JPH09327778A - Manufacture of clad steel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To excellently join a clad plate with a base material by stacking a sacrifice material of the prescribed thickness on a face side of the clad plate, and performing the hot rolling with the prescribed draft and the total rolling ratio. SOLUTION: A base material 1 consisting of carbon steel or low alloy steel, a clad plate 2 consisting of copper or copper alloy, and a sacrifice material 3 consisting of low alloy steel are prepared. The clad plate 2 is stacked so as to be held by the base material 1 and the sacrifice material 3. A clearance material 4 of the same material as the base material 1 is arranged between the base material 1 and the sacrifice material 3 so as to surround the circumference of the clad plate 2. Fillet parts of the clearance material 4, the base material 1, and the sacrifice material 3 are seal welded. The combined material is heated to 730-970 deg.C together with the clad plate, and rolled so that the draft is >=2% per pass, and the total rolling ratio is >=1.5. The clad plate can be press fitted to the base material in an early stage even with the relatively small reduction force.

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 clad steel for joining a carbon steel and a low alloy steel to a clad steel having the characteristics of two materials.

[0002]

2. Description of the Related Art In order to meet various purposes, a clad steel in which a base material of carbon steel or low alloy steel is joined with a laminated material having predetermined characteristics (for example, corrosion resistance) has been put into practical use.
As a method for producing this clad steel, methods such as an explosion welding method and a rolling method are known. Among them, the explosion welding method is to bond the laminated material to the base material by utilizing the explosive force of the explosive, It is known as a method for easily bonding even materials having poor workability. However, the explosive welding method is not suitable for joining materials with large areas. On the other hand, in the rolling method, the laminated base material and the laminated material are heated to a predetermined temperature, and the two are metal-bonded by rolling them, and even a large-area material can be well bonded. .

However, in the above rolling method, it is difficult to give a sufficient amount of reduction in the case of an extremely thick plate material, and when the difference in deformation resistance between the base material and the laminated material is large (for example, the laminated material is copper or When the deformation resistance is smaller than that of the base material such as copper alloy), the deformation will be uneven. Therefore, two sets of the superposed body in which the base material and the laminated material are laminated are further laminated so that the laminated materials face each other. Or a sacrificial material 12 having a deformation resistance equivalent to that of the base material and having a thickness similar to that of the base material on the surface side of the laminated material 11 laminated with the base material 10 as shown in FIG. The sacrificial material method of stacking is used. In addition, in these methods, as shown in FIG. 3, for example, the base material 10 and the sacrificial material 1 with the joining material 11 sandwiched therebetween.
After arranging the joining plate 13 around 2 and sealing-welding the joining plate 13, the base material 11 and the sacrificial material 12, respectively,
It is subjected to rolling, and the desired clad steel is obtained by peeling the sacrificial material 12 after rolling.

[0004]

However, the above-mentioned method for producing a clad steel (hot rolling method) has a problem that abnormal deformation occurs during rolling, which easily causes non-bonding and dimensional defects. . Conventionally, the above problems were considered to be caused by the difference in deformation resistance between the base material and the laminated material, but the present inventors have made various investigations on the causes of the above problems, and found. That is, in a method for producing a clad steel using copper and a copper alloy as a composite material, heating before rolling is usually performed at a low temperature (730 ° C.) in accordance with the composite material.
~ 970 ° C), the deformation resistance of carbon steel and low alloy steel becomes large and it is difficult to carry out strong reduction. Moreover, the adoption of the sandwich method or the sacrificial material method causes the joint surface to separate from the reduction surface. In this case, since the rolling force is not sufficiently transmitted to the joint surface, the base material and the laminated material are not sufficiently crimped until the rolling passes through a plurality of passes, and the above problem occurs during this time.

Therefore, the present inventors have reached a new conclusion that the reduction surface and the joint surface can be brought close to each other by reducing the thickness of the sacrificial material to a predetermined value or less, thereby preventing the occurrence of the above problems. It is a thing. In addition, when the difference in deformation resistance between the base material and the laminated material is large, there is a problem that the deformation is likely to be uneven by thinning the sacrificial material. In this case, the amount of reduction per pass is reduced. The problem can be easily avoided by reducing the size or using a sacrificial material having a larger deformation resistance than the base material.

That is, the present invention relates to the improvement of the hot rolling method, which is one of the methods for producing clad steel, and the thickness of the sacrificial material is regulated, so that the base material and the laminated material can be made good. It is an object of the present invention to provide a method for producing a clad steel that can be joined to.

[0007]

In order to solve the above-mentioned problems, a first invention of the method for producing a clad steel of the present invention is to subject a base material made of carbon steel or a low alloy steel to hot pressing a joining material by hot rolling. In the clad steel manufacturing method described above, a sacrificial material having a thickness of 1/4 or less of the base material is stacked on the surface side of the laminated material which is stacked with the base material, and these are rolled at a rolling reduction of 2% or more per pass. It is characterized in that hot rolling is carried out so that the ratio becomes 1.5 or more and the base material is pressed against the base material.

According to a second aspect of the invention, the laminating material is made of a material having a smaller deformation resistance than the base material, and when the laminating material is placed between the base material and the sacrificial material and overlapped with each other, the laminating material surrounds the laminating material. In the gap between the base material and the sacrificial material, a gap material having a larger deformation resistance than the laminated material and equal to or less than the deformation resistance of the base material is charged, and hot rolling is performed. To do.

Among the base materials used in the present invention, carbon steel is
It means iron and carbon as main components, and usually having a carbon content of 2% or less. In addition, as impurities, Si, Mn,
The inclusion of P, S, etc. is allowed. In addition, the low alloy steel of the other material that is the base material contains one or more alloy elements for a predetermined purpose.
It is contained at 0% or less, and usually contains alloying elements at several% or less. Examples of low alloy steels include those containing one or more of Mn of 2% or less, Ni of 4% or less, Cr of 2% or less, Mo of 0.6% or less, and V of 0.2% or less. Can be mentioned. The examples of the low alloy steels described above are merely examples, and the type and content of each component are not limited to the above.

Further, various materials are used as the material used as the laminating material in the present invention depending on the purpose. Examples include copper and copper alloys. In addition, specifically, oxygen-free copper as the above copper, Naval brass as the copper alloy, A
Examples thereof include BP (abbreviation of aluminum bronze), cupronickel (trademark) and the like.

Next, as the sacrificial material, a material having a deformation resistance equivalent to that of the base material is usually used, and the same material as the base material can be used. However, when the deformation resistance of the laminated material is smaller than that of the base material and the difference is large, it is desirable to use a material having a larger deformation resistance than the base material as the sacrificial material, in addition to adjusting by the rolling reduction. Although it is not easy to express this deformation resistance accurately with an absolute numerical value, it is possible to approximately compare it by the magnitude of tensile strength. As described above, when the difference in deformation resistance between the base material and the laminated material is large, it is exemplified that the ratio of tensile strength (laminated material / base material) is 0.8 or less. An example is one in which the strength ratio (sacrificial material / base material) is 1.2 or more. An example of such a sacrificial material is chrome molybdenum steel when the base material is carbon steel.

The reason why the thickness of the sacrificial material is set to 1/4 or less of the thickness of the base material is that the joining surface is brought close to the rolling surface and the base material and the laminated material are pressure-bonded at an early stage, and This is to prevent abnormal deformation and the like. Further, even if the reduction amount is reduced in order to prevent the occurrence of non-uniform deformation, the joint surfaces are close to each other, so good joining is possible. On the other hand, when the thickness of the sacrificial material exceeds 1/4 of the thickness of the base material, the above-described action cannot be sufficiently obtained, resulting in poor bonding. The thickness of the sacrificial material is preferably 20 mm or more in order to secure the leg length of the welded portion for reasons such as preventing the welded portion from breaking during rolling.

When the base material, the laminating material and the sacrificial material are overlaid, the laminating material is made smaller in width and length than the base material and the sacrificial material, and the base material and the sacrificial material sandwiching the laminating material are sacrificed. It is desirable to place a gap material between the materials so as to surround the periphery of the laminated material. It is desirable that the gap material is arranged so that there is as little gap as possible between the upper and lower base materials and the sacrificial material, and it is more desirable that they are closely attached. In addition, a certain space is secured between the laminated material and the laminated material so as not to interfere with the deformation of the laminated material. Further, a material having a deformation resistance equivalent to that of the base material can be used for this gap material, but naturally the same material as the base material can also be used.

The superposed body superposed as described above is rolled so that the rolling reduction per pass is 2% or more and the total rolling ratio is 1.5 or more. The rolling reduction is preferably smaller than the conventional one in order to prevent the deformation from becoming non-uniform during rolling, and the rolling reduction of less than 10% can surely prevent the non-uniform deformation. However,
As described above, if a material having a larger deformation resistance than the base material is used as the sacrificial material, nonuniform deformation can be avoided even if the rolling reduction is the same as the conventional one. Therefore, in the present invention, the rolling reduction is not limited to less than the above 10%.

The rolling reduction rate per pass is 2% or more,
The reason for setting the total rolling ratio to 1.5 or more is that non-bonding is likely to occur when the values are less than these values. Particularly, if the rolling reduction is less than 2%, the number of rolling passes increases and the finishing temperature becomes low, so that edge cracks easily occur in the laminated material. By the way, in the conventional sandwich method and sacrificial material method, it is said that the reduction rate per pass is required to be 10% or more in order to avoid non-bonding. Since it is close to the surface and the reduction force is efficiently transmitted, the reduction rate per pass can be reduced.

That is, according to the present invention, by reducing the thickness of the sacrificial material, the distance between the rolling surface and the joint surface is significantly reduced, and the rolling force is efficiently transmitted to the joint surface.
As a result, the base material and the laminated material are pressure-bonded to each other at an early stage of rolling, and abnormal deformation or the like is prevented. If the rolling reduction per pass is less than 10% or if the sacrificial material is a material having a larger deformation resistance than the base material, uneven deformation between the base material and the laminated material can be avoided, and warpage occurs. Etc. are prevented, and in particular, it works effectively when the difference in deformation resistance between the base material and the laminated material is large. It should be noted that these means (adjustment of the rolling reduction, selection of the material of the sacrificial material) can be adopted independently, but if both are adopted together, the above-mentioned action becomes more remarkable.

If a gap material equivalent to the base material is arranged between the base material and the sacrificial material so as to surround the periphery of the laminated material,
Due to the heat retaining effect of the gap material, the occurrence of cracks in the edges of the laminated material is prevented. In addition, when the deformation resistance of the laminated material is smaller than that of the base material, the laminated material may be preferentially rolled down, which makes it difficult to control the plate thickness. Of the base material and the laminated material can be deformed with a similar behavior, thereby facilitating the control of the plate thickness.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION A base material 1 made of a carbon steel or a low alloy steel manufactured by an ordinary method, a laminated material 2 made of copper or a copper alloy, and a sacrificial plate 3 made of a low alloy steel are prepared. In the method of FIG. 1, the base material 1 and the sacrificial material 3 have the same width and the same length, and the laminated material 2 has a width and a length smaller than these. On the other hand, in the method of FIG. 2, the width and the length are reduced in the order of the base material, the sacrificial material, and the laminated material. The laminated material 2 is superposed so as to be sandwiched between the base material 1 and the sacrificial material 3, and the base material 1 is surrounded between the base material 1 and the sacrificial material 3 so as to surround the periphery of the laminated material 2.
A gap member 4 made of the same material as the above is placed. In the method of FIG. 1, the gap material 4 projects in the width and length directions from the base material 1, and in the method of FIG. 2, the gap material 4 extends in the width and length directions more than the sacrificial material 3. Although protruding, it is contained within the width and length of the base material 1.

Since the above-mentioned laminated materials are welded to each other, in the method shown in FIG. 1, the laminated materials are inverted to form the fillet between the gap material and the base material and the fillet portion between the gap material and the sacrificial material. Seal weld. On the other hand, in the method of FIG. 2, it is not necessary to invert the combination material, and the fillet between the base material and the gap material and the fillet between the gap material and the sacrificial material are seal-welded. Although this method has a slightly poor material yield, it has the advantage that it does not require reversal during welding, has good work efficiency, and has high welding strength. The above combined material is heated to 730 to 970 ° C. according to the combined material, and the total rolling ratio is 1.5 at a reduction ratio of 2% or more per pass.
Roll to the above. In the obtained clad steel, the laminated material is satisfactorily pressure-bonded to the base material, and then the sacrificial material is peeled off to obtain the desired clad steel.

[0020]

[Examples] Examples of the present invention will be described below. The types and dimensions of each material used in this example (in units of mm)
Is as follows. Base material JIS SS400 carbon steel 250 thickness x 1600 width x 2100 length Composite material (1) 90/10 cupro nickel alloy (JIS C7060P) 15 thickness x 1500 width x 2000 length (2) Naval brass (JIS C4621P) 15 thickness x 1500 Width x 2000 length Sacrificial plate (1) Chrome molybdenum steel (JIS SCMV3) 60 thickness x 1550 width x 2050 length (2) Same as above 120 thickness x 1550 width x 2050 length 250 thickness x 1550 width x 2050 length Gap material JIS SS400 carbon Steel (for width direction) 15 thickness x 30 width x 1500 length (for length direction) 15 thickness x 30 width x 2000 length

The above materials were laminated in the combinations shown in Table 1, and in the invention method and the comparative method, as shown in FIG. 2, the base material, the bonding material, and the sacrificial material were welded and joined through a gap material,
In the conventional method, as shown in FIG. 3, the interposing material and the sacrificial material are welded to each other via a joining plate without using a gap material. After that, each of the superposed bodies was rolled in a plurality of passes at the heating temperature, the reduction rate and the total rolling ratio shown in Table 1. The target plate thickness ratio in the clad steel is 5.7% of the plate thickness of the laminated material and 94.3% of the plate thickness of the base material. The obtained clad steel is
After that, the sacrificial material was removed, and the bonding state of the bonded portion was evaluated by an ultrasonic test. Further, the occurrence of cracks in the laminated material was visually confirmed, and the plate thickness of the laminated material was further measured. It was judged that the amount of deviation from the target plate thickness within 2% was good, and the amount more than that was defective. The results are shown in Table 2.

As is clear from Table 2, according to the method of the present invention, the base material and the laminated material are well bonded, no crack occurs in the laminated material, and the plate thickness ratio is within the desired range. ing. On the other hand, in the comparative method out of the condition range of the conventional method or the method of the present invention, there is a problem in the joining of the base material and the laminated material, and there are some cases where the laminated material is cracked or the plate thickness accuracy is not good. However, good clad steel could not be obtained. It is also clear that the use of the gap material is effective in preventing the cracking of the laminated material and improving the plate thickness accuracy.

[0023]

[Table 1]

[0024]

[Table 2]

[0025]

As described above, according to the method for producing a clad steel of the present invention, a sacrificial material having a thickness of ¼ or less of the base material is overlaid on the surface side of the laminated material which is overlaid with the base material. Since these are hot-rolled at a reduction rate of 2% or more per pass so that the total rolling ratio is 1.5 or more and the bonding material is pressure-bonded to the base material, the bonding material can be early processed even with a relatively small rolling force. Can be pressure-bonded to the base material, and the laminated material can be satisfactorily bonded to the base material.

Further, when the laminated material is made of a material having a smaller deformation resistance than the base material, the deformation resistance is larger than that of the laminated material in the gap between the base material and the sacrificial material around the laminated material.
If a gap material that is equivalent to the base material or has a smaller deformation resistance than the base material is charged and hot-rolled, the base material of the laminated material is gradually deformed in accordance with the deformation of the laminated material, and the accuracy of the thickness of the laminated material is improved. High clad steel is obtained. Further, the laminated material is favorably deformed due to the heat retaining effect of the gap material, and the occurrence of cracks is surely prevented.

[Brief description of drawings]

FIG. 1 is a front cross-sectional view showing a superposed state of materials in an embodiment of the present invention.

FIG. 2 is a front cross-sectional view showing a modified example of the overlapping of materials.

FIG. 3 is a front cross-sectional view showing a superposed state of materials in a conventional example.

[Explanation of symbols]

 1 Base material 2 Laminated material 3 Sacrificial material 4 Space material

Claims (2)

[Claims] 1. A method for producing a clad steel in which a base material made of carbon steel or a low alloy steel is pressure-bonded to a base material by hot rolling, and the surface side of the base material to be laminated with the base material is 1/4 or less of the base material. Characterized in that the sacrificial materials having a thickness of 1 are stacked, and these are hot-rolled at a reduction ratio of 2% or more per pass so that the total rolling ratio is 1.5 or more, and the bonding material is pressure-bonded to the base material. Method for producing clad steel 2. The composite material is made of a material having a smaller deformation resistance than the base material, and when the composite material is placed between the base material and the sacrificial material and overlapped with each other, the composite material is aligned in the gap between the base material and the sacrificial material. A gap material having a larger deformation resistance than the laminated material and having a deformation resistance equal to or smaller than that of the base material is disposed so as to surround the periphery of the material, and hot rolling is performed.
Method for producing the described clad steel