, and when the lubricating oil is used, the lubricating oil having a lower viscosity than the lubricating oil of the tandem rolling mill 5 can be used to suppress the generation of oil pits. is necessary. Embodiment 2 FIG. 4 is a configuration diagram of a rolling mill in a second embodiment.
In this embodiment, a temper rolling mill is not used, and rolling is performed only by a tandem rolling mill 5 of five stands. First stand 5a
Is a six-high rolling mill, and the work roll 4a is a small diameter roll of 150 mm or less. The subsequent stand 5b is a normal four-fold rolling mill, and a work roll 4b having a large diameter of 150 mm or more is used.

When the rolling mill is configured in this manner, the amount of the rolling oil in the first stand 5a is small, so that generation of oil pits is small and work hardening occurs. Therefore, the surface of the rolled material is hardened in advance. Similar effects can be obtained.

[0016]

According to the present invention, an excellent effect that excellent surface gloss can be obtained by a highly efficient manufacturing method can be obtained.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a rolling mill according to a first embodiment of the present invention.

FIG. 2 is a graph showing the relationship between elongation and hardness in the present invention.

FIG. 3 is a graph showing the degree of improvement in glossiness for each product thickness in the present invention.

FIG. 4 is a configuration diagram of a rolling mill according to a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Steel strip 2 Work roll 3 Temper rolling mill 4, 4a 4b Work roll 5, 5a, 5b Tandem rolling mill

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-284701 (JP, A) JP-A-3-23001 (JP, A) JP-A-4-71702 (JP, A) JP-A-58-58 22330 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B21B 1/00-3/02 B21B 27/02 C21D 7/04

Claims (1)

(57) [Claims] When a stainless steel strip is cold-rolled by a tandem rolling mill, the work roll diameter of the first stand is set to 150 mm.
mm and a work roll diameter after the second stand
A method for producing a cold-rolled stainless steel strip, comprising: