JPH0454553B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a method for producing rolled clad steel sheets made of Ti and Ti alloys with excellent bondability. (Prior Art) Titanium clad steel sheets have heretofore been mainly manufactured by the explosion bonding method, which is subject to significant restrictions in terms of product dimensions, dimensional accuracy, productivity, and manufacturing costs.
Recently, an explosion rolling method has been proposed that involves rolling after explosion bonding.
Although the manufacturable range and dimensional accuracy are improving,
Difficulties remain in terms of productivity and manufacturing costs.
As a method for improving this, it is desired to establish a so-called rolled clad method using rolling welding, and several methods have already been proposed. Here, the rolling cladding method (formation of a clean surface)
→ (Assembling of clad material) → (Sealing by vacuum suction or sealing after inert gas injection) → (Heating)
→ (rolling), but the problems with this rolled clad method are (1) selection of insert material to be interposed between base material and composite material, (2) assembly of clad material by welding and vacuum Sealing by pulling or inert gas injection, and (3) rolling heating temperature. Titanium easily forms intermetallic compounds with other elements, and elements that form complete solid solutions with titanium are
There are limitations such as being limited to a few elements such as Mo, Nb, V, and Zr, these elements being expensive, and poor workability making it impossible to obtain plate-shaped insert materials. The role of insert material is
Both titanium and titanium alloys and the base metal have good bonding properties and do not form brittle intermetallic compounds, and carbon in the base metal diffuses and reacts with titanium in titanium or titanium alloys to form titanium carbide. This is to avoid deteriorating bonding properties. Currently,
Research has revealed that considerable bonding properties can be obtained by minimizing the formation of intermetallic compounds by adjusting the rolling heating temperature. However, the formation of titanium carbide due to the diffusion of carbon from the base metal particularly degrades the bond strength.
This must be avoided. To achieve this purpose, an insert material is interposed between the base material and the composite material, and there are methods using Ni, pure iron, and ultra-low carbon steel (Japanese Patent Application Laid-Open No. 1982-122681), a method of decarburizing the laminate side of the base material (Japanese Patent Application Laid-Open No. 1982-220292),
How to use Ni-metsuki (Japanese Patent Application Laid-Open No. 53-10347)
etc. have been proposed. Ni diffuses quickly in Ti, and during rolling heating and rolling, Ni transforms from α phase (hcp crystal structure) to β phase (bcc crystal structure), and Ni diffuses into Ti. Ni insert materials are more disadvantageous than iron-based insert materials because the rolling temperature is more restricted. (Problem to be solved by the invention) When using iron-based insert materials, carbon diffusion is significantly faster than in Ni, so it is difficult to prevent this by using pure iron or by decarburizing the surface of the base material. It has become clear from various research results that this is not possible. In addition, the method of adding carbon-fixing elements (Ti, Nb, Mo) to fix carbon in the base material and insert material, as in JP-A No. 56-122681, may contain excessive carbon. In clad steels whose base material is carbon steel or alloy steel that cannot exist as stable carbides even during rolling heating, it is not possible to sufficiently prevent the formation of titanium carbides at the interface. In particular, when the thickness of the clad steel is reduced by hot rolling and then reheated such as hot forming, welding, and strain relief annealing (SR treatment), the diffusion becomes easy. TiC generated in this way
is very hard and brittle, so the strength of the clad steel obtained in this way is unavoidable. (Means for Solving the Problems) Based on the results of such research and examination, the present inventors have determined that ultra-low carbon alloy steel containing sufficient carbon fixing elements in low carbon steel should be used on the titanium (including titanium alloy) side. Furthermore, by using Ni as an insert material on the base metal side to prevent the diffusion and intrusion of carbon from the base metal, the formation of intermetallic compounds at the interface can be suppressed, and titanium carbide at the interface can be suppressed. The present invention was completed based on the knowledge that it is possible to manufacture rolled titanium clad steel with excellent bondability by completely preventing the formation of titanium. Furthermore, in the present invention, by using N as the insert material on the base metal side, the plate thickness of the ultra-low carbon alloy steel used as the insert material on the titanium side can be made thinner, thereby reducing costs. , the profit is large. Here, the gist of the present invention is to use a titanium-based metal bonding material, a carbon content bonded to the bonding material being 0.05% by weight or less, and a carbon fixing element.
Ti: 0.01~5.0%, Nb: 0.05~10%, V: 0.01~
20% and Mo: 0.05 to 10%, a low carbon alloy steel plate containing one or more types, a nickel plate bonded to the low carbon steel plate, and a base steel plate bonded to the nickel plate. It is a titanium-based metal clad steel. From a further aspect, the present invention provides a method for manufacturing clad steel by laminating a titanium-based metal cladding material and a base steel plate and hot rolling, in which carbon content is added to the cladding material side between the two members. is 0.05% by weight or less, and further contains Ti: 0.01-5.0% and Nb: as carbon fixing elements.
0.05~10%, V: 0.01~20%, and Mo: 0.05~
A low carbon alloy steel plate containing 10% of one or more types is used as a clad material by interposing a nickel plate on the base steel plate side, so that oxygen is not supplied to the joint surface between these parts. After performing seal welding on the clad material, at least the joint surface between the titanium-based metal laminate and the low carbon steel plate is heated to 700 to 870°C in a non-oxidizing atmosphere, and then rolled and crimped. This is a manufacturing method for titanium-based metal clad steel. Here, "titanium-based metal" includes pure titanium and titanium-based alloys. In the present invention, so-called stainless steel is excluded as the above-mentioned "low carbon alloy steel" because it contains a relatively large amount of chromium. (Function) Next, the reason why the alloy composition and processing conditions are limited as follows in the present invention will be described. In this specification, "%" means "% by weight" unless otherwise specified. The reason for setting C to 0.05% or less is to make the carbon fixing elements shown below work effectively, and although it is desirable that this amount is low, it was set to 0.05% or less from the viewpoint of steel manufacturing costs. To fix carbon in the insert material, it is sufficient to add an amount corresponding to the chemical equivalent of the carbon contained as an impurity, but during rolling heating,
Alternatively, in order to stabilize the carbides seen during rolling or to capture carbon diffused from the base material and completely avoid the formation of titanium carbides at the interface between the insert material and titanium, it is necessary to is 0.01% or more,
Preferably 0.5% or more, each of Nb, V, and Mo
0.05% or more, 0.01% or more, and 0.05% or more, preferably 0.3% or more of each of Nb, V, and Mo is required. In addition, the larger the amount of these carbon fixing elements, the more advantageous it is in capturing and fixing carbon.
If the content is too large, the material will become brittle, making it impossible to manufacture plates or foils as insert materials, and forming intermetallic compounds with iron (TiFe ₂ ,
NbFe ₂ , VFe) and cannot maintain the strength as an insert material. Therefore, in the present invention, the upper limits of Ti, Nb, V, and Mo are each 5.0%,
10%, 20%, 10%. Si and Mn are added as deoxidizers to obtain good killed steel, and each is usually
The content is about 0.01% and 0.3%, and although there is no particular restriction in the present invention, excessive addition impairs the ductility of the insert material, so if necessary, the upper limit of each is 0.5% and 2.0%. It is. The thickness of the Ni insert material is not particularly limited in the present invention, and is approximately 30 μm in consideration of the diffusion of C into Ni.
Although a thickness of 50 μm or more is sufficient, it is preferably 50 μm or more in order to avoid local bonding defects due to cutting of the insert foil during rolling. The thickness of the ultra-low carbon alloy steel insert material is
If 50μm thick Ni insert material is used, 30μm
Although the formation of titanium carbide at the interface can be avoided even if the thickness is less than 50 μm, it is necessary to have a thickness of 50 μm or more in order to avoid local bonding defects due to cutting during rolling. There is no need to set an upper limit on the thickness of both insert materials, but from the standpoint of productivity and cost, it should be 5 mm or less. The present invention will now be described in more detail with reference to the accompanying drawings. FIG. 1 is a perspective view of a cladding material seen in the manufacturing process of a titanium-based metal clad steel plate according to the present invention. Even in the final clad steel, the clad structure itself is the same, so to explain with reference to FIG. 1, a nickel plate 2, which is an insert material, is provided on a base steel plate 1. Furthermore, an ultra-low carbon steel plate 3, which is another insert material, is provided. A titanium plate, which is a cladding material, is clad with this ultra-low carbon steel plate 3 interposed therebetween. As mentioned above, there is no particular restriction on the thickness of each plate material, but preferably the total thickness of the insert material as the final material is about 0.1 to 10% of the total length of the combined steel plates, usually about 0.5 to 3.0%. is good. Next, the method for producing clad steel according to the present invention will be described. First, a base steel plate, a titanium material as a cladding material, a nickel plate as an insert material, and an ultra-low carbon steel plate are prepared. It is preferable that each surface to be joined be made as clean as possible through a process such as degreasing. (1) Assembly: As shown in Figure 1, each material, steel plate 1, nickel plate 2, ultra-low carbon steel plate 3, and titanium plate 4, are laminated, and the sizes of each insert material and titanium plate are adjusted to the base material. By making the material slightly smaller than a steel plate, each material on the base material is covered with a cover 5 made of another ultra-low carbon steel plate, and each joint 6 is welded and sealed to form a clad material 7. The insert material shall be ultra-carbon steel on the mating material (titanium or titanium alloy) side and Ni plate on the base steel plate side. (2) Degassing: After obtaining the cladding material 7, the interior is degassed using a rotary pump or the like through the suction port 8 to create a vacuum of 10 ^-1 Torr or less. At this time, the vacuum degassing treatment is performed at least on the joint surfaces of the insert materials. In the degassing process, high vacuum can be achieved more easily by degassing while heating. When a predetermined amount of degassing is completed, the suction port 8 is shut off by appropriate means such as cutting it by melting. (3) Rolling: Excellent joint strength cannot be maintained unless the rolling heating temperature is 700°C or higher from the rolling perspective. Also
If the temperature exceeds 870°C, Ti will transform into the β phase, which will deteriorate the corrosivity of titanium, and will also promote the diffusion of iron, the main component of the insert material, into Ti, resulting in the formation of intermetallic compounds between iron and Ti. The formation is promoted and the bonding strength deteriorates. Thus, in the clad steel produced according to the present invention, virtually no TiC formation was observed, and no decrease in strength was observed even after post-heat treatment. After rolling, the desired titanium-based metal clad steel is obtained by peeling off the steel plate serving as the cover. Next, the present invention will be explained with reference to examples. Example 1 50Kg class low alloy high tensile strength steel with 90mm plate thickness (SS41 equivalent)
The base material is 10 mm thick industrial-grade pure titanium (equivalent to JIS H 4600 Class 1), and the plate thickness is
50μm ultra-low carbon steel insert material and 50μm plate thickness
Ni insert material and these materials are used as the first material.
It was assembled as shown in the figure, and the air was evacuated using a rotary pump through the deaeration hole provided at the end. as standard condition
After reducing the pressure to 10 ^-1 Torr or less, the deaeration hole was closed by welding, heated to 800° C. for 5 hours, and rolled at a reduction ratio of 5. Thereafter, the bondability was evaluated by a shear test. The results are shown in Table 1 along with the composition of the ultra-low carbon steel. In the same table, a shear tensile strength of 15 Kg/mm ² or more is indicated as bondability (〇), and it can be seen that according to the present invention, all exhibit excellent bondability.

[Table] Example 2 Ultra-low carbon steel composition (0.05%C-0.2%Si-0.3%
Mn) as standard composition, plus 0.02%Ti and 0.05
%Nb, 0.3% V and 0.06% Mo were used, and the operation of Example 1 was repeated to produce clad steel. At this time, the rolling heating temperature was varied and the resulting changes in bonding strength were observed. The results are summarized in a graph in Figure 2. It can be seen that a joining temperature of 15 kg/mm ² or more can be obtained when the rolling heating temperature is 700 to 870°C. Example 3 In this example, a 50 μm thick Ni
The resulting clad steel without and with the foil insert material
The relationship between the treatment time and bonding strength was evaluated when strain relief annealing, that is, SR treatment, was performed by reheating at 750°C. The results are summarized in a graph in Figure 3.
It can be seen that if Ni insert material is used, a bonding strength of 15 kg/mm ² or more can be secured even after 20 hours of heating. In addition, rolling heating in this case is performed at 800℃,
The composition of ultra-low carbon steel insert material is 0.05%C-0.2
%Si−0.3%Mn−0.25%Nb. Example 4 Example 1 was repeated in this example, but in this example, the standard composition of the ultra-low carbon steel insert material was changed to 0.05%C-0.05
%Si-0.3%Mn-Fe and the amount of Ti added was changed to examine the effect of the amount of Ti on the bonding strength.
The results are summarized in a graph in Figure 4. Similarly, the effects of the amounts of Nb, V, and Mo added on the bonding strength were also examined. The results are summarized in a graph in FIG. As can be seen from the results shown in FIGS. 4 and 5, according to the present invention, a bonding strength of 20 Kgf/mm ² or more can be obtained by adding any C-fixing element.

[Brief explanation of the drawing]

Figure 1 is a perspective view of the cladding material;
5 through 5 are graphs showing the results of each example of the present invention. 1: Base steel plate, 2: Ni plate, 3: Low carbon steel plate,
4: Titanium plate, 5: Cover, 6: Seam, 7: Clad material, 8: Suction port.

Claims (1)

[Scope of Claims] 1. A titanium-based metal laminate, the carbon content of which is bonded to the laminate is 0.05% by weight or less, and carbon fixing elements include Ti: 0.01 to 5.0% and Nb: 0.05 to 10%.
%, V: 0.01 to 20%, and Mo: 0.05 to 10%. A titanium-based metal clad steel consisting of a base steel plate. 2. In a method of manufacturing clad steel by laminating a titanium-based metal laminate and a base steel plate and hot rolling, the carbon content on the laminate side between both members is 0.05.
Ti as a carbon fixing element in less than weight%:
0.01~5.0%, Nb: 0.05~10%, V: 0.01~20%,
A low carbon alloy steel sheet containing one or more of Mo: 0.05 to 10% is further interposed with a nickel plate on the base steel sheet side to make a clad material, and the joint surface between these members is made of oxygen. After performing a seal weld on the cladding material to prevent feeding,
700~
A method for producing titanium-based metal clad steel, which is characterized by heating it to 870°C and then rolling and crimping it.