JPH0371956B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Field of Application) The present invention relates to a method for producing a cladding material by rolling, and in particular to assembly, rolling and finishing of a cladding material. (Prior art) Japanese Patent Application Laid-Open No. 55-100890 and the same
No. 55-128390, No. 56-122681, No. 57-
In all of the methods for manufacturing clad materials described in Publication No. 109587, layers are layered in the order of base material, laminate material, laminate material, and base material in a sandwich pattern, or in the order of covering material, laminate material, and base material. and the surface to be joined are in the same space, and there is a high possibility that the separation agent will contaminate the surface to be joined. Furthermore, in the method described in JP-A No. 57-115991, a separator is hermetically welded between the laminates, but if the welded part breaks due to rolling force, the separator will leak onto the surfaces to be joined. Since the separation agent is contained in the same space as the air release hole, there is a high possibility that the separating agent will contaminate the surface to be joined. After pushing out the air, the air vent hole is welded, but since a cold rolling process is added, there is a high possibility that manufacturing costs will increase. In addition, with conventional technology, when metals that easily generate carbides, such as titanium, zirconium, and chromium, are used as laminates, carbon content increases in the space where the laminates exist.
When 0.12% or more steel coexists and these are heated,
The carbon in the steel forms carbides with the laminate on the surface of the laminate, which adversely affects the bending process and shear strength of the product. This tendency is significantly increased when organic matter is present in the space where the laminate is present. (Problems to be Solved by the Invention) An object of the present invention is to provide a method for manufacturing clad steel that has strong joint strength and has small warpage during and after rolling. (Means for solving the problems) The gist of the present invention is as follows. (1) Seal the laminate with a cover steel plate with a carbon content of 0.03% by weight or less with bonding inhibiting substances removed from the space, and insert the cover steel plate assembly containing the laminate into the steel base material. After welding the steel base material and the warpage prevention member, the steel base material and the warpage prevention member are heated to a temperature range of 650°C or higher and 900°C or lower and hot-rolled to make both sides of the laminated material adjacent to each other. of titanium, titanium alloy, zirconium, zirconium alloy, or chromium-containing steel, which is characterized by joining the rolled material, cutting the periphery of the obtained rolled material, separating it at the separating agent position, and removing the covering steel plate on the outer surface of the laminated material. A method for manufacturing rolled clad steel sheets with a carbon concentration distance of 20 μm or less at the joint boundary. (2) With bonding inhibiting substances removed from the space in which the laminate exists, it is surrounded by a covering steel plate with a carbon content of 0.03% by weight or less, and while inert gas is blown into the interior, the four circumferences of the covering steel plate are surrounded. weld,
While heating the surface of the covering steel plate to 100°C or higher, the space containing the cladding material is depressurized to 10 ^-1 Torr or less and then sealed, and the covering steel plate assembly is sandwiched in layers between the steel base material and the warpage prevention member, After welding the steel base material and the warpage prevention member, the steel base material and the warpage prevention member are heated to a temperature range of 650°C or higher and 900°C or lower and hot rolled to join both sides of the laminated material to the adjacent surfaces, and the periphery of the resulting rolled material is Titanium, titanium alloy, characterized in that it is cut and separated at the separating agent position, and the covering steel plate on the outer surface of the laminate is removed.
A method for manufacturing a rolled clad steel plate with a carbon concentration distance of 20 μm or less at the joint boundary of zirconium, zirconium alloy, or chromium-containing steel. (3) With bonding inhibiting substances removed from the space in which the laminate exists, it is surrounded by a covering steel plate with a carbon content of 0.03% by weight or less, and while inert gas is blown into the interior, the four circumferences of the covering steel plate are surrounded. weld,
While heating the surface of the covering steel plate to 100°C or higher, the space containing the cladding material is depressurized to 10 ^-1 Torr or less and then sealed, and the covering steel plate assembly is sandwiched in layers between the steel base material and the warpage prevention member, After welding the steel base material and the warpage prevention member, the steel base material and the warpage prevention member are heated to a temperature range of 650°C or higher and 900°C or lower and hot rolled to join both sides of the laminated material to the adjacent surfaces, and the periphery of the resulting rolled material is Titanium, titanium alloy, zirconium, which is characterized by being cut and separated at the separating agent position, then reheated and hot rolled with the outer surface of the laminate covered with a steel plate.
A method for producing a rolled clad steel plate of zirconium alloy or chromium-containing steel with a carbon concentration distance of 20 μm or less at the joint boundary. (Operation of the invention) The basic constituent elements of the present invention and their operation can be summarized as follows. (1) In the present invention, the laminated material is sealed with a cover steel plate having a carbon content of 0.03% or less to isolate the steel base material with a high carbon content. This requirement makes the carbon content of the steel base material independent of carbide formation in the laminate, making it possible to increase the carbon content of the steel base material to increase its strength. Carbon steel, which does not contain alloying elements, is most suitable for this covering steel plate because it is cheap and easy to process, but the carbon steel
Steel containing alloying elements can be used if the content is 0.03% or less. The thickness of the covering steel plate is determined based on the strength of the plate during material assembly and the diffusion distance of carbon during rolling.
It is desirable that the thickness is 0.1 mm or more, and so-called foil is inappropriate. (2) In the present invention, by heating the material assembly to 900°C or less and rolling joining it, carbon in the covering steel plate moves to the laminate material during heating and forms carbides with the laminate material. suppress. Heating temperature is 900℃
If it exceeds this value, the carbonization of the cladding metal due to the release of carbon or carbide from the covering steel sheet becomes noticeable, and the bending or shearing properties of the clad steel product begin to deteriorate. Further, the heating temperature is desirably higher than the recrystallization temperature of the material, that is, 650°C. (3) In the present invention, the surface of the covering steel plate that seals the laminate is heated to 100°C or higher, while the space formed by the laminate and the covering steel plate is sealed by reducing the pressure to 10 ^-1 torr or less. By removing organic matter from this space, the decrease in carbon supply can be reduced, and the amount of carbide produced in the laminate can be reduced. (4) In the present invention, the cladding material is further fixed to the base material by a covering steel plate, and the surrounding steel plate is also firmly welded to the base material, so that displacement of the cladding material during the processing process, It is possible to prevent breakage of the steel plates and deterioration of the dimensional accuracy of the laminate due to their non-uniform deformation. In order to maximize these effects, the contact surface between the covering steel plate and the laminate used in the present invention is also kept sufficiently clean for the purpose of bonding, and the space where the laminate is present is free of any components that may impede bonding. Eliminate as much as industrially possible. By doing this, both sides of the laminate are completely joined, and by rolling with sufficient restraint, warping can be prevented and deformation can be made uniform. (5) In the present invention, it is desirable to assemble the materials as follows. In other words, the base material, the cladding material, and the covering steel plate are stacked in layers with their mating surfaces cleaned, and when welding the periphery of the base material and the covering steel plate, an inert gas such as argon or helium is applied between the base material and the covering steel plate. Internal contamination from welding spatter, welding fumes, or welding heat is prevented by sealingly welding the base metal and the covering steel plate while blowing in the welding material. (6) When a warpage prevention material is used in the present invention, it is necessary that the warpage prevention material and the contact steel plate can be easily separated after hot rolling.
For this purpose, an oxide layer with a thickness of 30 μm or more must be present on at least one of these contacting surfaces, or Al ₂ O ₃ , SiO ₂ , TiO ₂ , Cr ₂ O ₃ ,
A powder containing one or more of Fe ₂ O ₃ and Fe ₃ O ₄ as a main component is applied to a thickness of 10 μm or more using a resin as a vehicle. The reason why a resin is used as a vehicle is that it is inexpensive and has excellent paintability, but since it generates a large amount of gas during heating, it is desirable that the surface to be separated communicates with the outside air to exhaust this gas. Next, a method of assembling the materials used in the present invention and its structure will be explained. FIG. 1 shows an intermediate state of a material assembly for implementing the present invention. Covering steel plates 2 and 3, whose surfaces in contact with the cladding materials have been cleaned, are layered over the cleaned laminate material 1, and the four circumferences of these covering steel plates are welded to seal the laminate materials. At this time, in order to prevent the cladding material 1 and the covering steel plates 2 and 3 for the cladding materials from being contaminated by fumes and spatter during welding, inert gas such as argon or helium, or non-toxic gas such as nitrogen or carbon dioxide gas is supplied from the nozzle 4. It is desirable to blow in oxidizing gas. After welding the four circumferences of the cover steel plate, the nozzle 4 is closed, but before that, the space formed by the cladding material and the cover steel plate is heated while heating the cover steel plate surface to 100℃ or more.
It is desirable to reduce the pressure to 10 ^-1 torr or less. Heating the surface of the covered steel plate is effective in eliminating moisture and organic matter, and reducing the pressure is effective in eliminating moisture and organic matter even more efficiently and preventing oxidation of the surfaces to be joined. The timing of welding the cover steel plate and the base metal is not particularly limited, but after welding the four circumferences of the cover steel plate as shown in Fig. 1, welding the cover steel plate and the base metal 6 as shown in Fig. 2 is recommended. is the easiest to work with, and the surface to be joined can be kept clean. Figure 3 is a cross-sectional view of the completed material assembly, covering the steel plate 2.
A separating agent 8 is interposed between the anti-warp material 7 and the anti-warp material 7 . This separating agent can be used by forming an oxide layer of 30 μm or more in total on one or both of the outer surface of the covering steel plate 2 or the surface of the anti-warp material 7 in contact with the outer surface of the covering steel plate 2, or using Al ₂ O ₃ , SiO ₂ , TiO ₂ , _{Cr2O3 ,}
It is preferable that a powder containing one or more of Fe ₂ O ₃ and Fe ₃ O ₄ as a main component is coated and dried to a thickness of 10 μm or more using a resin as a vehicle. The distant piece 9 functions to prevent the cover steel plate 2 from being damaged when welding the four circumferences of the base material 6 and the anti-warp material 7. If a separating agent 8 is interposed between the distance piece 9 and the base material or anti-warpage material to prevent them from joining, if the distance piece 9 is cut after rolling, the mating material will be exposed to the atmosphere. The anti-warpage material can be removed without exposing it to the surface. Even if the clad material from which the anti-warp material has been removed is reheated as it is, the laminate material 1 will be completely prevented from oxidizing by the covering steel plate 2, and even during subsequent rolling, the laminate material will be oxidized by the rolls. It cannot be hurt directly. The covering steel plate on the outer surface of the laminate is removed by cutting, grinding, or pickling. The anti-warpage member 7 can be assembled as shown in FIG. That is, the assembly 2 shown in FIG.
As shown in FIG. 4, the pieces are assembled by welding the four circumferences so that the covering steel plates 2 face each other with the separating material in between. Two clad steel plates can be manufactured at once from such a material assembly. (Example) Table 1 shows examples. Steel base material is 0.17% carbon steel,
The covering steel material used was 0.01% ultra-low carbon steel. The assembled material is a small test piece with a width of 150 mm and a length of 200 mm, which is sufficient to evaluate the rolling conditions and quality for production rolling. All test pieces were welded using the MIG welding method, argon gas was blown into the interior to prevent weld contamination during welding, and the interior was depressurized to 10 ^-2 torr after welding was completed. The heating temperature was 800°C in all cases. In example 1 of the conventional method, a 6 mm thick steel base material is used for a 20 mm thick steel base material.
Stainless steel is directly fillet welded. In this example, there was a large warpage toward the stainless steel side during rolling, and the warpage increased after cooling, and the thickness deviation of the laminate (=maximum thickness - minimum thickness) was as large as 0.33 mm. Shear strength is low and bending test results are also poor. In example 2 of the conventional method, as shown in Fig. 4, the covered steel plates 2, 2',
Although the structure does not have 3,3', the shear strength is low and the side bending test results are also poor. Examples 3 and 4 of the present invention have the structures shown in FIGS. 3 and 4, respectively, and are asymmetrical structures to make warpage more noticeable, but warpage during rolling and cooling is within a sufficiently permissible range. be. Furthermore, the deviation in the laminated thickness, the shear strength of the base material and the laminated material, and the side bending test results are all good. The shear strength and side bending test results are related to the distribution thickness of carbides enriched near the joint boundary. Carbides are mainly TiC when the cladding material is titanium or titanium alloy, and are mainly Cr ₇ C ₃ and Cr ₂₃ C ₆ when the cladding material or covering steel plate is stainless steel. These carbides were collected using a Shimadzu EPMA (model name: EMX-SM) at an accelerating voltage of 20 kV, sample current of 0.01 μA, and beam diameter.
When line analysis of carbon is performed perpendicularly across the cross section of the joint with a diameter of 1 μm, and the count number is 0.5k as the full width of the recording paper, the carbon concentration distance at the joint boundary is measured as shown in Figure 5. This carbon enrichment distance is related to shear strength, and in the case of titanium clad steel, as shown in Figure 6, the shear value of 14 Kgf/mm ² specified by JIS G 3603 can be satisfied with a carbon enrichment distance of 20 μm or less. Such carbon enrichment at the titanium-steel joint interface is TiC, which improves shear strength if it is in trace amounts, but if the carbon enrichment distance is 20μ
When TiC is generated to an extent exceeding m, it becomes brittle and contains a mixture of low shear values. The above is the same when stainless steel is used as a laminate material or as an intermediate material; in this case, TiC
Instead, Cr ₇ C ₃ and Cr ₂₃ C ₆ are generated in the same way and exhibit similar behavior.

【table】

[Table] (Effects of the Invention) According to the present invention, clad steel with strong joint strength can be produced without oxidizing expensive laminates. In the present invention, the covering material is a steel plate with a carbon content of 0.03% or less, and the bonding material is a metal that easily forms carbides, such as titanium or its alloy, zirconium, or stainless steel. According to the present invention, assembly and welding of materials is also easy and inexpensive. Furthermore, steel with a carbon content of 0.12% or more, which conventionally had low shear test values, is used as the base material, making it possible to stabilize the shear test values at a high level.

[Brief explanation of drawings]

Figures 1 and 2 are diagrams showing an intermediate stage of assembling the rolling material of the present invention, Figures 3 and 4 are diagrams showing the state of the rolling material of the present invention after assembly, and Figure 5 is carbon enrichment. An explanatory diagram of distance, FIG. 6 is a diagram showing the relationship between carbon concentration distance and shear strength, which shows the effect of the present invention. 1: Laminating material, 2, 3: Covering steel plate, 4: Nozzle,
5: Side surface of the base material of the covering steel plate, 6: Base material, 7: Warpage prevention material, 8: Separation agent, 9: Distance piece, 1
0: Four circumference welded part.

Claims (1)

[Scope of Claims] 1. A covering steel plate assembly in which the laminate is sealed with a covering steel plate having a carbon content of 0.03% by weight or less, with bonding inhibiting substances excluded from the space in which the laminate exists, and the laminate is enclosed therein. is sandwiched between the steel base material and the warpage prevention member in a layered manner, and after welding the steel base material and the warpage prevention member,
The outer surface of the laminate is heated to a temperature range of 650℃ or higher and 900℃ or lower and hot-rolled to bond both sides of the laminate to the adjacent surfaces. Carbon enrichment distance at the joint boundary of titanium, titanium alloy, zirconium, zirconium alloy or chromium-containing steel, characterized by removing the covering steel plate.
A method for producing rolled clad steel sheets of 20μm or less. 2 With the bonding material excluded from the space in which it exists, it is surrounded by a covering steel plate with a carbon content of 0.03% by weight or less, and the four circumferences of the covering steel plate are welded while blowing inert gas into the inside. , while heating the cover steel plate surface to 100°C or higher, the space containing the cladding material is depressurized to 10 ^-1 Torr or less and then sealed, and the cover steel plate assembly is sandwiched in layers between the steel base material and the warpage prevention member. After welding the steel base material and the warpage prevention member, the steel base material and the warpage prevention member are heated to a temperature range of 650°C or higher and 900°C or lower and hot rolled to join both sides of the laminate to the adjacent surfaces, and the surroundings of the resulting rolled material are is cut and separated at the separating agent position,
A method for manufacturing a rolled clad steel plate having a carbon enrichment distance of 20 μm or less at the joint boundary of titanium, titanium alloy, zirconium, zirconium alloy, or chromium-containing steel, characterized by removing the covering steel plate on the outer surface of the laminated material. 3. With bonding inhibiting substances removed from the existing space, the laminate is surrounded by a cover steel plate with a carbon content of 0.03% by weight or less, and the four circumferences of the cover steel plate are welded while blowing inert gas into the interior. , while heating the cover steel plate surface to 100°C or higher, the space containing the cladding material is depressurized to 10 ^-1 Torr or less and then sealed, and the cover steel plate assembly is sandwiched in layers between the steel base material and the warpage prevention member. After welding the steel base material and the warpage prevention member, the steel base material and the warpage prevention member are heated to a temperature range of 650°C or higher and 900°C or lower and hot rolled to join both sides of the laminate to the adjacent surfaces, and the surroundings of the resulting rolled material are Joining of titanium, titanium alloy, zirconium, zirconium alloy, or chromium-containing steel characterized by cutting and separating at the separating agent position, then reheating and hot rolling with the outer surface of the laminate covered with a steel plate. A method for manufacturing rolled clad steel sheets with a boundary carbon concentration distance of 20 μm or less.