JPH09206961A - Manufacture of rolling titanium clad steel plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacture of a wide or thick rolling titanium clad steel plate having a superior joining strength using present equipment without spending excessive equipment cost. SOLUTION: A slab is constituted by inserting, between a base stock consisting of a carbon steel and a material to be laminated consisting of titanium or titanium alloy, as an intermediate material, an extra-low carbon steel plate containing 0.001-0.01wt.% C on the base stock side and a pure titanium plate containing Fe of 0.25wt.% or less and O of 0.15wt.% or above on the side of the material to be laminated; a titanium clad steel plate is obtained by rolling such slab.

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 wide-width or thick-rolled titanium clad steel sheet having excellent joining characteristics.

[0002]

2. Description of the Related Art Conventionally, in rolling type titanium clad steel plates,
In the manufacturing process, Cu, Cu alloy, Ni, Ni alloy, ultra-low carbon steel, between the base carbon steel and the composite material,
Alternatively, a combination of these is used as an intermediate material.

These intermediate materials prevent the elements contained in the base material and the composite material from diffusing and forming an embrittlement phase or a low melting point phase at the interface with the mating material. For example,
The intermediate material of the ultra-low carbon steel in the titanium clad steel plate inhibits the diffusion of carbon contained in the base material into the titanium material,
It has the effect of suppressing the formation of compounds such as iC to prevent embrittlement at the bonding interface and achieving excellent bondability.

For example, JP-B-57-55514, JP-A-62-895588, JP-A-62-158584,
JP-A-62-197285, JP-A-62-22758
6, JP-A-63-56370, JP-B-6-7596
No. 4, etc. discloses that Cu, Cu alloy, Ni, Ni alloy, ultra-low carbon steel, or a combination thereof is used as an intermediate material between the carbon steel as a base material and the laminated material in the manufacturing process. A method of applying, slab assembling, heating and rolling is disclosed.

Further, in Japanese Patent Laid-Open No. 1-309791, ferritic stainless steel, martensitic stainless steel, Nb, Ta, Fe, Mo, Cr, V on the base metal side.
Also disclosed is a method for producing a clad steel sheet having excellent bondability by interposing one or more of Ni and Ni, and interposing an α-type titanium alloy or an α + β-type titanium alloy on the side of the bonding material. This is because when the α-stabilizing element of titanium is contained in the intermediate material, the β-stabilizing elements such as Cr, Nb, Ta, Mo and V contained in the intermediate material on the base metal side are diffused in the composite material. , It is intended to increase the β phase in the vicinity of the interface of the laminated material and suppress the transformation of the β phase into the fragile ω phase in the cooling process after rolling, resulting in deterioration of the bondability. It is intended to prevent deterioration of sex.

[0006]

However, even in the technique of suppressing the compound formation by using these intermediate materials to obtain excellent bonding strength, the slab heating temperature during rolling is limited, and the temperature is relatively low. There is no choice but to use the rolling heating temperature. For this reason, in the titanium clad steel plate, even the normally manufactured 3600 mm wide material and 50 mm thick material have a disadvantage that the load on the rolling mill becomes large because the slab heating temperature is low.
In the production of a wide material having a width of more than 00 mm and a titanium clad steel sheet having a thickness of more than 70 mm, it is difficult to produce it with the existing equipment from the viewpoint of the rolling mill capacity and the deformation resistance of the slab material.

That is, when Cu is used as an intermediate material in the production of a titanium clad steel sheet using the current rolling equipment, if Ti and Cu have a heating temperature of 890 ° C. or higher, a liquid phase is formed by Ti and Cu. It is formed, and there is an inconvenience that the melt is scattered from the front surface and the side surface during rolling.
Also, when Ni is used as an intermediate material, Ti and N
There is a disadvantage that a brittle intermetallic compound composed of i is formed and the joint strength is lowered. Furthermore, when ultra-low carbon steel is used as an intermediate material, the intermediate material also contains a small amount of carbon, so if the rolling heating temperature is set to the β transformation point of the titanium material or higher, the titanium material Has a BCC structure in which carbon diffuses more rapidly, TiC is formed, and this leads to a decrease in bonding strength. Therefore, the rolling heating temperature must be lower than the β transformation temperature.

Further, α-type titanium alloy or α is provided on the side of the mating material.
In the method of interposing + β-type titanium alloy, in the case of α-type titanium alloy, a large amount of β-phase is formed when the rolling heating temperature is raised due to Fe contained as an impurity, and the β-phase part is formed. And β for α + β type titanium alloys
Since it contains a phase, there is a disadvantage that the embrittlement phase is formed due to the diffusion of C and the like in the β phase portion and the bonding characteristics are deteriorated.

That is, even in the method of double-inserting the intermediate material, the embrittlement phase is formed more due to the increase in the volume fraction of the β phase due to the increase in the rolling heating temperature, so that the rolling heating temperature is limited. is there.

On the other hand, manufacturing a wide or thick clad steel plate has advantages such as omission of welding and improvement of yield. However, as described above, at the current slab heating temperature, the rolling load increases due to the increase in deformation resistance during rolling due to the widening and thickening, so that it cannot be manufactured with the current rolling equipment. Further, even if rolling can be performed, sufficient reduction cannot be applied in each pass, rolling stress is low, and the laminated material does not plastically deform sufficiently, resulting in inconvenience that satisfactory joining strength cannot be obtained.

The present invention has been made in view of the above circumstances, and a rolled titanium clad steel plate capable of obtaining a wide or thick rolled titanium clad steel plate having excellent bonding strength with existing equipment without excessive equipment burden. It aims at providing the manufacturing method of.

[0012]

DISCLOSURE OF THE INVENTION In the production of wide or thick titanium clad steel sheets having excellent joint strength, the inventors of the present invention can produce these with current rolling capacity without modifying the rolling mill. As a result of repeated detailed studies on possible methods, an ultra-low carbon steel sheet with controlled C content on the carbon steel side as a base material and an Fe and O content on the titanium side as a composite material were used as intermediate materials. By controlling and inserting a pure titanium plate having a transformation point higher than that of the laminated material between the base material and the laminated material to assemble the slab, the joining strength of the embrittlement phase etc. can be maintained even if the rolling heating temperature is higher than before. It is possible to suppress the formation of a thick phase that adversely affects,
Moreover, it has been found that it is possible to reduce the deformation resistance and perform rolling by raising the rolling heating temperature.

The present invention has been made on the basis of such findings, and C: 0 is provided on the base material side as an intermediate material between the base material made of carbon steel and the composite material made of titanium or titanium alloy. Ultra low carbon steel sheet containing 0.001 to 0.01% by weight of Fe: 0.25% by weight or less and O: 0.1
The present invention provides a method for producing a titanium clad clad steel plate, which comprises assembling a slab by inserting a pure titanium plate containing 5% by weight or more and rolling the slab.

Further, according to the present invention, in the above method, the slab heating temperature T ° C. is 890 ≦ T ≦ 890 + 150 [O]
A method for producing a titanium clad steel sheet, which comprises rolling in a temperature range of -20 [Fe] (where [O] and [Fe] represent O content and Fe content, respectively). is there.

Further, in the above method, as an intermediate material, an ultra low carbon steel sheet containing C: 0.001 to 0.01% by weight on the base material side and Fe: less than 0.10% by weight on the bonding material side,
The present invention provides a method for producing a titanium clad steel plate, which comprises using a pure titanium plate containing O: 0.15 wt% or more.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described specifically. The rolled titanium clad steel sheet of the present invention has C: 0.001 to 0.001 on the base material side as an intermediate material between the base material made of carbon steel and the composite material made of titanium or titanium alloy.
Ultra low carbon steel sheet containing 0.01% by weight of F
It is obtained by inserting a pure titanium plate containing e: 0.25% by weight or less and O: 0.15% by weight or more to assemble a slab and rolling.

C: on the carbon steel side as a base material as an intermediate material:
The use of an ultra-low carbon steel sheet containing 0.001 to 0.01% by weight suppresses the diffusion of a large amount of C forming a thick embrittlement phase to another intermediate material and a laminated material, and also causes deterioration of characteristics. The formation of an extremely thin TiC that does not invite it has the effect of suppressing the formation of TiFe, which is an embrittlement phase that also deteriorates the bonding characteristics.

As another intermediate material, Fe:
The use of pure titanium containing 0.25% by weight or less and O: 0.15% by weight or more means that this material has a transformation point higher than that of the composite material. Even if the material transforms into a crystal structure (BCC structure in this case) in which C diffuses rapidly beyond the transformation point, the intermediate material does not exceed the transformation point and the diffusion rate of the element that adversely affects the bonding strength Slow and dense crystal structure (in this case HCP
Structure) and prevents C from diffusing to the joining characteristics from diffusing into the bonding material and the intermediate material on the bonding material side,
Even when the heating temperature for rolling is increased, it has the effect of suppressing the formation of an embrittled phase at the joint interface and achieving excellent joint characteristics.

In this case, if the C content of the intermediate material of the ultra-low carbon steel is more than 0.01% by weight, a brittle TiC phase is formed thickly at the interface with another intermediate material, and 0.001% by weight is formed. %
If the amount is less than this, the effect of suppressing TiFe formation by TiC is not exerted, and the formation of TiFe causes deterioration of the bonding characteristics.

When the Fe content of pure titanium constituting the other intermediate material is more than 0.25% by weight, the temperature at which β phase starts to be generated is lowered, and the rolling heating temperature is increased. A large amount of β phase is generated in the. Therefore, diffusion of C is promoted and TiC is thickly formed, resulting in deterioration of bonding characteristics. Further, when the O content is less than 0.15% by weight,
The transformation point of the intermediate material to be inserted on the side of the laminated material cannot be sufficiently raised, and when the heating temperature is raised to manufacture a wide material or a thick material, the intermediate material is Since the BCC structure is fast, TiC is formed thick and the bonding characteristics are deteriorated.

Therefore, the C content of the intermediate material of ultra-low carbon steel is 0.001 to 0.01% by weight, and the F content of the intermediate material of pure titanium is F.
The e content is 0.25 wt% or less, and the O content is 0.15 wt% or more. Further, when the Fe content of the intermediate material of pure titanium is less than 0.10% by weight, the joining characteristics are further improved. The O content of the intermediate material of industrial pure titanium is 0.4.
The practical upper limit is about% by weight.

The slab heating temperature T ° C. is 890 ≦ T
≦ 150 [O] -20 [Fe] (however, [O], [F
e] indicates the O content and the Fe content, respectively. ), The temperature will be controlled to a higher temperature than before, making it possible to reduce the deformation resistance during rolling and reduce the load on the rolling mill during rolling while suppressing the formation of the embrittlement phase. In addition, it is possible to apply a large reduction to the material in a single pass, which has the effect of further improving the joining characteristics.

If the slab heating temperature is less than 890 ° C., the deformation resistance during rolling cannot be sufficiently reduced, and (89
When the temperature is higher than 0 + 150 [O] -20 [Fe]) ° C, the pure titanium to be inserted on the side of the laminated material also exceeds the transformation point, and C
Since it has a BCC structure with fast diffusion of TiC, TiC is formed thick at the interface, leading to a decrease in bondability. Therefore, the slab heating temperature T ° C. is 890 ≦ T ≦ 890 + 150 [O] −
It is preferably in the range of 20 [Fe].

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described. (Example 1) A carbon material having a symbol A shown in Table 1 and a carbon steel having a thickness of 350 mm was used as a base material, a chemical composition having a symbol D shown in Table 2 was used, and a titanium material having a thickness of 50 mm was combined. Used as a material. Further, as the intermediate material on the base material side, reference numeral B1 shown in Table 1
Of the composition B3 to B5 having a thickness of 1 mm, the reference numeral C1 shown in Table 2 is used as the intermediate material on the side of the laminated material.
.About.C7 having a thickness of 1 mm having a composition of C3 was used. 1800 mm width × 1800 mm length, 4500 width × 1 using these base material, laminated material and intermediate material
Assemble 800 mm long and 1800 mm wide x 3600 mm long slabs and (35 + 5) mm from these slabs
Thickness x 4200mm width x 7000mm length and 17800
mm length, and (70 + 10) mm thickness x 4200 width x
A clad steel plate having a length of 7,000 mm was manufactured.

Further, in order to confirm the effectiveness of the intermediate material having a high transformation point on the side of the laminated material, only the ultra-low carbon steel is used as the intermediate material, and the width is 1800 mm width × 1800 mm length and 1800 mm.
From the slab of mm width x 3600 mm length, each (35
+5) mm thickness × 4200 mm width × 7000 mm length and (70 + 10) mm thickness × 4200 width × 7000 mm length of clad steel plate were manufactured.

Further, in order to compare the loads during rolling, a slab of 1800 mm width × 1800 mm length was used to measure (35 + 5) mm thickness × 3200 mm width × 850 by a conventional method.
A 0 mm long clad steel plate was produced.

Table 3 shows the slab assembly dimensions, slab dimensions, slab heating temperature and clad steel sheet dimensions. At this time, whether or not rolling is possible according to the planned pass schedule, the thickness of the TiC phase that deteriorates the joining characteristics in the as-rolled state, the shear strength in the as-rolled state, and the side bending and back-bending at R / t = 1 are determined. Table 4 shows whether or not cracks were generated at the joint interface during the heating.

As shown in these tables, using an intermediate material having the component composition within the present invention, manufactured according to the present invention,
Further, when the preferable slab heating temperature was set, it was possible to manufacture a titanium clad steel sheet having a width exceeding 4000 mm and a thickness exceeding 70 mm by rolling. In addition, the TiC layer thickness is thin, the shear strength is as high as 20 kgf / mm ² or more, cracks do not occur even in the bending test, and the joining characteristics of the titanium clad steel sheet over 4000 mm width and over 70 mm thickness are evaluated by any evaluation method. It was good.

(Example 2) Titanium having a chemical composition of symbol A shown in Table 1 and using carbon steel having a thickness of 350 mm as a base material, having the chemical composition of symbol D shown in Table 2 and having a thickness of 50 mm The material was used as a clad material. Further, as the intermediate material on the base material side, one having a thickness of 1 mm having the composition of reference numerals B1 to B5 shown in Table 1 was used, and as the intermediate material on the mating material side, reference numeral C shown in Table 2 was used.
A 1 mm thick film having a composition of 1 to C7 was used. Assemble the slab under the conditions shown in Table 5, and set the slab heating temperature to 90.
At 0 ° C., from a slab with a width of 1800 mm and a length of 1800 mm, a thickness of (35 + 5) mm, a width of 4200 mm, and a width of 7200 m
An m-length clad steel plate was manufactured. At this time, since the rolling heating temperature was raised, the deformation resistance was low under any condition and rolling was possible.

At this time, T which deteriorates the joining characteristics
Table 5 also shows the thickness of the iC phase in the as-rolled state, the shear strength in the as-rolled state, and the presence or absence of cracks at the joint interface when side bending and back bending at R / t = 1. .

As shown in Table 5, when an intermediate material having the component composition within the present invention was used and produced according to the present invention, the TiC layer thickness was thin and the shear strength was 20 kgf / mm ^2.
High as above, no cracks occurred in the bending test, and 4
The joining characteristics of the titanium clad steel plates having a width of more than 000 mm and a thickness of more than 70 mm were good in any evaluation method. Further, the Fe concentration of the intermediate material on the side of the laminated material is 0.
If it is less than 10% by weight, the shear strength is 25 kgf / mm.
It was confirmed that it was ² or more, and the bonding characteristics were further improved. As is clear from the above results, within the conditions of the present invention, it is possible to manufacture a wide-width and thick-walled clad steel plate with excellent joining characteristics using the current equipment.

[0032]

[Table 1]

[0033]

[Table 2]

[0034]

[Table 3]

[0035]

[Table 4]

[0036]

[Table 5]

The above-mentioned 890 ≦ T ≦ 890 + 150
The [O] -20 [Fe] formula is an empirical formula obtained from the result of detailed study of the relationship between the component composition and the transformation point.
In addition, although pure titanium was used as the bonding material in the above-mentioned examples, it is not limited to this, and Grade 7 or Ti-6 is used.
A Ti alloy such as Al-4V can be used.

[0038]

As described above, according to the present invention,
It is possible to produce a wide or thick rolled titanium clad steel sheet having excellent bonding strength with existing equipment without excessive equipment burden.

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Claims (3)

[Claims] 1. An ultra low carbon steel sheet containing C: 0.001 to 0.01% by weight on the base material side as an intermediate material between a base material made of carbon steel and a composite material made of titanium or a titanium alloy. On the composite material side, Fe: 0.25 wt% or less, O: 0.1
A method for producing a titanium clad clad steel sheet, comprising inserting a pure titanium plate containing 5% by weight or more to assemble a slab and rolling the slab. 2. The slab heating temperature T ° C. is 890 ≦ T ≦ 8
90 + 150 [O] -20 [Fe] (however, [O],
[Fe] indicates the O content and the Fe content, respectively. ) Rolling is carried out as a temperature range of 2), The manufacturing method of the titanium clad steel plate of Claim 1 characterized by the above-mentioned. 3. An intermediate material, C: 0.001 on the base material side.
An ultra low carbon steel sheet containing .about.0.01 wt% wo, and a pure titanium plate containing Fe: less than 0.10 wt% and O: 0.15 wt% or more are used on the side of the laminated material. Or the manufacturing method of the titanium clad steel plate according to claim 2.