JPH09262687A - Manufacture of rolled titanium clad steel plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method capable of manufacturing a wide or thick rolled titanium clad steel plate having excellent joining strength by an existing equipment without necessitating any excessive cost for the equipment. SOLUTION: A titanium clad steel plate is obtained by assembling a slab by inserting an extremely low carbon steel plate having the composition consisting of, by weight, 0.001-0.01% C in a base metal side and a α type titanium alloy plate having the composition consisting of <=0.25% Fe and <=0.15% contents specified by the formula [O]+1.1[C]+2.0[N]+[Al] of O, N, C, and Al in a clad plate side (where, [O], [C], [N], and [Al] respectively denote the O content, C content, N content, and Al content), and <=3.0% Al, as the intermediate member, between the base metal made of carbon steel and the clad plate made of titanium or titanium alloy, and rolling the assembled 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, as an intermediate material, between carbon steel as a base material and a composite 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 the base material and Fe, O, C, N on the titanium side as the joint material And, by controlling the Al content and inserting an α-type titanium alloy 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 rolling heating temperature can be made higher than before. Also, it is possible to suppress the formation of a thick phase such as an embrittlement phase that adversely affects the bonding strength, and it is possible to reduce deformation resistance by rolling at a higher heating temperature for rolling. I found that.

The present invention has been made on the basis of such findings, and as an intermediate material, a C content on the base material side is provided between a base material made of carbon steel and a composite material made of titanium or a titanium alloy. Is an ultra low carbon steel sheet having a Fe content of 0.001 to 0.01% by weight and a Fe content of 0.25% by weight or less and a content of O, N, C and Al on the side of the laminated material is [O] +1.1.
[C] +2.0 [N] +0.1 [Al] (however,
[O], [C], [N], and [Al] represent O content, C content, N content, and Al content, respectively.
Provided is a method for producing a titanium clad clad steel plate, which comprises assembling and rolling an slab by inserting an α-type titanium alloy plate having an Al content of 15% by weight or more and an Al content of 3.0% by weight or less. .

Further, according to the present invention, in the above method, the slab heating temperature T ° C. is 890 ≦ T ≦ 885 + 150 [O]
+160 [C] +300 [N] +20 [Al] -20
The present invention provides a method for producing a titanium clad steel sheet, which comprises rolling in a temperature range of [Fe] (where [Fe] represents the Fe content).

Further, in the above method, as an intermediate material, an ultra low carbon steel sheet having a C content of 0.001 to 0.01% by weight on the base material side and an Fe content of 0.10% by weight on the laminated material side. And content of O, N, C and Al is less than [O] +
1.1 [C] +2.0 [N] +0.1 [Al] (however, [O], [C], [N], and [Al] are O content, C content, N content, The present invention provides a method for producing a titanium clad steel sheet, characterized by using an α-type titanium alloy plate having an Al content of 0.15 wt% or more and an Al content of 3.0 wt% or less. is there.

Further, in the above method, when the thickness of the intermediate material installed on the side of the laminated material is tmm, and the total thickness of the base material, the above two kinds of intermediate materials, and the laminated material is Tmm, t / A method for producing a titanium clad steel sheet, wherein T ≦ 0.01.

[0017]

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 a C content of 0.00 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.
An ultra low carbon steel sheet of 1 to 0.01% by weight, Fe
Content is 0.25% by weight or less and O, N, C and A
The content of 1 is [O] +1.1 [C] +2.0 [N] +
0.1 [Al] (however, [O], [C], [N],
[Al] is O content, C content, N content, A
It is obtained by inserting an α-type titanium alloy plate having an Al content of 0.15% by weight or more and an Al content of 3.0% by weight or less, and assembling and rolling the slab.

The use of an ultra-low carbon steel sheet having a C content of 0.001 to 0.01% by weight on the carbon steel side as a base material as an intermediate material makes it thicker and more brittle than another intermediate material and a laminated material. By suppressing the diffusion of a large amount of C forming a phase and by forming an extremely thin TiC to the extent that characteristics are not deteriorated, it is possible to suppress the formation of TiFe, which is an embrittlement phase that also deteriorates the bonding characteristics.

As another intermediate material, the Fe content is 0.25% by weight or less and the contents of O, N, C and Al are [O] +1.1 [C] +2.0 [N] on the side of the composite material. +0.1
[Al] (however, [O], [C], [N], [Al]
Indicates O content, C content, N content, and Al content, respectively, and is 0.15% by weight or more and the Al content is 3.
Using an α-type titanium alloy plate of 0% by weight or less
Since this material has a higher transformation point than the laminated material, when the rolling heating temperature is raised, the laminated material exceeds the transformation point and C
In the case where the intermediate material is transformed into a crystal structure with a fast diffusion (in this case, a BCC structure), the intermediate material does not exceed the transformation point, and the fine-grained crystal structure with a slow diffusion rate of an element that has a bad influence on the bonding strength ( In this case, the HCP structure remains as it is, and it is possible to prevent C, which leads to deterioration of the joining characteristics, from diffusing into the laminated material and the intermediate material on the laminated material side, and also at the joint interface even when the heating temperature for rolling is increased. It has the effect of suppressing the formation of an embrittlement phase and achieving excellent bonding 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 obtained. %
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.

If the Fe content of the α-type titanium alloy constituting the other intermediate material is more than 0.25% by weight, the temperature at which β phase begins to be generated is lowered and the rolling heating temperature is increased. When this is done, a large amount of β phase is generated. For this reason,
The diffusion of C is promoted and TiC is thickly formed, resulting in deterioration of bonding characteristics. Further, the content of O, N, C and Al is [O] +1.1 [C] +2.0 [N] +0.1 [Al]
If it 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 the heating temperature is raised in order to produce a wide material or a thick material. At this time, since the intermediate material has a BCC structure in which C diffuses quickly, TiC is formed thickly, resulting in deterioration of bonding characteristics. Further, if the Al content is more than 3.0% by weight, a Basal Texture due to Al develops in the α-type titanium alloy during rolling, resulting in deterioration of workability.

Therefore, the C content of the intermediate material of ultra-low carbon steel is 0.001 to 0.01% by weight, the Fe content of the intermediate material of α-type titanium alloy is 0.25% by weight or less, O and N. , C and Al content is [O] +1.1 [C] +2.0 [N]
+0.1 [Al] is 0.15% by weight or more and the Al content is 3.0% by weight or less. Further, when the Fe content of the intermediate material of the α-type titanium alloy is less than 0.10% by weight, the joining characteristics are further improved. The contents of O, N and C in the intermediate material of the α-type titanium alloy are each preferably about 0.4% by weight or less.

The slab heating temperature T ° C. is 890 ≦ T
≦ 885 + 150 [O] +160 [C] +300 [N]
+20 [Al] -20 [Fe] (where [Fe] is F
e content is shown. ), 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 (88
5 + 150 [O] +160 [C] +300 [N] +20
When the temperature is higher than [Al] -20 [Fe]) ° C, the α-type titanium alloy inserted on the side of the laminated material also exceeds the transformation point and has a BCC structure in which C diffuses quickly, so that TiC is formed thick at the interface. As a result, the bondability is deteriorated.

Therefore, the slab heating temperature T ° C. is 890
≦ T ≦ 885 + 150 [O] +160 [C] +300
It is preferably in the range of [N] +20 [Al] -20 [Fe].

The thickness of the intermediate material installed on the side of the laminated material is tm
When the total thickness of m, the base material, the above two kinds of intermediate materials, and the combined material is Tmm, and t / T is larger than 0.01, the α-type titanium alloy inserted as the intermediate material is Since the workability is relatively low, the workability of the clad steel plate itself is reduced. Therefore, it is preferable that t / T ≦ 0.01.

[0027]

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 method of assembling the slab, the slab size, the slab heating temperature and the size of the clad steel plate. At this time, it is possible to perform rolling according to the planned pass schedule, the thickness of the TiC layer that deteriorates the joining characteristics in the as-rolled state, the shear strength in the as-rolled state, and side bending and back-bending at R / t = 1. 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 thickness of 50 mm and a chemical composition of A shown in Table 1 and using carbon steel having a thickness of 350 mm as a base material and having a chemical composition of D shown in Table 2 The material was used as a laminated material. In addition, as an intermediate material on the base material side, Table 1
1 to 1 mm in thickness having a composition of B1 to B5 shown in FIG.
A 1 mm thick one having a composition of C7 was used. Assemble the slab under the conditions shown in Table 5, and set the slab heating temperature to 920 ° C.
As a result, a clad steel plate having a (35 + 5) mm thickness × 4200 mm width × 7200 mm length was manufactured from a 1800 mm width × 1800 mm length slab. At this time, since the rolling heating temperature was raised, the deformation resistance was low under all conditions,
It could be rolled.

At this time, T which deteriorates the joining characteristics
Table 5 also shows the thickness of the iC layer 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.

(Embodiment 3) Titanium having a chemical composition of code A shown in Table 1, a carbon steel having a thickness of 350 mm as a base material, having a chemical composition of code 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, the one having a thickness of 1 mm having the composition of the code B3 shown in Table 1 was used, and as the intermediate material on the side of the laminated material, the one having the composition of the code C3 shown in Table 2 was used. A slab was assembled using the base material, the laminated material, and the intermediate material, and the rolling heating temperature was set to 920 ° C. to produce a (35 + 5) mm thickness × 4200 mm width × 7200 mm long clad steel plate from a 1800 mm width × 1800 mm length slab. At this time, the thickness of the intermediate material of α-type titanium is set to 1 mm, 3 mm, 5 mm and 10 mm,
The relation between the thickness and the workability of the clad steel plate is R / t =
The presence or absence of cracks at the joint interface during side bending and back bending in No. 1 and the table with slits reported at the 45th Plastic Working Union Lecture Meeting, which is a joint strength evaluation method during processing of clad steel sheets. It was investigated by a bending test. Table 6 shows the results. Regarding rolling, since the rolling heating temperature was raised, the deformation resistance was low under all conditions, and rolling was possible with the planned rolling pass schedule.

As is clear from Table 6, the thickness of the intermediate material installed on the side of the laminated material is tmm, the base material, two kinds of intermediate materials,
And when the total thickness of the laminated materials is Tmm, t / T
If ≦ 0.01, the workability of the manufactured clad steel sheet was good in any of the evaluation methods of side bending, back bending, and front bending test with slit. 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.

[0037]

[Table 1]

[0038]

[Table 2]

[0039]

[Table 3]

[0040]

[Table 4]

[0041]

[Table 5]

[0042]

[Table 6]

The above-mentioned 885 + 150 [O] +16
0 [C] +300 [N] +20 [Al] -20 [Fe]
The formula is an empirical formula obtained from the result of detailed examination of the relationship between the component composition and the transformation point. Also, [O] +1.1
The same was obtained under the condition of [C] +2.0 [N] +0.1 [Al] and 0.15 wt% or more. Further, although pure titanium is used as the bonding material in the above-mentioned embodiment, it is not limited to this, and Grade 7 or Ti may be used.
A Ti alloy such as -6Al-4V can be used.

[0044]

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.

Claims (4)

[Claims] 1. An ultra-low carbon having a C content of 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. The steel sheet has a Fe content of 0.25% by weight or less and a content of O, N, C and Al of [O] +1.1 on the side of the laminated material.
[C] +2.0 [N] +0.1 [Al] (however,
[O], [C], [N], and [Al] represent O content, C content, N content, and Al content, respectively.
A method for producing a titanium clad clad steel sheet, comprising inserting an α-type titanium alloy plate having an Al content of 15% by weight or more and an Al content of 3.0% by weight or less to assemble a slab and roll the slab. 2. The slab heating temperature T ° C. is 890 ≦ T ≦ 8
85 + 150 [O] +160 [C] +300 [N] +2
The method for producing a titanium clad steel sheet according to claim 1, wherein the rolling is performed in a temperature range of 0 [Al] -20 [Fe] (where [Fe] represents the Fe content). 3. An intermediate material having a C content of 0.
The ultra low carbon steel sheet of 001 to 0.01% by weight has a Fe content of less than 0.10% by weight and an O, N, C and Al content of [O] +1.1 [C] on the side of the composite material. +2.0 [N]
+0.1 [Al] (however, [O], [C], [N],
[Al] is O content, C content, N content, A
The titanium according to claim 1 or 2, wherein an α-type titanium alloy plate having an Al content of 0.15 wt% or more and an Al content of 3.0 wt% or less is used. Manufacturing method of clad steel sheet. 4. The thickness of the intermediate material installed on the side of the laminated material is t
mm, the base material, the two kinds of intermediate materials, and the total thickness of the laminated materials are Tmm, t / T ≦ 0.01. 4. A method for manufacturing a titanium clad steel sheet according to the item.