JPH0763723B2 - Composite manufacturing method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing a composite material of round bars, which is obtained by fitting an outer layer material on the outside of a core material.

[Prior Art] As a composite material, there is, for example, a material in which a material having excellent corrosion resistance is coated on the outer surface thereof in order to improve the corrosion resistance of a highly conductive spring material. In other words, if the good conductive spring material is Al, Al alloy, it will corrode if it is used as it is in a corrosive environment, so the outer surface of Ti, Ti with excellent corrosion resistance
It coats a layer made of an alloy or the like.

By the way, in the case of manufacturing a round bar-shaped composite material, various methods have been proposed as a manufacturing method thereof, and one of them has been disclosed in Japanese Patent Laid-Open No. 54-
There is a method of No. 160551. In this method, a tubular outer layer material is fitted on the outside of a core material having a circular cross section, and this is cold drawn by die wire drawing or hydrostatic extrusion to reduce the diameter, and then annealed. In this method, the interface between the core material and the outer layer material is joined by diffusion.

However, when diffusion occurs, a brittle intermetallic compound composed of both metals is generated at the interface, so there is a problem that the bonding strength is low.

As a method for solving this problem and producing a composite material, a method disclosed in JP-A-59-110486 has been proposed. This method
Cu, Cu alloy and Al, Al alloy core material pipe-shaped Ti, Ti
The alloy is fitted as a skin material and cold drawing is performed, and Ti and Ti alloy plates are welded to both ends of the fitting material by friction welding, then heated and hot rolled in the temperature range of 600 to 750 ° C. Alternatively, it is a method for manufacturing a Ti clad wire rod, which is characterized by performing hot extrusion, followed by pickling and cold drawing, and the order of diameter reduction processing and heating is the reverse of the above method.

[Problems to be solved by the invention]

Since the composite material manufactured by this method is first subjected to diffusion and then subjected to diameter reduction processing, the thickness of the intermetallic compound layer tends to be thin and the bonding strength tends to increase. However, when the diameter reduction processing is performed by hot extrusion, sufficient bonding strength cannot be obtained, and in order to solve this, it has been attempted to apply a method of hot isostatic extrusion (special feature). Kosho 54-8188
No. 61-42416). However, the present situation is that even the composite material produced by this method does not have sufficient bonding strength to withstand peeling of the bonded portion during secondary working in the cold. On the other hand, in the invention disclosed in Japanese Patent Laid-Open No. 59-110486, when the diameter reduction work is performed by hot rolling with a hole roll, the portion which is rolled by the hole roll and compressed is rolled as described later. There was a problem that the tensile strength was received in the radial direction at the joint interface during rolling by the next type of rolls whose directions differed by 90 °, so that peeling occurred at the interface between the core material and the outer layer material, and the joint strength decreased. .

As described above, various methods for producing a round bar-shaped composite material have been tried, but a method for producing a composite material having a satisfactory adhesive strength has not been established yet.

The present invention has been made in view of such circumstances, and by using an inclined rolling mill having three or more cone-shaped rolls, which has never been used in this type of technology, the bonding strength is improved. An object of the present invention is to provide a method for efficiently manufacturing a high round bar-shaped composite material by a hot rolling method.

[Means for solving problems]

The method for producing a composite material according to the present invention is a method for producing a round bar-shaped composite material in which an outer layer material is fitted to the outside of a core material having a circular cross section, and a cylindrical outer layer made of a material having a larger deformation resistance than the core material. Degreasing the outer surface of the core material and the inner surface of the outer layer material using
Clean and fit, then heat this fitting material to a temperature lower than the melting point of each of the core material, outer layer material and these intermetallic compounds, and use an inclined rolling machine having three or more cone type rolls per pass. It is characterized by being stretch-rolled at a surface reduction rate of 30% or more.

[Action]

The present inventors have conducted experiments by combining various kinds of different metals by the conventional methods such as the hot extrusion method, the hot isostatic extrusion method, and the hole-type roll rolling method. It often happened that the material broke during processing and even composite materials could not be manufactured. Even if it could be manufactured, it had a very low adhesive strength and could not be put to practical use. Therefore, as a result of various studies to change the hot working method itself, other than that, it is possible to manufacture a composite material with high adhesive strength by limiting the combination of dissimilar metals using an inclined rolling mill. We came to discover that.

In the present invention, the layer thickness becomes thin even if an intermetallic compound is produced because it is hot-rolled under high pressure by an inclined rolling mill after heating, and the material is determined in consideration of the deformation resistance,
Further, since tensile stress does not act on the joint interface of the rolled materials, the interface between the core material and the outer layer material does not peel off even if hot rolling is performed, and the joint strength increases.

〔Example〕

The present invention will be specifically described below with reference to the drawings. FIG. 1 is a front sectional view of a fitting material used in the present invention, FIG. 2 is a side view thereof, and 10 in the drawing shows the fitting material. The fitting material 10 is a round bar in which a tubular outer layer material 12 is fitted to the outside of a core material 11 having a circular cross section, and is provided on the downstream side of the heating furnace after being heated in a heating furnace (not shown). It is fed to the inclined rolling mill capable of high pressure rolling.

FIG. 3 is a schematic diagram showing the inclined rolling mill 4 used in the present invention (rolls 1 and 2 are sectional views taken along the line III-III in FIG. 4), and FIG. 4 is IV- in FIG. Front view by IV line,
FIG. 5 is a side view showing the inclination angle β. The inclined rolling mill 4 has three cone-shaped rolls 1, 2 and 3 facing the pass line, and the three rolls 1, 2 and 3 are located at the exit end of the fitting material 10 and have a gorge portion 1a, 2a, 3a, the entrance side of the mating member 10 is gradually reduced in diameter toward the shaft end with the gorge portion as a boundary, and the exit side is enlarged to form a truncated cone-shaped inlet surface 1b, 2b, 3b and Exit face 1c, 2c,
The exit faces 1c, 2c, 3c are provided with a 3c, and the distance between the exit line 1c, 2c, and 3c matches the distance between the gorge portion and the pass line.

All of the cone-shaped rolls 1, 2 and 3 have their inlet surfaces 1b, 2b and 3b positioned upstream of the fitting member 10 in the moving direction, and the axis Y-Y and gorge The intersection point 0 (hereinafter referred to as the roll setting center) with the plane including the parts 1a, 2a, 3a is approximately equidistant around the pass line XX on the same plane orthogonal to the pass line XX of the fitting material 10. It is arranged to be located at. The axes Y-Y of the rolls 1, 2, and 3 are around the roll set center, and the front shaft end is the pass line as shown in FIG. 3 in relation to the pass line XX of the fitting material 10. Cross (tilt) by crossing angle γ so as to approach toward XX
Further, as shown in FIGS. 4 and 5, the front shaft end is inclined toward the same side in the circumferential direction of the fitting material 10 by the inclination angle β. The rolls 1, 2, 3 are connected to a drive source (not shown), and are driven to rotate in the same direction as indicated by the arrow in FIG. 4, and the hot fitting material 10 caught between these rolls is It is moved in the axial direction while being driven to rotate about its axis, that is, it is moved by screwing.

While the fitting material 10 is screwed between the rolls, the third
After the outer diameter is narrowed by the roll bite A as shown in the drawing, and the pressure reduction surface B of the fitting material 10 is formed into a truncated cone shape, for example, under high pressure with a maximum surface reduction rate of 80 to 90%. The composite material 13 is a round bar material having a predetermined outer diameter at the gorge portion and the exit surface.

Next, a method of manufacturing the composite material according to the present invention, in which the above-mentioned fitting material is rolled by such an apparatus, will be described.

The fitting material 10 is an oil that degreases and cleans the outer surface of the core material 11 having a circular cross section and the inner surface of the cylindrical outer layer material 12 having the same inner diameter as the outer diameter dimension of the core material 11 to prevent diffusion. Etc. are removed and then these are fitted together to form the outer layer material 12 having a larger deformation resistance than the core material 11.

The reason for using such a material will be described in detail. For example, when a material having a smaller deformation resistance than the core material 11 is used as the outer layer material, the outer layer material is deformed more than the core material 11 when it is hot-rolled by the inclined rolling mill 4 as shown in FIG. 12a is deformed more and the thickness is reduced. Due to this thickness reduction, the peripheral length becomes longer, and a phenomenon in which the lengthened portion overhangs between the rolls, so-called flaring, occurs, and the core material 11 and the outer layer material 12
A gap C is generated between a and. That is, peeling occurs in the diffusion layers of both metals already formed by heating. In order to prevent the peeling, a material having a larger deformation resistance than the core material 11 is used as the outer layer material 12 in the present invention.

Next, the mating material that is mated using the above materials
A mating material 10 is formed to form a diffusion layer on the above interface of 10 and to join them.
To heat. The heating temperature is lower than the melting points of the core material 11, the outer layer material 12 and these intermetallic compounds. This is because if at least one of the core material 11 and the outer layer material 12 is melted, a crack is generated in that portion during solidification and the joint strength is reduced. The heating temperature is determined in consideration of the amount of processing heat generated under high pressure.

The fitting material 10 thus heated up is hot-rolled by the inclined rolling mill 4. The reason for using the inclined rolling mill 4 is
This is because the joining strength, which was insufficient in the case of the conventional hole-rolling, is increased, which will be specifically described below. For example, in the case of hole rolling, two pairs of hole rolls are provided along the pass line with the rolling directions being different from each other by 90 degrees.
In 10, there are a part restrained by the roll and a part not restrained by the roll.

Here, for the unconstrained portion, the strain in the stretching direction of the core material 1 due to rolling is εz ₁ , the strain in the direction perpendicular to the stretching direction (radial direction) is εr _1, and the two strains of the outer layer material 12 are Let ε z ₂ and ε r ₂ respectively. Since the core material has a smaller deformation resistance than the outer layer material 12, if it is rolled at the same time, εz ₁ >
ε z ₂ .

By the way, since the volume is constant even if it is deformed by being pressed, εz ₁ + εo ₁ + εr ₁ = 0 (εo ₁ : circumferential strain of the core material), εz
₂ + εo ₂ + εr ₂ = 0 (εo ₂ : the circumferential strain of the outer layer material) is satisfied, and if εo ₁ ≈εo _{2 then} εr ₁ <εr ₂ . That is, the outer layer material 12 has a larger strain in the direction perpendicular to the stretching direction (radial direction), and a radial tensile stress is generated at the interface between the outer layer material 12 and the core material 11. That is, the portion compressed by rolling of a certain roll pair becomes an unrestrained portion during rolling by the next roll pair whose rolling directions differ by 90 °, and the above tensile stress acts, so that peeling easily occurs.

In addition, as shown in FIG. 7, the cross section of the hole-rolled composite material has protrusions E formed at positions equidistantly arranged in the circumferential direction of the core material 11,
The wall thickness of the outer layer material 12 becomes thin at that portion and becomes uneven.

On the other hand, when an inclined rolling mill is used, as is clear from Figs. 3, 4, and 6, there are a constrained portion and a non-constrained portion on the same circumference of the fitting material. Since the composite material 10 advances spirally between the rolls, no tensile stress acts on the portion that receives the compression pressure.

Therefore, in the case of using the inclined rolling mill, the tensile stress generated in the hole rolling does not occur, which is advantageous for joining the interfaces. When using an inclined rolling mill, the area reduction rate is expressed by the following equation (1), Stretch rolling is possible with a maximum reduction of 80 to 90% per pass.

Therefore, according to the present invention, in order to increase the joining strength, which was insufficient in the conventional die rolling, to a sufficient strength, the fitting material 10 is subjected to a high pressure reduction at a reduction rate of 30% or more per one pass, as will be described later. To roll. As a result, the fitting material heated to the aforementioned low temperature
Processing heat is generated in 10 and diffusion is promoted. Further, even if an intermetallic compound is produced, the thickness of the intermetallic compound layer can be reduced by rolling under high pressure, and the composite material 11 having excellent bondability can be manufactured.

The use of an inclined rolling mill having three or more cone-shaped rolls avoids an internal crack due to so-called Mannesmann fracture in the central portion of the rolling mill in an inclined rolling mill having two rolls. Therefore, an inclined rolling mill having three or more rolls is adopted.

Next, the relationship between the surface reduction rate, the heating temperature, and the shear strength of the joint will be described based on examples.

(Example 1) First, a case where a composite material of a core material: Al and an outer layer material: Ti is manufactured will be described.

Outer diameter: 49 mmφ (accuracy: -0.1 to +0.0 mm), material: Pure Al (1
070) core material, outer diameter: 55 mmφ, inner diameter: 49 mmφ (accuracy: 0.0
~ +0.1 mm), material: An outer layer material of pure Ti (JIS type 2) was created by mechanical processing, degreased and cleaned, and then the core material and the outer layer material were fitted together. This mating material is 400 ℃, 500 ℃, 600 ℃
Change the heating temperature and heat at each temperature for 1 hour, and reduce the area reduction rate at each temperature for 20%, 30%, 40%, 60%,
Hot rolling was performed by an inclined rolling mill while changing to 80%. For the setting conditions of the inclined rolling mill, the cross angle (γ): 5 °, the inclination angle (β): 13 °, roll diameter: 120 mmφ, roll material: SCM440,
Roll rotation speed: 100 rpm.

Fig. 8 shows the heating temperature (° C) on the horizontal axis and the surface reduction rate (%) on the vertical axis. The composite material produced at each heating temperature and surface reduction rate was cut with a shear, and the cut surface FIG. 7 is a diagram showing the quality of the joint between the core material and the outer layer material in FIG. As can be seen from this figure, when the area reduction rate is 30% or more, a titanium-clad aluminum composite material having good composite properties can be manufactured.

In addition, scanning electron microscope (SEM) observation, electron probe microanalyzer (EPMA) observation, and ultrasonic flaw detection were performed on the bonded interface, but as a result, there was no delamination, oxide, or defect.

For comparison, a titanium clad aluminum composite material was manufactured by hole rolling. As for the manufacturing conditions, the same mating material as before was heated to 600 ° C and the outer diameter was changed from 55mmφ to 30mmφ in 6 passes.
Continuous rolling was performed (average area reduction rate per pass was 18%).
In this way, the composite material produced by performing the die-rolling was visually observed on the sheared surface, and the core material and the outer layer material were separated, and when this was observed by SEM, separation was observed at several places. .

Therefore, in the stretching / rolling process, high-pressure rolling is performed by using the inclined rolling method.

(Example 2) Next, a titanium or titanium alloy clad whose core material is pure Cu {tough pitch copper (C 1100)} and outer layer material is pure Ti (JIS type 2) and Ti-6Al-4V The copper material will be described.

Create a mating material for the core material and outer layer material in the same way as before, and
After heating at 600, 700, and 800 ° C. for 1 hour each, hot rolling was performed in the same manner as above using an inclined rolling mill. Regarding the titanium clad copper material, the fitting material was subjected to a drawing process to reduce the outer diameter by 2 mm with a die, and then hot rolling was performed. That is, two types of mating materials differ, and one type of manufacturing method differs.
A total of 3 types were manufactured.

In order to investigate the bonding strength of the manufactured composite material, one end side of the composite material of a predetermined length is left as it is with a constant length h as shown in FIG. 9, and the other end side has an outer diameter smaller than the outer diameter of the core material. Create two test pieces for each of the materials to be surveyed, which were made into a columnar part, and at the edge of the circular opening with a diameter slightly larger than the outer diameter of the core material,
The load P, which is in contact with the outer layer material portion on one end side of the test piece, is applied with a pressing force from the other end side in that state, and the load P at which the core material and the outer layer material are broken is measured. And shear strength = P / (π · D · h) (2) where D = outer diameter of core material Shear strength was determined.

Figure 10 shows the heating temperature (° C) on the horizontal axis and the shear strength (kg f / mm ² ) on the vertical axis, and investigates the shear strength of the composite material manufactured at each heating temperature and surface reduction rate. It is a graph that summarizes the results,
Since the shear strengths of three types of composite materials having different materials and manufacturing methods and having the same heating temperature and surface reduction rate were almost the same, they are represented by averaging them. ■ in the figure,
△, ▲, ○ and ● are the reduction rates of 20%, 30%, 40% and 6 respectively.
Indicates 0% and 80%. As can be understood from this figure, if the shear strength reference value for copper and copper alloy clad steel (JIS G 3604) is used as the minimum reference value for shear strength, 10 kgf / mm ²
The area reduction rate is 30 to satisfy this standard value.
%, And since the present invention uses an inclined rolling mill capable of rolling under high pressure, shear strength, that is, bonding strength can be satisfied.

At the joint interface, SEM observation, EPMA observation, and ultrasonic flaw detection were performed, and as a result, there was no delamination, oxide, or defect, respectively.

For comparison, a titanium clad copper material prepared in the same manner as in Example 1 was heated to 800 ° C. and subjected to hole rolling.
The bonding strength of the manufactured composite material was measured and found to be 6.5 kgf / mm ² , which was below the standard value.

FIG. 11 is a SEM photograph of the joint interface of the composite material produced by the present invention with an area reduction rate of 80%, and FIG. 12 is the joint interface of the composite material produced by die rolling for the above comparison. The same is a photograph of SEM observation. As can be understood from these figures, in the case of the comparative example, cracks were observed at the interface between the diffusion layer and the Cu side, and it was confirmed that peeling was present at the joint. On the other hand, peeling did not occur in the case of the present invention.

(Example 3) Furthermore, a case where the core material is pure Cu {tough pitch copper (C1100)} and the outer layer material is a stainless clad copper material of SUS304 will be described.

A fitting material for the core material and the outer layer material is prepared in the same manner as in Example 1,
This was heated at 900, 950, and 1000 ° C. for 1 hour each, and rolled in the same manner as in Example 1 by using an inclined rolling mill. Further, the fitting material was drawn by a die to reduce its outer diameter by 2 mm and rolled in the same manner as above. Then, two test pieces as shown in FIG. 9 were prepared from each of the manufactured composite materials, and the shear strength was measured.

In Fig. 13, the horizontal axis shows the heating temperature (° C) and the vertical axis shows the shear strength (kgf / mm ² ), and the measurement results of the shear strength of the composite material manufactured at each heating temperature and surface reduction rate are shown. Is a graph that summarizes
Since the shear strengths of two types of composite materials produced by different manufacturing methods and having the same heating temperature and surface reduction rate were substantially the same, they are shown as an average. The display section in the figure is the same as that in the second embodiment. As can be understood from this figure, when 10 kg f / mm ² is used as the minimum standard of shear strength as before, the shear strength becomes the standard value or more by setting the area reduction rate to 30% or more, and the shear strength, That is, the bonding strength can be satisfied.

Also, there was no abnormality in the bonding interface.

In the above description, the material in which two kinds of metals are fitted is heated as it is and stretch-rolled by an inclined rolling mill, or the fitted material is cold-drawn and then heated and stretched by an inclined rolling mill. Although rolling is carried out, a method of heating a material in which an intermediate material is interposed between the two metals for the purpose of preventing carburization and performing stretching rolling with an inclined rolling mill also belongs to the method of the present invention.

〔effect〕

As described above in detail, in the case of the present invention, the intermetallic compound layer can be thinned because it is heated and then rolled under a high pressure by an inclined rolling mill, and flaring can be prevented because a material considering deformation resistance is used. In addition, since the tensile stress in the radial direction does not act on the joint interface, it is possible to increase the joint strength, which makes it possible to manufacture a round bar-shaped composite material having excellent joint strength between the core material and the outer layer material by hot rolling, For this reason, the present invention can be applied to applications where high stress acts, which could not be used in the past, and the applications can be expanded, and the step of sealing both ends of the fitting material by friction rolling can be omitted. Since rolling is performed with a surface reduction rate of 30% or more in one pass, the manufacturing efficiency is high when manufacturing small diameter ones. Furthermore, when the fitting material is cold drawn by a die, the bondability can be made more uniform, and the present invention has excellent effects.

[Brief description of drawings]

FIG. 1 is a front sectional view of a fitting material used in the present invention, FIG. 2 is a side view thereof, FIG. 3 is a schematic view showing an inclined rolling mill used in the present invention, and FIG. 4 is a view of FIG. Front view taken along line IV-IV,
FIG. 5 is a side view showing the inclination angle β, FIG. 6 is a schematic view showing the occurrence of flaring, FIG. 7 is a front cross-sectional view of a composite material rolled by hole rolling, and FIG. A graph showing the quality of joining when a titanium clad aluminum material is manufactured by changing the area reduction rate, FIG. 9 is an explanatory view of the measurement content of shear strength, and FIG. A graph showing the relationship between the heating temperature and the shear strength in the case of the manufactured titanium or titanium alloy clad copper material, FIG. 11 is the vicinity of the interface between the core material and the outer layer material of the titanium or titanium alloy clad copper material manufactured by the present invention. Fig. 12 is a photograph showing the structure in the vicinity of the interface of a composite material similar to the one before manufactured by die rolling, and Fig. 13 is a stainless clad copper material manufactured by the present invention by changing the surface reduction rate. Is a graph showing the relationship between the heating temperature and the shear strength in the case of It 1,2,3 …… Cone type roll, 4 …… Inclined rolling mill, 10 ……
Mating material, 11 …… Core material, 12 …… Outer layer material

Claims (1)

[Claims] 1. A method for producing a round rod-shaped composite material in which an outer layer material is fitted on the outside of a core material having a circular cross section, wherein a cylindrical outer layer material having a larger deformation resistance than the core material is used. The outer surface and the inner surface of the outer layer material are degreased, cleaned and fitted, and then the fitting material is heated to a temperature lower than the melting points of the core material, the outer layer material and these intermetallic compounds, and 3
A method for producing a composite material, which comprises stretching and rolling at a reduction rate of 30% or more per one pass by an inclined rolling machine having at least one cone type roll.