JPH03183741A - Steel having excellent vibration damping properties and its manufacture - Google Patents

Abstract

PURPOSE:To improve the vibration damping properties in the steel by subjecting steel stock having reduced content of C and N and incorporated with a specified amt. of Al to heat treatment under a specified temp. condition. CONSTITUTION:A steel constituted of, by weight, 0.0005 to 0.01% C, 0.0005 to 0.01% N, 0.001 to 0.25% Si, 0.005 to 0.20% Mn, 0.3 to 1.5% acid soluble Al and the balance Fe with inevitable impurities is refined to manufacture an ingot by a mold. In the case an A3 transformation point is present in the steel stock (in the case the content of Al is <0.9%), it is heated from >=900 deg.C to the A3 transformation point or below. In the case an Al point is not present therein (in the case the content of Al is >=0.9%), it is subjected to heat treatment at 900 to 1300 deg.C. In this way, the steel having good vibration damping properties in which the average size of ferrite crystals is coarsened to >=0.1mm and coercive force in the state free from strains is regulated to <=0.7 Oe can be obtd.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a steel material with excellent vibration damping properties useful for vibration and soundproofing when applied to structural component parts, machine parts, containers, fixtures, etc. and its manufacturing method.

[Problems to be solved by conventional techniques and inventions] In recent years,
Efforts are being made everywhere to reduce various vibrations and noises. Structural improvements have been made for the purpose of vibration and soundproofing, and the effects have been achieved to some extent. Furthermore, using a material with excellent vibration damping properties (hereinafter abbreviated as vibration damping material) is also an extremely effective means for vibration and sound insulation.

Based on this, we have developed a wide range of products including resin-based materials such as plastics and rubber, composite materials of steel plates and resins, Mn-Cu alloys, flaky graphite cast iron, steel materials with internal defects such as inclusions and minute cracks, and high Cr. Many studies have been conducted on various damping materials such as ferrite stainless steel and soft iron.

Among these damping materials, iron-based damping materials (hereinafter referred to as damping steel materials) have high strength, high Young's modulus, good vibration damping characteristics even at temperatures of 100°C or higher, and are inexpensive. It has advantages and is in high demand.

Among these damping steel materials, high Cr ferrite stainless steel,
Soft iron is a damping material that utilizes ferromagnetism, and when applied to structures and mechanical parts, it is much more reliable than steel materials that contain internal defects.

By the way, regarding the vibration damping mechanism of ferromagnetic vibration damping steel materials, for example, Amano et al., "Ferromagnetic vibration damping alloy" Material Science No. 5/6, Vol. 115 (1978), No. 25
ONl:! A-listed tale. Here, the vibration energy causes a 90° domain wall movement through magnetostriction, resulting in
It has been shown to produce magneto-mechanical hysteresis and absorb vibrational energy by converting it into thermal energy. In addition, there are ways to improve this function, such as reducing impurity elements, removing internal strain by heat treatment, coarsening crystal grains, and reducing the coercive force of the material associated with these, and increasing magnetostriction by adjusting the chemical composition. It has been shown that it is effective to facilitate domain wall movement.

Many patents have also been filed for ferromagnetic damping steel materials. Japanese Patent Publication No. 56-28982, Japanese Patent Publication No. 57-43681, and Japanese Patent Publication No. 59-5653 are based on mild steel or pure iron and are designed to improve vibration damping characteristics. Among these, the special public official
28982 includes reduction of interstitial impurity elements, Si, M
n, A.I.

It is disclosed that the vibration damping properties are improved by magneto-mechanical hysteresis by addition of Cr, and in addition to this, the vibration damping properties are improved by the movement of dislocations after cold working. Tokuko Sho 57-43681, Tokuko Sho 5
Nos. 9 to 5653 all aimed to reduce interstitial elements on the premise of decarburization annealing.

Special Publication Showa 57-181360. Special Publick Showa 582262 is A
A damping steel material containing 1.5 to 9.0% of 1 is disclosed. There are no regulations regarding heat treatment or coarsening of crystals, and there is no provision for reducing impurities and Al,
The main purpose of the invention is to increase tensile strength without impairing vibration damping properties by adding Mn.

On the other hand, in Japanese Patent Publication No. 56-46529, Si of 3% or less and AI of % or less were added in combination, and 6% was added after cold working.
A vibration-damping steel material is disclosed in which the crystal grains are coarsened by performing strain annealing at a temperature of 50° C. or higher, thereby improving vibration damping characteristics. This steel material has an upper limit of Cff1 of 0.1%.
Therefore, it is difficult to raise the transformation point to a sufficiently high temperature. Therefore, in that example, the upper limit of the annealing temperature is 950.
℃, and the coarse grains also have a grain size number of -
No. 2 (JIS GO552), which indicates that the vibration damping characteristics are not sufficient.

Japanese Patent Publication No. 52-115720, Japanese Patent Publication No. 57-44740, etc. disclose high Cr vibration damping steel materials. Special Public Service 1987
-44740 states that in order to obtain good vibration damping characteristics with high Cr vibration damping steel materials, two-stage heat treatment corresponding to quenching and tempering treatments is required.

Furthermore, high Al type vibration damping steel materials are disclosed in Japanese Patent Publication No. 52-803, Japanese Patent Publication No. 58-27325, etc.

However, among the distributed steel materials disclosed in the above publications, etc.,
Those that exhibit satisfactory vibration damping properties require special heat treatments such as decarburization or two-step heat treatment, or require a large number of alloying elements, resulting in high manufacturing costs.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a low-cost steel material with excellent vibration damping properties and a method for manufacturing the same.

[Means and effects for solving the problem] The steel material having excellent vibration damping characteristics according to the present invention has a weight percentage of 0.0005
0.01% C10,0005 0.01% N
, 0.001-0.25% Si, 0.005-0
．． It consists of 20% Mn, 0.3 to 1.5% acid-soluble At, the balance Fe and unavoidable impurities, the average grain size of the ferrite crystal is 0.1 square or more, and the coercive force in the unstrained state is In particular, the method for producing a steel material having excellent vibration damping properties according to the present invention is characterized in that the carbon content is 0.7 Oe or less.
0,0005-0.01% N, 0.001-0.
25% Si.

0.005-0.20% Mn, 0.3-1.5%
A material consisting of acid-soluble Al, the balance Fe and unavoidable impurities is A, and if there is no transformation point, the temperature is 900°C or higher13
9 if the A3 transformation point exists at a temperature below 00°C.
It is characterized in that the heat treatment is carried out at a temperature of 00°C or higher and lower than the A3 transformation point.

In order to obtain a steel material with excellent vibration damping characteristics, it is desirable that the material be a single ferrite phase and have large crystal grains, as typified by pure iron vibration damping steel materials.

Based on this premise, the inventors of the present application conducted various studies on steel materials that are low in cost and have excellent vibration damping characteristics, and as a result, the following findings were obtained.

■Reducing interstitial impurity elements such as C and N to the extent that does not result in extremely high costs using current steelmaking technology, and
Steel materials containing I tend to have a higher A transformation point than pure iron, and when the AI content exceeds a certain amount, the A transformation point no longer exists.

This will be explained with reference to FIG. FIG. 1 is a graph showing the influence of Ali on the transformation temperature of ultra-low CSN steel, with the content of acid-soluble AI on the horizontal axis and the temperature on the vertical axis. This shows the results.

In addition, here, C is 0.001 to 0.002% by weight,
A steel material containing 0.0006 to 0.0020% by weight of N was used. As confirmed from this graph, the transformation temperature is approximately 900"C in the absence of AI, but as Aljl increases, the transformation temperature tends to increase.
is 0.3%, the transformation temperature is 950°C. Therefore, A
When I is set to 0.3% or more, it becomes possible to maintain the ferrite single phase even if heat treatment is performed at a high temperature of 950° C. or higher. Furthermore, from this graph, it can be confirmed that when 0.9% or more of AI is contained, there is no transformation temperature and a single phase of ferrite occurs in the entire temperature range.

(2) In heat treatment to actively coarsen ferrite crystal grains, the upper limit of the treatment temperature is usually A, the transformation point. AI
If the amount added is less than 0.9%, A, a transformation point exists, so
In order to perform such heat treatment at a high temperature of 900°C or higher, it is necessary to maintain the A3 transformation point at least at 900°C or higher. Therefore, A, C significantly lowers the transformation point,
It is necessary to particularly reduce the N content. Furthermore, even if the AI content is 0.9% or more, if the C and H contents are large, the A3 transformation point may appear. It is desirable to sufficiently reduce the However, if the C and N contents are sufficiently reduced and AI is contained at 0.9% or more, the metallurgical reason is that the ferrite is a single phase over the entire temperature range, as described above. There is no upper limit for the heat treatment temperature.

■As mentioned above, ultra-low C, N and AI-containing steel materials can be heat treated at high temperatures, so no matter what processing history they undergo, heat treatment at temperatures as high as 900°C or higher will significantly coarsen the grains. can be made into In addition, such heat treatment can also reduce coercive force, which leads to improvement in vibration damping characteristics. That is,
Coercive force depends not only on the composition but also on the particle size, so extremely low C, N
By coarsening the crystal grains in this manner while maintaining the Al-containing composition, the coercive force can be lowered, thereby improving vibration damping characteristics.

The present invention having the above configuration has been made based on such knowledge of the present inventor.

The present invention will be explained in detail below.

As mentioned above, the steel material according to the present invention has a weight percentage of 0.
0005-0.01% C10,0005-0.0
1% NSO, 001-0.25% Si, 0.00
It is composed of 5 to 0.20% Mn, 0.3 to 1.5% acid-soluble Al, and the balance Fe and inevitable impurities.

The reasons for limiting the composition will be explained below.

Both C and N invade the crystal lattice of iron as impurity elements, significantly impairing the vibration damping characteristics based on magneto-mechanical hysteresis, and also significantly lowering the transformation temperature that should be raised by adding A1. Therefore, it is desirable to reduce these as much as possible. However, with the current level of steel manufacturing technology, it is difficult to reduce these to an extreme degree, and it also results in high costs. From this point of view, both C and N are defined within the range of 0.0005 to 0.01%. In addition, when the amount of AI added is less than 1%, the content of C and N is preferably 0.005% or less from the viewpoint of preventing the transformation temperature from decreasing as much as possible.

Like AI, Si has the effect of stabilizing the ferrite phase and increasing the transformation temperature, but this effect is smaller than that of AI, and in this invention, this effect is carried out by AI.
Aggressive addition of St is unnecessary and simply results in higher costs. On the other hand, extremely reducing the St content also results in higher costs. Therefore, taking these into consideration, Si is defined within the range of 0.001 to 0.25%.

Mn is a substitutional impurity element, and has little adverse effect on vibration damping characteristics and coercive force, which has a strong correlation therewith. Further, when hot working is performed, a certain amount of Mn is necessary from the viewpoint of preventing processing deterioration such as cracking due to S inevitably mixed in as an impurity. On the other hand, aggressive Mn
Although the addition of Cr increases the mechanical strength of the material, too much Cr may lower the transformation temperature. Furthermore, extremely lowering the Mn content results in an increase in cost.

From this point of view, Mn was set within the range of 0.005 to 0.20%.

AI is an element mainly added to increase the transformation temperature, and as mentioned above, adding 0.3% or more can significantly increase the transformation temperature, and adding 0.9% or more This also makes it possible to substantially eliminate the transformation point. As a result of the transformation temperature increasing or disappearing,
By increasing the heating temperature during high-temperature heat treatment or hot working, coarsening of crystal grains and a corresponding decrease in coercive force can be effectively prevented. On the other hand, if the content exceeds 1.5%, steel manufacturing costs such as increased raw material costs and consumption of refractories will increase. Therefore, AI is defined as acid-soluble AI within the range of 0.3 to 1.5%.

In addition to such compositional limitations, the present invention also defines the ferrite crystal grain size and coercive force.

As mentioned above, in order to obtain good vibration damping characteristics ε, it is sufficient to increase the ferrite crystal grain size and decrease the coercive force. Conventional pure iron vibration damping steel has an average grain size of 0.1■ and a coercive force of 0.7Oe in an unstrained state.
Therefore, the average crystal grain size of ferrite is set to 0.1.
By setting the coercive force at m11 or more and 0.7 Oe or less in a state without distortion, it is possible to obtain better vibration damping characteristics than conventional pure iron vibration damping steel materials. In order to obtain good vibration damping characteristics, it is preferable that the average crystal grain size of the ferrite is 0.2 square or more and the coercive force is 0.50e or less. In addition, since it has been known that vibration damping characteristics deteriorate in a state where machining strain remains, it is preferable that no machining strain remains in the steel material.

However, with the steel material according to the present invention, even if processing strain remains, it is possible to obtain vibration damping characteristics comparable to or higher than that of conventional pure iron vibration damping steel materials.

With steel materials within the above composition range, it is possible to increase the heat treatment temperature higher than that of conventional pure iron vibration damping steel materials, so it is possible to increase the size of ferrite grains by adjusting heat treatment and hot working. An average particle size of 0.1 mm or more can be achieved. Further, in conjunction with this, the coercive force in a state without processing distortion can be reduced to 0.7 Oe or less.

A specific method for manufacturing the damping steel material according to the present invention as described above will be explained.

In the present invention, a material within the above-mentioned composition range is heat-treated to coarsen the crystal grains, thereby improving vibration damping characteristics. Therefore, the method of forming the material is not particularly limited, and any of hot working, warm working, and cold working can be applied. This means that the steel materials targeted by the present invention include hot-worked steel materials, warm-worked steel materials, and cold-worked steel materials, and the types of steel materials include thick plates, thin plates, long steel (shaped steel, etc.), and forged steel. This means that it includes steel, etc.

The heat treatment is preferably carried out at as high a temperature as possible in order to sufficiently coarsen the ferrite crystal grains.

Specifically, if A, a transformation point exists (i.e., AI
When the AI content is less than 0.9%), it is carried out at a temperature of 900 °C or higher, A, at a temperature below the transformation point, and A, when the transformation point does not exist (i.e., when the AI content is 0.9% or more) ) is preferably carried out at a temperature of 900°C or higher and 1300°C or lower.

A. If there is a transformation point, beyond which it will be impossible to maintain the ferrite single phase;
If the temperature is below .degree. C., the crystals cannot be sufficiently coarsened, and the effect of increasing the transformation temperature caused by the addition of AI cannot be effectively utilized. A
If there is no transformation point, there is no metallurgical upper limit on the heat treatment temperature, but heat treatment at temperatures higher than 1300°C is unrealistic and will increase costs, so the upper limit is set at 1300°C. stipulate. Further, although it is difficult to specify the heat treatment holding temperature because it changes depending on the heat capacity of the target steel material, it is generally preferable to hold the heat treatment for 30 minutes or more. In addition, when hot working at 900°C or higher and then manufacturing steel products without rapid cooling (preferably by slow cooling), the result is that the heat treatment for grain coarsening is completed during processing. Become. In this case, good vibration damping characteristics can be obtained without performing a separate heat treatment afterwards.

In addition, when using it in a solidified state, such as by casting, it is possible to coarsen the crystal grains without performing final heat treatment by cooling slowly, preferably without rapid cooling during the cooling process. It is possible to obtain excellent vibration damping characteristics.

As described above, in the present invention, a steel material with extremely good vibration damping characteristics can be obtained without increasing the alloy component of the material and without performing special and complicated heat treatment. Therefore, a steel material with excellent vibration damping characteristics can be obtained at low cost.

[Example] Examples of the present invention will be described in detail below.

Here, steel having the composition shown in Table 1 was melted, and then an ingot was produced in a mold, which was heated to 1100 to 1200°C, hot rolled, and formed into a plate with a thickness of 12 to 50 mm. A test piece was prepared and subjected to the test. In Table 1, A to ■ are steel types within the composition range of the present invention, and J-L are comparative steel types outside the composition range of the present invention. In addition, in Table 1, So
1, AI indicates acid-soluble AI.

Table 2 shows the heat treatment conditions, average grain size, coercive force, and logarithmic decay rate of the plate material produced as described above. Experiment numbers 1 to 9 in Table 2 are based on this invention.
No. 3 is a comparative example outside the scope of this invention.

The vibration damping characteristics are the logarithmic damping rate of the amplitude when a tuning fork that vibrates at approximately 800 Hz is machined from a plate material and is vibrated approximately 125 times after approximately 0.4 seconds after excitation. evaluated. Specifically, the logarithmic attenuation rate δ is expressed by the following formula.

However, n: 125 X: Amplitude after 0.4 seconds after excitation did. In these cases, the influence of processing strain on the test specimen has been removed.

In addition, the coercive force is determined by δ using the method based on JIS C2504.
The average crystal grain size was determined based on micrographs.

As is clear from Table 2, test numbers 1-
No. 9 shows a high logarithmic attenuation rate. It is also confirmed that the lower the coercive force, the higher the logarithmic attenuation rate.

On the other hand, among test numbers 10 to 3 which are comparative examples, test number 10.11 is based on Japanese Patent Publication No. 57-44740, and is based on steel type J containing a large amount of Cr as an alloy component. Test number 10 is Special Publication No. 57-4474
Similarly to Test No. 0, after quenching at 1000°C, tempering treatment was performed at 750°C, and Test No. 11 was subjected to heat treatment only at 1000°C. As shown in Table 2,
Test No. 10 showed relatively good vibration damping characteristics after two heat treatments, but test No. 11, which underwent one heat treatment, had residual machining distortion and had insufficient vibration damping characteristics. In other words, with high Cr ferrite stainless steel such as Japanese Patent Publication No. 57-44740, good vibration damping characteristics cannot be obtained with one heat treatment as in the present invention, and even with two heat treatments, the vibration damping characteristics themselves cannot be achieved. It was confirmed that the value was lower than that of the example. Furthermore, this high Cr ferrite stainless steel is expensive and disadvantageous in terms of cost.

It can be seen that in test number 12.13, the transformation temperature was not increased by the addition of AI, and the ferrite crystal grains were not sufficiently coarsened. Therefore, compared to the example, the coercive force is large and the logarithmic attenuation rate is small.

Regarding test numbers 5, 12.13, tuning forks were fabricated by machining after heat treatment or without heat treatment, and the test was conducted with machining distortion remaining.

Test number 5-. 12'', 13- in Table 3.

Table 3 As shown in Table 3, it can be confirmed that due to residual machining strain, the coercive force increases and the logarithmic attenuation rate decreases. 5', a logarithmic damping factor almost equivalent to test number 12 of the conventional pure iron vibration damping material was obtained. That is, the steel material of the present invention is
It was confirmed that high vibration damping characteristics were maintained even if machining distortion remained.

Note that FIG. 2 shows a chart of actual vibration damping in test number 5, which is an example, and FIG. 3 shows a chart of actual vibration damping in test number 13, which is a comparative example.

As is clear from these figures, the example exhibits extremely good vibration damping characteristics, while the comparative example exhibits poor vibration damping characteristics.

FIG. 4 is a diagram showing the relationship between coercive force and logarithmic decay rate based on these test results. In the figure, black circles indicate a state in which there is no distortion, and white circles indicate a state in which distortion remains. From this figure, the smaller the coercive force, the higher the logarithmic decay rate, and when the coercive force becomes 0.7 Oe or more in the absence of distortion,
It was confirmed that the logarithmic attenuation rate was a good value of 100 or more. It can also be seen that the logarithmic attenuation rate tends to decrease in a state where distortion remains.

Next, the damping ratio was measured when there were multiple resonance frequencies. Here, a vibrator having an outer diameter of 43 mg+, an inner diameter of 36 m and a length of 200 cm was prepared using Steel E1 and Steel J1 in Table 1, and the vibration damping characteristics were measured after heat treatment. Here, the vibration damping characteristics were evaluated using the frequency domain partial division method for the vibration damping behavior obtained by the percussion excitation method. The results are explained in Table 4. In Table 4, test number 14 is an example within the scope of the present invention, and test numbers 15 and 16 are comparative examples. Among these, test number 15 is based on Japanese Patent Publication No. 57-44740, and contains a large amount of Cr as an alloy component, requiring complicated heat treatment and high cost. Here, the resonance frequencies are 5.2 kHz, 6.0 kHz, 6.
7 kilohertz was used.

Table 4 As shown in Table 4, test number 14 of the example showed better values than test number 16 of the comparative example, and it was confirmed that it showed the same characteristics as test number 15, which was more expensive. .

[Effect of the invention] According to the invention, while maintaining excellent vibration damping characteristics,
A steel material that can be manufactured at low cost and a method for manufacturing the same are provided. Therefore, the present invention is extremely useful in the field of soundproofing and vibrationproofing.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the relationship between aluminum content and transformation temperature, Fig. 2 is a diagram showing the vibration damping characteristics of a steel material according to an example of the present invention, and Fig. 3 is a diagram showing the vibration damping characteristics of a steel material according to a comparative example. FIG. 4 is a diagram showing the relationship between coercive force and logarithmic damping rate of steel material.

Claims (2)

[Claims] (1) 0.0005 to 0.01% C by weight%, 0
．． 0005-0.01% N, 0.001-0.25% Si, 0.005-0.
It consists of 20% Mn, 0.3 to 1.5% acid-soluble Al, the balance Fe and unavoidable impurities, the average grain size of the ferrite crystal is 0.1 mm or more, and the coercive force in the unstrained state is 0. A steel material with excellent vibration damping properties characterized by a vibration damping property of .7 Oe or less. (2) C, 0.0005 to 0.01% by weight, 0
．． 0005-0.01% N, 0.001-0.2
5% Si, 0.005-0.20% Mn, 0.3
A material consisting of 1.5% to 1.5% acid-soluble Al, the balance Fe and unavoidable impurities is
A method for producing a steel material with excellent vibration damping properties, characterized in that heat treatment is performed at a temperature of 00°C or more and 1300°C or less, and if an A_3 transformation point exists, a temperature of 900°C or more and A_3 transformation point or less.