JPH07102368B2 - Method for manufacturing tree skin steel pipe - 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 manufacturing a steel pipe having a tree-like texture.

[0002]

2. Description of the Related Art Conventionally, metal materials such as steel have been used for outer walls, pillars, beams, gate posts, gates of buildings, and fences and stanchions in road parks. . In recent years, it has been desired that such building materials, road facilities, and the like that are exposed to the public outdoors be provided with, for example, a pattern such as a bark of a natural tree so as not to damage the natural environment. ing.

Conventionally, in the case of manufacturing such a metal material having a large number of unevenness like a wooden surface, particularly a steel pipe, for example, similar to the method of manufacturing a striped plate, unevenness is provided on the roll surface of the final stand of the rolling mill. Manufactured by rolling.

However, when such a method is adopted, a dedicated roll set is required, and the unevenness on the rolls is very much worn, resulting in a large equipment cost. Furthermore, when manufacturing a steel pipe that does not require the formation of irregularities, the stand must be recombined, which leads to a reduction in efficiency.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for manufacturing a tree skin steel pipe which can economically and efficiently manufacture the tree skin steel pipe.

[0006]

In order to solve the above-mentioned problems, the present invention relates to a tube made of Fe-Si-Al alloy at a temperature of at least 500 ° C.
Provided is a method for producing a wood-skinned steel pipe, which comprises rolling at least 40% at a reduction ratio of the outer diameter.

The inventors of the present application have made earnest studies on a method for economically and efficiently producing a wood-like steel pipe, and as a result, use Fe--Si--Al as a steel material and define the production conditions within a certain range. It was found that by doing so, a tree-like surface can be obtained without forming irregularities on the rolling roll. The present invention was made based on such knowledge.

That is, in order to obtain a tree-like surface, it is necessary to make the crystal grain size 0.1 mm or more and to form irregularities on the surface, but the Fe-Si-Al alloy has such a coarse grain. Can be easily obtained, and unevenness is likely to occur due to the large particle size. Therefore, by appropriately adjusting the rolling conditions, it is possible to form the desired unevenness, and it is possible to form a tree-like texture. In this way, a tree-like surface can be obtained without using a special roll, which is economical and efficient.

Further, by further performing tensile processing,
The unevenness extends in the pulling direction, and a more excellent tree-like surface can be obtained. The degree of processing at this time is appropriately determined according to the surface pattern to be formed.

Here, the rolling temperature should be at least 50.
The reason for defining 0 ° C is that if the temperature is less than 500 ° C, the crystal grain size becomes too small due to processing.
Even if the temperature is 0 ° C. or higher, if the rolling reduction is less than 40%, it is not possible to form appropriate irregularities on the surface. The present invention can be applied to both welded steel pipes and seamless steel pipes as long as they are steel pipes.

[0011]

Embodiments of the present invention will be specifically described below. In this example, the following alloy compositions were used. C: 0.0014 Si: 0.51 Mn: 0.01 P: 0.0010 S: 0.0004 Al: 2.35 N: 0.0014 O: 0.0014 (unit:% by weight)

A rolled coil having this composition was entirely heated at 1200 ° C., and then only an end portion was heated to 1400 ° C. and pressure-bonded to manufacture a raw pipe. Such a forged welded tube was finished with a roll to a predetermined outer diameter to obtain a steel tube. At this time, various reduction rolling ratios of finish rolling were tested. Whether or not the desired unevenness was formed was evaluated by the surface roughness, and if this value was 100 μm or more in R _(a) , it was judged to be sufficient as tree skin. FIG. 1 shows the relationship between the outer diameter reduction rate and the surface roughness R _(a) at that time. As is clear from FIG. 1, those satisfying the present invention had a surface roughness R _(a) of 100 μm or more, which was a value suitable for tree skin. On the other hand, when the rolling reduction was less than 40%, the surface roughness R _(a) was less than 100 μm even if the crystal grain size was large, which was insufficient.

[0013]

According to the present invention, a steel pipe having a resin-like surface can be economically and efficiently obtained.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship between an outer diameter reduction rate and surface roughness.

Claims (2)

[Claims] 1. A dendritic steel pipe, characterized in that, at least at a temperature of 500 ° C., a rolling process of at least 40% is carried out at a reduction ratio of the outer diameter with respect to a raw pipe made of an Fe—Si—Al alloy. Production method. 2. The method for producing a wood-skinned steel pipe according to claim 1, further comprising a tensile process.