KR102144708B1 - Damping alloy - Google Patents

Abstract

An Fe-Mn-(Cr, Ni)-Si-based vibration damping alloy containing at least one of Cr and Ni, or a vibration damping alloy further containing Al, and as a component composition, 5% by mass ≤ Mn ≤ 28% by mass, 0 Mass%≤Cr≤15mass%, 0mass%≤Ni<15mass%, 0mass%<Si<6.5mass%, 0mass%≤Al<3mass%, balance Fe and unavoidable impurities, [% Ni]+0.5[%Mn]>0.75[%Cr]+1.125[%Si]+2[%Al], also 37<[%Mn]+[%Cr]+2[%Ni]+5[%Al ]<45 ([%Ni], [%Mn], [%Cr], [%Si], and [%Al] in the formula mean the mass% of Ni, Mn, Cr, Si, and Al) It is characterized by being satisfied.
As a result, in Fe-Mn-(Cr, Ni)-Si-based alloys, the strength and the stress amplitude after repeated tensile and compressive deformation are reduced, and the number of rupture repetitions is increased. Also, it is possible to provide a vibration damping alloy for mass-producible elastoplastic dampers.

Description

Damping Alloy {DAMPING ALLOY}

The present invention relates to a vibration damping alloy capable of elastoplastic deformation with low stress and excellent fatigue properties.

Due to the Great East Japan Earthquake disaster that occurred on March 11, 2011 and the active earthquake activity thereafter, the awareness of disaster prevention against huge disasters has risen to an unprecedented level. In particular, since metropolitan areas are included in areas where huge earthquakes are predicted, such as Tokai, Tonankai, and Nankai earthquakes, earthquakes directly under the capital, etc., in addition to reinforcing disaster prediction and disaster prevention systems, building structures from earthquake damage The utmost efforts are also being made to countermeasures against industrial mitigation such as vibration isolation and seismic isolation technology.

The vibration damper is a vibration damping device that absorbs vibration energy input to a building by wind or earthquake and prevents the vibration from reaching the structure body. When the vibration damping dampers proposed and developed so far are largely distinguished, there are viscous dampers (patent document 1), viscoelastic dampers (patent document 2), lead dampers (patent document 3), and elastic dampers (patent document 4).

Among them, especially as a vibration damping damper for reducing the vibration of a structure during an earthquake, since an elastoplastic damper using a double-point resistant steel is excellent in performance, cost, and maintainability, it has been particularly popular in recent years.

This elastoplastic damper has a function of reducing vibration of the building by mainly absorbing seismic energy input to the building as thermal energy by plastic deformation of an alloy used as a core material for a damper.

The plastic deformation characteristics of the vibration damping alloy used as the core material have an important influence on the performance of the vibration damper. It is preferable that the yield stress or proof stress of the vibration damping alloy is low in order to plastically deform earlier than the structure body. In addition, since the core material for a damper itself is repeatedly elastoplastic after an earthquake occurs, changes in mechanical properties due to repeated hardening and metal fatigue are a problem from the viewpoint of long-term use.

Repetitive hardening causes remarkable damage to the vibration suppression function, such as an increase in the starting strength of the vibration damping damper, and when metal fatigue progresses, it finally leads to damage of the vibration suppression device itself due to fatigue fracture. In order to avoid such a situation, a vibration damping alloy with a low cyclic hardening rate and a long fatigue life is expected.

Currently, the most widely used vibration damping alloy is a resistance double point steel that intentionally lowers the yield stress or 0.2% proof stress to about 100 to 225 MPa, but the lower the yield stress, the higher the initial cyclic hardening rate in elastoplastic deformation. The fatigue life is naturally higher than that of steel used for main skeletons such as pillars and beams of structures, but there is no significant difference in fatigue properties, and it is difficult to say that there is a clear advantage.

Therefore, the conventional resistance double-point strong vibration damper is designed to be plasticized only during earthquakes, not to plasticize the core material (elastic range) against wind shakes exposed to multiple repetitions with low deformation amplitude (small amplitude). However, it has been inevitable to design in consideration of fatigue damage.

In addition, after a major earthquake, due to problems of performance change due to repeated hardening or accumulated fatigue damage, inspection and replacement may be required in some cases. As a result, a disaster recovery period or cost is incurred.

In addition, in recent high-rise buildings, the building resonates during an earthquake, and the so-called long-period seismic motion problem is attracting attention, in which the building resonates during an earthquake, and the vibration of relatively large deformation continues for a long time. There is a growing demand for alloys.

On the other hand, the inventors have disclosed that an Fe-Mn-Si-based shape memory alloy containing NbC can be used as a vibration damping alloy for a structure (see, for example, Patent Document 1).

This invention focuses on the fact that the plastic deformation remaining after the earthquake can be removed by the shape memory effect by heating to restore the initial shape. In addition, the change in the metal structure of the alloy due to tensile compression plastic deformation occurs reversibly between the γ austenite phase of the FCC type crystal (face-centered cubic lattice structure) and the ε martensite phase of the HCP type crystal (hexagonal tightest packing structure). Therefore, other effects as a vibration damping alloy were also found, such as a low cyclic hardening rate and a long fatigue life (see, for example, Non-Patent Document 1).

In general, a mechanism for heating the damper member is required in order to utilize the shape memory effect, but according to the above proposal, even if such a heating mechanism is not installed, at least the curing rate due to repeated deformation is low, and the fatigue life is long. It can also be used as a high-performance damping alloy that works effectively.

It is suggested in Patent Document 5 that the Fe-Mn-Si-based shape memory alloy is effective as a vibration damping alloy with almost the same composition, but the appropriate range of components as a shape memory alloy and a suitable range of components as a vibration damping alloy due to the progress of subsequent research. It has also been made clear that they are not completely consistent.

In Patent Document 5, the alloy to which NbC is added in order to improve shape memory characteristics has a very high stress amplitude of 650 MPa or more for cyclic tensile and compressive deformation of 1% amplitude. If the core material for an elastic damper is not elastically deformed before the structure body, the vibration absorbing effect to protect the structure body cannot be exhibited.

In other words, the strength must be lower than that of the main body of structures such as buildings. Therefore, when a material with high material strength is used for a core material for a damper, it is necessary to reduce the cross-sectional area of the damper so as not to exceed the strength of the structure.

However, since a damper having a small cross-sectional area increases the risk of buckling during compression deformation, it is advantageous for the damper core material to have a somewhat lower material strength in order to secure a wide applicable range as a damper.

In order to solve this problem, the inventors further investigated and tried to control the plastic deformation characteristics by addition of Al based on a Fe-30Mn-6Si shape memory alloy that does not contain precipitates such as NbC.

As a result, it is disclosed that an alloy containing 1 to 3% by mass of Al is useful as a vibration damping alloy capable of operating at a stress amplitude as low as 300 MPa with respect to cyclic tensile and compressive deformation of 1% amplitude (for example, Patent Document 6 See).

On the other hand, according to Non-Patent Document 2, the addition of Al in excess of 1% by mass to the Fe-30Mn-6Si shape memory alloy almost eliminates the shape memory effect, and this also makes the shape memory alloy and vibration damping alloy optimal. It is clear that the component ranges do not necessarily match.

In addition, the ability to produce core materials for elasto-plastic dampers at low cost using existing mass-produced steelmaking facilities is an important request for early advancement of earthquake resistance of structures. Since the known vibration damping alloy disclosed in Patent Document 6 contains Mn at a high concentration of 30% by mass, it is difficult to make it in a facility where general steel materials such as arc furnace melting are produced.

The reason is that the boiling point of Mn is 2010°C, which is very low compared to that of Fe at 3070°C, and it is more likely to generate oxides than Fe, so the reduction of Mn yield due to evaporation or oxidation of Mn, reaction with refractories in the melting furnace, etc. This is because it is inevitable and involves difficulties both in terms of operation and cost. Therefore, in order to mass-produce and put the Fe-Mn-Si-based vibration damping alloy into practical use from economical and technical requests, it is essential to develop an alloy with a lower Mn content.

In addition, in Fe-Mn-Si-based shape memory alloys, a component system in which a part of Mn is replaced with Cr or Ni for improving corrosion resistance is known (for example, see Non-Patent Document 3), but this simultaneously reduces the content of Mn. Since it is lowered, it suggests that substitution by Cr or Ni is effective.

However, the fatigue properties of shape memory alloys obtained by substituting Mn with Cr or Ni have not been disclosed or suggested until now. As described above, the appropriate component range of the shape memory alloy and the vibration damping alloy do not necessarily match. Therefore, the optimum component range of the Fe-Mn-Cr-Ni-Si system as a vibration damping alloy is unclear. According to Non-Patent Document 4, in the Fe-Mn-Si alloy to which Cr or Ni is added, second phases such as δ ferrite phase, silicide, and α'martensite phase are easily formed, but the effect of these second phases on fatigue properties. It is also unclear.

On the other hand, the fatigue properties of Fe-Mn-based austenitic steels have been actively studied in recent years. This is because it is recognized as a new automotive steel sheet excellent in strength and ductility balance, and in TWIP (Twinning Induced Plasticity: Twinning Induced Plasticity) steel, twin deformation of the γ austenite phase has a good effect on fatigue properties as well ( For example, see Non-Patent Document 5).

The fatigue properties of the Fe-Mn-Cr-Ni alloy are also investigated from the same viewpoint, and the relationship between the fatigue properties and the structure is partially known (see, for example, Non-Patent Document 6). However, the plastic deformation structure of these Fe-Mn alloys and Fe-Mn-Cr-Ni alloys is a complex combination of deformation twins, α'martensite phase, ε martensite phase, lamination defect, dislocation, etc., and fatigue properties and structure It cannot be said that the relationship between the two has been sufficiently elucidated.

As a result of experiments and research conducted by the inventors so far, it has been demonstrated that ε martensite is effective in improving the fatigue properties, but in TWIP steel and Fe-Mn-Cr-Ni alloys, ε martensite is not affected by fatigue properties. Little has been elucidated on the impact it has. In addition, austenitic structural steels, including TWIP steel, are usually designed as structural materials so that they can be laid as long as they have yield strength, and are not suitable for core materials for elastoplastic dampers.

Further, a Fe-Mn-Cr-Si-Al-C alloy has been disclosed as a vibration damping alloy using an ε martensite phase (for example, see Patent Document 7). However, this damping alloy improves internal friction in the elastic deformation region by including 15% or more of the ε martensite phase in the γ austenite phase in the state before deformation, and the fatigue properties against elastoplastic deformation are not disclosed. .

In the state before deformation, the ε martensite phase is already included, or the γ austenite phase is high strength because it contains carbon, which has a very strong solid solution hardening property, and is not suitable for a core material for an elastoplastic damper. Therefore, there is neither disclosure nor suggestion of a component for increasing the fatigue life and the low proof strength and low stress amplitude required for the vibration damping alloy.

As described above, the properties required for vibration-isolating steel or vibration-isolating alloy, which are used mainly for protecting the structure from earthquakes, as the core material for the elastoplastic damper in the vibration isolating device of a building structure are low strength, low repetitive hardening. The fatigue life is long (the number of fracture repetitions is large) at the rate and large deformation. However, there was no vibration damping alloy as a core material for an elastoplastic damper having a good balance of all of these properties.

Japanese Patent Laid-Open Publication No. Hei 5-263858 Japanese Patent Laid-Open Publication No. 2001-146855 Japanese Patent Laid-Open Publication No. Hei 5-106367 Japanese Patent Laid-Open Publication No. Hei 5-26274 Japanese Patent Laid-Open No. 2006-194287 Japanese Patent Laid-Open No. 2008-56987 Japanese Patent Laid-Open No. 2011-214127

T. Sawaguchi, P. Sahu, T. Kikuchi, K. Ogawa, S. Kajiwara, A. Kushibe, M. Higashino, T. Ogawa, "Vibration mitigation by the reversible fcc/hcp martensitic transformation during cyclic tension-compression loading of an Fe-Mn-Si-based shape memory alloy" Scripta Materialia, 54(2006)1885 M. Koyama, M. Murakami, K. Ogawa, T. Kikuchi, T. Sawaguchi, "Influence of Al on Shape Memory Effect and Twinning Induced Plasticity of Fe-Mn-Si-Al System Alloy" Mater. Trans.(2007) H. Otsuka, H. Yamada, T. Maruyama, H. Tanahashi, S. Matsuda, M. Murakami, "Effects of Alloying Additions on Fe-Mn-Si Shape Memory Alloys" Isij International, 30(1990)674 B. C. Maji, M. Krishnan, V. V. R. Rao, "The microstructure of an Fe-Mn-Si-Cr-Ni stainless steel shape memory alloy" Met. Mat. Trans. A,34A(2003)1029 T. Niendorf, F. Rubitschek, HJ Maier, J. Niendorf, HA Richard, A. Frehn, "Fatigue crack growth-Microstructure relationships in a high-manganese austenitic TWIP steel" Materials Science and Engineering a-Structural Materials Properties Microstructure and Processing , 527(2010)2412 A. Glage, A. Weidner, H. Biermann, "Cyclic Deformation Behavior of Three Austenitic Cast CrMnNi TRIP/TWIP Steels with Various Ni Content" Steel Research International, 82(2011)1040

The present invention solves the conventional problems from the above background, decreases the stress amplitude after repeated tensile and compressive deformation in the Fe-Mn-(Cr, Ni)-Si-based alloy, and increases the number of fracture repetitions. The task is to provide a damping alloy for elastoplastic dampers that can be used without maintenance even after a long period of earthquake motion and can be mass-produced.

That is, the vibration damping alloy of the present invention is characterized by the following.

First, a vibration damping alloy based on Fe-Mn-(Cr, Ni)-Si containing at least one of Cr and Ni, or a vibration damping alloy further containing Al, as a component composition, 5% by mass ≤ Mn ≤ 28% by mass , 0% by mass ≤ Cr ≤ 15% by mass, 0% by mass ≤ Ni <15% by mass, 0% by mass <Si <6.5% by mass, 0% by mass ≤ Al <3% by mass, the remainder of Fe and inevitable impurities, [%Ni]+0.5[%Mn]>0.75[%Cr]+1.125[%Si]+2[%Al], also 37<[%Mn]+[%Cr]+2[%Ni]+5[ %Al] <45 (in the formula [%Ni], [%Mn], [%Cr], [%Si], [%Al] means the mass% of Ni, Mn, Cr, Si, Al) It is characterized by satisfying the conditions.

Second, in the vibration suppression alloy of the first invention, it is characterized in that it contains 10% by mass≦Mn≦20% by mass and 2% by mass≦Ni≦10% by mass.

Third, in the vibration damping alloy of the first or second invention, it is characterized in that it contains 2% by mass≦Si≦6% by mass.

Fourth, in the vibration damping alloy of any one of the first to third inventions, the metal structure of the alloy after plastic working and solution heat treatment is less than 15% by volume ε martensite phase (HCP structure), and the remainder is γ Consisting of only an austenite phase (FCC structure), and from this state, the state after repeated tensile and compressive deformation of 1% amplitude for more than 100 cycles is an ε martensite phase of less than 50% by volume and α'martense of less than 3% by volume. It is characterized in that the zite phase and the remainder are γ austenite phase.

Fifth, in the vibration damping alloy of any one of the first to fourth inventions, the stress amplitude after repeating the tensile and compressive deformation of 280 MPa or less and amplitude of 1% for 100 cycles or more is 400 MPa or less, and repeated fracture. It is characterized in that the number is more than 2000 cycles.

(Effects of the Invention)

In the vibration damping alloy of the present invention, since the amount of Mn is not more than 28% by mass, it is easy to manufacture compared to the conventional vibration damping alloy of Fe-30Mn-Si-Al. Particularly, for the case where the amount of Mn is less than 20% by mass, the conventional Fe-30Mn-Si-Al vibration damping alloy could only be dissolved in a vacuum induction furnace, but there is a possibility that it can be dissolved in an arc, which is a significant cost. A decline is expected.

In addition, the number of rupture repetitions is approximately 1 value longer than that of the conventional resistance double-point steel for elastomeric dampers, and it can be used for long-period earthquake motion.

In addition, the vibration damping alloy under the conditions stipulated in the present invention has a proof strength of 280 MPa or less, a stress amplitude of 400 MPa or less after repeating tensile and compressive deformation of 1% amplitude more than 100 times, and a fracture repetition number of 2000 cycles or more. It is a vibration suppression alloy for elastoplastic dampers that can be operated at a low strength level due to its low proof strength and stress amplitude compared to Fe-Mn-Si-based shape memory/vibration alloys containing NbC. I can.

Fig. 1 is a graph showing the relationship between stress and strain in the first cycle of tensile compression deformation in Example 2 (4S).
2 is a graph showing a change in stress amplitude due to repeated tensile and compressive deformation of the alloys of Examples and Comparative Examples.

In general, the vibration damping alloy refers to a structural material that mainly increases internal friction in an elastic deformation region and absorbs mechanical vibration in machine tools, precision equipment, automobiles, etc. by achieving both high strength as a metallic material.

On the other hand, in order to distinguish this from this, the letters ``vibration suppression'' are sometimes assigned to vibration suppression, which is mainly used to counter earthquake motion.However, in addition to earthquakes, the suppression of daily vibrations caused by wind shakes is also used for structures. Since it is important for vibration dampers, the notation of "vibration suppression" has become mainstream in recent years.

In accordance with this trend, the present invention also uses the notation "vibration suppression", but its main object is suppression of vibrations on structures during earthquakes. However, suppression of relatively minute vibrations due to wind shaking or the like is also included in the effect.

In the vibration suppression alloy of the present invention, in the Fe-Mn-(Cr, Ni)-Si-based alloy, the elastoplastic deformation is mutually converted between the γ austenite phase and the ε martensite phase by controlling the content of Mn, Cr, Ni, and Si. By creating a situation that proceeds reversibly, and suppressing irreversible deformation such as formation of an α'martensite phase, the proof strength is 280 MPa or less, and the stress amplitude after repeated tensile compression deformation of 1% amplitude is 400 MPa or less, In addition, it is a vibration suppression alloy with more than 2000 cycles of fracture repetition.

The plastic deformation mechanism in an austenitic iron-based alloy is the sliding motion of the lattice dislocation, which is a general plastic deformation mechanism of metals, and the sliding of the expansion dislocation, in which the lattice dislocation is decomposed into two partial dislocations and a lamination defect sandwiched therebetween. It takes various forms such as motion, twin transformation, ε martensite transformation, and α'martensite transformation, and usually a plurality of plastic deformation mechanisms are simultaneously expressed.

In the vibration damping alloy of the present invention, the structural change due to the tensile compression plastic deformation is reversibly progressed by the two-way martensite transformation of the γ austenite phase and the ε martensite phase, thereby suppressing the repeated hardening and the number of fracture repeats. Plan to increase

For that purpose, it is preferable that the state before deformation is γ austenite single phase, and the plastic deformation mechanism proceeds mainly by ε martensite transformation. In that case, some of the twin deformation, lattice dislocation slip, and expansion dislocation slip, which inevitably occur simultaneously with the ε martensite transformation, may be included, but the α'martensite transformation remarkably hardens the alloy, so the occurrence is not suppressed. It must be.

The essential additive element that has a central influence on the plastic deformation mechanism of the Fe-Mn-(Cr, Ni)-Si alloy is Mn. Mn has an effect of stabilizing the γ austenite phase in the iron-based alloy and lowering the stacking defect energy to create a state in which martensite transformation from the γ austenite phase to the ε martensite phase is likely to occur.

Therefore, during tensile compression plastic deformation, the ε martensite transformation and this reverse transformation are alternately generated from the strain induced γ, and the formation of the α′ martensite phase can be suppressed to improve the fatigue properties.

In addition, the austenite stabilization action of Mn can be partially replaced with Ni, and the layering defect energy reduction action can be partially replaced with Cr.

In the present invention, in order to reduce the dissolution cost, it is assumed that Cr or Ni is necessarily included as an alternative addition element of Mn. Further, Al, which has an effect of improving the vibration damping properties of the Fe-Mn-Si shape memory alloy, may also be added as an Mn replacement element.

The effect of Mn, Cr, Ni, and Al on the plastic deformation mechanism can be represented by the mass% of Mn giving an equivalent effect. In the present invention, this is defined as Mn equivalent ([%Mn]eq), and the Mn equivalent is expressed by the following formula (1) using the content (mass%) of each component element.

Mn equivalent ([%Mn]eq)=[%Mn]+[%Cr]+2[%Ni]+5[%Al] (1)

In addition, [%Mn], [%Cr], [%Ni], and [%Al] in the formula refer to the mass% of Mn, Cr, Ni, and Al as chemical components of the vibration damping alloy.

In addition, in the present invention, the range of the Mn equivalent for expressing the martensite transformation in two directions between the γ austenite phase-the ε martensite phase is under the conditions represented by the following formula (2).

37<[%Mn]eq<45 (2)

When the Mn equivalent is not more than 37% by mass, the thermodynamic stability of the ε martensite phase is very high, so that the ε martensite phase once deformed is not reversely transformed into the γ austenite phase even if it is deformed in the reverse direction thereafter.

As a result, the volume ratio of the ε martensite phase monotonously increases due to the repeated tensile and compressive deformation, and when the volume ratio becomes more than 50% by volume, the probability of crack occurrence or the crack diffusion rate at the locations where the formed ε martensite phases collide with each other decreases. It rises and the number of repetitions of fracture decreases.

In addition, when the Mn equivalent is 30% by mass or less, an ε martensite phase having a volume ratio of 15% by volume or more is formed at the time of cooling from the solution heat treatment temperature to room temperature, and the subsequent formation of the modified organic ε martensite phase It becomes an inhibitory factor for the rupture, so the number of rupture repetitions decreases.

In addition, when the Mn equivalent is 45% by mass or more, the stacking defect energy increases, and? Martensite is not formed.

On the other hand, Si, which is another essential element, has little effect on the Mn equivalent, but it is an experiment to improve the reversibility of the two-way martensite transformation of the γ austenite phase and the ε martensite phase, thereby improving the number of fracture repetitions. Clarified by Si can achieve about 2000 cycles of fracture repetition number even without addition, but the addition of Si dramatically increases the number of fracture repetitions, and exhibits the most effect around 4% by mass.

However, when Si is excessively added, the number of rupture repetitions is reduced. In particular, when Si is added in an amount of 6.5% by mass or more, the alloy is remarkably hardened, causing problems such as an increase in the stress amplitude of repeated tensile and compressive deformation.

Regarding the amount of Mn, Cr, Ni, and Si added, the balance adjustment between the total amount of Ni and Mn as austenite stabilizing elements and the total amount of Cr, Si, and Al as ferrite stabilizing elements so that the metal structure before deformation becomes γ austenite single phase It is important. The higher the ferrite stabilizing element concentration and the lower the austenite stabilizing element concentration, the easier the δ ferrite phase is formed, and when the ferrite stabilizing element concentration and the austenite stabilizing element concentration are both low, the α'martensite phase is more likely to be formed.

As a result of the experiment of the inventors, in the case of water cooling after solution heat treatment at 1000°C for 1 hour in the alloy system of the present invention, the amount of addition of component elements must be satisfied in order to obtain a single phase of γ austenite by suppressing the formation of δ ferrite phase. It turned out that the conditions are given by the following formula (3).

[%Ni]+0.5[%Mn]>0.75[%Cr]+1.125[%Si]+2[%Al] (3)

In addition, [%Ni], [%Mn], [%Cr], [%Si], and [%Al] in the formula refer to the mass% of Ni, Mn, Cr, Si, and Al as chemical components of the damping alloy. .

In addition to the above conditions, the addition amount of each component element of Mn, Cr, Ni, Si, and Al is limited due to manufacturing restrictions. It will be described in detail below.

<Mn>

Mn is an essential additive element having two effects of stabilizing austenite and reducing the energy of lamination defects, but in the vibration damping alloy of Patent Document 6 in which 30% by mass of Mn is added, the Mn yield is reduced due to evaporation or oxidation of Mn, and the melting furnace refractories and It is difficult to dissolve at a practical cost because the reaction of

In the present invention, in order to reduce the dissolution cost, the addition amount of Mn is made 28% by mass or less by addition of Cr or Ni. Further, if the amount of Mn added is less than 20% by mass, it is possible to produce an alloy by melting an arc furnace suitable for mass production.

On the other hand, when the addition amount of Mn is less than 10% by mass, both Cr, which is effective in reducing the stacking defect energy, and Ni, which is an austenite stabilizing element, must be added in large amounts, which lowers the dissolution cost but increases the material cost.

In addition, when the amount of Mn is less than 5% by mass, the formation of an α'martensite phase harmful to fatigue properties cannot be avoided even if the amounts of Cr and Ni are adjusted. From the above, in the present invention, the amount of Mn added is 5% by mass≦Mn≦28% by mass, more preferably 10% by mass≦Mn≦20% by mass.

<Cr>

Cr is an element that lowers the stacking defect energy of the γ austenite phase and promotes the martensite transformation into the ε martensite phase, thereby improving the fatigue properties of the vibration damping alloy of the present invention. In addition, it further contributes to the improvement of corrosion resistance and high temperature oxidation resistance. However, when the addition amount of Cr is 15% by mass or more, it becomes difficult to suppress the formation of the α'martensite phase no matter how other components are adjusted, and since it forms an intermetallic compound with Si and a low melting point, the solvent of the alloy is difficult. Is done. From the above, in the present invention, the amount of Cr added is in the range of 0% by mass ≤ Cr ≤ 15% by mass.

<Ni>

Ni is an element that replaces the austenite stabilization action of Mn. In particular, when the addition amount of Mn is less than 20% by mass, a single γ austenite phase cannot be obtained as a state before deformation unless 2% by mass or more of Ni as an austenite stabilizing element is added.

On the other hand, when the addition amount of Ni is 15% by mass or more, since an intermetallic compound with Si and a low melting point is formed, hot workability of the alloy is deteriorated.

Further, from the viewpoint of material cost, it is preferable that Ni, which is an expensive element, is less than 10% by mass. From the above, in the present invention, the amount of Ni added is in the range of 0% by mass≦Ni<15% by mass, more preferably 2% by mass≦Ni≦10% by mass.

In addition, at least one of Cr and Ni is contained in the vibration damping alloy of the present invention, and neither is 0 mass%.

<Si>

Si is an essential element of the Fe-Mn-Si-based shape memory alloy and its component range is 3.5 to 8% by mass, but the Si concentration range of the alloy that can be used industrially is 5 to 6% by mass or less.

On the other hand, even in the vibration suppression alloy of the present invention, Si is an element that plays an important role in improving the number of fracture repetitions, but the optimum component concentration is different from that of the shape memory alloy. As a result of experiments and studies by the inventors, in the present invention, in order to make the number of fracture repetitions at least 2000 cycles, the amount of Si added is 0 mass% <Si <6.5 mass%, more preferably 2 mass% ≤ Si ≤ 6 mass. It should be in the range of %.

<Al>

Since Al is an element that affects the Mn equivalent by a factor of 5, it may be added as a substitute element for Mn. However, since it is also a ferrite stabilizing element, when Al is excessively added, a δ ferrite phase is easily formed. When heat-treated in the air, there is a possibility that Al, which has high affinity with nitrogen, forms nitrides and embrittles the alloy.

As described above, Al is effective in the adjustment of the Mn equivalent even in a small amount, and may be detrimental when excessively added. Therefore, the addition amount is in the range of 0% by mass ≤ Al <3% by mass.

<Other>

In the present invention, in addition to the above, as an element having an effect of replacing Mn, Co, Cu, C, and N may be added. However, since the addition of Co and Cu leads to an increase in material cost, in the present invention, it is in the range of Co<0.2% by mass and Cu<2% by mass.

In addition, C and N have a function of solid solution hardening of the alloy, increase the yield strength and impair the performance as a core material for an elastoplastic damper, so the upper limit of the addition amount is C<0.1% by mass and N<0.08% by mass, respectively. Make it a range.

In addition, for the purpose of removing the interstitial elements C and N dissolved in the iron matrix, the addition of elements such as Nb, Ta, V, Ti, and Mo having high affinity with C and N to form carbides or nitrides It is widely practiced in the field.

In the vibration damping alloy of the present invention, in order to reduce the stress amplitude in the proof stress and repeated tensile and compressive deformation, the influence of solid solution strengthening of the matrix by the interstitial elements C or N needs to be as small as possible. Therefore, in the present invention, Nb, Ta, V, Ti, and Mo may be added to remove solid solution C or solid solution N by applying a conventional method.

However, when the addition amount of each element is too large, the yield strength and the stress amplitude increase due to precipitation hardening of the formed carbide or nitride. In order to avoid this, in the present invention, it is in the range of Nb<0.05 mass%, Ta<0.05 mass%, V<0.05 mass%, Ti<0.05 mass%, and Mo<0.05 mass%.

The state before deformation is preferably γ austenite single phase, but if it is a small amount, the ε martensite phase may be included. An alloy adjusted to a state in which ε martensite transformation is liable to be induced by deformation may unintentionally form an ε martensite phase due to a change in temperature of the environment or the influence of processing.

These unintentionally formed ε martensite phases, unlike ε martensite phases whose crystallographic orientation is subsequently deformed, become a barrier to the growth of the deformed organic ε martensite phase, so their volume fraction is less than 15% by volume. To do.

The tensile compression plastic deformation of the vibration damping alloy of the present invention is mainly performed by alternating martensite transformation from the γ austenite phase to the ε martensite phase and its reverse transformation. The ε martensite phase induced during tensile deformation reverses to the γ austenite phase when the direction of deformation is reversed to compression.

On the other hand, compression deformation generates a new ε martensite phase with a crystal orientation different from that of the tensile deformation at the same time as the reverse transformation of the ε martensite phase induced by tension. When the compression-induced ε martensite phase also reverses to tension, it reverses to the γ austenite phase. As described above, the increase in the cumulative volume ratio of the ε martensite phase due to repeated tensile and compressive deformation is small because the tensile induction ε and the compression induction ε are alternately generated and destroyed by repeated tensile compression. This is why the fatigue properties are excellent.

However, as the deformation amplitude or the number of cycles increases, the volume ratio of the ε martensite phase gradually increases but increases, and when it exceeds 50% by volume, the probability of crack occurrence or the crack diffusion rate increases, leading to fracture. Therefore, in order to increase the number of repetitions of fracture to 2000 cycles or more with respect to the tensile and compressive strain having an amplitude of 1%, it is preferable that the volume fraction of ε martensite after 2000 cycles of deformation is less than 50% by volume.

In addition, since the α'martensite phase hardens the alloy, the volume ratio should be less than 3% by volume. When the volume ratio of the α'martensite phase becomes 3% by volume or more, the stress amplitude increases by curing, and the increase in the stress amplitude causes a new α'martensite phase transformation in a chain, so the damper performance by increasing the stress level It leads to a decrease in the number of fracture repetitions as well as a decrease in

The proof strength of the vibration damping alloy of the present invention is 280 MPa or less. If the proof force is higher than this, the cross-sectional area of the damper core material for optimizing the starting strength of the damper becomes too small, and it becomes easy to buckling at the time of elastoplastic deformation. In order to avoid buckling, it is necessary to install a buckling reinforcing jig, but installation of the buckling reinforcing jig increases the manufacturing cost of the damper member.

Further, when the tensile and compressive strain is repeated, the stress amplitude increases due to repeated hardening, but from the viewpoint of long-term use, the stress amplitude after repeating the tensile and compressive strain of 1% amplitude 100 or more times is preferably 400 MPa or less.

When the stress amplitude exceeds 400 MPa, the yield strength of the damper core material increases after the occurrence of a major earthquake, exceeds the strength of the building body, and it becomes difficult to operate as a damper in subsequent earthquakes. The vibration suppression alloy of the present invention is a core material for vibration suppression dampers capable of coping with long-period earthquake motion, and is intended to be used in a vibration suppression device such as a high-rise building, so the final number of repetitions leading to fracture or buckling is 2000 cycles or more.

Example

Hereinafter, the present invention will be specifically described based on Examples. Of course, the present invention is not limited at all by these examples.

Each 10 kg of alloys of each compounded chemical component of Examples 1 to 6 and Comparative Examples 1 to 8 shown in Table 1 were prepared by a vacuum induction melting furnace, hot forging and hot rolling at 1100°C, and then in an argon atmosphere. After heating at 1000°C for 1 hour, it was water-cooled to obtain an ingot. In addition, the addition amount of each component in Table 1 represents mass%.

In Table 1, in order to facilitate understanding of the characteristics of the ingredients of Examples and Comparative Examples, Examples 1 to 6 are also indicated as symbols 2S, 4S, 6S, 2A, 25M8N, 25M15C, and Comparative Examples 1 to 8 are symbols 0S, Also shown as 8S, 5M, 25M, 2N, 15N, PRE and 30M1A.

From each of the ingots of Examples 1 to 6 and Comparative Examples 1 to 8, a low-cycle fatigue test piece was produced by lathe processing with a parallel part diameter of 8 mm, and a triangular wave of 0.1 Hz and a strain control of 1% amplitude in room temperature atmosphere. A cycle fatigue test was performed.

Fig. 1 shows the relationship between stress and strain in the first cycle of tensile compression deformation in Example 2 (4S). If the tensile strain increases from the state O without strain, plastic strain continues to occur in the elastic strain OA, reaching the point B of 1% of the tensile strain.

Thereafter, when the strain is reversed to compression, the tensile-plastic strain continues to decrease in the elastically deformed portion BC where the tensile elastic stress decreases in proportion to the decrease in the tensile strain, and the strain becomes zero at point D.

In addition, when compression deformation proceeds, compression plastic deformation occurs. When the compressive strain reaches the point E of -1%, the strain changes from compression to tensile again, and the first cycle continues with elastic strain EF and plastic strain FG. The second cycle starts along the curve of GB' indicated by the dotted line, and then repeats the same transformation as in the first cycle.

In one cycle of deformation, work energy equal to the area drawn by the stress-strain curve is converted into heat energy and absorbed, thereby damping vibration.

At the time of tensile deformation, the point at which plastic deformation started was evaluated by 0.2% proof stress. In addition, as shown in Fig. 1, the stress amplitude in tensile compression deformation was determined from the maximum stress on the tensile side. The same evaluation was performed for all the alloys of Examples 1 to 6 and Comparative Examples 1 to 8. In addition, Fig. 2 shows Example 1 (2S), Example 2 (4S), Example 3 (6S) and Comparative Example 1 (0S), Comparative Example 3 (5M), Comparative Example 4 (25M), and Comparative Example 5 (2N), Comparative Example 7 (PRE), Comparative Example 8 (30M1A) shows the change in the stress amplitude due to the repeated tensile and compressive deformation of the alloy.

Most alloys exhibit approximately stable stress amplitude after cyclic hardening in the initial 10 cycles. However, 5M showed repeated curing even after 10 cycles. Moreover, the initial hardening of PRE was small, and after exhibiting remarkable hardening over 10 cycles to 200 cycles, it became a stable stress amplitude. In order to evaluate the change in the stress amplitude due to the repeated tensile and compressive deformation, the stress amplitude (σa) at the 100th cycle was calculated, and the curing rate was calculated by the following equation (4).

Curing rate (H)=(σa100-σa1)/σa1 (4)

Table 2 shows the yield strength, the first cycle stress amplitude, the 100th cycle stress amplitude, the curing rate, and the final repetition number determined from these results.

Examples 1 to 6 (2S, 4S, 6S, 2A, 25M8N, 25M15C) all have a proof strength of 280 MPa or less, a stress amplitude of the 100th cycle of 400 MPa or less, and a final repetition number of 2000 cycles or more. In Comparative Example 1 (0S) in which Si was not added, the number of repeated fractures was slightly less than 2000.

Comparative Example 2 (8S) in which Si was added in a larger amount than the component range of the present invention was unable to prepare a sample due to rolling cracking. It is thought that the occurrence of cracks is due to the formation of a low melting point intermetallic compound.

In Comparative Example 3 (5M) in which the Mn equivalent was reduced to 31, repeated hardening was remarkable, and the number of repeated fractures was 1000 or less. It is believed that the repeated curing is due to the strain induced α'martensite phase.

In Comparative Example 4 (25M) in which the Mn equivalent was increased to 51, since ε was not formed due to deformation, the number of rupture repetitions was 1000 or less.

Comparative Example 5 (2N), in which the addition amount of Ni was reduced from the invention material to be 2% by mass, and as a result, the Mn equivalent was reduced to 29, had remarkably high cyclic hardening, and the number of repeated fractures was 1000 or less. This is considered to be due to the formation of an ε martensite phase and an α'martensite phase of 50 vol% or more.

Comparative Example 6 (15N) containing 15% by mass of Ni at a higher concentration than in the examples had cracks during hot rolling, and thus the test piece could not be manufactured. This is considered to be because Ni formed a low melting point intermetallic compound with Si.

Comparative Example 7 (PRE) is a vibration damping alloy of the NbC precipitate addition type disclosed in Patent Document 5. Although the number of rupture repetitions is excellent at 3000 cycles or more, the stress amplitude is very high at 620 MPa.

Comparative Example 8 (30M1A) is an Al-added vibration damping alloy disclosed in Patent Document 6. Although the number of rupture repetitions is 2000 or more and the stress amplitude is low, it is not suitable for mass production because it contains 30% by mass of Mn.

From these results, the vibration damping alloys of Examples 1 to 6 under the conditions specified in the present invention lower the yield strength and the stress amplitude after repeated tensile and compressive deformation, compared to the alloys of Comparative Examples 1 to 8 out of the conditions, and reduce the number of fracture repetitions. It was confirmed that it is a vibration damping alloy that can be used without maintenance even after a long period of earthquake motion and can be mass-produced.

(Industrial availability)

By using the vibration suppression alloy of the present invention, it is an elastic damper that suppresses vibration of building structures due to earthquakes and wind shakes.It operates with low stress and manufactures a low-cost vibration suppression device that can be used without maintenance even when exposed to repeated earthquakes. Things become possible.

It is a high-performance damper that does not damage the vibration suppression performance even if the vibration with a large amplitude continues for a long period of time, such as a long-period earthquake motion, and can be particularly used for vibration suppression of high-rise buildings. In addition, in all forms of chemical plants, power plants, halls, towers, fuel tanks, elevated railroads, roads, bridges, pipelines, tunnels, wind power plants, etc. as a building structure, vibration suppression at places that are repeatedly deformed by large deformation It is expected to exert an effect on.

Claims (7)

It is an Fe-Mn-(Cr, Ni)-Si-based damping alloy containing at least one of Cr and Ni, or a damping alloy further containing Al, and as a component composition, 5 mass% ≤ Mn <20 mass%, 0 Mass%≤Cr≤15mass%, 0mass%≤Ni<15mass%, 0mass%<Si<6.5mass%, 0mass%≤Al<3mass%, balance Fe and unavoidable impurities, [% Ni]+0.5[%Mn]>0.75[%Cr]+1.125[%Si]+2[%Al], also 37<[%Mn]+[%Cr]+2[%Ni]+5[%Al ]<45 (in the formula, [%Ni], [%Mn], [%Cr], [%Si], [%Al] means the mass% of Ni, Mn, Cr, Si, Al) A vibration suppression alloy characterized in that satisfactory. The method of claim 1,
A vibration damping alloy comprising 10% by mass ≤ Mn <20% by mass and 2% by mass ≤ Ni ≤ 10% by mass. The method according to claim 1 or 2,
A vibration suppression alloy comprising 2% by mass ≤ Si ≤ 6% by mass. The method according to claim 1 or 2,
After plastic working and solution heat treatment, the metal structure of the alloy consists of less than 15% by volume of the ε martensite phase (HCP structure) and the remainder of the γ austenite phase (FCC structure), and from this state, the amplitude is 1%. A vibration damping alloy, characterized in that the state after repeated tensile and compressive deformation of 100 cycles or more is an ε martensite phase of less than 50% by volume, an α'martensite phase of less than 3% by volume, and a γ austenite phase with the remainder. The method according to claim 1 or 2,
A vibration damping alloy having a yield strength of 280 MPa or less, a stress amplitude of 400 MPa or less after repeated tensile and compression deformations having an amplitude of 1% for 100 or more cycles, and a fracture repetition number of 2000 or more cycles. delete delete

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