Composite fe-mn damping steel with excellent low-temperature toughness and preparation method

Abstract

The present application relates to a kind of composite Fe-Mn damping steels with excellent low temperature toughness and preparation method, steel has ε martensite organization and MnS phase, MnS phase is dispersed in organization, and the morphology of MnS phase is short rod or oval with less than 3 of aspect ratio.The present application uses high manganese component and adds a certain amount of sulfur element, so that Fe-Mn damping steel has ε martensite organization and MnS phase, product has not only the damping mechanism of partial dislocation and layer crack interface movement, but also complex-phase damping mechanism, under the joint action of two kinds of damping mechanism, finally obtain the high damping performance comparable with traditional Mn-Cu alloy;By high temperature zone rapid rolling and again heating after long time heat preservation, make the long strip MnS phase in steel into short rod or oval, so that steel has good mechanical property, especially excellent low temperature toughness, product can be used as a kind of structural function integration material in low temperature environment.

Description

Technical Field

[0001] This invention relates to the field of damping steel technology, and in particular to a composite Fe-Mn damping steel with excellent low-temperature toughness and its preparation method. Background Technology

[0002] In recent years, the demands of modern industrial development have led to a continuous increase in the power of large machinery. Simultaneously, the harmful noise generated by vibration has also increased. This high-intensity vibration can cause material fatigue, reducing the reliability of mechanical components and posing potential safety hazards, even leading to significant losses. Taking large military equipment as an example, the vibration and noise generated by its core components, especially the engine, can interfere with the normal operation of the instrument and reduce its concealment. According to a survey by a US national authority, at least one-tenth of workers worldwide are in working environments with severe noise pollution (above 90 dB). Various complex noises not only reduce people's quality of life but also stimulate the central nervous system, inducing various diseases. Furthermore, the complex sources of various noises have resulted in persistently high noise reduction costs, thus making noise reduction a widely recognized issue worldwide.

[0003] There are three main methods to suppress vibration and noise generated by machinery: first, structural reinforcement to suppress vibration and thus reduce noise; second, adding sound insulation devices to the machinery; and third, using new vibration-damping materials. The first two methods increase the size and weight of the machine, making the situation more complex and increasing costs. Therefore, for mechanical and structural parts operating under dynamic conditions, using high-damping alloys to reduce the resonant peak stress of vibration is an effective way to reduce harmful vibration and noise.

[0004] Currently, the more mature research on metallic damping materials can be classified according to their damping mechanism into multiphase type (cast iron), superplastic type (Zn-Al alloy), dislocation type (Mg and Mg alloy), twinned type (Mn-Cu alloy), and ferromagnetic type (Fe-Cr). Fe-Mn damping steel is a novel metallic damping material developed in the last decade or so. Among metallic damping materials, Fe-Mn damping steel has the highest strength (tensile strength greater than 700 MPa) and the lowest cost (only 1 / 4 that of Mn-Cu damping alloy). Its damping performance increases with increasing strain amplitude, is unaffected by external magnetic fields, and maintains high damping performance even at high service temperatures. Fe-Mn damping steel is very suitable for use in components subjected to large vibrations and impacts.

[0005] Although Fe-Mn damping steel, as a high-Mn iron-based material, exhibits high damping performance, it still lags significantly behind traditional high-damping Mn-Cu alloys. Therefore, how to further improve the damping performance of Fe-Mn damping steel while maintaining its excellent mechanical properties, enabling its wider application in vibration and noise control, and ultimately improving the safety of mechanical and building structures and reducing noise, is a problem worthy of serious research.

[0006] Chinese invention patent CN112899577B discloses a "method for preparing a Fe-Mn based high-strength, high-damping alloy." The method involves smelting, forging, and hot rolling to obtain a 2-20mm hot-rolled plate, followed by annealing or cold rolling to obtain the high-strength, high-damping alloy. While this method achieves a damping alloy with a tensile strength greater than 900MPa through complex heat treatment and cold rolling processes, its damping performance still lags behind that of Mn-Cu alloys, given the increasingly stringent requirements for the damping performance of metallic materials.

[0007] Chinese invention patent CN107699668B discloses "A method for improving the corrosion resistance of iron-manganese damping alloys." This method involves high-temperature heat treatment in a vacuum environment to create a ferrite layer on the surface of the iron-manganese damping alloy, thereby improving its corrosion resistance and damping performance. However, this method requires high-temperature heat treatment in a vacuum environment, which is demanding, and the ferrite layer on the surface significantly reduces the strength of the damping alloy.

[0008] Chinese patent application CN103966529A discloses "a high-damping Mn-Fe-based vibration-damping alloy and its preparation method." The method involves melting in an induction furnace under an argon protective atmosphere, performing a 24-hour homogenization heat treatment, forging at 900–1150℃, annealing at 1000℃, and finally solution treatment at 1000℃ to obtain the high-damping vibration-damping alloy. While this method yields a damping alloy with good performance, the complex preparation process, involving multiple heat treatment steps (homogenization, annealing, solution treatment, etc.) and forging, results in high production costs and is only suitable for small-batch production, making large-scale production difficult.

[0009] Chinese patent application CN106282786A discloses "an Nb-containing iron-manganese-based damping alloy and its preparation method," which employs vacuum arc melting followed by homogenization heat treatment, hot rolling, shaping, and solution treatment to obtain the damping loss factor. A high-damping alloy with a strength of 0.055 was obtained. Although this method yielded a high-damping alloy, the alloy prepared by arc melting is small in weight, limiting its application. Furthermore, the process of heat-treating the alloy inside a stainless steel tube is difficult to promote and use. Therefore, this method is only suitable for applications requiring the preparation of damping alloys in the laboratory stage or for applications with extremely small damping alloy sizes.

[0010] Chinese patent application CN106011636A discloses "a marine iron-manganese-based high-strength and high-toughness damping alloy." By controlling the microstructure—with ε-martensite content not less than 70% and α-martensite + austenite content not exceeding 30%—a marine iron-manganese-based damping alloy with a good strength-toughness balance was obtained. Although the damping alloy obtained by this method exhibits good strength and toughness, its damping performance remains relatively low among high-damping alloys, posing significant challenges for its application in the marine field.

[0011] Chinese patent application CN115404412A discloses "A Mo-containing high-strength, high-toughness, and corrosion-resistant iron-manganese damping alloy and its preparation method." The method involves adding 0.2-1.2% Mo to steel, smelting it in a converter or electric furnace, holding it at 1080-1240℃ for 1-4 hours, followed by rolling at an initial rolling temperature of 1030-1170℃ and a final rolling temperature of 760-910℃, then water-cooling to room temperature. Subsequently, it undergoes heat treatment at 700-1000℃ for 30-90 minutes, followed by water cooling to room temperature to obtain the target iron-manganese damping alloy. This method is simple and produces excellent performance, but the addition of Mo significantly increases the alloy cost, and its damping performance remains relatively low among high-damping alloys.

[0012] Chinese invention patent CN 112662942 B discloses a "damping steel and its preparation method". The composition, by mass percentage, includes C: ≤0.015%, Si: 0.1-0.3%, Mn: 0.6-2.5%, P: ≤0.01%, S: 0.15-0.55%, Al: 0.01%-0.03%, [N]: ≤0.01%, [O]: 0.002-0.005%, Mg: 0.001-0.003%, with the balance being Fe and unavoidable impurities. This steel, by adding a certain amount of Mg and S, achieves excellent damping performance, as well as excellent machinability and mechanical properties. Its product is a damping steel with ferrite and pearlite structure. Although it obtains MnS inclusions by using S element and forms intragranular ferrite by using Mg element, and obtains certain damping performance, its damping performance is still at a low level. Moreover, MnS inclusions will greatly deteriorate the mechanical properties, which has huge defects in practical applications. Summary of the Invention

[0013] This invention provides a composite Fe-Mn damping steel with excellent low-temperature toughness and its preparation method. It employs a high-manganese composition and adds a certain amount of sulfur, enabling the Fe-Mn damping steel to possess both ε-martensite and MnS phases. The product exhibits both damping mechanisms from partial dislocation and stacking fault interface movement, as well as a multiphase damping mechanism. Under the combined effect of these two damping mechanisms, it ultimately achieves high damping performance comparable to traditional Mn-Cu alloys. Through rapid rolling in a high-temperature zone and prolonged holding after reheating, the elongated MnS phase in the steel is transformed into short rod-shaped or elliptical phases, giving the steel good mechanical properties, especially excellent low-temperature toughness. The product can be used as a structural-functional integrated material in low-temperature environments.

[0014] To achieve the above objectives, the present invention employs the following technical solution:

[0015] A composite Fe-Mn damping steel with excellent low-temperature toughness has the following chemical composition by weight percentage: Si≤0.5%, Mn:13.5%~32.5%, S:0.05%~0.85%, (Mn-12.5%) / S≥5, P≤0.015%, with the balance being Fe and unavoidable impurity elements. The steel has an ε-martensite structure and a MnS phase. The MnS phase is dispersed in the structure and its morphology is short rod-shaped or elliptical with an aspect ratio of less than 3.

[0016] A method for preparing a composite Fe-Mn damping steel with excellent low-temperature toughness includes smelting, casting, rolling, and heat treatment. The rolling process employs a rapid high-temperature rolling process with an initial rolling temperature ≥1100℃ and a final rolling temperature ≥1000℃, followed by water cooling to room temperature. The heat treatment process specifically involves holding the rolled steel plate at 950–1050℃ for X minutes, where X is the holding time, and X = (T × 5 min / mm) + 120 min, where T is the steel plate thickness. After holding, the steel plate is water-quenched to room temperature, then stress-relief annealed at 180–220℃ for 180–240 min, and finally furnace-cooled to room temperature.

[0017] Furthermore, the composite Fe-Mn damping steel has a yield strength ≥345MPa, tensile strength ≥500MPa, elongation after fracture ≥35%, and impact absorption energy at -20℃ ≥200J; damping value

[0018] Furthermore, the smelting is carried out using an electric furnace or a converter.

[0019] Furthermore, the casting is carried out using continuous casting or ingot casting.

[0020] Furthermore, the rolling process is carried out using a medium-thickness plate rolling mill, and the thickness of the rolled steel plate is 8-60 mm.

[0021] Compared with the prior art, the beneficial effects of the present invention are:

[0022] 1) This invention reduces the formation of elongated, strip-shaped MnS phases through rapid rolling in a high-temperature zone, followed by rapid cooling to room temperature. By reheating to 950–1050°C and holding at that temperature for an extended period, the morphology of the elongated MnS phases in the steel gradually transforms, with most of the elongated MnS phases converting into short rod-shaped or nearly elliptical forms. This morphology of MnS significantly reduces its detrimental effect on the low-temperature toughness of damping steel, resulting in composite Fe-Mn damping steel exhibiting excellent low-temperature toughness.

[0023] 2) Through the heat treatment process, this invention successfully controls the morphology of the MnS phase to be short rod-shaped or elliptical with an aspect ratio of less than 3, minimizing the harm of MnS phase to the low-temperature toughness of steel. At the same time, the dispersed MnS phase can give full play to its multiphase damping mechanism and organically combine with the Fe-Mn type damping mechanism, greatly improving the damping performance of Fe-Mn damping steel.

[0024] 3) The composite Fe-Mn damping steel described in this invention has both the ε-martensite structure of Fe-Mn damping steel and the MnS phase, which makes the composite Fe-Mn damping steel possess both the damping mechanism of partial dislocation and stacking fault interface movement, that is, the damping characteristics that are not affected by the external magnetic field and gradually increase with the increase of strain; at the same time, the presence of the MnS phase has a multi-phase damping mechanism. Under the combined effect of these two damping mechanisms, the high damping performance that is comparable to that of traditional Mn-Cu alloys is finally obtained.

[0025] 4) The composite Fe-Mn damping steel of this invention has a yield strength ≥345MPa, tensile strength ≥500MPa, elongation after fracture ≥35%, and impact absorption energy at -20℃ ≥200J; damping value The composite Fe-Mn damping steel described in this invention possesses excellent damping performance as well as excellent low-temperature toughness, and can be used as a structural and functional integrated material in low-temperature environments. Detailed Implementation

[0026] The present invention discloses a composite Fe-Mn damping steel with excellent low-temperature toughness. The chemical composition of the steel, by weight percentage, is Si≤0.5%, Mn:13.5%~32.5%, S:0.05%~0.85%, (Mn-12.5%) / S≥5, P≤0.015%, with the balance being Fe and unavoidable impurity elements. The steel has an ε-martensite structure and a MnS phase. The MnS phase is dispersed in the structure, and the morphology of the MnS phase is short rod-shaped or elliptical with an aspect ratio of less than 3.

[0027] The present invention discloses a method for preparing a composite Fe-Mn damping steel with excellent low-temperature toughness. The production process includes smelting, casting, rolling, and heat treatment. The rolling process employs a rapid high-temperature rolling process with an initial rolling temperature ≥1100℃ and a final rolling temperature ≥1000℃, followed by water cooling to room temperature. The heat treatment process specifically involves holding the rolled steel plate at 950–1050℃ for X minutes, where X is the holding time, and X = (T × 5 min / mm) + 120 min, where T is the steel plate thickness. After holding, the steel plate is water-quenched to room temperature, then stress-relief annealed at 180–220℃ for 180–240 min, and finally furnace-cooled to room temperature.

[0028] Furthermore, the composite Fe-Mn damping steel has a yield strength ≥345MPa, tensile strength ≥500MPa, elongation after fracture ≥35%, and impact absorption energy at -20℃ ≥200J; damping value

[0029] Furthermore, the smelting is carried out using an electric furnace or a converter.

[0030] Furthermore, the casting is carried out using continuous casting or ingot casting.

[0031] Furthermore, the rolling process is carried out using a medium-thickness plate rolling mill, and the thickness of the rolled steel plate is 8-60 mm.

[0032] The mechanism of action of each alloying element in the composite Fe-Mn damping steel with excellent low-temperature toughness described in this invention is as follows:

[0033] Si: For damping steel, the addition of Si can reduce stacking fault energy and increase the stacking fault probability and the number of Shockley partial dislocations in the alloy's γ-austenite and ε-martensite. However, Si causes significant lattice distortion, resulting in a marked increase in vacancy defects and making it difficult for Shockley partial dislocations to move, which is detrimental to damping performance. For smelting, Si is an important deoxidizer. Furthermore, the addition of Si also helps to improve the corrosion resistance of steel to some extent. Considering all these factors, this invention controls the Si content to ≤0.5%.

[0034] The damping performance of Fe-Mn damping steel is mainly determined by stacking faults in ε-martensite, stacking faults in γ-austenite, the γ / ε two-phase interface, and the phase interfaces of various martensite variants. Among these, ε-martensite plays a major role, and its performance is primarily influenced by the Mn content. Changes in Mn content significantly affect the phase composition and proportion in the damping steel. With increasing Mn content, the amount of α' martensite decreases, the content of ε-martensite increases, the number of extended dislocations increases, and their mobility is enhanced, thus improving damping performance. Furthermore, Mn combines with S to form the MnS phase, which exists in the microstructure as a bulk defect and can effectively improve the damping performance of Fe-Mn damping steel. However, excessively high Mn levels can inhibit the formation of ε-martensite, which is detrimental to damping performance. Considering all these factors, this invention controls the Mn content between 13.5% and 32.5%.

[0035] S: In ordinary low-alloy steel, sulfur (S) is a harmful element that significantly affects the steel's ductility and toughness. However, in Fe-Mn damping steel, the MnS phase formed by the combination of S and Mn is dispersed in the microstructure. As a bulk defect, it helps to improve the damping source in the microstructure, thereby improving the damping performance of Fe-Mn damping steel. However, if the S content is too high and the amount of MnS phase in the microstructure is excessive, the ductility and toughness of Fe-Mn damping steel will be significantly reduced. Therefore, the S content needs to be strictly controlled. Taking all factors into consideration, this invention controls the S content to be between 0.05% and 0.85%.

[0036] P is an element that has an adverse effect on the low-temperature impact toughness of damping steel. It can segregate in the center of the steel plate and accumulate at the grain boundaries, thereby impairing the low-temperature toughness of the steel. In order to ensure that the damping steel has excellent comprehensive performance, the present invention controls the P element content to below 0.015%.

[0037] The following embodiments are implemented based on the technical solution of the present invention, and provide detailed implementation methods and specific operation processes. However, the scope of protection of the present invention is not limited to the following embodiments.

[0038]

Example

[0039] Table 1 shows the chemical composition (weight percentage) of each embodiment and comparative example. The comparative example is a composite Fe-Mn damping alloy without special heat treatment. Table 2 shows the rolling and heat treatment process parameters of each embodiment and comparative example; Table 3 shows the product performance of each embodiment and comparative example.

[0040] Table 1. Chemical composition (wt.%) of each example and comparative example.

[0041]

[0042] Table 2. Rolling and heat treatment process parameters for each embodiment and comparative example.

[0043]

[0044]

[0045] Table 3 Product performance of each embodiment and comparative example

[0046]

[0047] As can be seen from Table 3, the composite Fe-Mn damping steel prepared in each embodiment of the present invention has significantly higher plasticity and toughness (especially low-temperature toughness) than the comparative example, and its damping performance is significantly better than that of the comparative example.

[0048] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A composite Fe-Mn damping steel with excellent low-temperature toughness, characterized in that, The chemical composition of the steel, by weight percentage, is: Si ≤ 0.5%, Mn: 13.5%–32.5%, S: 0.05%–0.85%, (Mn-12.5%) / S ≥ 5, P ≤ 0.015%, with the balance being Fe and unavoidable impurity elements. The steel possesses an ε-martensite structure and a MnS phase. The MnS phase is dispersed throughout the structure, and its morphology is short rod-shaped or elliptical with an aspect ratio less than 3. The production process of the composite Fe-Mn damping steel includes smelting, casting, rolling, and heat treatment; among these, rapid rolling is employed. The high-temperature rolling process involves an initial rolling temperature ≥1100℃ and a final rolling temperature ≥1000℃, followed by water cooling to room temperature. The heat treatment process is as follows: the rolled steel plate is held at 950~1050℃ for X minutes, where X is the holding time, and X = (T×5min / mm) + 120min, where T is the steel plate thickness. After holding, the steel plate is water-quenched to room temperature, then stress-relief annealed at 180~220℃ for 180~240min, and finally furnace-cooled to room temperature. The composite Fe-Mn damping steel exhibits a yield strength ≥345 MPa, tensile strength ≥500 MPa, elongation after fracture ≥35%, and impact absorption energy at -20℃ ≥200 J; the damping value tanφ ≥0.

13.

2. The method for preparing a composite Fe-Mn damping steel with excellent low-temperature toughness as described in claim 1, characterized in that, The production process includes smelting, casting, rolling, and heat treatment. Among them, the rolling adopts a rapid high-temperature rolling process, with an initial rolling temperature ≥1100℃ and a final rolling temperature ≥1000℃, followed by water cooling to room temperature. The heat treatment process is as follows: the rolled steel plate is held at 950~1050℃ for X min, where X is the holding time, and X=(T×5min / mm)+120min, where T is the thickness of the steel plate. After holding, the steel plate is water quenched to room temperature, then stress-relief annealed at 180~220℃ for 180~240min, and finally furnace cooled to room temperature.

3. The method for preparing a composite Fe-Mn damping steel with excellent low-temperature toughness according to claim 2, characterized in that, The composite Fe-Mn damping steel has a yield strength ≥345 MPa, tensile strength ≥500 MPa, elongation after fracture ≥35%, and impact absorption energy at -20℃ ≥200 J. Damping value tanφ≥0.

13.

4. The method for preparing a composite Fe-Mn damping steel with excellent low-temperature toughness according to claim 2, characterized in that, The smelting is carried out using an electric furnace or a converter.

5. The method for preparing a composite Fe-Mn damping steel with excellent low-temperature toughness according to claim 2, characterized in that, The casting is carried out using continuous casting or die casting.

6. The method for preparing a composite Fe-Mn damping steel with excellent low-temperature toughness according to claim 2, characterized in that, The rolling process is carried out using a medium-thickness plate rolling mill, and the thickness of the rolled steel plate is 8-60 mm.

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