KR900004207B1 - Manufacturing method of a stainless clad steel - Google Patents

Abstract

A stainless clad steel plate is manufactured by hot-rolling three- layer slab consisting of carbon steel as base material, stainless steel as combined material, and low carbon steel as intermediate material between base material and combined material. Specially low carbon steel comprises not more than 0.015 wt.% carbon. The obtained clad plate is used for chemical container and has the improved shearing strngth and bonding strength.

Description

Manufacturing method of stainless clad steel

1 shows an embodiment of a method according to the invention.

2 is a micrograph of the interfacial structure of the steel produced by the present invention and the steel produced by the conventional method.

* Explanation of symbols for main parts of the drawings

1: cladding material 2: base carbon steel

3: ultra low carbon steel sheet

The present invention relates to a method for producing stainless clad steel used in chemical containers and the like. In general, stainless clad steel is manufactured by joining hot rolled stainless steel and carbon steel. As a result, the base carbon generated during heat treatment is diffused into the clad material. The problem of reducing the effective stainless thickness by forming Cr-carbide has emerged.

In order to solve such a problem, prior to joining SUS stainless steel and 0.15% carbon steel as a base material, Ni plating was performed on the surface of the stainless steel joint.

However, Ni plating on stainless steel is not only difficult to process but also expensive, and the plating thickness is limited, so the total thickness after rolling is only a thin layer of 20-30 μm, which can greatly prevent the diffusion of the base carbon. There was no problem.

Accordingly, an object of the present invention is to prevent the diffusion of carbon more strongly than before, in the manufacture of stainless clad steel without the difficult and expensive Ni plating, to secure the effective thickness of the stainless steel to bond the strength of the interface It is to provide a method of manufacturing stainless steel cladding that can be improved. Hereinafter, the present invention will be described in detail.

The present invention in the manufacture of stainless clad steel by hot-rolling a stainless steel as a cladding material and a carbon steel as a base material, the initial thickness of 0.5mm-1mm between stainless steel as a cladding material and carbon steel as a base material and The present invention relates to a method for producing stainless clad steel that is hot rolled after inserting an ultra low carbon steel sheet containing carbon of 0.015% by weight or less.

Carbon is diffused from the base metal to the cladding material during the heat treatment after hot rolling of the stainless clad steel. To prevent this, the hot rolled ultra low carbon steel sheet must have a certain thickness, but if the thickness is too thick, Since the bond strength is lowered, the final thickness of the ultra low carbon steel sheet is preferably in the range of 100-200 µm.

)이 2.5-5.0 정도인 점을 고려하면, 상기 극저 탄소강판의 초기두께는 0.5-1mm 정도가 바람직한데, 그 이유는 초기두께가 0.5mm 이하인 경우에는 100μm 이상의 최종두께는 얻기가 곤란하여 탄소가 열처리시 탄소강인 모재에서 스테인레스인 크래드재로 확산하므로서, 열처리후 냉각시 스테인레스재 계면부에서 Cr-카바이드(carbide)를 형성하여 유효스테인레스두께를 감소시키기 때문이며, 초기두께가 1mm 이상인 경우에는 200μm 이하의 최종두께를 얻기가 곤란하여 전단강도 및 박리강도와 같은 접합강도를 저하시키기 때문이다.Of course, depending on the application of stainless clad steel, the final thickness of the ultra-low carbon steel may have a thickness smaller than the lower limit (100 μm) or greater than the upper limit (200 μm). Normally, the total reduction rate of hot rolling in the manufacture of stainless clad steel (

Considering that 2.5) is about 2.5-5.0, the initial thickness of the ultra-low carbon steel sheet is preferably about 0.5-1 mm, because when the initial thickness is 0.5 mm or less, a final thickness of 100 μm or more is difficult to obtain. This is because it diffuses from the carbon steel base material to the stainless steel cladding during heat treatment, thereby reducing the effective stainless thickness by forming Cr-carbide at the interface of the stainless steel during cooling after heat treatment, and when the initial thickness is 1mm or more, 200μm or less This is because it is difficult to obtain the final thickness of the bond and lowers the bonding strength such as the shear strength and the peel strength.

The carbon content of the ultra low carbon steel sheet in the present invention is preferably limited to 0.015% by weight or less in order to minimize the carbon diffusion from the insertion layer itself to the clad material. Hereinafter, the present invention will be described in more detail with reference to Examples.

Example 1

Table 1 below shows an example of the remaining chemical composition except for iron (Fe) of the ultra-low carbon steel sheet used as the insertion layer of the present invention.

TABLE 1

(Unit: weight%)

The 0.5mm thick ultra low carbon steel sheet 3 having the composition shown in Table 1 is inserted between the cladding material 1 and the solid material 2, as shown in FIG. 1 (a), and then made a slab pack. All the large spaces around the slab pack were welded and the inside was vacuumed through the exhaust port 4 at 0.01 torr.

Thereafter, as shown in FIG. 1 (b), the plate was heated to 1250 ° C., hot rolled, heat-treated and cooled, and separated into two plates.

The interfacial structure and mechanical properties of the stainless clad plate obtained above were compared with the conventional clad steel, and the micrograph of the interfacial structure is shown in FIG. 2 and the mechanical properties are shown in Table 2 below.

(A) and (b) are interface texture photographs obtained after experimenting under the same rolling and heat treatment conditions, (a) is an interface obtained by the present invention, and (b) shows an interface obtained by a conventional Ni plating method. .

As shown in FIG. 2, the ultra-low carbon steel sheet layer by the method according to the present invention is thick after 150 μm even after rolling, thereby greatly preventing the base carbon from diffusing into stainless steel, and the pearlite structure at the interface between the base material and the insertion layer. Although it continues to exist, the Ni plating layer by the conventional Ni plating method is as thin as 20 μm, and as a result, the base carbon is decarburized during heat treatment, so that the interface between the base material and the Ni plating layer is hardly visible and contains very low carbon concentration. It can be seen that only ferrite tissue is known to be present.

Table 2 below compares the mechanical properties of the stainless clad steel produced by the method of the present invention and the conventional Ni plating method, and the test was conducted by JIS G 0601 method.

TABLE 2

According to Table 2, the stainless clad steel produced by the method according to the present invention was superior in shear strength and peeling strength than the stainless clad steel produced by conventional Ni plating, and the tensile strength was the same. appear.

The improvement of the stainless clad steel produced by the method according to the present invention in the bonding strength such as shear strength, peeling strength was improved in the present invention, rather than the Fe-Ni-bonded dissimilar metal atom bond in the conventional method, in the present invention. This is because atomic bonding is easy and the bonding force is strong.

As described above, the method of manufacturing stainless clad steel according to the present invention has a larger carbon diffusion energy than the conventional Ni plating method, and has an excellent process simplifying effect by omitting the Ni plating process, and at the same time, joining such as shear strength and peel strength. Strength is also improved.

Claims (1)

In the manufacture of stainless clad steel by hot rolling between stainless steel as clad material and carbon steel as base metal, the initial thickness is 0.5mm-1mm and carbon content 0.015 weight between stainless steel as clad material and carbon steel as base material. A method for producing stainless clad steel, characterized in that hot rolling is performed after inserting an ultra low carbon steel sheet of less than or equal to%.

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