JPS62114785A - Production of ti or ti alloy clad steel - Google Patents

Abstract

PURPOSE:To form a Ti clad steel having excellent joint strength by a rolling method by preliminarily working the mating surface of an insert material with a cladding metal to ruggedness. CONSTITUTION:A Ti or Ti alloy plate 3 which is the cladding metal is imposed via an insert material 2 on a steel slab 1 which is the base metal and the entire part is enclosed with a mild steel plate 4 and is sealed at a weld zone 5. The mating surface of the insert material 2 with the cladding metal is subjected to knurling to 0.5-5mm groove depth and 1-20mm groove space. The Ti clad steel having the excellent joint strength is obtd. if such assembly is subjected to deaeration heating, then to hot rolling. The reason thereof lies in that the contact area in the heating stage is decreased by knurling and that the formation of a laminar inter-metallic compd. at the boundary face is obviated even in a long period of high-temp. heating. The Ti clad steel having the excellent joint strength is, therefore, formed by a rolling method.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a method for producing Ti or Ti alloy clad steel, particularly a method for producing Ti or Ti alloy clad steel, in particular a method for producing Ti or Ti alloy clad steel, in which an insert material is interposed between a Ti or Ti alloy sheathing material and a steel base material. The present invention relates to a method for producing Ti or Ti alloy clad steel.

(Prior Art) Ti-clad steel has been known in the past, and such Ti-clad steel has been practically produced by an explosion bonding method. However, the explosion bonding method not only limits the types of materials that can be manufactured, but also limits the manufacturing dimensions due to the small size of the assembled slab. Moreover, if hot rolling is performed thereafter, not only the bonding strength will be significantly reduced, but also the manufacturing cost will be generally high.

Therefore, various methods using rolling, which are cheaper and relatively free from dimensional constraints, have been studied, but when rolling is used, carbide precipitation occurs at the interface with the cladding material, and even if pure iron is inserted as an intermediate material, the insert Diffusion of iron from the material toward the titanium side causes a brittle intermetallic compound layer to grow at the interface, resulting in a decrease in bond strength. Therefore, when using insert materials made of pure iron, there are manufacturing constraints in that the rolling temperature cannot be kept high to suppress the growth of brittle intermetallic compounds, and large reduction rolling is difficult. This loses the original advantage of the rolling method.

In addition, various methods have been studied for rolling methods, such as the use of low carbon steel insert materials (Japanese Patent Laid-Open Nos. 53-94249 and 56-122681).
, most of the clad material and low carbon steel insert material come into surface contact during the heating stage, which inevitably causes mutual diffusion, making it difficult to control the thickness of the intermetallic compound layer after rolling, and requiring large reductions. High temperature heating to facilitate rolling was not possible, and none of the results were satisfactory. Incidentally, there are no proposals for N1 insert material at all.

(Problems to be Solved by the Invention) Therefore, an object of the present invention is to provide a method for producing Ti or Ti alloy clad steel by a rolling method.

Another object of the present invention is to provide a method for producing Ti or Ti alloy clad steel that does not cause the growth of a brittle intermetallic compound layer at the joint interface even when subjected to large reductions at high temperatures.

(Means for Solving the Problems) Thus, in order to achieve the above-mentioned object, the present inventors have obtained the following findings as a result of various studies: (1) Titanium or titanium alloy on the mating surface side. Irregular processing on the plate surface, the insert material surface, or both surfaces,
For example, if knurling is applied, for example, if a nickel plate is used as the insert material, the temperature will rise to 900°C, CO,
When a carbon steel plate containing 0.01% by weight or less is used, it has excellent bonding strength even when hot rolled up to 1050°C.

(2) Second, inserting a Kel plate or a carbon steel plate with C0.01% by weight or less as an intermediate material is effective in preventing a decrease in joint strength due to carbide precipitation. In this case, an intermetallic compound layer grows and the bonding strength decreases. When the thickness exceeds 3 μm, the bonding strength rapidly decreases.

The present invention was discovered as a result of further studies based on the above-mentioned knowledge, and its gist is 1. interposing an insert material, sealing each mating surface to form a cladding assembly, deaerating the sealed mating surfaces, heating the sealed and deaerated cladding assembly, and heating the sealed and deaerated cladding assembly. A method of manufacturing a cladding material by hot rolling a cladding assembly, wherein one or both of the mating surface of the cladding material and the surface of the insert material in contact with the cladding material are subjected to roughening in advance. This is the production of characteristic Ti or T1 alloy clad steel.

According to one aspect of the invention, the insert material is a Ni slope.

According to another aspect, the insert material has a carbon content of 0.
．． The groove plate may have a content of 0.01% by weight or less.

Here, the sealing of each of the mating surfaces is carried out by, for example, welding the periphery to provide weight resistance, but preferably a mild steel plate is used to surround the Ti or Ti alloy composite and the insert material, and the carbon fi71 plate is attached to a steel base. This is done by welding to the material.

The reason why each mating surface is sealed and degassed is because mutual diffusion will not occur if an oxide layer is formed on the surfaces of both parts during heating in the furnace.
This is to perform vacuum deaeration and prevent surface oxidation.

"Uneven processing" refers to a process that forms an uneven pattern on the surface to be treated by physical or chemical treatment.For example, physical means include so-called knurling and machining, and chemical means include so-called knurling and machining. Examples include surface roughening treatment by corrosion and selective etching.

(Function) Next, embodiments of the present invention will be specifically described with reference to the flow sheet of the method of the present invention shown in FIG. 1 of the drawings with ta.

First, each material to be assembled to the clad steel is prepared, and the mating surfaces of the insert material and/or the clad steel mating material are subjected to uneven processing. In a preferred embodiment, a groove depth of 0.5 to 5 mm and a groove interval of 1 to 20 mm are formed on the mating material surface on the mating surface side, the insert material surface, or both surfaces.
It is preferable to perform rectangular or triangular knurling. Normally, roughening only the mating surfaces of mating and overturning is sufficient.

Next, each of the materials prepared in this manner is used as a clad assembly material. In other words, T is inserted into the steel slab through an insert material.
A cladding material of i or Ti alloy is placed to form a clad assembly material. Next, the insert material and the T1 or Ti alloy composite material placed on the steel slab are covered with mild steel,
The surrounding area is welded and each joint surface is shielded from the outside air to form a hermetic clad assembly.

A schematic cross-sectional view of the cladding assembly is shown in FIG.

Inserts 1 and 2 are placed on top of the base material, the 1-hole slag.
A TI or T1 alloy plate 3, which is a laminate material, is placed therebetween. In the illustrated example, the mating surface of the insert material 2 with the mating material is knurled. The insert material and the laminate material are entirely surrounded by a mild steel plate 4, and the periphery is sealed by a welded portion 5.

It is best to weld the steel plates together.

After constructing the cladding assembly, the inside is vacuum degassed. Preferably, it is degassed using a rotary pump etc., and the
Degas to a breathability below Torr. As mentioned above, this is to prevent oxidation of the internal surface and to improve the adhesion of each material.

The clad assembly thus vacuum degassed is heated in a furnace prior to hot rolling, preferably at 500°C or higher and 900°C when using a nickel plate as the insert material.
If carbon steel is used as the insert material, heat to a temperature of 1050"C or lower and 500"C or higher.

In the case of temporary nickel, the intermetallic compound generated is 942°C
Heat to below 900°C to melt. On the other hand, in the case of carbon steel, the heating temperature was set to 1050°C or lower because locally generated intermetallic compounds turn into a liquid phase at temperatures above 1085°C.

In both cases, 500
“Heating is performed above C.

The finishing temperature of rolling is preferably 400°C or higher for work hardening and deformation resistance relaxation. There are no particular restrictions on the degree of processing or rolling operation, but it is economically preferable to set the rolling ratio to 2 or more. The preceding heating and holding time is required to be 3 hours or more.

Here, the principle of the present invention will be explained as follows.

In other words, interdiffusion is essential for bonding steel and titanium, but if this progresses too much, an intermetallic compound layer will also grow, and if the length reaches more than 3 μm, the bonding strength will drop significantly. Therefore, it is necessary to control it so that it is less than this.

Furthermore, even when a nickel slope is used as the insert material, nickel easily diffuses into Ti or Ti alloy, resulting in the formation of a brittle intermetallic compound layer at the interface. When the thickness exceeds 3 μm, the bonding strength decreases significantly.

However, this interdiffusion is a function of temperature and time and is greater in the U7 pre-rolling heating stage than during rolling. Moreover, it is added! '11 If the cranoid material and the insert material come into contact mainly at the surface from the initial stage, a thick layer of intermetallic compounds will naturally form at the interface after rolling, which will cause a decrease in joint strength. .

However, if the insert material and/or the mating material surface on the mating surface side is subjected to low-left processing to give the surface an uneven pattern as in the present invention, the contact area during heating is reduced, so even during high-temperature and long-time heating. This makes it possible to prevent the formation of uniform intermetallic compounds in a layered manner at the interface, making it possible to produce clad steel with excellent bonding strength even during high-temperature, large-reduction rolling.

However, if oxidation progresses while heating the clad assembly, mutual diffusion will be suppressed, causing a decrease in bonding strength or variations. To this end, we seal-welded all sides of the assembled materials to cut off the supply of oxygen to the joint surfaces, and also
It is preferable to deaerate the air to a degree of air below 1 Torr.

Next, the present invention will be explained in more detail based on examples.

Example I Titanium plate equivalent to JIS +14000 class 1 (thickness 10
Various tests were conducted using a carbon steel plate (thickness 90 mm) equivalent to SS 41 (mm) and SS 41.

Industrial pure Ni plates having the chemical components shown in Table 1 were knurled in various ways to produce insert materials.

Table 1 (% by weight) These materials were assembled as shown in FIG. 2, and degassed using a rotary pump through a deaeration hole provided at the end. 8
After degassing to X10 Torr, the degassing hole was sealed by welding, and heated and maintained to a predetermined temperature. Rolling end temperature 700℃
After hot rolling at a reduction ratio of 2 to 3, the shear strength of the obtained clad steel was measured according to JTS GO601 and JIS G3603. The shear strength of similar Ti craft steel manufactured by the explosion bonding method is approximately 14k.
gf was 7mm2.

The results are summarized in graphs in FIGS. 3 and 4.

Figure 3 shows a 17mm thick nickel plate with triangular linear low-left processing applied to the mating surface with various groove depths and a groove spacing of 10mm, and 900°C × 5 without processing. A comparison of shear strength after time-heat rolling (rolling ratio 3) is shown as an example. As is clear from the illustrated graph, particularly excellent shear strength can be obtained when knurling with a groove depth of 0.5 mm or more is performed.

Figure 4 shows the heating temperature before hot rolling of 500 to 900'.
It shows the effectiveness of adhesive strength by knurling when changing to c. However, the heating holding time in this case was kept constant at 5 hours in all cases. Further, the test was conducted with the rolling reduction ratio set to 2. As can be seen from the graph shown, the knurled material has excellent adhesive strength even when heated at a high temperature of 900°C.

In addition, the contents of each symbol in the figure are as follows.

×: Both the mating material and the insert material have a polished surface and no knurling.

Δ: Triangular linear knurling was performed on the surface of the mating surface of the insert material at a depth of 0.5 to 4.5 mm and an interval of 1 to 20+++n+.

: The same knurling process as above was performed on the mating surface of the mating material.

The same knurling process as above was performed on each mating surface of the 02 mating material and the insert material.

Example 2 In this example, Example 1 was repeated, but a carbon steel plate having a thickness of 15 mm and containing less than 0.01% carbon as shown in Table 2 was used as the insert material.

Table 2 (% by weight) The results are summarized in graphs in FIGS. 5 and 6 as in the Examples.

According to this example, the same tendency as in Example 1 is observed, but as shown in FIG. 6, it can be seen that it has good adhesive strength even at a high temperature of 1050°C.

It was also confirmed that similar excellent adhesive strength could be obtained when the insert material was roughened by corrosion.

(Effects of the Invention) As described in detail above, according to the present invention, Ti or Ti alloy clad steel is manufactured by a relatively easy-to-operate rolling method, and moreover, it is possible to produce Ti or Ti alloy clad steel by rolling at a high temperature. However, the formation of brittle intermetallic compounds is not observed, and clad steel is produced that exhibits high adhesive strength and shear strength, and its effects on this industry are immeasurable.

[Brief explanation of drawings]

FIG. 1 is a flow sheet of the method of the present invention; FIG. 2 is a schematic cross-sectional view of a clamp assembly; FIGS. 3 through 6 are graphs showing data for embodiments of the present invention. Construction: Steel slab, 2: Insert material, 3: Titanium alloy plate, 4: Mild steel plate, 5: Connection part 47 section, 3 concave gable,

Claims (4)

[Claims] (1) An insert material is interposed between the Ti or Ti alloy mating material and the steel base material, and each mating surface is sealed to form a clad assembly. A method of manufacturing clad steel by heating a deaerated clad assembly and hot rolling the heated clad assembly, the method comprising: a mating surface of the cladding material and the cladding material of the insert material. 1. A method for producing Ti or Ti alloy clad steel, characterized in that one or both of the surfaces in contact with the steel are textured in advance. (2) The manufacturing method according to claim 1, wherein the insert material is a Ni plate. (3) The manufacturing method according to claim 1, wherein the insert material is a steel plate with a carbon content of 0.01% by weight or less. (4) The uneven processing has a groove depth of 0.5 to 5 mm and a groove interval of 1
The manufacturing method according to any one of claims 1 to 3, wherein the knurling process is performed to have a thickness of ~20 mm, and the space between each mating surface is degassed to a degree of vacuum of 10^-^1 Torr or less.