JPH0849039A - Fe-Cu-Al steel having excellent vibration damping property and method for producing the same - Google Patents

Abstract

(57) [Summary] [Structure] C: 0.02 mass% or less, Si: 0.02 mass% or less,
Mn: 0.08 mass% or less, Cu: 0.05 to 1.50 mass%, Al: 1.0
Fe-Cu containing up to 7.0 mass% and N: 0.008 mass% or less, the balance consisting of Fe and inevitable impurities, and having a ferrite grain volume ratio of 0.1 mm or more of 20% or more, which is excellent in vibration damping property. -Al steel. This steel has a temperature range of 700-1050 ℃ for 1h
After heating and holding and cooling as described above, it is obtained by further subjecting to heat treatment at 450 to 650 ° C. [Effect] It has excellent vibration damping properties and a tensile strength of 400 MPa or more, which is sufficient as a structural material, and has industrially useful properties of good toughness and excellent economical efficiency.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steel suitable for use as a member of a structure and the like, and particularly proposes a steel having a tensile strength of 400 MPa or more, which is excellent in vibration damping characteristics capable of suppressing vibration and noise. It is a thing. In recent years, there have been severe vibrations caused by the movement of heavy vehicles such as railway bridges and road bridges for automobiles, especially vibrations caused by the vibrations of facilities or structures such as factories and workshops located near the residential area, or the accompanying vibrations. The noise that is heard is considered to be a social problem.
As a countermeasure for this, various methods such as using a sound absorbing material, a sound insulating material, or a vibration insulating material, and increasing the rigidity of the structure to avoid resonance are taken, but in practice, Vibration, which is a noise source, is complicated, and it is generally difficult to eliminate its cause. Therefore, attention has been paid to a method of imparting a vibration damping property, that is, a vibration damping property, to a material itself as a structural member to thereby drastically improve vibration and noise of a structure.

[0002]

2. Description of the Related Art Regarding steel materials having the above-mentioned vibration damping property,
Several proposals have already been made. For example, Japanese Examiner Sho 60-
Japanese Patent No. 26813 proposes a method for producing a vibration-proof steel material having a low yield point and coarse grains. In addition, JP-A-52-1443
No. 17 discloses a vibration-proof steel in which 3 to 40 mass% (hereinafter simply referred to as%) Cr and Ti and Al are further added.
181360 discloses a damping thick steel plate containing 1.5-9% Al, and JP-B-57-22981 discloses 4-7% Cr,
Steel materials containing 3 to 5% Al and having vibration damping properties are disclosed. However, all the steel materials have low strength and cannot be used as structural members. In addition, there are problems that the vibration damping property is not sufficient and that the alloy component is added in a large amount and is expensive.

On the other hand, the inventors first set the Mn amount to 0.08%.
By adding Cu to the steel having a substantially pure iron composition reduced below and further adding Al in an amount of 1.0 to 7.0% or more, while maintaining the vibration damping function, the strength and toughness as a structural steel material are maintained. We have proposed a steel sheet that has both functions (see Japanese Patent Laid-Open No. 4-13847). The vibration damping mechanism of such a steel sheet is considered as follows. That is, in the ferromagnetic steel, strain (magnetostriction) is generated in the crystal lattice corresponding to the uniform magnetic spin, and the inside is divided into magnetic domains mainly affected by this. When an external force (vibration) is applied to such steel, magnetic domain walls move due to interaction with magnetostriction. Then, an eddy current is generated so as to cancel the movement of the magnetic domain wall generated inside the ferromagnetic material, that is, a change in magnetization, and the eddy current causes distortion through magnetostriction. Since the phase of this strain is delayed with respect to the external force, a vibration damping characteristic appears due to so-called magneto-dynamic hysteresis type internal friction. This steel plate is
This is a structure in which strength and toughness are added to the excellent vibration damping property of pure iron having a similar vibration damping mechanism so that it can be applied as a structural member.

[0004]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
The steel sheet disclosed in the publication is excellent in strength, toughness, and vibration damping property, but further improvement in vibration damping property has been desired. Therefore, steel that can be mass-produced, has higher vibration damping properties, has the toughness with the strength required for structural steel, is relatively inexpensive, has excellent vibration damping characteristics, and has a tensile strength of 400 MPa or more. It is an object of the present invention to propose a method of manufacturing the same and its advantageous manufacturing method.

[0005]

Means for Solving the Problems As a result of various investigations aimed at improving the vibration damping characteristics of the above-mentioned steel, the inventors have improved the damping property by controlling the ferrite grain size of the steel. In particular, it was found that the damping property is remarkably improved when the volume ratio of recrystallized ferrite grains having a grain size of approximately 0.1 mm or more is 20% or more.

Based on the above findings, the present invention, which has further improved vibration damping ability as compared with the above steel, has C: 0.02% or less, Si: 0.02% or less, Mn: 0.08% or less, Cu: 0.05 to 1.50.
%, Al: 1.0 to 7.0% and N: 0.008% or less,
The balance consists of Fe and inevitable impurities, and the grain size is 0.1.
It is a Fe-Cu-Al steel (first invention) having a volume fraction of ferrite particles of 20 mm or more and having excellent vibration damping property.

Further, according to the present invention, C: 0.02% or less, Si: 0.
02% or less, Mn: 0.08% or less, Ni: 0.05 to 1.5%, Cu: 0.
05 to 1.50%, Al: 1.0 to 7.0% and N: 0.008% or less, the balance consisting of Fe and unavoidable impurities, and the volume fraction of ferrite grains with a grain size of 0.1 mm or more is 20% or more Fe-Cu-Al steel (second invention) having excellent properties.

Further, according to the present invention, C: 0.02% or less, S
i: 0.02% or less, Mn: 0.08% or less, Cu: 0.05 to 1.50%, A
l: 1.0 to 7.0% and N: 0.008% or less, the balance being steel consisting of Fe and unavoidable impurities, heated and held in the range of 700 to 1050 ° C. for 1 hour or more, and then 450 to 650.
Fe-excellent in vibration damping characterized by heat treatment at ℃
It is a manufacturing method (3rd invention) of Cu-Al steel.

Further, the present invention is C: 0.02% or less,
Si: 0.02% or less, Mn: 0.08% or less, Ni: 0.05 to 1.5%,
Cu: 0.05 to 1.50%, Al: 1.0 to 7.0% and N: 0.008%
Steel containing the following and balance Fe and unavoidable impurities is heated and held and cooled in the range of 700 to 1050 ° C for 1 hour or more, and then heat-treated at 450 to 650 ° C. Excellent Fe-Cu-Al steel manufacturing method (4th invention)
Is.

[0010]

The reason why the composition of the structural steel of the present invention having excellent vibration damping characteristics is limited to the above range will be described. C: 0.02% or less C is contained as a strengthening component in ordinary steel, but in the steel of the present invention, the strengthening action due to the precipitation of Cu is utilized, so the amount as a strengthening component is not necessary. Rather, the C content is
If it exceeds 0.02%, the vibration damping property deteriorates, so it was limited to 0.02% or less. Si: 0.02% or less Si addition to steel with reduced Mn content deteriorates the vibration damping property, so 0.02% was made the upper limit. Mn: 0.08% or less Mn has a bad influence on toughness when strengthened by addition of Cu, so the lower the content, the better. The upper limit of the content is 0.08%, so Mn was limited to 0.08% or less.

Cu: 0.05-1.50% Cu is precipitated as fine ε-Cu by aging treatment,
It is a component that strengthens steel, and is used for steel with a reduced Mn content.
By containing Cu, it is possible to achieve both strength and toughness without impairing the vibration damping property. Therefore, although it is an essential component in the present invention, if the Cu content is less than 0.05%, its effect is poor, while if it exceeds 1.5%, hot cracking may occur, so 0.05-1.50%
Range.

Al: 1.0-7.0% Al improves vibration damping characteristics in steel having a substantially pure iron composition with Mn reduced to 0.08% or less, but its content is
If the content is less than 1.0%, the effect is not effective, while if the content exceeds 7.0%, the toughness deteriorates, so the content was made 1.0 to 7.0%. N: 0.008% or less N content is preferably low in terms of vibration damping and toughness, and the allowable upper limit is 0.008% or less.

According to the second aspect of the invention, the steel of the present invention further contains Ni in an amount of 0.05 to 1.5% in addition to the above components. Ni
Can suppress the tendency of hot cracking due to the addition of Cu without impairing the vibration damping property. If the Ni content is less than 0.05%, its effect is poor, while if it exceeds 1.5%, it is not economical. Therefore, the Ni content is 0.05 to 1.5%.
Range.

In the present invention, in addition to the above components, P and S of 0.01% and 0.005%, respectively, can be allowed as impurity components. P deteriorates the vibration damping property as its content increases, but up to 0.01% is acceptable, so the upper limit is made 0.01%. S, like P, is a component that is not preferable for vibration damping,
If the content exceeds 0.005%, the vibration damping property is particularly deteriorated. Therefore, the upper limit of S content is 0.005%.

In addition to the above component composition ranges, the steel of the present invention specifies that the volume ratio of ferrite grains having a grain size of 0.1 mm or more is 20% or more. Since the vibration damping performance of the present steel material is brought about by the movement of the domain wall and the rotation of the magnetic spin, the smaller the grain boundaries that hinder the domain wall movement, the better the performance. That is, the larger the particle size, the more preferable. Since the ferrite grain size needs to be 0.1 mm or more in order to easily cause the domain wall movement and the magnetic spin rotation, the ferrite grain size is limited to 0.1 mm or more. However, if the volume ratio of ferrite particles of 0.1 mm or more is less than 20%, good vibration damping characteristics of the steel material as a whole cannot be exhibited.Therefore, ferrite particles of 0.1 mm or more may exist in a volume ratio of 20% or more. is necessary.

The material of the present invention can be formed into a thick steel plate by ordinary melting, casting and rolling, and can be used not only in a thick steel plate but also in a thin steel plate, shaped steel, steel bar, wire rod and the like. Generally, as-rolled steel sheet, the ferrite grains expand,
Further, since the grain size is also small, in the present invention, the desired ferrite grain size of 0.1 mm or more is obtained by heat treatment. It is necessary to raise the temperature to 700 ℃ or more to eliminate the processing strain during rolling and to grow grains, but heating at a temperature higher than 1050 ℃ may cause fine cracks on the steel surface, so heating The temperature shall be in the range of 700-1050 ℃. Since the holding time at the temperature is 1 h or more and the desired ferrite grain size and its volume ratio are obtained, the lower limit is set to 1 h. Since the particle size and volume ratio increase as the holding time becomes longer, the vibration damping characteristics become better, but the upper limit of the holding time should be set individually considering the purpose of use of the steel material, the required characteristics and the industrial economic efficiency. It is preferably, but not particularly limited to. Further, it is preferable to perform normal tempering for the precipitation of Cu. The tempering temperature is in the range of 450-650 ° C. If the tempering temperature is below 450 ° C, it will take a long time for the precipitation process,
On the other hand, when the temperature exceeds 650 ° C, the strength increase due to precipitation becomes insufficient, so the temperature was limited to 450-650 ° C. This tempering treatment time is not particularly limited because it depends on the size of the object, etc., but from the viewpoint of achieving both sufficient precipitation strengthening and economical efficiency.
The range of 600-3600S is preferred. However, if high strength is not required, this precipitation treatment can be omitted.

[0017]

[Examples] Steels having various compositional compositions shown in Table 1 were melted and cast according to a conventional method, further finished to 25 mm by ordinary hot rolling, and annealed at 700 to 1050 ° C for 3 hours. did.
Thereafter, as a Cu precipitation aging treatment, a heat treatment was performed at 575 ° C for 1 hour. In Table 1, symbols A to E are steel plates having the composition of the steel of the present invention. On the other hand, symbols F to J are comparative examples, and all of them have a low volume fraction of ferrite grains having a grain size of 0.1 mm or more because the annealing treatment according to the present invention is not performed. The symbol K is SS400 as conventional steel.
Showed steel. With respect to these steel sheets, the tensile properties and internal friction Q ^-1 of the base material were measured, and the obtained results are also shown in Table 1.

[0018]

[Table 1]

As is clear from the table, all of the steels A to E which are claimed in the present invention satisfy the tensile strength of 400 MPa or more required as a structural steel sheet. In addition, the internal friction value is far superior to the conventional SS400 steel, and the vibration damping property is improved. Moreover, it can be seen that the internal friction value is further improved and the vibration damping property is improved as compared with the comparative example in which the volume ratio of the ferrite particles having a particle size of 0.1 mm or more is low.

[0020]

EFFECTS OF THE INVENTION The steel material excellent in the vibration damping characteristics of the present invention is obtained by adding Cu to steel having a composition of almost pure iron whose Mn content is reduced to 0.08% or less and further adding 1.0 to 7.0% of Al. In steel with improved vibration damping, by setting the volume fraction of ferrite particles with a grain size of 0.1 mm or more to 20% or more, it is possible to obtain better vibration damping and a tensile strength of 400 MPa or more sufficient for structural materials. In addition, it has industrially useful characteristics that it has good toughness and excellent economical efficiency.

Front page continued (72) Inventor Yasushi Morikage 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Kawasaki Steel Corporation Steel Research & Development Division Steel Research Laboratory (72) Inventor Shinichi Amano Chuo-ku, Chiba-shi, Chiba Kawasaki-cho No. 1 Kawasaki Iron & Steel Co., Ltd.

Claims (4)

[Claims] 1. C: 0.02 mass% or less, Si: 0.02 mass% or less, Mn: 0.08 mass% or less, Cu: 0.05 to 1.50 mass%, Al: 1.0 to 7.0 mass% and N: 0.008 mass% or less. However, the balance consists of Fe and inevitable impurities, and
Fe-Cu-Al steel with excellent damping properties with a ferrite grain volume ratio of 0.1 mm or more of 20% or more. 2. C: 0.02 mass% or less, Si: 0.02 mass% or less, Mn: 0.08 mass% or less, Ni: 0.05 to 1.5 mass%, Cu: 0.05 to 1.50 mass%, Al: 1.0 to 7.0 mass% and N: 0.008 mass% or less is contained, the balance is Fe and inevitable impurities, and the particle size is
Fe-Cu-Al steel with excellent damping properties with a ferrite grain volume ratio of 0.1 mm or more of 20% or more. 3. C: 0.02 mass% or less, Si: 0.02 mass% or less, Mn: 0.08 mass% or less, Cu: 0.05 to 1.50 mass%, Al: 1.0 to 7.0 mass% and N: 0.008 mass% or less. However, the balance is steel consisting of Fe and unavoidable impurities.
After heating and holding for 1 h or more in the range of 50 ° C for more than 45 hours,
A method for producing Fe-Cu-Al steel having excellent vibration damping property, which is characterized by performing a heat treatment at 0 to 650 ° C. 4. C: 0.02 mass% or less, Si: 0.02 mass% or less, Mn: 0.08 mass% or less, Ni: 0.05 to 1.5 mass%, Cu: 0.05 to 1.50 mass%, Al: 1.0 to 7.0 mass% and N: 0.008 mass% or less, with the balance being 700 to 10 steel consisting of Fe and inevitable impurities.
After heating and holding for 1 h or more in the range of 50 ° C for more than 45 hours,
A method for producing Fe-Cu-Al steel having excellent vibration damping property, which is characterized by performing a heat treatment at 0 to 650 ° C.