JPH0366995B2 - - Google Patents

Description

[Detailed description of the invention]

(a) Technical field The present invention relates to a method for manufacturing titanium clad steel. (b) Prior Art Conventional methods for manufacturing titanium clad steel used as materials for chemical equipment, etc. include roll crimping, diffusion bonding, and explosion bonding. Both the roll pressure bonding method and the diffusion bonding method require heating and pressure bonding steps. However, in these methods, since intermetallic compounds are generated at the joint between the titanium plate and the steel plate, a good joint cannot be obtained. In order to prevent the formation of intermetallic compounds, there is a method of providing an insert material between the titanium plate and the steel plate. For example, in Japanese Patent Publications No. 1286-1986, No. 1287-1987, and No. 71590-1987, chromium, molybdenum, vanadium, or composite materials of these metals and chromium, nickel, and copper are used as insert materials. The method used is shown. However, titanium clad steel manufactured by such a method has a low bonding strength, which causes problems such as delamination between the titanium plate and the steel plate when plastic working such as spinning is applied. Furthermore, the diffusion bonding method has to be carried out in a high vacuum or in an inert gas, which has the problem of poor productivity. Since the roll crimping method and the diffusion bonding method have the above-mentioned problems, the explosion bonding method is mainly put into practical use. However, the explosive bonding method also has the following problems. In other words, the explosion bonding method is not suitable for mass production, and the base material must have the strength to withstand explosive pressure, so the thickness of titanium clad steel that can be manufactured using this method is limited to 20 mm or more. There is. In addition, plastic workability is also unfavorable in the explosively bonded state. In order to improve the plastic workability of titanium clad steel, it is necessary to anneal it at a temperature of 650°C or higher, which is the temperature at which titanium sufficiently softens, but annealing at such a temperature significantly reduces the bonding strength. In order to solve these problems, when attempting to thin the titanium clad steel manufactured by the explosion bonding method by thinning it by hot rolling or softening it by annealing, it is difficult to solve the problem by using the roll crimping method and diffusion bonding method described above. Similarly, a problem arises in that intermetallic compounds are formed between the titanium plate and the steel plate. Tokuko Showa 53-10347
No. 53-133458 and Japanese Patent Publication No. 53-133458 show a method of providing nickel as an insert material between a titanium plate and a steel plate in order to solve the above problems. However, sufficient joint strength has not been obtained, and the thickness of the plate that can be manufactured is only 10 mm.
The extent is the limit. (c) Purpose of the invention The present invention solves the above-mentioned problems in the conventional titanium clad steel manufacturing method, and provides a titanium clad steel that can efficiently produce titanium clad steel with high bonding strength and good plastic workability. The purpose is to obtain a manufacturing method for. (d) Structure of the Invention The present inventor has discovered that the bonding strength of titanium clad steel manufactured by the conventional titanium clad steel manufacturing method is reduced due to the following three factors. In other words, (1) a decrease in strength due to weak intermetallic compounds that form between titanium and steel; (2) Brittleness due to hydrogen absorption of titanium. (3) Strength decreases due to carbon in the steel sheet diffusing into the titanium side and fragile titanium carbide precipitating. There are three factors. In order to prevent the joint strength from decreasing due to the three factors mentioned above, insert materials with two layers of nickel and copper or nickel and copper are recommended.
The inventor has discovered that it is necessary to provide a three-layer insert material of copper and nickel. That is,
The method for manufacturing titanium clad steel according to the present invention includes arranging two thin layers of copper and nickel as insert materials between a titanium plate and a steel plate so that the nickel layer faces the titanium plate, or arranging two thin layers of copper and nickel as insert materials between a titanium plate and a steel plate.・Arrange three thin layers of nickel, stack them on top of each other, and roll and join them at a rolling joining temperature of 600 to 900°C with a rolling joining reduction ratio of 70% or more, and then softening annealing at a softening annealing temperature of 650 to 750°C. It consists of each process. In addition to each of the above steps,
After rolling joining and before softening annealing, rolling thickness reduction can be performed at a rolling thickness reduction temperature of 400° C. or higher. Note that the thin layer of the insert material herein refers to "plating" or "peeling", and preferably has a thickness of 5 microns or more after rolling. In addition, plating shall be applied to the steel plate or insert material, and the titanium plate shall not be directly plated. This is because the bonding strength decreases when titanium is plated. By the method of the present invention having the above-described structure, the three factors that reduce the bonding strength described above can be eliminated. First, according to the method of the present invention, the above-mentioned factor (1) can be eliminated. That is, even when annealing is performed at a high temperature of 650 to 750°C, fragile intermetallic compounds are not generated at the joint between the titanium plate and the steel plate. Intermetallic compounds are formed between titanium and nickel, but
This intermetallic compound has a certain degree of ductility. Therefore, it is also possible to reduce the thickness by roll rolling. Note that this intermetallic compound is very susceptible to work hardening at room temperature, but there is no problem if it is rolled at a temperature of 400°C or higher. Furthermore, nickel and copper and copper and steel plate form a complete solid solution, and no intermetallic compounds are generated. In addition, if the steel plate is an alloy containing many components other than iron, there is a possibility that fragile intermetallic compounds may be formed between the copper and the steel plate.
In this case, there is a nickel layer between the titanium plate and the steel plate.
This can be prevented by providing an insert material consisting of three thin layers of copper and nickel. Furthermore, according to the method of the present invention, the above-mentioned factor (2) can also be eliminated. That is, embrittlement due to hydrogen absorption of titanium can be prevented. This is because the intermetallic compound formed between titanium and nickel prevents hydrogen from entering. However, since there is a possibility that titanium absorbs hydrogen during heating before joining to generate this intermetallic compound, it is necessary to perform dehydrogenation treatment after the combined seal welding of the titanium plate and steel plate. Furthermore, according to the method of the present invention, the above-mentioned factor (3) can also be eliminated. That is, it is possible to prevent carbon in the steel sheet from diffusing toward the titanium side. This is a result of using copper as the insert material. The carburization prevention effect of copper is several times greater than that of nickel, and even when annealing at 750°C, for example, a thickness of about 5 microns is sufficient. (E) Effect Generally, in the case of titanium clad steel, vacuum sealing (combination) or rolling is carried out in vacuum, but in the present invention, the above-mentioned insert material is interposed between the titanium plate and the steel plate, and rolling joint is performed. If rolled at a temperature of 600℃ or higher and a rolling joint reduction rate of 70% or higher,
Based on the knowledge that complete bonding can be achieved without special vacuum treatment, the reduction rate of rolling bonding has been increased.
The rolling bonding temperature was limited to 70% or more, and the lower limit of the rolling bonding temperature was set at 600°C. On the other hand, when the rolling joining temperature exceeds 900°C, the deformation resistance of titanium becomes too low compared to steel, and a large amount of intermetallic compounds occur on the joint surface, causing delamination during rolling even if the clad material is once joined. Since this is likely to occur, the upper limit of the rolling bonding temperature was set at 900°C. In addition, if the softening annealing temperature is lower than 650℃, titanium will not soften sufficiently and cannot withstand severe processing conditions such as deep drawing. Therefore, the lower limit of the softening annealing temperature should be set to 650℃. did. on the other hand,
When the softening annealing temperature is set higher than 750℃,
Many intermetallic compounds occur between titanium and steel,
Since flaking occurs during processing of the clad material, which impedes workability, the upper limit of the softening annealing temperature was set at 750°C. Note that when titanium clad steel is cold rolled, delamination occurs and rolling becomes impossible because the deformation resistances of the steel and titanium are significantly different. However, when the rolling thickness reduction temperature reaches 400℃ or higher, the deformation resistance of steel and titanium become almost the same, so it is possible to roll the sheet to the desired thickness, and obtain the same surface texture as cold rolling. Therefore, the rolling thickness reduction temperature was set at 400℃.
limited to the above. (F) Example Next, the effects of the present invention will be explained based on specific test results. Table 1 shows the mechanical properties of titanium clad steel produced by the method of the present invention and titanium clad steel produced by the conventional method. Samples A to F were obtained by the method of the present invention, and samples G to J were obtained by the conventional method.

[Table] Samples A to C are 60mm (thickness) x 1000mm (width) x
2000mm (length) steel plate and 10mm (thickness) x 950mm
A titanium plate measuring (width) x 1950 mm (length) was used. A 100 micron thick copper plating was applied to the steel plate, and a 100 micron thick nickel plating was applied on top of this copper plating. The two-layer plated steel plates with inserts were stacked so that the nickel plated surface faced the mating surface of the titanium plate, and the surroundings were sealed and welded to form a clad package. After this clad package was evacuated at 110 to 150°C, the pressure was reduced to 10 ^-2 Torr, and argon gas was replaced, the rolling joining reduction was set at a rolling joining temperature of 600 to 900°C.
The plate was hot rolled at 91.5% {Note: rolling joining reduction rate = (reduced thickness ÷ initial thickness) x 100%} to reduce the plate thickness to 6 mm. Sample A was annealed at a softening temperature of 650℃.
Sample B was softened and annealed for 30 minutes at a softening annealing temperature of 750°C.
Sample C is obtained by further warm rolling the titanium clad steel described above to a thickness of 3 mm at a rolling thickness reduction temperature of 600 to 400°C, and then softening annealing at a softening annealing temperature of 750°C for 30 minutes. These samples A to C are the first
As shown in the table, it has good mechanical properties. Samples D to F are 50mm (thickness) x 1000mm (width)
×2000mm (length) steel plate and 10mm (plate thickness) ×950mm
A titanium plate measuring (width) x 1950 mm (length) was used. The insert material used was a 0.8 mm thick copper plate with 100 micron thick nickel plating on both sides. These were hot rolled in the same manner as Samples A to C at a rolling joining reduction rate of 80.3% to reduce the plate thickness to 12 mm. Sample D has a softening annealing temperature of 650
Sample E was softened and annealed at a temperature of 750°C for 30 minutes.
Sample F is obtained by warm rolling the titanium clad steel described above to a thickness of 3 mm at a rolling thickness reduction temperature of 600 to 400°C, and then softening annealing at a softening annealing temperature of 750°C for 30 minutes. As shown in Table 1, good mechanical properties were also obtained for these samples D to F. Samples G and H produced by the conventional method used steel plates plated with nickel. That is, they were manufactured in exactly the same manner as Samples A to C except that copper plating was not applied. Sample G is as-rolled, and sample H is annealed at a softening annealing temperature of 650° C. for 30 minutes. Sample G has good joint strength but lacks ductility.
In addition, although sample H has good ductility, the bonding strength is significantly reduced. As a result of analyzing the joint boundary of this sample H by EPMA analysis,
It was found that titanium carbide was precipitated at the titanium side interface. Samples I and J are without any insert material. That is, they were manufactured by the same process as Samples A to C except that no insert material was used. Sample I is as-rolled, and sample J is annealed at a softening annealing temperature of 650° C. for 30 minutes. The mechanical properties of Samples I and J were also insufficient due to low bonding strength. As is clear from the above test results, it can be seen that the titanium clad steel manufactured by the method of the present invention has sufficient bonding strength to withstand plastic working. (G) Effects of the Invention As explained above, according to the present invention, two thin layers of copper and nickel are arranged as insert materials between a titanium plate and a steel plate, with the nickel layer facing the titanium plate. or nickel
Three thin layers of copper and nickel are arranged, stacked on top of each other, and rolled and joined at a rolling joining temperature of 600 to 900°C with a rolling joining reduction ratio of 70% or more, followed by softening annealing at a softening annealing temperature of 650 to 750°C. This makes it possible to mass-produce titanium clad steel having sufficient bonding strength. Note that before the softening annealing, the sheet can be rolled to a desired thickness at a rolling thickness reduction temperature of 400° C. or higher.

Claims (1)

[Claims] 1. Two thin layers of copper and nickel are arranged between the titanium plate and the steel plate as an insert material so that the nickel layer faces the titanium plate, or a thin layer of nickel, copper, and nickel is placed between the titanium plate and the steel plate. Three thin layers are arranged, stacked on top of each other, and rolled at a joining temperature of 600 to 900.
A method for producing titanium clad steel, comprising rolling joining at a rolling joining reduction rate of 70% or more at °C, and then softening annealing at a softening annealing temperature of 650 to 750 °C. 2. Place two thin layers of copper and nickel as an insert plate between the titanium plate and the steel plate, with the nickel layer facing the titanium plate, or place three thin layers of nickel, copper, and nickel as an insert plate. Place them on top of each other and roll them at a joining temperature of 600 to 900.
℃ at a rolling joining reduction rate of 70% or more, then rolling thickness reduction at a rolling thickness reduction temperature of 400℃ or more,
A method for manufacturing titanium clad steel, which is then subjected to softening annealing at a softening annealing temperature of 650 to 750°C.