KR102109898B1 - LOW-Cr FERRITIC STAINLESS STEEL WITH EXCELLENT VIBRATION DAMPING PROPERTY AND MANUFACTURING METHOD THEREOF - Google Patents

Abstract

Disclosed is a low-Cr ferritic stainless steel having excellent vibration damping ability that absorbs external vibration energy through control of precipitates and a method for manufacturing the same.
Low Cr ferritic stainless steel having excellent vibration damping ability according to an embodiment of the present invention, by weight, C: 0.005 to 0.01%, N: 0.005 to 0.01%, Si: 0.1 to 0.9%, Mn: 0.1 to 0.9 %, Cr: 9 to 14%, Ni: 0.3% or less, P: 0.04% or less, S: 0.002% or less, Ti: 0.15 to 0.3%, Nb: 0.15 to 0.3%, Cu: 0.15 to 0.3%, Al: 0.01 to 0.05%, containing the remaining Fe and unavoidable impurities, and includes at least 5 × 10 ² / mm ² of Nb labes phase precipitates and Cu precipitates.

Description

Low-Cr ferritic stainless steel with excellent vibration damping ability and its manufacturing method {LOW-Cr FERRITIC STAINLESS STEEL WITH EXCELLENT VIBRATION DAMPING PROPERTY AND MANUFACTURING METHOD THEREOF}

The present invention relates to a low-Cr ferritic stainless steel excellent in vibration damping ability to absorb external vibration energy and a method for manufacturing the same.

Ferritic stainless steel has excellent corrosion resistance even with a small amount of expensive alloying elements, and has a higher price competitiveness than austenitic stainless steel. In particular, 9 to 14% of low-Cr ferritic stainless steel is more cost-competitive, and is used in exhaust system parts (Muffler, Ex-manifold, Collector cone, etc.) corresponding to the exhaust gas temperature range of room temperature to 800 ° C. The steel sheet for automobile exhaust systems must be able to absorb noise and vibrations generated during engine or other driving, and must be able to withstand external environmental factors such as exhaust gas, rain or fog generated inside the vehicle. Should be secured.

In order to solve this, in the case of high-Cr ferritic stainless steel, attempts have been made to improve vibration damping capacity by adjusting the number of precipitates, solid solution C, N, and inclusion size and shape, and the effect has been reported. However, there are no attempts and achievements to improve vibration damping performance by specializing in low-Cr ferritic stainless steel.

Embodiments of the present invention is to provide a low Cr ferritic stainless steel and its manufacturing method to maximize the vibration damping performance by utilizing the Nb, Cu fine precipitated phase.

Low Cr ferritic stainless steel having excellent vibration damping ability according to an embodiment of the present invention, by weight, C: 0.005 to 0.01%, N: 0.005 to 0.01%, Si: 0.1 to 0.9%, Mn: 0.1 to 0.9 %, Cr: 9 to 14%, Ni: 0.3% or less, P: 0.04% or less, S: 0.002% or less, Ti: 0.15 to 0.3%, Nb: 0.15 to 0.3%, Cu: 0.15 to 0.3%, Al: 0.01 to 0.05%, containing the remaining Fe and unavoidable impurities, and includes at least 5 × 10 ² / mm ² of Nb labes phase precipitates and Cu precipitates.

Further, according to an embodiment of the present invention, the stainless steel may satisfy the following formula (1).

(1) (Nb + Cu) / Ti ≥ 1.5

Here, Nb, Cu, Ti means the content (% by weight) of each element.

Further, according to an embodiment of the present invention, the stainless steel may satisfy the following equation (2).

(2) Nb + Cu ≤ 0.5

Here, Nb and Cu mean the content (% by weight) of each element.

Further, according to an embodiment of the present invention, the Nb-Labes-phase precipitate is Fe ₂ Nb, and the size of the Nb-Labes-phase precipitate and Cu precipitate may be 1 to 200 nm.

In addition, according to an embodiment of the present invention, the vibration damping index (Q-1) of the stainless steel may be 2.0 × 10 ^-4 or more at 25 ° C, 2.5 × 10 ^{-4 or} more at 300 ° C.

The method for manufacturing a low-Cr ferritic stainless steel having excellent vibration damping ability according to an embodiment of the present invention is, by weight, C: 0.005 to 0.01%, N: 0.005 to 0.01%, Si: 0.1 to 0.9%, Mn: 0.1 To 0.9%, Cr: 9 to 14%, Ni: 0.3% or less, P: 0.04% or less, S: 0.002% or less, Ti: 0.15 to 0.3%, Nb: 0.15 to 0.3%, Cu: 0.15 to 0.3%, Al: 0.01 to 0.05%, a step of cold rolling annealing a ferritic stainless steel cold rolled steel sheet containing the remaining Fe and unavoidable impurities at a temperature of (Ac1-10) ° C. or lower; And rapidly cooling to 400 to 600 ° C to maintain for 5 minutes or more.

In addition, according to an embodiment of the present invention, the cold rolled steel sheet may satisfy the following formula (1).

(1) (Nb + Cu) / Ti ≥ 1.5

Here, Nb, Cu, Ti means the content (% by weight) of each element.

Further, according to an embodiment of the present invention, the cold rolled steel sheet may satisfy the following formula (2).

(2) Nb + Cu ≤ 0.5

Here, Nb and Cu mean the content (% by weight) of each element.

The low-Cr ferritic stainless steel according to the embodiment of the present invention can increase vibration damping capacity by 100% or more through a sound absorbing mechanism by the movement of solid solution C and N and a vibration damping mechanism through suppression of precipitation of carbonitride.

In addition, the low-Cr ferritic stainless steel according to an embodiment of the present invention has excellent corrosion resistance, so that quietness and durability can be secured when used in automobile exhaust system parts and the like.

1 is a graph showing the correlation between the vibration damping index according to the number of Nb-Labes precipitates and Cu precipitates.
Fig. 2 is a photograph showing the distribution of Nb-Labes-like precipitates and Cu precipitates at a known interface.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following examples are presented to sufficiently convey the spirit of the present invention to those of ordinary skill in the art. The present invention is not limited to only the examples presented herein, but may be embodied in other forms. In order to clarify the present invention, the drawings may omit portions of parts not related to the description, and the size of components may be exaggerated to help understanding.

Also, when a part “includes” a certain component, this means that other components may be further included, rather than excluding other components, unless otherwise specified.

Singular expressions include plural expressions, unless the context clearly has an exception.

The present inventors conducted various studies to improve the vibration damping capacity of low Cr ferritic stainless steel, and the following findings were obtained.

The sound absorption mechanism (Snoek Effect) causes the energy loss as the C and N employed in the vibration change position within the grid, resulting in sound absorption. The sound absorption effect by solid solution C and N has a characteristic proportional to the amount of solid solution C and N, and the vibration damping effect by magnetic domain wall interferes with the movement of the magnetic domain wall such as precipitates, dislocations, and internal stress. The more elements there are, the better.

In general, a small amount of Ti and Nb is added to the ferritic stainless steel for exhaust system for corrosion resistance of the welding part. In the case of such a ferritic stainless steel containing Ti and Nb, Ti (C, N) and Nb (C, in the ferrite matrix of the surface layer inevitably) N) A large amount of carbonitride is precipitated. Since these Ti (C, N) and Nb (C, N) precipitates inhibit (Pinning) the movement of the magnetic domain wall (Magnetic Domain Wall), which is one of the vibration damping mechanisms during vibration, the vibration damping ability of ferritic stainless steel is essentially inferior. Becomes In addition, since C and N are mostly combined with precipitates of Nb and Ti, there are almost no solid solution C and N present in the ferrite matrix, and the sound absorption mechanism by the movement of solid solution C and N during vibration (Snoek Effect) Also, you cannot expect.

Meanwhile, Nb is added to the ferritic stainless steel applied to a high temperature of 400 ° C. or higher for exhaust gas for high temperature strength, and Cu is additionally added as a solid solution strengthening element. In this case, under certain heat treatment conditions, Nb Laves Phase (Fe ₂ Nb) and Cu precipitation phase having a fine size of 1 to 200 nm may be generated, and the interface between the precipitation phase having coherent and the base is external. It vibrates together in response to vibration, and absorbs external vibration energy to increase vibration damping capacity. At this time, the effect is further enhanced when it is precipitated in a complex than when it is precipitated with Nb Laves or Cu alone. However, when the size of the precipitate is coarse to more than 200 nm, the consistency of the precipitate and the base is lowered, and the number of precipitates is reduced, and the effect of improving vibration damping performance is rather offset. Therefore, it is possible to maximize the vibration damping ability by depositing fine Nb Laves-like precipitates and Cu precipitates at a known interface.

Low Cr ferritic stainless steel having excellent vibration damping ability according to an embodiment of the present invention, by weight, C: 0.005 to 0.01%, N: 0.005 to 0.01%, Si: 0.1 to 0.9%, Mn: 0.1 to 0.9 %, Cr: 9 to 14%, Ni: 0.3% or less, P: 0.04% or less, S: 0.002% or less, Ti: 0.15 to 0.3%, Nb: 0.15 to 0.3%, Cu: 0.15 to 0.3%, Al: 0.01 to 0.05%, containing the remaining Fe and unavoidable impurities, and includes at least 5 × 10 ² / mm ² of Nb labes phase precipitates and Cu precipitates.

Hereinafter, the reason for the numerical limitation of the alloying element element content in the embodiment of the present invention will be described. In the following, unless otherwise specified, the unit is weight%.

The content of C is 0.005 to 0.01%.

C is a key element that causes sound absorption, and since the solid solution C continuously moves from the original position in the known lattice to another position when the steel plate vibrates, energy loss occurs and sound absorption occurs. In general, as the solid solution C in the base increases, the sound absorption and vibration damping ability increases. However, if the content exceeds 0.01%, the concentration of solid solution C reaches the limit, and it combines with Cr to produce Cr ₂₃ C ₆ precipitates, which hinders the movement of the magnetic domain wall, and is golden due to local Cr depletion in the base. Dust (Golden dust) is generated and the corrosion resistance is lowered.

The content of N is 0.005 to 0.01%.

Among steels, N is a key element that causes sound absorption and vibration damping through the same mechanism as C. As the solid solution N in the matrix increases, the vibration damping ability increases. However, if it exceeds 0.01%, the concentration of solid solution N reaches the limit, and it combines with Cr and produces Cr ₂ N precipitates, hindering the movement of the magnetic domain wall, and the local Cr depletion of the golden dust in the base (Golden dust) Occurs and the corrosion resistance decreases.

By controlling the content of C + N to 0.02% or less, the solid solution C and N in the matrix can be increased to suppress carbonitride precipitation, and vibration damping performance by smooth movement of the magnetic domain wall can be improved.

The content of Si is 0.1 to 0.9%.

Si is an element that acts as a deoxidizer in steel making and contains 0.1% or more. However, when a large amount is contained in the steel, inclusions are generated due to Si oxide, and since these inclusions interfere with the movement of the magnetic domain walls and inhibit the vibration damping ability, the content is limited to 0.9% or less.

The content of Mn is 0.1 to 0.9%.

Mn stabilizes austenite. When contained in a large amount, since the austenite-ferrite transformation point (Ac1) is lowered, and high temperature annealing capable of solidifying C and N after cold rolling becomes impossible, its content is limited to 0.9% or less.

The content of Cr is 9 to 14%.

Cr increases the magnetostriction constant of the steel to further promote the movement of the magnetic domain wall when it vibrates, compared to carbon steel, and increases the vibration damping ability due to the magnetic domain wall movement. It also plays a positive role in the vibration damping effect by C and N. However, when the content of Cr exceeds 14%, carbonitride is easily generated by easily combining with C and N, thereby lowering the amount of solid solution C and N, and the content of the content in the above range because the precipitates interfere with the movement of the magnetic domain wall. Limit.

The content of Ni is 0.3% or less.

Ni is an imperatively contained impurity in the steel by scrap melting, and may contain about 0.1%, and its upper limit is limited to 0.3%.

The content of P is 0.04% or less.

P is an inevitable impurity contained in the steel and is limited to 0.04% or less because it causes grain boundary corrosion during pickling or inhibits hot workability. The preferred content of P is 0.01 to 0.04%.

The content of S is 0.002% or less.

S is an unavoidable impurity contained in the steel, and its content is limited to 20 ppm or less because it is segregated at grain boundaries and hinders hot workability.

The content of Ti is 0.15 to 0.3%.

Ti is required to be added in order to increase the corrosion resistance of the weld, so add 0.15% or more. However, Ti combines with C and N to form Ti (C, N) precipitates, lowering the amount of solid solution C and N, and because Ti (C, N) precipitates interfere with the movement of magnetic domain walls, the vibration damping capacity is inferior. To make. Therefore, the content is limited to 0.3% or less.

The content of Nb is 0.15 to 0.3%.

Nb is also an essential element to increase the corrosion resistance of the welded part, and if it satisfies appropriate component conditions and heat treatment conditions, fine laves phase precipitates are generated to help improve vibration damping ability. . However, Nb combines with C and N to form Nb (C, N) precipitates, thereby lowering the amount of solid solution C and N, and Nb (C, N) precipitates are inferior in vibration damping ability because they interfere with the movement of magnetic domain walls. In order to do so, the content is limited to 0.3% or less.

The content of Cu is 0.15 to 0.3%.

Cu produces fine precipitates by appropriate heat treatment and helps to improve the vibration damping ability, so 0.15% or more is added. However, when the content of Cu is high, high-temperature hot workability may be impaired, thereby limiting the content to 0.3% or less.

The content of Al is 0.01 to 0.05%.

Al combines with N to form AlN precipitates to lower the amount of solid solution N, and the AlN precipitates interfere with the movement of the magnetic domain wall, making the vibration damping ability inferior. In addition, Al is an alloy component added as a deoxidizing agent during steelmaking, but it is present as a non-metallic inclusion when added in large amounts, thereby limiting its content to 0.01 to 0.05% because it causes sleeve defects of the cold rolled strip.

The rest of the ferritic stainless steel, excluding the alloy elements described above, is made of Fe and other unavoidable impurities.

Low Cr ferritic stainless steel according to an embodiment of the present invention may satisfy the following formula (1).

(1) (Nb + Cu) / Ti ≥ 1.5

As Ti content increases, Ti (C, N) precipitate production increases, lowering the solid solution C, N, and the vibration damping ability decreases because the precipitate itself interferes with the movement of the magnetic domain wall. In order to overcome this, by increasing the Nb + Cu content, the vibration damping effect by the fine Nb Laves-like precipitates and Cu precipitates must be increased. When the above formula (1) is satisfied together with the above-described alloy component composition, it is possible to dramatically improve the vibration damping ability compared to the conventional one.

In addition, the low Cr ferritic stainless steel according to an embodiment of the present invention may satisfy the following formula (2).

(2) Nb + Cu ≤ 0.5

When the Nb + Cu content becomes higher than necessary, precipitation coarsening easily occurs. In this case, the interface coherent between the precipitate and the base falls, and the number and total interface area of the precipitate decrease, making it difficult to exhibit a vibration damping effect due to the Nb-Labes precipitate and Cu precipitate. Therefore, the Nb + Cu content is limited to 0.5% or less.

The Nb-Laves precipitate is Fe ₂ Nb, and the size of the Nb-Laves precipitate and Cu precipitate may be 1 to 200 nm. As described above, when the sizes of the Nb Laves-like precipitates and Cu precipitates are coarse, the number of precipitates is relatively small compared with those of the fine precipitates, and the coherence between the precipitates and the matrix interface is poor, resulting in a small vibration damping effect. Therefore, it is preferable to control the size of the precipitate to 200 nm or less in order to maximize the vibration damping ability.

The Nb Laves phase precipitate, and the precipitate of Cu 200㎚ than 5 × 10 ² pieces / low-Cr ferritic stainless steel according to the present invention comprises at least ㎟ is, the vibration attenuation factor (Q-1) is 2.0 × 10 eseo 25 ℃ ^- It can exhibit excellent vibration damping performance at 2.5 × 10 ^-4 or higher at ⁴ or more and 300 ° C.

Next, a method of manufacturing a low Cr ferritic stainless steel having excellent vibration damping ability according to an embodiment of the present invention will be described.

The method for manufacturing low-Cr ferritic stainless steel having excellent vibration damping ability of the present invention can be manufactured as a cold-rolled steel sheet through a normal manufacturing process, and the ferritic stainless steel cold-rolled steel sheet containing the above-described alloy component composition is (Ac1-10) ℃ Cold rolling annealing at the following temperature; And rapidly cooling to 400 to 600 ° C to maintain for 5 minutes or more.

For example, a slab containing the above-described alloy component composition may be hot-rolled, annealed and heat-treated by hot-rolled hot-rolled steel sheet, and cold-rolled to produce a cold-rolled steel sheet.

The cold-rolled steel sheet is cold-annealed in a temperature range of 10 ° C or lower than the austenite-ferrite transformation temperature (Ac1). In the Cr content range of the present invention, since austenite phase is partially present, the annealing temperature is limited to (Ac1-10) ° C or less to prevent reverse transformation. Annealing is performed so that C and N can be sufficiently dissolved in the base in the above temperature range.

In addition, rapid quenching is required in the temperature range of 400 to 600 ° C after cold-rolled annealing to suppress the production of Cr carbonitride, and the number of fine Nb Laves-like precipitates and Cu precipitates is heated through heat treatment to maintain the temperature range for at least 5 minutes By increasing, it is possible to maximize the vibration damping ability.

At this time, when the Nb + Cu content according to Equation (2) exceeds 0.5%, the number of precipitates is reduced by coarsening of the precipitates compared to the Nb Laves phase precipitates and Cu precipitates additionally generated by the heat treatment. Can be. Therefore, when the Nb + Cu content exceeds 0.5%, it is preferable not to perform an additional heat treatment after cold rolling annealing.

Hereinafter will be described in more detail through a preferred embodiment of the present invention.

Example

The vibration damping performance was measured using IMCE's “RFDA LTVP800” equipment. The above equipment obtains a vibration damping index (Q-1) by measuring the degree of attenuation of sound after generating a vibration at a natural frequency by giving a sample of 80 mm (length) * 20 mm (width) with a constant force shock. The higher the vibration damping index, the faster the vibration damping. That is, the vibration damping performance is excellent. In the above equipment, the vibration damping index can be obtained for the temperature range of 25 ~ 800 ℃. For each final heat-treated alloy, vibration damping indices for room temperature (25 ° C) and 300 ° C were obtained. The natural frequency was 1 kHz.

The number of Nb-Labes precipitates and Cu precipitates was measured only for precipitates having a size of 200 nm or less.

division C N Si Mn Cr Ti Nb Cu (Nb + Cu)
/ Ti (Nb + Cu) Inventive Example 1 0.007 0.008 0.27 0.41 11.7 0.19 0.18 0.23 2.16 0.41 Inventive Example 2 0.006 0.007 0.35 0.28 12.5 0.16 0.22 0.27 3.06 0.49 Comparative Example 1 0.005 0.009 0.45 0.33 10.5 0.11 0.12 0.12 2.18 0.24 Comparative Example 2 0.008 0.006 0.29 0.29 13.1 0.38 0.34 0.32 1.74 0.66 Comparative Example 3 0.005 0.006 0.23 0.22 11.2 0.25 0.16 0.17 1.32 0.33 Comparative Example 4 0.009 0.009 0.17 0.53 11.8 0.16 0.28 0.27 3.44 0.55

division After annealing, keep at 500 ℃ for more than 5 minutes Nb and Cu
Total amount of precipitate
(ea / ㎟) Vibration damping index
(Q-1, × 10 ^-4 )
@ 25 ℃ Vibration damping index
(Q-1, × 10 ^-4 )
@ 300 ℃ Inventive Example 1 × 528 2.3 2.5 ○ 679 3.1 3.3 Inventive Example 2 × 613 2.8 3.1 ○ 718 3.5 3.7 Comparative Example 1 × 289 1.1 1.2 ○ 360 1.2 1.3 Comparative Example 2 × 336 1.3 1.4 ○ 435 1.5 1.6 Comparative Example 3 × 359 1.4 1.5 ○ 460 1.5 1.7 Comparative Example 4 × 410 1.6 1.6 ○ 275 1.1 1.2

1 is a graph showing the correlation of the vibration damping index according to the number of Nb-Labes precipitates and Cu precipitates. The results of analyzing data of Inventive Examples and Comparative Examples of Tables 1 to 2 with reference to FIG. 1 are as follows.

Looking at the invention examples 1 and 2, by satisfying both the component system of the present invention and formulas (1) and (2), after annealing, the total amount of Nb laves-like precipitates and Cu precipitates without heat treatment at 500 ° C for 5 minutes or more ㎟ It is more than 500 sugars and the vibration damping index (Q-1) at room temperature was measured to be 2.3 × 10 ^-4 or more. In particular, when heat treatment was performed, it was found that the total amount of precipitates increased by 100 to 150 and increased by 15 to 30%. Accordingly, the vibration damping index (Q-1) also increased by 20 to 35% to 3.1 × 10 ^-4 or more. It was measured.

Comparative Example 1 satisfies the formulas (1) and (2), but the contents of Ti, Nb, and Cu are less than 0.15%, and even after annealing and additional heat treatment at 500 ° C., the total amount of precipitates was less than 360. This was found to be due to the lack of Nb and Cu contents for forming the Nb Laves-like precipitate and Cu precipitate.

In Comparative Example 2, the contents of Ti, Nb, and Cu all exceeded 0.3%, so that the Nb + Cu value of Equation (2) exceeded 0.5%, and thus the total amount of precipitates was 500 even after annealing and additional heat treatment at 500 ° C. It did not reach / ㎟. This is satisfied by the equation (1), but the Ti and Nb content is high to form C, N and carbonitride to lower the solid solution C and N, and also the vibration damping ability is lowered because the carbonitride itself interferes with the movement of the magnetic domain wall. Was confirmed. In addition, it was estimated that the total amount of precipitates was lower than that of the invention example due to coarsening of the precipitates due to high Cu content as well as Nb.

Comparative Example 3 satisfies all the ranges of the component system of the present invention including Ti, Nb, and Cu, but the content of Ti is higher than that of Nb + Cu, so that the formula (1) is unsatisfactory, and accordingly, Ti (C, N) carbonitride is abundant. Precipitated. FIG. 2 is a photograph showing the distribution of Nb Laves-like precipitates and Cu precipitates at the base interface of Comparative Example 3. It can be seen that TiN was generated due to the high Ti content, and these TiN precipitates not only lowered the solid solution C and N, but the precipitates themselves interfered with the movement of the magnetic domain wall, and the vibration damping index was also 1.7 × 10 ^-4 or less after additional heat treatment. It was measured as.

Comparative Example 4 satisfies the component range and the formula (1) of the present invention including Ti, Nb, and Cu, but the formula (2) is unsatisfactory because the Nb + Cu content is high. In Comparative Example 4, the content of Nb + Cu was 0.55%, so that it was estimated that the Nb Laves phase precipitate and Cu precipitate were coarse. In particular, as a result of heat treatment at 500 ° C. after annealing, it was confirmed that the total amount of precipitates having a size of 200 nm or less was reduced, which was attributable to coarsening of the precipitates. When the precipitate coarsens, the coherence of the matrix interface and the interface area are lowered and the vibration damping effect is lowered. After the additional heat treatment of Comparative Example 4, the vibration damping index was the lowest despite satisfying the component range of the present invention.

As described above, although exemplary embodiments of the present invention have been described, the present invention is not limited thereto, and a person skilled in the art does not depart from the concept and scope of the following claims. It will be understood that various modifications and variations are possible.

Claims (8)

In weight percent, C: 0.005 to 0.01%, N: 0.005 to 0.01%, Si: 0.1 to 0.9%, Mn: 0.1 to 0.9%, Cr: 9 to 14%, Ni: 0.3% or less, P: 0.04% or less , S: 0.002% or less, Ti: 0.15 to 0.3%, Nb: 0.15 to 0.3%, Cu: 0.15 to 0.3%, Al: 0.01 to 0.05%, including the remaining Fe and unavoidable impurities, C + N: 0.02% Satisfy the following,
Contains 5 × 10 ² / mm ² or more of Nb laves phase precipitates and Cu precipitates,
Low Cr ferritic stainless steel with excellent vibration damping ability with a vibration damping index (Q-1) of 2.0 × 10 ^-4 or higher at 25 ° C and 2.5 × 10 ^-4 or higher at 300 ° C. According to claim 1,
The stainless steel is a low-Cr ferritic stainless steel excellent in vibration damping ability satisfying the following formula (1).
(1) (Nb + Cu) / Ti ≥ 1.5
(Here, Nb, Cu, Ti means the content (% by weight) of each element) According to claim 1,
The stainless steel is a low-Cr ferritic stainless steel excellent in vibration damping ability satisfying the following formula (2).
(2) Nb + Cu ≤ 0.5
(Here, Nb, Cu means the content (% by weight) of each element) According to claim 1,
The Nb-Laves precipitate is Fe ₂ Nb,
The size of the Nb Laves-like precipitate and Cu precipitate is a low Cr ferritic stainless steel having excellent vibration damping ability of 1 to 200 nm. delete In weight percent, C: 0.005 to 0.01%, N: 0.005 to 0.01%, Si: 0.1 to 0.9%, Mn: 0.1 to 0.9%, Cr: 9 to 14%, Ni: 0.3% or less, P: 0.04% or less , S: 0.002% or less, Ti: 0.15 to 0.3%, Nb: 0.15 to 0.3%, Cu: 0.15 to 0.3%, Al: 0.01 to 0.05%, including the remaining Fe and unavoidable impurities, C + N: 0.02% Cold-annealing the ferritic stainless steel cold-rolled steel sheet satisfying the following at a temperature of (Ac1-10) ° C. or lower; And
It comprises a step of rapidly cooling to 400 to 600 ℃ to maintain for 5 minutes or more, including,
A method of manufacturing a low Cr ferritic stainless steel with excellent vibration damping ability with a vibration damping index (Q-1) of 2.0 × 10 ^-4 or more at 25 ° C or more and 2.5 × 10 ^-4 or more at 300 ° C. The method of claim 6,
The cold-rolled steel sheet is a low-Cr ferritic stainless steel manufacturing method excellent in vibration damping ability satisfying the following formula (1).
(1) (Nb + Cu) / Ti ≥ 1.5
(Here, Nb, Cu, Ti means the content (% by weight) of each element) The method of claim 6,
The cold-rolled steel sheet is a low-Cr ferritic stainless steel manufacturing method excellent in vibration damping ability satisfying the following formula (2).
(2) Nb + Cu ≤ 0.5
(Here, Nb, Cu means the content (% by weight) of each element)

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