JPH06226469A - Titanium clad stainless steel sheet - Google Patents

Abstract

PURPOSE:To provide a titanium clad stainless steel sheet having high joining strength and excellent bending workability and rollability by joining titanium and a stainless steel by an explosive welding method, then subjecting the titanium and the stainless steel to hot and cold rolling in such a manner that the total rolling rate attains a specific value. CONSTITUTION:The titanium clad stainless steel slab formed by joining the titanium which is a cladding metal and the stainless steel which is a base material having <=0.08wt.% carbon content by the explosive welding method is subjected to the hot and cold rolling in such a manner that the total rolling rate attains >=90%. As a result, carbides do not exist at the boundary of the explosive welded slab and the metallurgically tightly adhered structure is obtd. The explosive welded slab has a gentle hardness distribution of the part near the boundary and the broad setting of the subsequent hot rolling and cold rolling operation conditions is possible. The range of production conditions is thus widened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a titanium clad stainless steel sheet obtained by coating stainless steel with titanium having high durability.

[0002]

2. Description of the Related Art Titanium is a metal having excellent weather resistance and corrosion resistance. Since Japan is surrounded by the sea, the humidity is high, and the corrosion of metals due to environmental changes leads to a great loss of social resources such as a decrease in resources and an unsightly appearance due to corrosion.

Therefore, titanium, which is a so-called maintenance-free metal material having good corrosion resistance, light weight and excellent strength and requiring no surface treatment such as painting, is used as a roof material,
It is being used as various exterior materials such as outer wall materials, but it is currently not widely used because of its high price. On the other hand, although stainless steel is advantageous in terms of cost, it is insufficient in corrosion resistance and durability as compared with titanium, and is particularly insufficient as an exterior material that requires a long life.

In order to solve such a problem, a composite material has been proposed in which titanium is used as a joining material and joined to stainless steel as a base material. For example, a composite material in which titanium, which is a composite material, is joined to stainless steel, which is a base material, by a polyester adhesive is provided. However, in this composite material, the coefficient of thermal expansion of the base material and the base material are different from each other, which causes a shift due to aging, or deterioration of the adhesive force due to aging, and further, the base material and the base material. Due to the different bending stress of the material, there is a problem that bending is difficult and welding is impossible.

Therefore, a method of producing a titanium clad steel material by the explosive deposition method is conceivable. According to this method, the joint interface between the laminated material and the base material is instantly formed in a cold state.
It is possible to provide a composite material in which a carbide, a nitride, or a layered Ti—Fe-based metal compound is not formed, has clean boundaries, and has a high bonding strength. Since this explosive slab has a gentle hardness distribution in the vicinity of the interface, the subsequent hot rolling and cold rolling working conditions can be set broadly and the range of manufacturing conditions is widened. The degree of freedom in setting the spreading conditions is great, and excellent quality characteristics can be secured. However, an intermetallic compound, which becomes an embrittlement layer, is formed between the laminated material and the base material, and the embrittlement layer causes interfacial delamination during rolling and a defective shape, which deteriorates the rolling property.

In order to solve this problem, a method of rolling by suppressing the formation of an embrittlement layer by a sandwich structure of a base material, a metal intermediate layer, and a laminated material (JP-A-60-170586).
No.) or interposing a joining intermediate material between the titanium and the base material, and defining the distance between the joining intermediate material and titanium, avoiding the formation of intermetallic compounds between the titanium and the base material by the joining intermediate material. Rolling method (JP-A-63-56370)
Japanese Patent Laid-Open No. 2-295682), in which a Fe-based thin metal is explosion-deposited on titanium, and a composite slab is assembled with this and a hot rolling is performed.

[0007]

However, with the conventional sandwich construction, not only the material cost is high, but the productivity is low, and moreover, the rolling is carried out in a vacuum or under reduced pressure, which is economical and economical. It was a heavy burden. The present invention has been made in order to solve the above problems, and its object is to have a large bonding strength between a laminated material and a base material, excellent bending workability, excellent rolling property, and excellent productivity. It is to provide a high titanium clad stainless steel plate.

[0008]

The invention according to claim 1 is a titanium-clad stainless steel obtained by joining titanium, which is a laminated material, and stainless steel, which is a base material having a carbon content of 0.08% by weight or less, by an explosive welding method. It is characterized in that the slab is hot-rolled and cold-rolled so that the total rolling rate becomes 90% or more.

According to a second aspect of the present invention, the ratio of the thickness of titanium as a laminated material to the thickness of stainless steel as a base material is 1/5 to 1/2.
It is characterized by being 0. The invention according to claim 3 is characterized in that the thickness of titanium which is a laminated material is 100 μm or more.

[0010]

In the invention of claim 1, since the carbon content of the stainless steel is 0.08% by weight or less, there is no carbide at the interface of the explosive slab, resulting in a metallurgically adherent structure. Also, since the explosive-bonded slab has a gentle hardness distribution in the vicinity of the interface, it is possible to set a wide range of subsequent hot-rolling and cold-rolling work conditions, which widens the range of manufacturing conditions. There is no. Further, it can be hot-rolled in the atmosphere, and the burden on the apparatus and economically can be reduced. Furthermore, the total rolling rate is 9
Since it is 0% or more, the steel sheet has excellent bonding strength and surface smoothness.

According to the second aspect of the invention, the ratio of the thickness of titanium which is the laminated material to the thickness of stainless steel which is the base material is 1/5.
Since it is from 1/20, the titanium layer is not locally broken during hot rolling or working, the base material is not exposed, and the proportion of titanium is not too large, which may impair the economic effect. Absent. According to the third aspect of the invention, since the thickness of the titanium as the joining material is 100 μm or more, the stainless steel plate is not exposed during processing.

The present invention will be described in detail below. In the present invention, the base material is stainless steel, and either austenitic steel or ferritic steel is applicable. The carbon content of stainless steel is 0.08% by weight or less. 0.
If it exceeds 08% by weight, a carbide that becomes an embrittlement layer will be formed at the bonding interface with titanium.

[0013] Further, titanium used as a mating material has a smooth surface and is clean, and it is preferable that the longitudinal width and the lateral width are larger than those of the base material, for example, by about 50 mm. In addition, the thickness of titanium is 100μ or more after rolling, which is 1 with respect to the base metal.
/ 5 to 1/20 is preferable. If it is larger than ⅕, the expensive titanium occupies too large a ratio, so that there is no economic effect to make a clad steel plate, and the difference in material characteristics between titanium and stainless steel is not reduced, and various shapes are obtained. This makes it difficult to process the product. On the other hand, if it is smaller than 1/20, titanium may be locally broken during hot rolling or forming, exposing the base material stainless steel.
Further, it tends to be difficult to secure desired corrosion resistance and durability.

In the present invention, the base material stainless steel and the joining material titanium are joined by the explosive deposition method.
First, a stainless steel slab is finished to be smooth by scarfing and the scale is removed to be a base material. In order to obtain a strong interfacial bond strength, the stainless steel slab and the titanium of the laminated material are arranged so as to have a constant gap. For example, it is 1 mm. This is an appropriate explosion speed, eg 2000
Explosion is caused by an explosive having an explosive velocity of m / sec or less. Next, depending on the location of the explosive, the peripheral edge of titanium, which is the composite material, has a shape protruding from the end of the stainless steel slab, so it is mechanically cut and removed to produce a titanium clad stainless slab with excellent end face shape. To do.

Thereafter, the titanium clad stainless slab is heated at 700 to 950 ° C. for 1 to 5 hours and hot-rolled in a reverse or tandem type in several stages, for example, a pass schedule using 5 stands to obtain a titanium clad stainless heat treatment. Obtain a rolled steel sheet. The cold rolling is performed after dipping in a nitric hydrofluoric acid-based pickling solution in the same manner as applied to the base material, stainless steel, in order to remove the scale generated during hot rolling.

The cold rolling rate naturally varies depending on the plate thickness of the product to be manufactured, and the number of passes also varies. However, when it is necessary to have a large cold rolling rate such that the difference in deformation resistance causes warpage of the product, It is necessary to change the frictional resistance between the roll and the material at the different peripheral speed rolling and other upper and lower surfaces. In this case, the work roll itself should be as small in diameter as possible to secure the rolling rate,
It is advantageous in terms of shape improvement and energy reduction.

Although the smoothness of the surface of the steel sheet can be obtained by cold rolling, the steel sheet after cold rolling may be annealed and temper-rolled depending on the application. The titanium clad stainless steel sheet produced in this manner has high durability and can be suitably used as an exterior material such as a roof material and a wall material. Next, the present invention will be specifically described based on Examples. In the following,% indicating the ratio of components is% by weight. (Example 1) C: 0.06%, Si: 0.80
%, Mn: 1.50%, P: 0.03%, S: 0.02
%, Ni: 8.50%, Cr: 18.80%, Fe: B
al. And, thickness 30mm, length 2000mm, width 900m
The stainless steel slab of m was finished to be smooth by scarfing, and the scale was removed to obtain a base material.

Next, a stainless steel slab and a laminated material having a thickness of 3.0 mm, a length of 2100 mm, and a width of 1000 mm are arranged at an interval of 1 mm, and 1500
Explosion was caused by explosives having an explosive velocity of m / sec or less. To do. Next, a titanium clad stainless slab is manufactured by mechanically cutting and removing the peripheral edge portion of the stainless steel slab of titanium, which is a laminated material, protruding from the end portion.

Thereafter, the titanium clad stainless slab was heated at 850 ° C. for 3 hours and hot-rolled in a reverse type using one stand to obtain a titanium clad stainless hot rolled steel sheet. The rolling rate was 60%. Then, after removing the scale generated during hot rolling, cold rolling was performed using a 6-high cold rolling mill (work roll diameter 200 mm) 2 stands. Mineral oil was used as the rolling oil. The rolling rate was 80%.

In this way, a titanium clad stainless steel plate having a total rolling rate of 92% and a product thickness of 2.64 mm was manufactured. (Example 2) Hot rolling rate is 70%, cold rolling rate is 90%
A titanium clad stainless steel sheet having a total rolling ratio of 97% and a product thickness of 0.99 mm was manufactured in the same manner as in Example 1 except for the above. (Example 3) Component C: 0.06%, Si: 0.62
%, Mn: 0.63%, P: 0.03%, S: 0.02
%, Cr: 17.20%, Fe: Bal. And thickness 30
mm, length 2000 mm, width 900 mm, stainless steel slab, hot rolling rate 60%, cold rolling rate 80
The total rolling rate is 92% in the same manner as in Example 1 except that the percentage is
Manufactured a titanium clad stainless steel plate having a product thickness of 2.64 mm. (Example 4) Hot rolling rate is 70%, cold rolling rate is 90%
A titanium clad stainless steel sheet having a total rolling rate of 97% and a product thickness of 0.99 mm was manufactured in the same manner as in Example 3 except for the above. (Example 5) A titanium clad stainless steel plate having a total rolling rate of 92% and a product thickness of 2.80 mm was manufactured in the same manner as in Example 1 except that titanium having a thickness of 5.0 mm was used. (Example 6) A titanium clad stainless steel plate having a total rolling rate of 92% and a product thickness of 2.54 mm was manufactured in the same manner as in Example 1 except that titanium having a thickness of 1.8 mm was used. (Comparative Example 1) C: 0.13%, Si: 0.62
%, Mn: 0.63%, P: 0.03%, S: 0.02
%, Cr: 17.20%, Fe: Bal. And thickness 30
A titanium clad stainless steel plate having a total rolling rate of 92% and a product thickness of 2.64 mm was manufactured in the same manner as in Example 1 except that a stainless steel slab having a length of 2000 mm, a length of 2000 mm, and a width of 900 mm was used. (Comparative Example 2) C: 0.10%, Si: 0.80
%, Mn: 1.50%, P: 0.03%, S: 0.02
%, Ni: 8.50%, Cr: 18.80%, Fe: B
al. And, thickness 30mm, length 2000mm, width 900m
A titanium clad stainless steel plate having a total rolling ratio of 97% and a product thickness of 0.99 mm was manufactured in the same manner as in Example 2 except that a stainless steel slab of m was used. (Comparative Example 3) Hot rolling rate is 60%, cold rolling rate is 62%
A titanium clad stainless steel sheet having a product thickness of 4.95 mm was manufactured in the same manner as in Example 1 except that the total rolling ratio was 85%. (Comparative Example 4) A product was manufactured in the same manner as in Example 3 except that titanium having a thickness of 2.0 mm was used, the hot rolling rate was 70%, the cold rolling rate was 60%, and the total rolling rate was 88%. A titanium clad stainless steel plate having a thickness of 3.84 mm was manufactured. (Comparative Example 5) The product thickness was 3.30 in the same manner as in Example 1 except that only hot rolling was performed to obtain a total rolling rate of 90%.
mm titanium clad stainless steel plate was produced. (Comparative Example 6) A titanium clad stainless steel plate having a product thickness of 3.04 mm was manufactured in the same manner as in Example 1 except that titanium having a thickness of 8.0 mm was used. Comparative Example 7 A titanium clad stainless steel plate having a product thickness of 2.48 mm was manufactured in the same manner as in Example 3 except that titanium having a thickness of 1.0 mm was used. The following qualities were evaluated for the titanium clad stainless steel sheet produced in this manner. The results are shown in Table 2. A. Appearance The appearance was visually observed to see if there were any abnormalities.

◯: Uniform appearance ×: When surface defects (roughness, turning of titanium layer, exposure of stainless layer, etc.) are present B. Presence / absence of non-bonded portion The presence / absence of a non-bonded portion was examined by ultrasonic flaw detection according to JIS G3603. ◯: When no non-bonded part was observed ×: When no non-bonded part was recognized C. Existence of Carbide in Joined Part A cross section of the joined part was observed with a microscope in accordance with JIS G3603 to examine the state of precipitation of carbide.

◯: When no precipitation of carbide was observed ×: When precipitation of carbide was observed D. Shear strength (kgf / mm ² ) E. Bending test Side bending was performed so that the titanium side of the steel plate was on the inside, and the bending angle was 180 ° and the bending radius R was 2.0 mmt (t; plate thickness).

◯: Good bending was possible ×: Bending was impossible F. Corrosion Resistance and Durability Test A salt spray test for 30 days was performed in accordance with JIS Z2301 to examine the occurrence of rust.

◯: No occurrence of spot rust was observed. ×: Generation of spot rust was observed. G. Corrosion resistance and durability test The sample after the bending test carried out in Evaluation E was used for 7 days for 7 days.
It was immersed in 5% salt water at 0 ° C., and the presence or absence of permeation of the salt water into the interface and the accompanying peeling was observed.

◯: No peeling was observed ×: Peeling was observed Table 1 Manufacturing conditions Base material Laminated product Product Rolling rate (%) C (%) Thickness (mm) Thickness (mm) Thickness (mm) HR CR TR Example 1 0.06 30 3.0 2.64 60 80 92 2 0.06 30 3.0 0.99 70 90 97 3 0.06 30 3.0 2.64 60 80 92 4 0.06 30 3.0 0.99 70 90 97 5 5 0.06 30 5.0 2.80 60 80 92 6 0.06 30 1.8 2.54 60 80 92 Comparative example 1 0.13 30 3.0 2.64 60 80 92 2 0.11 30 3.0 0.99 70 90 97 3 0.06 30 3.0 4.95 60 62 85 4 0.06 30 3.0 3.84 70 60 88 5 0.06 30 3.0 3.30 90 − 90 6 0.06 30 8.0 3.04 60 80 92 7 0.06 30 1.0 2.48 60 80 92 Table 2 Quality evaluation test Appearance Non-bonded part Carbide Shear strength Bending test Salt spray Soaking test Test example 1 ○ ○ ○ 32 ○ ○ ○ 2 ○ ○ ○ 40 ○ ○ ○ 3 ○ ○ ○ 36 ○ ○ ○ 4 ○ ○ ○ 42 ○ ○ ○ 5 ○ ○ ○ 38 ○ ○ ○ 6 ○ ○ ○ 48 ○ ○ ○ Comparative example 1 ○ × × 20 × ○ × 2 ○ × × 22 × ○ × 3 ○ ○ ○ 24 × ○ − 4 ○ ○ ○ 22 × ○ × 5 × ○ ○ 28 × ○ ○ 6 ○ ○ ○ 22 × ○ -7 × × ○ 40 ○ ○ × From the results of Table 2, in Comparative Examples 1 and 2, the carbon content of the base metal was 0.13 each. % And 0.10%, non-bonded portions were recognized and carbide precipitation was also recognized. Therefore, the shear strength was low and bending was impossible.

Further, in Comparative Examples 3 and 4, since the rolling rate was 90% or less, the shear strength was small and bending was impossible. Further, in Comparative Example 5, since only hot rolling was performed, the surface was found to be rough, and carbide was also precipitated at the joint interface, so that the shear strength was small and bending was impossible.

Further, in Comparative Example 6, since the titanium was too thick, bending was impossible. On the contrary, in Comparative Example 7, since titanium was too thin, the titanium was turned over and the stainless steel was exposed. On the other hand, it is understood that the examples of the present invention are excellent in all qualities and can be suitably used as exterior materials such as roofing materials and wall materials.

[0028]

According to the invention of claim 1, since the joining interface between the laminated material and the base material is instantly formed in a cold state by the explosive deposition method, carbides or nitrides or a layered Ti-Fe-based metal is formed. No compound is formed, it has clean boundaries and the bond strength is high. In addition, since the explosive-bonded slab has a gentle hardness distribution near the interface, the subsequent hot rolling and cold rolling working conditions can be set widely, and the range of manufacturing conditions will be widened. Absent. There is a high degree of freedom in setting hot rolling and cold rolling conditions for securing the material according to the application, and excellent quality characteristics can be secured. Also, since the carbon content of stainless steel is 0.08% by weight or less, there is no intermetallic compound at the interface of the explosive slab, and the structure is a metallurgically adherent structure, so that it can be hot rolled in the atmosphere and is suitable for equipment. Economically, the burden is small. Also, since there is no scale at the time of slab manufacturing on the titanium and stainless steel base material surface of the slab by the explosive deposition method,
Since the pickling after hot rolling and before cold rolling is easy, the yield of expensive materials increases, and the total rolling ratio is 90%.
As described above, the steel sheet has excellent bonding strength and surface smoothness.

According to the second aspect of the invention, the ratio of the thickness of titanium which is the laminated material to the thickness of stainless steel which is the base material is 1/5.
Since it is from 1/20, the titanium layer is not locally broken during hot rolling or working, the base material is not exposed, and the proportion of titanium is not too large, which may impair the economic effect. Absent. According to the third aspect of the invention, since the thickness of the titanium as the joining material is 100 μm or more, the stainless steel plate is not exposed during processing.

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Claims (3)

[Claims] 1. A titanium material as a composite material and a carbon content of 0.
A titanium clad stainless slab obtained by joining a base material stainless steel of not more than 08% by weight by an explosive welding method is hot-rolled and cold-rolled so that the total rolling rate becomes 90% or more, and titanium is formed. Clad stainless steel plate. 2. The titanium-clad stainless steel plate according to claim 1, wherein the ratio of the thickness of titanium as a laminated material to the thickness of stainless steel as a base material is 1/5 to 1/20. 3. The titanium clad stainless steel sheet according to claim 1, wherein the thickness of titanium which is a laminated material is 100 μm or more.