WO2011129062A1

WO2011129062A1 - Iron alloy having excellent processability, and vibration damping member comprising same

Info

Publication number: WO2011129062A1
Application number: PCT/JP2011/001859
Authority: WO
Inventors: 啓太山名; 元治谷澤; 正則原田
Original assignee: 株式会社豊田自動織機
Priority date: 2010-04-14
Filing date: 2011-03-29
Publication date: 2011-10-20
Also published as: JP2011219842A

Abstract

Disclosed is an iron alloy comprising 3 to 8% of chromium (Cr), 0.4 to 2% of aluminum (Al), manganese (Mn) in such an amount that the ratio of the content of Mn to the content of Al (i.e., an Mn/Al ratio) is 0.6 to 2.3 by mass, and a reminder made up by iron (Fe) and unavoidable impurities and/or a reforming element (wherein "%" is an abbreviation of "mass%" and the total amount of the iron alloy is 100 mass%). The iron alloy has a vibration damping property at an effective level for the use as a vibration damping member and also has excellent processability.

Description

Iron alloy with excellent workability and damping member using the same

The present invention relates to an iron alloy used as a damping material and a damping member.

In a device or device having a movable part that is mechanically movable, the movable part serves as a vibration source, and vibration is often generated in each part. Such vibration is not preferable because it causes various noises and leads to deterioration of fatigue strength. Therefore, various damping materials that suppress this vibration are used. For example, if the mechanical properties such as strength and rigidity are not required so much and the usage environment (for example, the usage atmosphere) is mild, a resin material that easily absorbs vibrations or a material partially using the resin ( For example, a damping steel plate in which a resin material is sandwiched between steel plates is used as the damping material.

However, mechanical properties such as strength are required, and such a damping material cannot be easily used for a member used in a high-temperature atmosphere, and a damping material made of a metal material is often used. . Until now, iron alloys that have excellent mechanical properties such as strength, heat resistance, and workability, and have relatively low raw material costs have been proposed. As specific examples, Patent Document 1 and Patent Document 2 below are proposed. Can be mentioned.

JP-A-5-255813 JP-A-6-100706

In Patent Document 1, it is advantageous to improve workability (ductility) and strength when at least one of Cu, Cr, Si and Ni is added to an Fe—Mn alloy containing 10 to 27 mass% of manganese (Mn). It is described. Furthermore, C, N, P, S and Al are added, and in the examples, the amount of Al added is about 0.03 to 0.04 mass%.

Patent Document 2 discloses an iron alloy containing 3 to 11% by mass of Al, 5 to 70% by mass of Cu, and 3 to 9% by mass of Cr. Patent Document 2 states that the addition of Al is to improve workability, but the addition amount is required to be 3% by mass or more.

It is known that excessive addition of Al to the iron alloy promotes the formation of Fe ₃ Al intermetallic compounds. Fe ₃ Al-based intermetallic compounds are generally known to have poor ductility and very poor workability. Therefore, it is necessary to suppress the amount of Al added to an iron alloy to some extent. On the other hand, the addition of Al to the damping alloy is effective in improving damping properties. Therefore, if the amount of Al added to the iron alloy is reduced, it becomes impossible to achieve both damping properties and workability.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide an iron alloy exhibiting vibration damping properties that can be used as a vibration damping member and having excellent workability.

In the Fe—Cr—Mn alloy, which is a representative damping alloy, the present inventors have included Mn content relative to the Al content while containing Al to such an extent that high damping required for a damping member can be maintained. It has been newly found out that the ductility can be improved without impairing the effect of improving the vibration damping property due to the addition of Al.

That is, the iron alloy of the present invention is an iron alloy having excellent workability used for a vibration damping member, and the total amount is 100% by mass (hereinafter simply referred to as “%”), and 3 to 8% chromium. (Cr), 0.4 to 2% aluminum (Al), manganese (Mn) with a mass ratio (Mn / Al) to Al of 0.6 to 2.3, and the balance of iron (Fe). It consists of impurities and / or modifying elements.

The iron alloy of the present invention contains a suitable amount of Cr, Al, and Mn, and thus exhibits vibration damping properties superior to those of an Fe—Cr—Mn alloy and excellent ductility (workability). Specifically, in a distortion amplitude region of 1 × 10 ⁻⁴ to 2 × 10 ⁻⁴ and a frequency region of 90 to 120 Hz, a loss coefficient indicating damping characteristics is 0.01 or more, further 0.02 or more. A vibration member is preferable. Moreover, it is preferable that it is an iron alloy whose breaking elongation at normal temperature is 30% or more, further 40% or more.

Al is an element that is effective in improving vibration damping properties and stabilizes the ferrite (α) phase. On the other hand, Mn is known as an austenite (γ) element in an iron alloy, and a σ phase composed of a Cr ₂ FeMn compound is generated in addition to an α phase at room temperature, and the γ phase is stabilized at a high temperature. That is, the presence of Mn provides the effect of crystal grain refinement using fine dispersion of inclusions and phase transformation, and the solidified structure is refined to improve ductility. The refinement of the solidification structure is affected by the area ratio of the α phase and the γ phase in the metal structure. Furthermore, even if it is an iron alloy with the same Al content, the damping property is lowered due to the influence of the Mn amount. Therefore, an iron alloy having an appropriate ratio of Al to Mn (Mn / Al) can be used as a damping member that exhibits high ductility and has excellent damping properties.

Incidentally, as an index indicating the vibration damping ability, there are a logarithmic damping factor δ, a specific damping ability W, and the like in addition to the loss coefficient η mainly used in the present specification. These are related to each other and are related by a relational expression of δ = πη or W = 2πη. Therefore, even when the vibration damping ability indexes are different, they can be compared with each other by conversion using these relational expressions.

In the iron alloy of the present invention, such excellent vibration damping properties are stable not only in the low temperature range and the normal temperature range but also in the high temperature range (up to about 300 ° C.). High temperature stability. Therefore, the iron alloy of the present invention can be used for a wider variety of members than before.

By the way, the mechanism and the reason why the iron alloy of the present invention (including “iron alloy member” as appropriate, simply referred to as “iron alloy”) exhibits such excellent vibration damping properties are not necessarily clear, Then, it is thought as follows.

First, the vibration damping property is a phenomenon in which vibration energy is reduced by being partially absorbed inside the vibration damping material, and vibration transmission is hindered. Incidentally, the absorbed vibration energy is mainly converted into thermal energy and released to the outside. As such a vibration energy reduction mechanism (damping mechanism), a ferromagnetic type that absorbs vibration by the movement of the domain wall (domain boundary), a dislocation type that absorbs vibration by the movement of the dislocation of the metal crystal, and a martensitic transformation It is said that there are a twin type that absorbs vibrations due to the movement of twins generated in the above, and a composite type that absorbs vibrations by viscous flow near the interface between a matrix (such as Fe) and soft dispersed particles (such as graphite).

The iron alloy of the present invention seems to exhibit excellent vibration damping properties by fusing multiple vibration damping mechanisms. However, due to its component composition, the iron alloy is strong in that vibration is absorbed by movement of the domain wall. It seems to be a magnetic type. However, it is considered that the iron alloy of the present invention to which plastic working has been added absorbs vibration also by dislocation movement.

The above-described iron alloy of the present invention includes not only a member (iron alloy member) that has been subjected to plastic working or the like to give a desired shape, but also a material before processing (iron alloy material). Although its use is not necessarily limited, it is obvious that it is suitable as a vibration damping material, as is clear from the excellent vibration damping properties as described above. And since the iron alloy material consisting of the iron alloy of the present invention has high ductility (breaking elongation at room temperature is 30% or more), in addition to normal plastic working such as press molding, forging, rolling, etc., depending on the composition, deep drawing, Strong processing such as drawing is possible, and an iron alloy member having a desired shape is obtained. In addition, the ductility of the iron alloy of the present invention and the degree of vibration damping of the iron alloy member may be appropriately selected based on an appropriate composition range depending on the processing to be performed and the use of the member.

In addition, the “reforming element” in the present specification is an element other than Fe, Cr, Al, and Mn, and is effective for improving the characteristics of the iron alloy. There are no limitations on the types of properties to be improved, but there are vibration damping properties, soft magnetism, strength, toughness, ductility, high temperature stability, and the like. Specific examples of the modifying element include Cu and Ni. The combination of each element is arbitrary. The content of these modifying elements is not limited, and the content is usually very small.

“Inevitable impurities” are impurities contained in the raw material powder, impurities mixed in at each step, etc., and are elements that are difficult to remove due to cost or technical reasons. Examples of the iron alloy according to the present invention include carbon (C), phosphorus (P), and sulfur (S). Of course, the composition of the modifying element and the inevitable impurities is not particularly limited.

Unless otherwise specified, “ab” in this specification includes a lower limit a and an upper limit b. Further, the lower limit and the upper limit described in the present specification can be arbitrarily combined to constitute a range such as “cd”.

The form of “iron alloy” or “iron alloy member” in this specification is not limited. In particular, the iron alloy may be a material such as a bulk shape, a plate shape, a rod shape, or a tubular shape, or may be a final shape or a structural member close to the final shape.

Also, the iron alloy material used as the material may be a melted material or a sintered material, but if it is a melted material, a dense and stable quality material can be obtained at low cost. On the other hand, in the case of a sintered material, an iron alloy material in a state close to the final product shape can be obtained by a (near) net shape.

The iron alloy of the present invention containing appropriate amounts of Cr, Al, and Mn has high vibration damping required for the vibration damping member, and exhibits high ductility, and is excellent in workability.

6 is a graph showing a loss coefficient η with respect to Mn / Al value for an Fe-5Cr—yAl—xMn alloy (unit: mass%). 4 is a graph showing elongation with respect to Mn / Al value for an Fe-5Cr—yAl—xMn alloy (unit: mass%). 2 is a drawing-substituting photograph showing a metal structure of an Fe-5Cr-0.5Al-1Mn alloy (unit: mass%). 3 is a drawing-substituting photograph showing a metal structure of an Fe-5Cr-0.6Al-1Mn alloy (unit: mass%). 3 is a drawing-substituting photograph showing a metal structure of an Fe-5Cr-0.8Al-1Mn alloy (unit: mass%). 2 is a drawing-substituting photograph showing a metal structure of an Fe-5Cr-1Al-0.5Mn alloy (unit: mass%). 3 is a drawing-substituting photograph showing a metal structure of an Fe-5Cr-1Al-1Mn alloy (unit: mass%). 2 is a drawing-substituting photograph showing a metal structure of an Fe-5Cr-1Al-3Mn alloy (unit: mass%). 2 is a drawing-substituting photograph showing a metal structure of an Fe-5Cr-2Al-4Mn alloy (unit: mass%). It is explanatory drawing which shows the calculation method of the loss factor which indexes damping property.

The present invention will be described in more detail with reference to embodiments of the invention. In addition, the content demonstrated by this specification including the following embodiment is suitably applied not only to the iron alloy which concerns on this invention but to an iron alloy member and its manufacturing method. For this reason, the configuration selected from the following can be added to any of the inventions, in a superposed manner or arbitrarily over the category, to the above-described configuration of the present invention. For example, if it is the structure regarding the composition of an iron alloy, it is related also to the manufacturing method as well as an iron alloy member. Even if it looks like a configuration related to a manufacturing method, if it is understood as a product-by-process, it can also be a configuration related to an iron alloy. Note that which embodiment is the best depends on the target, required performance, and the like.

<Alloy composition>
The iron alloy, iron alloy member, and iron alloy material (hereinafter simply referred to as “iron alloy”) of the present invention are composed of Fe, which is a main component, and Cr, Al, and Mn. Specifically, the iron alloy of the present invention has a total content of 100% by mass (hereinafter simply referred to as “%”), 3 to 8% Cr, 0.4 to 2% Al, and Mn / Al is 0.6 to 2.3 Mn, and the balance is Fe and inevitable impurities and / or modifying elements. The modifying element and inevitable impurities are as described above.

Cr is an element effective for improving at least the vibration damping property of the iron alloy. By coexisting with Al and Mn, the vibration damping property is remarkably improved.

The iron alloy added with Cr has high magnetic properties and excellent vibration damping. However, if the Cr content is less than 3%, the effect of improving the magnetic properties is small, and sufficient vibration damping properties cannot be obtained. A preferable Cr content is 4% or more, further 4.5% or more. However, if the Cr content is excessive, the γ phase is not generated even at a high temperature (for example, 750 ° C. or higher), and the α phase is stabilized. Therefore, if the Cr content is excessive, the α phase becomes coarse in a high temperature environment and the ductility decreases. Further, if Cr is excessive, the cost becomes high. Therefore, the Cr content is 8% or less. The preferable Cr content is 7% or less, 6% or less, and further 5.5% or less.

Al is an element effective for improving vibration damping properties and an element effective for improving soft magnetic properties. If the Al content is less than 0.4%, sufficient vibration damping properties cannot be obtained. A preferable Al content is 0.5% or more, further 0.7% or more. However, if the amount of Al added is too large, the α phase becomes coarse and the ductility is lowered, leading to high costs. Therefore, the Al content is preferably 1.5% or less, 1% or less, 0.9% or less, and further 0.8% or less.

Mn is an element effective for improving ductility by refining the solidification structure of the iron alloy, and suppresses the coarsening of the α phase due to Al. Therefore, a preferable Mn content is Mn / Al (mass ratio) and is 1.2 or more. On the other hand, if the Mn content is excessive, it is difficult to move the domain wall and the vibration absorbing ability is reduced, so that the effect of improving the vibration damping by Al is reduced. A preferable Mn content is Mn / Al (mass ratio), which is 2.1 or less, and further 1.8 or less. In particular, when Mn / Al is 0.6 to 1.8 and the Al content is 0.4 to 0.8%, further 0.4 to 0.6%, the vibration damping property and workability are good. This is preferable because it is compatible at a high level.

<Metallic structure>
The iron alloy of the present invention is excellent in workability due to high ductility due to the crystal grain fine effect. In an iron alloy before processing (an alloy material in an as-cast state) or an alloy material after hot working, the average grain size of the crystal grains is preferably 200 μm or less, more preferably 50 μm or more and 150 μm or less. The crystal grain size can be calculated from various micrographs of the cross section. Specifically, the maximum diameter of a plurality of crystal grains (maximum value of the interval between parallel lines when the particles are sandwiched between two parallel lines) is measured from a micrograph, and the arithmetic average value thereof is determined as the average grain size. do it.

From the viewpoint of workability, a smaller crystal grain size is desirable. However, the larger the crystal grain size, the higher the damping performance. Accordingly, in the vibration damping member made of the iron alloy of the present invention, the average grain size is preferably 50 to 200 μm, more preferably 100 to 150 μm.

<Manufacturing method>
<1. Alloy material>
The iron alloy of the present invention may be a melted material or a sintered material as long as it has the above-described composition. However, since the damping properties and mechanical properties of the iron alloy can be lowered by the inclusion of oxides or the like, the iron alloy is preferably cast or sintered in an antioxidant atmosphere or a vacuum atmosphere. Then, the alloy member is subjected to the following steps as necessary to obtain a vibration damping member.

<2. Plastic working>
The plastic working performed on the iron alloy of the present invention includes a hot working process and a cold working process.

The hot working step is a step of performing plastic working in a state where the iron alloy material is heated to a recrystallization temperature (about 750 ° C.) or higher. When heated to a temperature higher than the recrystallization temperature, a γ phase is generated and the crystal grains are further refined by the stress load of processing. Examples of such plastic working include hot rolling and hot forging. The temperature at which this hot working step is performed (hot temperature) is equal to or higher than the recrystallization temperature, but is preferably 850 to 1150 ° C., more preferably 950 to 1100 ° C., for example.

The cold working process is a process in which an iron alloy material is subjected to plastic working at a cold temperature lower than its recrystallization temperature. Such cold working includes various processes such as punching, bending, and drawing according to the specifications of the iron alloy member. The cold working process is preferably performed on the iron alloy material (before the annealing process described later) after the hot working process in which crystal grains are further refined. However, since the ductility of the iron alloy of the present invention is high even in an as-cast state, cold working may be performed directly on the as-cast material. The cold working process performed after the hot working process is a process in which the iron alloy material is made into a shape of the final product (iron alloy member) or a shape close thereto. The cold working process in this case is an effective process when mass-producing an iron alloy member with a specified specification at a low cost.

The degree of work performed in these hot working processes and cold working processes varies depending on the size of the iron alloy material and the size of the final iron alloy member, so it cannot be specified unconditionally, but the degree of work is the damping property of the iron alloy. Has also been shown to affect. This is because the processing strain increases, the processing strain and dislocations introduced into the iron alloy material or the iron alloy member increase, and the crystal grain size also decreases, which moves the domain wall that absorbs vibration energy. This is thought to be due to changes in properties and dislocation density. As an index of the degree of work in the hot working process, for example, there is a reduction ratio (change in thickness after working / thickness before working). In the iron alloy of the present invention, for example, the rolling reduction is preferably 50 to 90%, more preferably 60 to 80%.

<3. Annealing process>
The annealing process is a process in which the iron alloy material after plastic working is gradually cooled after being heated to an annealing temperature not lower than the recrystallization temperature. As a result, processing strain and dislocation introduced in the previous plastic processing can be removed or reduced. In addition, the damping properties are improved by growing and growing the crystal grains. The annealing temperature is equal to or higher than the recrystallization temperature, similar to the hot temperature described above, but is preferably 850 to 1150 ° C., more preferably 950 to 1100 ° C., for example. The heating time is preferably 30 minutes to 1.5 hours, more preferably 45 minutes to 60 minutes.

By slowly cooling the iron alloy material from the annealing temperature, the annealing process is completed, and an iron alloy member having excellent vibration damping properties is obtained. If the cooling rate exceeds 1000 ° C./min (for example, water cooling), the vibration damping performance deteriorates due to distortion in the vibration damping alloy member, which is not desirable. Therefore, it may be performed by air cooling or furnace cooling using a heating furnace. The cooling rate is preferably 1 to 10 ° C./min, more preferably 3 to 6 ° C./min.

<Damping alloy member>
The iron alloy member of the present invention is excellent in various mechanical properties such as strength, rigidity, and toughness because the base is Fe in addition to the above-described vibration damping properties and elongation. For example, the tensile strength is 360 MPa, which is sufficiently high. In addition, since the iron alloy of the present invention is excellent in heat resistance (high temperature stability of vibration damping), even if the usage environment is at a high temperature (up to about 300 ° C.), the vibration damping property hardly decreases. Thus, since it is excellent in various mechanical characteristics, the iron alloy of the present invention can be sufficiently used as a structural member. Therefore, if the conventional structural member is replaced with the iron alloy member of the present invention, the above-described vibration damping properties can be provided. In particular, a desirable application of the vibration damping member made of the iron alloy of the present invention includes general mechanical equipment used in a strain amplitude region (near 1 × 10 ⁻⁴ ) in which the vibration damping property is satisfactorily exhibited. .

The present invention will be described more specifically with reference to examples and comparative examples.

<Manufacture of test pieces>
(1) Melting of iron alloy material Pure ingots of pure Fe, pure Cr, pure Al, and pure Mn were prepared as raw materials and blended in various alloy compositions shown in Table 1. These blended raw materials were put in an alumina crucible and melted in a high-frequency vacuum melting furnace. In this dissolution, after evacuating to 0.1 to 0.5 torr (13.322 to 66.661 Pa), Ar gas was introduced to 100 torr (133332.2 Pa), and after degassing, Ar gas to 500 torr (66661 Pa) was introduced. Was carried out in an atmosphere introduced. The melting temperature at this time was 1530 ° C., and 5 kg of molten metal was prepared by one melting. The molten iron alloy thus obtained was poured into a cast iron mold under an argon gas atmosphere and solidified by natural cooling. In this way, a cylindrical test piece material (iron alloy material) of φ70 mm × 130 mm was obtained.

(2) Hot working process Hot rolling (plastic working) was performed on these test piece materials in an air atmosphere (hot working process). Prior to the rolling, heating (preheating) at 1000 ° C. for 1 hour was performed in advance. The rolling reduction ratio expressed by (thickness before rolling−thickness after rolling) / (thickness before rolling) was 75%.

(3) Annealing process The test piece material after hot rolling was placed in a heating furnace in an air atmosphere and heated at 1050 ° C for 60 minutes, and then cooled to room temperature over 6 hours. The cooling rate was about 5.4 ° C./min.

Through the above steps, a plate-like test piece (10 mm width × 160 mm length × 3 mm thickness) for vibration damping evaluation was obtained.

<Measurement>
(I) Analysis of alloy composition About each sample obtained by said procedure, the composition analysis was carried out by the wet analysis, and the analysis composition of the whole iron alloy was obtained. The basic element compositions thus obtained are shown in Table 1 as “analytical values”. In Table 1, “-” indicates any of unblended, unanalyzed or unmeasured, unanalyzed or unmeasurable.

(II) Evaluation of vibration damping property The loss factor was measured by the cantilever method using the plate-like test piece after heat treatment. FIG. 10 is an explanatory diagram of the cantilever method. The cantilever method is a method of measuring a strain attenuation curve by generating a free vibration by fixing one end of a test piece with a vise to form a cantilever having a predetermined free length. As measurement conditions, a strain gauge was bonded at a position 80 mm from the other end, the free length was 130 mm, and the other end was vibrated with a hammer to generate free vibration. The applied vibration had a frequency of 100 Hz and a strain amplitude of 1 × 10 ⁻⁴ . Then, a signal from a dynamic strain meter connected to the strain gauge was detected with an oscilloscope to obtain a strain attenuation curve.

An outline of the strain attenuation curve is shown in the lower right of FIG. The loss factor was calculated by reading the amplitude of the response displacement from the damped free vibration waveform and calculating η using the equation of FIG. The results are shown in Table 1 and FIG.

(III) Evaluation of ductility A tensile test was performed to measure the elongation at break of the iron alloy material (test piece material). The elongation was measured at 25 ° C. according to JISG0567. The results are shown in Table 1 and FIG.

(IV) Observation of metal structure From the results of the above tensile test, # 41, # 42 and # 52 where the elongation was less than 40%, # 13, # 21, # 32 and # 52 where the elongation was 40% or more A cross section of 46 iron alloy materials (test specimen materials) was observed using a metal microscope. The results are shown in FIGS.

The column “Evaluation” in Table 1 indicates a case where the loss factor η exceeds 0.0173 and the elongation is 30% or more. , And. Further, since # 00 does not contain Al, the Mn / Al value cannot be calculated, but the Mn / Al value is set to “0” and shown in FIGS.

According to the analysis of the alloy composition, in the samples # 11 to # 71 shown in Table 1, 0.41 to 5% of Al is added to # 00 and the Mn content is in the range of 0.48 to 4.97%. there were.

From # 61 and # 71, it was found that when the Al content is large, the vibration damping property is improved, but the ductility is lowered. In order to improve the ductility, that is, the workability of the iron alloy material, the Al content needs to be 2% or less, and further, the elongation is 40% or more by making the Al content 0.8% or less. I found out.

From FIG. 1, the loss factor tended to decrease as the Mn / Al value increased. From the vicinity of the Mn / Al value of 2.1, η greatly decreased as the Mn / Al value increased. It was found that when the Mn / Al value exceeds 2.3, the loss factor is lower than that of # 00 containing no Al. When the Mn / Al value was 1.8 or less, a loss coefficient of 0.03 or more was shown regardless of the amount of Al.

On the other hand, the elongation tended to improve as the Mn / Al value increased from FIG. The Mn / Al value was 0.6 or more, and the elongation was 30% or more. For each sample having an Al content of 0.4 to 1%, the ductility tends to increase until the Mn / Al value is 1.2, and the elongation of about 40 to 55% is stabilized at 1.2 or more. Showed.

That is, an Fe—Cr—Al—Mn alloy having a Mn / Al value of 0.6 to 2.3 and an Al content of 0.4 to 0.8% is superior to # 00 in vibration damping properties. % Elongation was found. In particular, an Fe—Cr—Al—Mn alloy having an Mn / Al value of 0.6 to 1.8 and an Al content of 0.4 to 0.6% has both vibration damping properties and workability compared to # 00. I found it excellent.

Further, from observation of the metal structure, it was found that the crystal grain becomes finer as the sample has a higher ductility and a higher Mn / Al value. # 41 was a sample with poor elongation and a small Mn / Al value, and several crystal grains were observed in one field of view shown in FIG. As the amount of Mn increases in the order of # 41 (FIG. 6), # 42 (FIG. 7), and # 46 (FIG. 8), the number of crystal grains observed in one field of view increases. The solidification structure was fine due to the grain refinement effect. However, # 13 (FIG. 3), # 21 (FIG. 4) and # 32 (FIG. 5), which have larger crystal grains than # 46, had a larger elongation. In other words, the solidified structure was finer when the Mn content was higher, but when the Mn content was 3% or more and more than 4% (for example, # 46 and # 53), it was ductile for the size of the crystal grains. Was found not to improve.

Claims

When the total is 100% by mass (hereinafter simply referred to as “%”),
3-8% chromium (Cr),
0.4-2% aluminum (Al),
Manganese (Mn) having a mass ratio (Mn / Al) to Al of 0.6 to 2.3;
An iron alloy excellent in workability used for a vibration damping member, wherein the balance is iron (Fe) and inevitable impurities and / or modifying elements.
The iron alloy according to claim 1, comprising 0.4 to 0.8% of Al.
The iron alloy according to claim 1 or 2, wherein Mn / Al is 0.6 to 1.8.
The iron alloy according to any one of claims 1 to 3, comprising 0.4 to 0.6% of Al.
The iron alloy according to any one of claims 1 to 4, comprising 4 to 6% of Cr.
A loss coefficient indicating the vibration damping property in the strain amplitude range of 1 × 10 −4 to 2 × 10 −4 and the frequency range of 90 to 120 Hz is 0. A vibration damping member characterized by being .01 or more.