JPS58144421A - Manufacture of stainless clad steel plate - Google Patents

Abstract

PURPOSE: To manufacture the titled as-rolled steel plate at a low cost without injuring its corrosion resistance, by using the base plate of low-carbon steel having carbon content and carbon eq. lower than those of stainless steel as a cladding plate, and acceleratively cooling the clad steel plate with the ratio of the volume of water in response to a clad ratio after hot-rolling it.

CONSTITUTION: The base plate of carbon steel having carbon content lower than that of stainless steel as a cladding plate and the composition whose carbon eq.= C+Si/24+Mn/6 is in the range of 0.2W0.35 is put on said stainless steel. Thereafter, the layered materials are heated above 1,000°C and hot-rolled. In succession, the clad plate is acceleratively cooled with the density of the volume of water of 0.3W4.0m³/min in a manner such that the volumes of water from the upper and lower surfaces are controlled at such the ratio to countervail the differences in thermal expansion and sectional area between the sides of the base plate and the cladding plate. Consequently, the deformation of the clad steel plate is substantially eliminated.

COPYRIGHT: (C)1983,JPO&Japio

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing rolled stainless clad steel by rolling at low cost without impairing corrosion resistance.

Conventional rolled stainless clad steel is produced by welding, explosive welding, overlay welding, etc. on the surface of a carbon steel base material, and then reheating the stainless steel materials to a high temperature and then hot rolling them. n has arrived. The rolling edge is air cooled. In this case, even though it is stainless clad steel, it must have a tensile strength of 41 If/y' or more because it is used for machine structures, so the base material has a carbon content of Carbon steel with +1.25% or more added Si, Mn!) is used.
! leather. On the other hand, stainless steel with corrosion resistance in mind usually has a low amount of carbon that is harmful to corrosion, and is generally (1,0
The level is 81 or below. In this process, if there is a difference in carbon concentration between the base material and the cladding material, carbon will diffuse from the base material to the stainless steel side during high-temperature heating for hot rolling, during hot rolling, and during the air cooling process, resulting in poor results. E. The corrosion resistance of stainless steel as a cladding material deteriorates. Therefore, in the conventional method, stainless steel 1 and base material 2 are shown as 3VC in Figure 1.
It is necessary to take measures to prevent carbon diffusion and apply Nl plating, a spacer with a low carbon component, and an underlay force with a low carbon component, which may complicate the manufacturing process and increase manufacturing costs. I'm confused as to the cause.

In addition, in the conventional method, stainless steel 1 and carbon steel 2 are
Due to the difference in the coefficient of thermal expansion between the two, warping deformation inevitably occurs, and cold realignment is unavoidable.

The inventor has studied methods that can fundamentally solve all of these problems.5. As shown in Figure 2, we devised a new manufacturing method in which a new simple combination of a rad material and a base material is hot-rolled and then cooled at an accelerated rate. However, in the new combination material, the carbon content of the base material carbon steel 2 itself is lower than the level of stainless steel 1.

Care was taken to prevent diffusion of carbon from the base metal 2 to the stainless steel 1 side during heating and hot rolling, and furthermore, by accelerated cooling after hot rolling, even with low carbon I and low carbon equivalent, 41
K4//w" or higher strength, and at the same time, the amount of water from the top and bottom surfaces during accelerated cooling down to water cooling is designed to compensate for the difference in thermal expansion and cross-sectional area between the base metal side and the cladding side. A stainless steel clad steel plate that almost eliminates the deformation of the steel plate by controlling the cal ratio to the #1 level, that is, the present invention is a clad plate in which the carbon steel base material having a composition in the stainless steel range and the stainless steel are laminated together. After heating the mixed material to over 1000℃.

Hot rolling, followed by c), 3-4. This is a method for producing an as-rolled stainless steel clad steel sheet, which is characterized by performing area accelerated cooling at a water density of +ITfI'/min and at a water volume ratio controlled by the cladding ratio.

The details of the present invention and the reasons for limiting the scope of the claims will be described below.

First, let's look at the chemical composition of carbon steel 2, which is the base material.

Carbon'fit should be at least less than the content of stainless steel, which is the cladding material, and 1.
Since the rail is 11.111 to 11.08%, it is desirable to set it to 0.05% or less. This is the concentration of carbon
□It is true that differences are a factor in diffusion. Next, the carbon equivalent regulation limits the strength of steel sheets to 41/IIj' to 613Kf/9 (8M
The lower limit was set as the range that could be maintained using this manufacturing method. In other words, L E shown in Figure 3
l), when the carbon equivalent is less than 2, when water cooling is performed at the lower limit of the appropriate water flow density, 411 Kg/j! If the tensile strength is less than +1", or the carbon equivalent is 1), and the carbon equivalent is more than 35, the tensile strength will be 60 Kq when water-cooled at the upper limit of the appropriate water density.
/, over 9. The stainless steel used for the cladding material is selected from austenitic and ferritic stainless steels depending on the level of corrosion resistance required.

The hot rolling conditions are the same as those used for ordinary carbon steel and stainless steel, but only the heating temperature is ff 1.
If the temperature is not higher than 111111°C, there is an increased possibility that the temperature in the final process of practical multi-pass hot rolling will drop too much and rolling will become impossible.

Next, accelerated cooling after rolling has an important meaning in the present invention, and it is necessary to select an appropriate water flow density range to improve operability and tensile strength, and to prevent deformation of the steel plate by It is necessary to control the ratio of water amount to the material side. The water density is 41 to 6 when the carbon equivalent is 0.2 to 35%.
(The range to obtain the tensile strength of Kl/y soda is wide, but considering the ease of cooling control and the excessive cost of water cooling equipment, the total of both sides () is 3 to 4.1 lni"/ minutes,
rII'' is the upper and lower limit.The water ratio between the base metal 2 side and the stainless steel 1 side is determined from the shape of the steel plate, but as shown in Fig. 4, this value is determined by the cladding ratio (thickness of cladding material 1). ζ／
The thickness of the base metal 2) changes by K machining, and the normal cladding ratio (0
, 1) 5 to o, 3) 1.11 to 3. +
In the range of 1, it is sufficient to control the water amount ratio = 3.3 M cladding ratio + 1.5 on average. Figure 4 shows the experimental results when the upper surface is made of stainless steel. In the (U) region, the shape is good for practical use, and in the (■) region, the VC is convex on the stainless steel side.

In the region (1), the shape is convex toward the base metal, and because there is a difference in thermal expansion between stainless steel and carbon steel, that difference plus the difference in effective water amount on the upper and lower surfaces (approximately (), 5 times the upper surface This shows that a good shape cannot be obtained unless the water volume ratio is large considering

In addition, when stainless steel is combined with the subsurface of the soil, or when clad steel on one side is hot-rolled and cooled in two or more stages, the symmetrical shape of the launch occurs, so the above water ratio of 1. Is the cladding ratio 1.11? It should be considered as a standard.

Next, embodiments of the present invention will be presented.

Table 1 shows At-A7 as an example of the steel of the present invention.

If the requirements of the present invention, such as low rotation content I and appropriate slab heating and water cooling conditions, are satisfied, the stainless steel part l
There is no increase in carbon content, and the tensile strength is f
f 41 b /w9-6 EI Kl /msx".

Furthermore, it is clear that the shape of the steel plate is also FRAN)K.

On the other hand, with the comparative method and conventional steel, it is clear that one or more of the above-mentioned problems with stainless clad steel have not been solved.

As described above, according to the present invention, complicated treatment for preventing carbon diffusion in stainless clad steel assembly can be performed without polishing.
In combination with G and Vc, it is possible to flatten the shape of the steel plate, and it is possible to manufacture strong stainless clad steel at a very low cost and with no deterioration in corrosion resistance. Since water cooling after rough rolling achieves much more accelerated cooling than air cooling, there is no worry that the carbon in the stainless steel will precipitate as chromium carbide during cooling of the steel sheet and deteriorate its corrosion resistance.

In this process, the present invention makes it possible to produce stainless steel clad steel that is inexpensive and has a good shape without deteriorating its corrosion resistance. It's a good thing.

[Brief explanation of the drawing]

Figure 1 shows the cross section of an assembled slab for stainless clad steel according to the conventional method (r), Figure 2 shows the cross section of the present invention. The shape of the steel shows the influence of the carbon equivalent. Figure 4 shows the relationship between the shape of the water-cooled material after rolling and the cladding ratio and water l ratio. 1... Stainless steel, 2... Low 0 carbon steel%3...
Carbon diffusion prevention layer agent Patent attorney Masa Akizawa Tapered 2 people 0 (vw-/+I#) Immersion borrowed 1ρ

Claims (2)

[Claims] (1) S with less weight made of stainless steel clad plate
i BJn A composition having a carbon content and a carbon equivalent range of 0.2 to 11.35 with an index of 0+/+76?
A material in which a carbon steel base material having a carbon steel base material and the stainless steel are superimposed is heated at a temperature of 1° C. or higher and hot rolled. A method for producing as-rolled stainless steel clad steel sheet, characterized in that accelerated cooling is performed using a water volume ratio controlled by a water ratio. (2) Water ratio 'e between carbon steel base metal side and stainless steel side
3.3 The method according to claim 1, wherein cooling is performed while controlling the X cladding ratio +1.5±(),5.