KR920007939B1 - Fe-mn alloy for damping capacities & the making process - Google Patents

Abstract

The vibration damping alloy steel having martensite type structure is prepared by adding 10-22 wt.% Manganese to iron based steel; (a) producing the ingot by dissolving an electrolytic iron and an electrolytic manganese together, (b) hot rolling the ingot after heat treating the above homogeneously at 1,000-1,300 deg.C for 20-40 hrs., (c) cooling by air or water after heating it at 900-1,100 deg.C for 30n mins. - 1 hr.

Description

Fe-Mn vibration damping alloy steel and its manufacturing method

1 is a binary state diagram of an Fe—Mn alloy.

2 is the transformation amount of the Fe-Mn alloy.

3 is a vibration damping curve of Fe-Mn alloy

3a is a state diagram of an Fe-4% Mn alloy.

3b is a state diagram of the Fe-17% Mn alloy.

The present invention relates to an anti-vibration alloy having a vibration damping ability, and more particularly, to an iron-based (Fe-Mn) vibration damping alloy having excellent damping ability while maintaining high strength and a method of manufacturing the same.

Recently, the use of anti-vibration alloy materials having excellent damping ability has been widely used to prevent vibration and noise generated by machines and devices in various industries such as aircraft, ships, vehicles, machinery, or precision instruments. As the conventional anti-vibration alloy, Cu-Mn alloy, Ni-Ti alloy and stainless alloy steel using twin transformation are known. Such alloys have excellent damping ability in the vicinity of room temperature, but are expensive factors due to the use of expensive metals, and deterioration of cold workability and precision and complexity in the manufacturing process for each element are required. In addition, Al-Zn alloys and cast iron alloys do not meet the tensile strength or hardness. On the other hand, austenite-based low-temperature anti-vibration alloy, which is a high Mn steel, is known from Japanese Laid-Open Patent Publication No. 56-258.

In this alloy, the addition of chromium (Cr) and aluminum (Al) or elements such as Mo, V, Nb, Ti increases the price of the product, and in order to obtain a stable austenite structure, in particular, carbon (C) And physical properties appropriate for austenite, such as the need to precisely adjust the Cr content.

There are three main types of vibration damping: relaxation, resonance, and hysteresis.

The damping by the relaxation type does not depend on the amplitude of the vibration but depends on the frequency and is not considered in terms of dust protection.

The resonance type, like the relaxation type, depends not on the amplitude of the vibration but on the frequency. In this case, the maximum damping capacity appears at the resonance frequency. However, this type of damping capacity is also not important in terms of the anti-vibration alloy.

Hysteresis is a damping form caused by different paths in stress-strain when external stress is applied and when stress is removed. In this case, energy corresponding to hysteresis loss causes attenuation. Therefore, this type of damping ability is independent of the frequency and is highly dependent on the strain amplitude. This hysteresis type may exhibit a large damping ability irrespective of the frequency, and thus may have an industrial dustproof effect.

Therefore, the alloy of the present invention has developed a hysteresis type dustproof alloy, and based on iron (Fe), manganese (Mn) is added thereto, thereby maintaining excellent strength while maintaining high strength without using expensive elements as in the prior art. It is an object of the present invention to provide an inexpensive, low-cost vibration damping alloy that can be used at room temperature.

Hereinafter, the present invention will be described in more detail.

The present invention is made of a Fe-Mn-based vibration damping alloy which is a martensite structure in which 10% to 22% of Mn is added as a weight% based on Fe.

In manufacturing the alloy steel according to the present invention, first, the electrolytic iron and the manganese prepared in the above composition ratio, the melting temperature of the electrolytic iron first in the induction furnace or electric furnace to 1500 ℃ or more, and then the electrolytic iron is melted here Add manganese to the melt. It is then cast into a mold to make an ingot. This was homogenized at 1000-1300 ° C. for 20-40 hours and then hot rolled to produce dimensions of a predetermined shape. And after heating at 900-1100 degreeC for about 30 minutes-1 hour, air-cooling or water cooling gives the alloy steel of this invention which is a martensitic structure.

In the present invention, the amount of Mn is 10-22% by weight, α'-martensite is produced up to 10% Mn, ε-martensite starts to form at 10% or more, and becomes austenite structure at 20% or more Mn. , α′-martensite structure has a small vibration damping ability and ε-martensite tissue has a very large vibration damping ability, so the vibration damping ability is set to 10-22%.

In the present invention, the C, Si, P, and S elements are not particularly limited, but the present invention is intended to obtain martensite structure as a high Mn steel, and thus does not significantly affect the effects of C and Si.

Therefore, C, Si, P, S is an inevitable impurity, and is not particularly limited unless it is more than a range that affects steel. In addition, the homogenization treatment conditions (temperature, time) are for the complete solution of Mn and other impurity elements in austenite.

Next, the effect of the present invention will be described according to the embodiment of Tables 1 to 3 and FIGS.

1 and 2 show the Fe-side portion of the binary system diagram of Fe-Mn, which is the basis of the present invention. The transformation point of the diagram is a thermal expansion test, magnetic analysis, and X-ray after cooling at a cooling rate of 3 ° C / min. It determined by performing a diffraction test, an optical microscope test, etc.

In FIG. 1, up to 10% Mn produces α′-martensite, at 10-15% Mn produces mixed martensite of α ′ + ε, and at 15-28% ε martensite.

FIG. 2 shows the volume fraction of each phase by heating each Mn alloy at 1000 ° C. and air-cooling at room temperature.

As shown in Table 1, the alloys showing α′-martensite have very low vibration damping ability, and the alloys showing ε martensite structure have very high vibration damping ability and excellent tensile strength. there was.

TABLE 1

Comparison of Vibration Attenuation by Martensitic Structures

The reason why the ε-martensite has a larger vibration damping ability than the α'-martensite is that the lower structure of the α'-martensite is dislocation, so that ε + γ is reduced to absorb the vibration energy caused by the vibration of the potential. In the mixed structure, as mentioned above, the material was subjected to vibration stress and the interface of ε / γ moved and absorbed vibration energy.

TABLE 2

Comparison of Vibration Attenuation by Mn Composition Ratio

As shown in Table 2, the alloy steel according to the present invention had excellent damping ability without significant difference in air cooling or water cooling as compared with the comparative steel.

TABLE 3

Comparison of Hardness after Water Cooling with Mn Composition Ratio

In the present invention, as shown in Table 3, the hardness value (HRB) is in the range of 88-90, whereas the comparative steel is 85 or less, and in particular, Fe-28% Mn was lowered to 60 because of the austenite structure.

On the other hand, the alloy is hot-rolled after homogenizing 20-40 hours at 1000-1300 ℃, the reason for heating about 900-1100 ℃ 30 minutes-1 hours at room temperature will be described in Table 4 below. If heated above 1000 ℃, the grain becomes coarse and the tensile strength is lowered.If heated below 900 ℃, the temperature is too low to refine the grain and the tensile strength is increased. . Therefore, the most appropriate heat treatment temperature with damping ability and tensile strength is 900-1100 ℃.

TABLE 4

Damping ability and mechanical properties according to the heat treatment temperature (water cooling)

3 shows the amplitude attenuation curve when the maximum surface strain is oscillated at γ = 2 × 10 ⁻⁴ with rod-shaped specimens.

In Fig. 3a, the amplitude of the Fe-4% Mn steel, which is α 'martensite structure, is almost unchanged over time. Attenuated and disappearing. Therefore, it can be seen that the alloy steel within the Mn% range according to the present invention has superior vibration damping performance as compared with the comparative steel.

Claims (2)

Fe-Mn-based vibration damping alloy steel, which is a martensite structure, characterized by forming 10-22% of manganese (Mn) as a weight% based on iron (Fe). By mixing and dissolving electrolytic iron and manganese, Mn is 10-22% by weight, and the remainder is cast as molten metal by Fe to make an ingot, which is homogenized at 1000-1300 ° C. for 20-40 hours and hot rolled. Method for producing a Fe-Mn-based vibration damping alloy steel of martensitic structure characterized in that the air-cooled or water-cooled after heating 30 minutes to 1 hour at 900-1100 ℃ temperature.

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