JP2681395B2 - Manufacturing method of composite type damping steel sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is a composite in which metal sheets are metallurgically bonded by diffusion between superposed steel sheets and insert metal in which the steel sheets are substantially evenly distributed therebetween. The present invention relates to a method for producing a composite type vibration-damping steel plate capable of producing a type vibration-damping steel plate so as to have sufficient adhesive strength even after being subjected to heat treatment (quenching and tempering) during processing.

[Conventional technology]

In recent years, due to the problem of noise pollution and the demand for a quiet environment, interest in vibration damping materials has increased, and its application range is expanding.

In such a situation, as a composite type vibration damping steel plate that has excellent heat resistance and weldability, can be heat treated, and can be applied to high-strength members, it is almost uniform between the superposed steel plates. Forming a joint having a metallurgical joint as a main joining factor due to diffusion between the insert metal having a minute width and distributed in the above and the above-mentioned steel plates, and joining other than the joint by metallurgical joining Abutting without
A composite vibration-damping steel sheet in which the sum of the cut surfaces of the joint on the same plane as the contact surface is 0.5 to 50% in the ratio (hereinafter, may be referred to as the ratio of the total cross-sectional area of the joint) to the area of the steel Have been proposed by the applicant of the present invention and confirmed to have excellent vibration damping performance (Japanese Patent Laid-Open No. 246235/1988).
No.). And as a manufacturing method of this composite type vibration damping steel plate,
The insert metal with a small width is sandwiched between the steel sheets in a substantially uniform distribution state, and diffusion occurs between each steel sheet and the insert metal under an inert gas atmosphere with a surface pressure applied between the steel sheets. A method for manufacturing a composite type vibration-damping steel sheet, which is annealed at a temperature that occurs, has been proposed together with the above, and it has been confirmed that it has sufficient bonding strength (JP-A-63-246238).
No.). Since this composite type vibration damping steel plate can be heat treated, if special steel is used as the steel plate, it can be used for applications that require damping as well as base metal such as diamond cutters and chipsaws, and gears. It has applicable features.

In the method for manufacturing the composite vibration-damping steel plate described above, as the type of insert metal, nonferrous metals such as Cu, Ni, and Ag that can be joined to the steel plate by diffusion without generating brittle alloys are considered to be good choices. However, it is not particularly limited, and in reality, steel is the most easy-to-use metal in terms of cost and scraping. And as for the type of steel,
Mild steel, such as low carbon aluminum killed steel or titanium killed steel, which is inexpensive and easy to be processed into a thin shape which is the shape of insert metal, has been used.

However, heat treatment (quenching and tempering) was performed on the composite type damping steel sheet obtained by using the above-mentioned mild steel such as low carbon aluminum killed steel and titanium killed steel as the insert metal and the special steel such as carbon steel and low alloy steel as the steel sheet. In this case, if the conditions for quenching are harsh, there is a problem that the joint portion is peeled off during the heat treatment. That is, the stress caused by the heat distortion or transformation distortion caused by the heat treatment becomes larger than the bonding strength between the insert metal and the steel plate, and the phenomenon of peeling of the bonded portion occurs. If peeling occurs at the joint, it cannot be used as a structural member, and if vibration damping property is significantly lost, a problem arises. As described above, the conventional manufacturing method has a drawback in that the obtained composite vibration-damping steel plate causes a problem due to heat treatment.

[Problems to be solved by the invention]

An object of the present invention is to solve the above-mentioned drawbacks of the prior art and to enable the production of a composite type vibration damping steel sheet having sufficient bonding strength and vibration damping property even after being subjected to heat treatment.

[Means for solving the problem]

The present invention will be described together with the process of investigations conducted by the present inventors to solve the above problems.

The present inventors examined the type of metal used as the insert metal and the annealing conditions.

First, low carbon aluminum killed steel is used for the insert metal.
In addition, a composite type vibration damping steel plate (hereinafter sometimes referred to as a composite steel plate) that uses low alloy tool steel SKS5 for each steel plate is subjected to quenching treatment, and the steel plate is peeled off by the quenching process. The metallographic structures of the samples before and after annealing and the peeled samples that were sampled in 1. were observed. The insert metal had a low C ferrite structure before annealing, but C diffused from the steel sheet during annealing and the structure after annealing exhibited a high C pearlite structure. When this was quenched and the structure was observed, the steel sheet had a more uniform martensite structure, while the insert metal had an incompletely hardened structure containing troostite. this is,
Although the insert metal has a high C content, it contains almost no alloying element that enhances the hardenability, so that the hardenability is low and a uniform martensitic structure cannot be obtained. It is presumed that such a difference in the structure between the insert metal and the steel plate during the quenching treatment caused a stress causing peeling.

From the above knowledge, it is only necessary to use steel having the same composition as the steel sheet for the insert metal. However, when the insert metal is steel containing high C and an alloying element that enhances hardenability, the deformation stress at high temperature increases, and the adhesion between the insert metal and the steel plate during annealing for diffusion bonding the insert metal and the steel plate Will decrease and the bonding strength will decrease. Further, in the case of an alloy element that easily oxidizes, an oxide is formed at the interface between the insert metal and the steel sheet, which becomes an obstacle to atomic diffusion, which also contributes to a decrease in bonding strength.

That is, it is necessary to use, as the insert metal, steel that suppresses the increase of deformation stress at high temperature as much as possible and suppresses the formation of oxides that hinder the diffusion while enhancing the hardenability.

Further, since the addition of the alloying element tends to increase the deformation stress and decrease the adhesion between the insert metal and the steel sheet, it is necessary to adopt an annealing method to compensate for this.

The present invention has been achieved as a result of further studies in accordance with the concept described above.

Also in the present invention, the insert metal having a minute width is sandwiched between the steel plates in a substantially uniform distribution state so that the ratio of the cross-sectional area of the entire joint is a predetermined ratio, and the surface pressure is applied between the steel plates. In this state, annealing is performed in an inert gas atmosphere at a temperature at which diffusion occurs between each steel sheet and the insert metal, as in the conventional method for manufacturing a composite vibration-damping steel sheet.

The features of the present invention are that a carbon steel or a low alloy steel having a C content of 0.3 to 1.0% is used as the steel plate, and C ≦ 0.010%, Si ≦ 0.01%, Mn ≦ as the insert metal in% by weight.
0.15%, P ≦ 0.01%, S ≦ 0.01%, 0.5% ≦ Ni ≦ 3.0%, Cr ≦ 0.
2%, N ≦ 0.010% and C + N ≦ 0.012%, the balance of using insert metal of steel consisting of Fe and unavoidable impurities, and between each steel plate and insert metal under inert gas atmosphere austenite region after having conducted the (Ac ₁ point -50 ° C.) to Ac step heating of 30 minutes or more in a temperature region of ₁ point of the steel to be used as the insert metal in the course of heating to the annealing temperature in the annealing performed at a temperature at which diffusion occurs The point is that the temperature is raised to the temperature and the annealing is performed.

The reasons for each of the above limitations in the present invention will be described below.

C content of carbon steel or low alloy steel as a steel plate is 0.3 to
The reason for setting the range to 1.0% is that if the C content is less than 0.3%, the product strength after heat treatment of the composite steel sheet cannot be sufficiently high, and if it exceeds 1.0%, the product strength after heat treatment increases. However, it has poor toughness and cannot be put to practical use.

The reasons for limiting the composition of the steel used as the insert metal are as follows.

C is an element effective as an element that enhances the hardenability of the insert metal, and it is preferable to have the same content as that of the steel sheet from the viewpoint of hardenability. However, since C is an infiltration type solid solution element and is an element that greatly increases the deformation stress of the insert metal at high temperature, it is preferable to reduce it as much as possible in terms of the adhesion between the insert metal and the steel sheet.
Also, if the insert metal and the steel plate are in good contact,
It is relatively easy for C to diffuse from the steel plate to the insert metal,
Even if the C content of the insert metal before annealing is low, the C concentration of the insert metal after annealing is almost close to the C concentration of the steel sheet. As described above, it is desirable to set the C content by placing importance on the adhesiveness between the insert metal and the steel plate, and therefore the C content is set to 0.010% or less.

N is a kind of impurity mixed from the atmosphere when steel is melted, but like C, it is an element that increases the deformation stress with a small amount of content. Therefore, it is effective to reduce the content of N as much as possible to enhance the adhesion between the insert metal and the steel sheet, and it is necessary to set it to 0.010% or less in order to sufficiently reduce the deformation stress at high temperature.

Here, since C and N are elements having the same influence, the deformation stress cannot be sufficiently lowered only by reducing the content of either one. Therefore, C
The content of + N must be 0.012% or less.

P and S are elements that increase the deformation stress and reduce the toughness after heat treatment such as quenching and tempering. Therefore, it is desirable to reduce the content as much as possible.
It should be 0.01% or less.

Si is an element that increases hardenability, but the degree of increase in hardenability with respect to its content is not so large. Further, since it is an element which increases the deformation stress and is easily oxidized, an oxide is formed at the interface between the insert metal and the steel sheet during annealing, which becomes an obstacle to diffusion and deteriorates the bondability. For this reason, it is desirable to lower the content as much as possible, and it was set to 0.01% or less.

Mn is an element effective in increasing the hardenability of insert metal. But on the other hand, increasing the deformation stress,
Since it is more easily oxidized than Fe, it is an element that also has the property of forming an oxide at the interface between the insert metal and the steel sheet, which interferes with diffusion and deteriorates the bondability. Therefore, the Mn content is set to 0.15% or less.

Cr, like Mn, is to be contained because it is to increase the hardenability, but it is an element that is easily oxidized, so it was made 0.2% or less.

Ni is an important element as a steel component as insert metal in the method of the present invention. Compared to Mn and Cr, the effect of increasing the hardenability per unit content is smaller, but it has a sufficient effect of increasing the hardenability of the insert metal. On the other hand, Mn
It is an element that is less likely to be oxidized than Cr and Cr, and is less likely to deteriorate the bondability by forming an oxide film on the interface. Since Ni has such characteristics, it is an extremely effective element for maintaining the bondability between the insert metal and the steel sheet during annealing and at the same time ensuring the hardenability during heat treatment and preventing the occurrence of peeling. 0.
Less than 5% is not enough to secure hardenability, 3.0%
If the content of Ni exceeds 0.5%, the deformation stress during annealing becomes high and the adhesion between the insert metal and the steel plate decreases, and hardenability of more than 3.0% is not usually required.
It was set to 3.0%.

The elements other than the above contained in the steel are inevitably contained. This is because it is desirable to reduce the content as much as possible in order to reduce the deformation stress and enhance the adhesion between the insert metal and the steel sheet. Also,
As an alloying element that increases the hardenability, for example, Mo and the like are not positively added, it is easy to oxidize these elements like Si, Mn, Cr, etc., and become oxides at the interface between the insert metal and the steel sheet to diffuse. This is because it becomes an obstacle and deteriorates the bondability.

 Next, the reasons for limiting step heating in annealing will be described.

In order to improve the adhesion between the insert metal and the steel sheet during annealing, it is effective to reduce the deformation stress of the insert metal at the annealing temperature.

In the method of the present invention, the step heating is adopted before the annealing in order to reduce the above-mentioned deformation stress.

In the heat cycle of annealing, when the temperature rises from room temperature to the austenite formation temperature range, the deformation stress decreases as the temperature rises, but when austenite is generated from ferrite, the deformation stress conversely increases. This is because austenite has a stronger structure than ferrite. When the temperature is further raised to a higher temperature, the deformation stress of austenite decreases, so it is suitable to raise the temperature to such a high temperature only considering the adhesion of the insert metal to the steel plate. However, heating to such a high temperature causes deterioration of the material due to the coarsening of crystal grains, and therefore cannot be practically adopted.

From the above-mentioned phenomenon, in order to reduce the deformation stress of the insert metal and improve the adhesiveness, it is effective to heat it in the temperature range where the ferrite is generated and at a temperature as high as possible. That is, the steel used as the insert metal is step-heated in a temperature range from the Ac ₁ point to immediately below (Ac ₁ point −50 ° C.) and then heated to the austenite temperature range. As step heating zone chose temperature range of (Ac ₁ point -50 ° C.) to Ac ₁ point, this higher than the deformation stress of ferrite in the low temperature side, since not obtain the effect of the step heating. The reason why the step heating time is set to 30 minutes or more is that the deformation of the insert metal has a creep-deformation element, and it is necessary to hold it for 30 minutes or more in order to evenly heat the material in practical use. Because it is.

It should be noted, Here, the Ac ₁ point of the insert metal to say, say the Ac ₁ point of the insert metal in front of the annealing. That is, during the annealing, C diffuses from the steel sheet into the insert metal and the composition of the insert metal changes, but the adhesion between the insert metal and the steel sheet becomes a problem because the initial stage of annealing without diffusion occurs. Since this is a stage, the temperature may be controlled with reference to the Ac ₁ point of the insert metal before annealing.

〔Example〕

Hereinafter, the method of the present invention will be described more specifically with reference to Examples and Comparative Examples.

In a high-frequency melting furnace, six types of steel with the chemical composition shown in Table 1 were melted into 30 kg ingots, respectively, and then hot forged, hot rolled, and cold rolled through the steps of 0.2 mm in thickness. Six types of thin plates were manufactured. The Ac ₁ point of each steel was as shown in Table 1. Each of these thin plates was cut to make thin pieces on a chip of 2.0 mm square, which were respectively used as insert metals. Of the steel Nos. Shown in Table 1, IV is V because it does not contain Ni.
In addition to the reason of Steel No. IV, C is a large amount of C, and VI is a point that does not contain Ni and a large amount of Cr, and is outside the composition of the insert metal specified in the present invention.

On the other hand, three kinds of steel, low carbon steel, carbon tool steel, and alloy carbon tool steel having the chemical composition shown in Table 2 were melted in a converter and made into slabs by continuous casting, followed by hot rolling. , Cold rolling, shearing process, thickness 1.0mm, width 600mm, length 1000
Three types of mm steel plates were manufactured.

After degreasing and cleaning the surface of each of the above steel plates, the above-mentioned insert metal of Steel No. I was applied to this steel plate at approximately 200 per 1 m ^2.
A set of unbonded composite vibration-damping steel plate laminates (hereinafter referred to as "unbonded laminates") by stacking the same kind of steel plates that had been degreased and washed, and then sprayed by evenly distributing them at a rate of 0 Got In this way, three sets of unbonded laminated bodies obtained by using three types of steel plates for each type of insert metal (hereinafter referred to as unbonded laminated body group) are prepared for each type of insert metal. I made it. Then, the unbonded laminated body group is annealed in an annealing furnace in an atmosphere of an inert gas of 5% H ₂ + 95% N ₂ while placing a weight on the steel plate of the uppermost unbonded laminated body while applying surface pressure. This was performed for each unbonded laminated body group. The weight used at this time had a weight of 3500 kg, and the annealing was performed with the following two types of thermal history. That is, one is a heating rate of about 150 ° C / hour up to 900 ° C, a uniform heating of 900 ° C x 5 hours,
It is a thermal history of cooling at about 50 ° C./hour (Comparative Examples 1 to 9).
The other one is that if the temperature of each insert metal is raised from Ac ₁ point to (Ac ₁ point −50 ° C.) at a heating rate of about 150 ° C./hour, the temperature of the insert metal is kept within the above temperature range for 1 hour. This is a thermal history in which step heating is further performed, the temperature is further raised to 900 ° C. at a heating rate of about 150 ° C./hour, and thereafter the same annealing as described above is performed (Examples 1 to 9 and Comparative Examples 10 to 18). By performing annealing while applying surface pressure under the above conditions, diffusion bonding between the insert metal and each steel plate was performed.

Regarding the composite steel sheets obtained in the above process, in order to evaluate the degree of joining, T of 25 mm width shown in Fig. 1 (a) and (b)
The bonding strength was measured by a tensile test method using a letter-shaped test piece. Table 3 shows the results.

When measuring the bonding strength, insert metal 1
The bonding strength per piece can be measured.

As is clear from this result, when the steel as insert metal is a high C material (steel No. V) or a high Cr content material (steel No. VI), the deformation stress is high and the diffusion of oxides at the interface It can be seen that by suppressing the above, the joining strength between the insert metal and the steel plate is smaller than that in the case of the low C material (steel No. IV) and the steel used in the method of the present invention (steel No. I to III).

Next, a disc with a diameter of 500 mm was cut out from the composite steel sheet obtained above, and the joining state after heat treatment (quenching and tempering treatment) was examined using this disc. ℃ × 10 minutes, then immersed in quenching oil at 50 ℃ to quench, then further tempering 500 ℃ ×
It was press tempered for 1 hour.

The test piece shown in FIG. 1 was taken from the disc after the heat treatment to measure the bonding strength. Table 3 also shows the results. As can be seen from these results, the ones which were step-heated at the time of annealing by the method of the present invention (Examples 1 to 9) had a larger bonding strength than the ones which were annealed without step heating (Comparative Examples 1 to 9). It can be seen that even after the heat treatment, the bonding strength is sufficient for practical use. When the composition of the insert metal is out of the range specified in the present invention (Comparative Examples 10 to 18), the joining strength is low even if step heating is performed during annealing, and in most cases during the heat treatment, the steel sheet peels off. I know that it can not be used at all.

Regarding the damping properties after heat treatment of the composite steel plates obtained in Examples 1 to 9 and Comparative Examples 1 to 9, the damping property to be measured 2 was attached to the support frame 1 of the apparatus shown in FIG. Three
Table 3 also shows the results of measuring the sound pressure level by the amplifier 6 while the suspension hammer is held and the rotatable hammer 4 is rotated and dropped from the horizontal state, the impact sound is received by the microphone 5, and the amplifier 6 measures the sound pressure level. The sound pressure level of the composite steel sheet obtained by the method of the present invention is significantly lower than that of the single steel sheets shown as Reference Examples 1 to 3 even after the heat treatment, and the composite steel sheet has sufficient performance as a vibration damping steel sheet. confirmed.

[Advantages of the Invention] According to the method for manufacturing a composite type vibration damping steel sheet according to the present invention described in detail above, a steel sheet and an insert metal having a specific composition are used, respectively, and in annealing, in a specific temperature range during temperature increase during heating. By carrying out the step heating of (1), it becomes possible to manufacture a composite type vibration damping steel sheet which has sufficiently high bonding strength and vibration damping property even after being subjected to heat treatment such as quenching and tempering. The present invention as described above is extremely useful in expanding the applications of the composite vibration-damping steel sheet.

[Brief description of the drawings]

FIG. 1 is a diagram showing the shape of a test piece for measuring the joint strength of a composite steel sheet. (A) is a front view, (b) is a side view, and FIG. 2 is a sound pressure level of hammering sound. It is a perspective view of the apparatus to measure. In the drawing 1 ...... Support 2 ...... Vibration damping measurement target 3 ...... Thread 4 ...... Hammer 5 ...... Maguirophone 6 ...... Amplifier

Claims (1)

(57) [Claims] 1. An insert metal having a small width is sandwiched between steel sheets in a substantially uniform distribution state, and each steel sheet and the insert metal are placed under an inert gas atmosphere in a state where a surface pressure is applied between the steel sheets. In producing a composite type vibration damping steel sheet by annealing at a temperature at which diffusion occurs between carbon steel or a low alloy steel having a C content of 0.3 to 1.0%,
As insert metal, weight% C ≦ 0.010%, Si ≦ 0.01
%, Mn ≦ 0.15%, P ≦ 0.01%, S ≦ 0.01%, 0.5% ≦ Ni ≦ 3.0
%, Cr ≦ 0.2%, N ≦ 0.010% and C + N ≦ 0.012%
, And the use of a steel balance being Fe and unavoidable impurities, 30 minutes in the temperature range of (Ac ₁ point -50 ° C.) to Ac ₁ point of the steel to be used as a middle inserted metal that heated to the annealing temperature in the annealing After performing the above step heating, the method for producing a composite type vibration-damping steel sheet is characterized in that the temperature is raised to a temperature in the austenite region and annealed.