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

Abstract

The present application relates to a kind of composite Fe-Mn damping steels with excellent low-temperature impact toughness and preparation method, the chemical composition of steel is Si≤0.5%, Mn:13.5%~32.5%, S:0.05%~0.85%, and (Mn-12.5%) / S≥3;Mg:0.0010%~0.0070%, and Mg≥S / 147+0.0010%;P≤0.015%, the balance is Fe and impurities;Composite Fe-Mn damping steel has both ε martensite organization of Fe-Mn damping steel, also has MnS phase;By adding a certain amount of Mg element, make full use of the effect of Mg element in the process of smelting heterogeneous nucleation agent to increase the nucleation point of MnS, by the accurate control to the form and distribution quantity of MnS, composite Fe-Mn damping steel is realized while ensuring excellent damping performance with excellent low-temperature impact toughness.

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 impact 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 impact toughness and its preparation method. The composite Fe-Mn damping steel has both the ε-martensite structure of Fe-Mn damping steel and the MnS phase. Under the combined effect of the two damping mechanisms, it ultimately achieves high damping performance comparable to traditional Mn-Cu alloys. By adding a certain amount of Mg element, the heterogeneous nucleating agent of Mg element in the smelting process is fully utilized to increase the nucleation sites of MnS. Through precise control of the morphology and distribution of MnS, the composite Fe-Mn damping steel achieves excellent low-temperature impact toughness while ensuring excellent damping performance.

[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 impact toughness is disclosed. The chemical composition of the steel, by weight percentage, is as follows: Si ≤ 0.5%, Mn: 13.5%–32.5%, S: 0.05%–0.85%, and (Mn-12.5%) / S ≥ 3; Mg: 0.0010%–0.0070%, and Mg ≥ S / 147+0.0010%; P ≤ 0.015%, with the balance being Fe and unavoidable impurity elements. The steel contains ε-martensite and MnS phase. The MnS phase is dispersed in the structure, and the morphology of the MnS phase is mostly nearly spherical, with a small amount remaining as short rods.

[0016] A method for preparing a composite Fe-Mn damping steel with excellent low-temperature impact toughness includes smelting, casting, rolling, and heat treatment. Specifically, the heat treatment process involves holding the rolled steel plate at 750–950℃ for 160–320 min, followed by water quenching to room temperature. Subsequently, stress-relief annealing is performed at 130–150℃ for 120–180 min, followed by furnace cooling to room temperature.

[0017] Furthermore, the composite Fe-Mn damping steel has a yield strength ≥355MPa, tensile strength ≥500MPa, elongation after fracture ≥30%, and damping value. Impact absorption energy at -20℃ ≥256J.

[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) 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 Fe-Mn damping steel have 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 also gives it a multi-phase damping mechanism. Under the combined effect of these two damping mechanisms, high damping performance comparable to that of traditional Mn-Cu alloys is finally obtained.

[0023] 2) The composite Fe-Mn damping steel with excellent low-temperature impact toughness described in this invention, by adding a certain amount of Mg element, makes full use of the heterogeneous nucleating agent role of Mg element in the smelting process, increases the nucleation points of MnS, and uniformly disperses the MnS phase in the microstructure, reduces the size of the MnS phase in the composite Fe-Mn damping steel, and reduces the harm of MnS to the low-temperature impact toughness of the damping steel.

[0024] 3) MnS inclusions are a harmful presence in ordinary low-alloy steel. However, in the composite Fe-Mn damping steel described in this invention, due to the excellent plasticity and toughness of Fe-Mn damping steel and the presence of stress-induced phase transformation during deformation, the influence of MnS on the mechanical properties of Fe-Mn damping steel is significantly lower than its influence on the mechanical properties of ordinary low-alloy steel. However, excessive MnS inclusions will significantly reduce the damping performance of the alloy. This invention achieves excellent low-temperature impact toughness in composite Fe-Mn damping steel while ensuring excellent damping performance through precise control of the morphology and distribution of MnS.

[0025] 4) The composite Fe-Mn damping steel of the present invention has excellent low-temperature impact toughness, with a yield strength ≥355MPa, tensile strength ≥500MPa, and elongation after fracture ≥30%. Compared with conventional Fe-Mn damping steel, it maintains the damping value... Based on this, the impact absorption energy at -20℃ was increased from 106J to over 256J. Detailed Implementation

[0026] The present invention discloses a composite Fe-Mn damping steel with excellent low-temperature impact toughness. The chemical composition of the steel, by weight percentage, is as follows: Si ≤ 0.5%, Mn: 13.5%–32.5%, S: 0.05%–0.85%, and (Mn-12.5%) / S ≥ 3; Mg: 0.0010%–0.0070%, and Mg ≥ S / 147 + 0.0010%; P ≤ 0.015%, with the balance being Fe and unavoidable impurity elements. The steel contains ε-martensite and MnS phase. The MnS phase is dispersed in the structure, and the morphology of the MnS phase is mostly nearly spherical, with a small amount remaining as short rods.

[0027] The present invention discloses a method for preparing a composite Fe-Mn damping steel with excellent low-temperature impact toughness. The production process includes smelting, casting, rolling, and heat treatment. Specifically, the heat treatment process involves: holding the rolled steel plate at 750–950°C for 160–320 min, followed by water quenching to room temperature; then performing stress-relief annealing at 130–150°C for 120–180 min, and finally furnace cooling to room temperature.

[0028] Furthermore, the composite Fe-Mn damping steel has a yield strength ≥355MPa, tensile strength ≥500MPa, elongation after fracture ≥30%, and damping value. Impact absorption energy at -20℃ ≥256J.

[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 impact toughness described in this invention is as follows:

[0033] Mg: During the smelting process of damping steel, the added Mg element will form complex inclusions with other nitrogen oxides, such as Al2O3-MgO, TiN-MgO, Ti2O3-MgO, etc. Therefore, the addition of Mg element will greatly inhibit the aggregation of these nitrogen oxides, enabling them to be dispersed in the molten steel and avoiding the formation of large inclusions in the steel. During the casting and solidification process of molten steel, MnS will use these fine nitrogen oxide inclusions as nucleation sites, and then form fine and dispersed MnS phases in the microstructure of damping steel. The microstructure of MnS phase is mostly nearly spherical, with a small amount being short rod-shaped. However, excessive Mg addition will significantly reduce the dispersion distribution of inclusions and increase costs. Therefore, the Mg content needs to be strictly controlled. Taking all the above factors into consideration, the Mg content in this invention is controlled at 0.0010% to 0.0070%.

[0034] 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. In addition, the addition of Si also helps to improve the corrosion resistance of steel to some extent. Taking all the above factors into consideration, this invention controls the Si content to ≤0.5%.

[0035] 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. 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 MnS, 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 content inhibits the formation of ε-martensite, which is detrimental to damping performance. Therefore, considering all factors, this invention controls the Mn content between 13.5% and 32.5%.

[0036] 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, MnS inclusions formed by the combination of S and Mn are dispersed in the microstructure. As a bulk defect, this helps to improve the damping source in the microstructure and enhance the damping performance of Fe-Mn damping steel. However, if the S content is too high and the amount of MnS 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%.

[0037] 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, thus impairing the low-temperature toughness. In order to ensure that the damping steel has excellent comprehensive performance, the content of P element is controlled below 0.015% in this invention.

[0038] The present invention discloses a method for improving the low-temperature impact toughness of composite Fe-Mn damping steel. Compared with the prior art, the present invention adds Mg element during the smelting process of composite Fe-Mn damping steel, forming fine and dispersed nitrogen oxide inclusions in the molten steel, providing nucleation sites for the subsequent formation of MnS. Consequently, uniform and dispersed MnS is obtained in the Fe-Mn damping steel, with the MnS morphology mostly being nearly spherical and a small amount being short rod-shaped. This greatly reduces the strip-shaped distribution of MnS in the composite Fe-Mn damping steel, reducing the harmful effect of MnS on the low-temperature impact toughness of the composite Fe-Mn damping steel. At the same time, the fine and dispersed MnS is also beneficial to the strength and damping performance of the composite Fe-Mn damping steel. The present invention provides a method for improving low-temperature impact toughness. Without compromising the strength and damping properties of composite Fe-Mn damping steel, it significantly reduces the harmful effects of MnS on low-temperature impact toughness. This allows composite Fe-Mn damping steel to achieve both higher damping performance and excellent low-temperature impact toughness, providing favorable performance assurance for the application of composite Fe-Mn damping steel as a structural and functional integrated material.

[0039] 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.

[0040]

Example

[0041] Table 1 shows the chemical composition (weight percentage) of each embodiment and comparative example. The comparative example is a composite Fe-17Mn damping steel without added Mg. Table 2 shows the heat treatment process parameters of each embodiment and comparative example; Table 3 shows the product performance of each embodiment and comparative example.

[0042] Table 1. Chemical composition (wt.%) of each example and comparative example.

[0043]

[0044] Table 2 Heat treatment process parameters for each embodiment and comparative example

[0045]

[0046] Table 3 Product performance of each embodiment and comparative example

[0047]

[0048] As can be seen from Table 3, the low-temperature impact absorption energy of the composite Fe-Mn damping steel prepared in each embodiment at -20℃ is much higher than that of the comparative embodiment. At the same time, the plasticity of the composite Fe-Mn damping steel prepared in each embodiment is also significantly improved.

[0049] 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 impact 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%, and (Mn-12.5%) / S≥3; Mg: 0.0010%~0.0070%, and Mg≥S / 147+0.0010%; P≤0.015%, balance being Fe and unavoidable impurity elements; The steel contains ε-martensite and MnS phase. The MnS phase is dispersed throughout the structure, and most of the MnS phase is nearly spherical, with a small amount being short rod-shaped. The production process of composite Fe-Mn damping steel includes smelting, casting, rolling, and heat treatment. Specifically, the heat treatment process involves holding the rolled steel plate at 750–950℃ for 160–320 min, followed by water quenching to room temperature. Then, stress-relief annealing is performed at 130–150℃ for 120–180 min, and finally furnace cooling to room temperature. The composite Fe-Mn damping steel has a yield strength ≥355 MPa, tensile strength ≥500 MPa, elongation after fracture ≥30%, damping value tanφ ≥0.11, and impact absorption energy at -20℃ ≥256 J.

2. The preparation method of a composite Fe-Mn damping steel with excellent low-temperature impact toughness as described in claim 1, characterized in that, The production process includes smelting, casting, rolling and heat treatment; the heat treatment process is as follows: after rolling, the steel plate is held at 750-950℃ for 160-320 min, and then water-quenched to room temperature; then stress-relief annealing is carried out at 130-150℃ for 120-180 min, and finally furnace-cooled to room temperature.

3. The method for preparing a composite Fe-Mn damping steel with excellent low-temperature impact toughness according to claim 2, characterized in that, The composite Fe-Mn damping steel has a yield strength ≥355 MPa, tensile strength ≥500 MPa, elongation after fracture ≥30%, damping value tanφ ≥0.11, and impact absorption energy at -20℃ ≥256J.

4. The method for preparing a composite Fe-Mn damping steel with excellent low-temperature impact 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 impact 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 impact 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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