High-aluminum manganese system fe-mn-al-c low-density steel and treatment method thereof

Abstract

The application discloses high-aluminum-manganese Fe-Mn-Al-C low-density steel and a processing method thereof. The method comprises the following steps: providing low-density steel with a composition of Fe-1.80Mn-1.05Al-0.09C-0.80Si-0.55(Ti+Ni+Nb); and performing heat treatment on the low-density steel, which comprises the following steps: heating the low-density steel to 1250 DEG C to obtain heated low-density steel; cooling the heated low-density steel to 1000 DEG C-1150 DEG C to perform rough rolling to obtain rough-rolled low-density steel; performing fine rolling on the rough-rolled low-density steel at a fine rolling temperature of 950 DEG C-1000 DEG C to obtain fine-rolled low-density steel; cooling the fine-rolled low-density steel to 500 DEG C-550 DEG C to obtain cooled low-density steel; coiling the cooled low-density steel to obtain coiled low-density steel; and performing air cooling on the coiled low-density steel to obtain high-aluminum-manganese Fe-Mn-Al-C low-density steel. The method can guarantee the performance of the high-aluminum-manganese Fe-Mn-Al-C low-density steel in a service environment, can realize stable industrial production of the high-aluminum-manganese Fe-Mn-Al-C low-density steel, and can reduce the blockage and steel defects in the process of slagging corrosion of a ladle and continuous casting.

Description

Technical Field

[0001] This application pertains to steel smelting technology, and particularly relates to a high-alumina manganese Fe-Mn-Al-C low-density steel and its processing method. Background Technology

[0002] In recent years, companies have taken many measures to reduce vehicle emissions, one of which is vehicle lightweighting. Studies have shown that for every 10% reduction in the overall weight of a vehicle, its fuel efficiency can improve by 6% to 8%, while emissions of harmful pollutants can be reduced by more than 1%.

[0003] Fe-Mn-Al-C series low-density high-strength steel is an excellent material for achieving lightweighting in automobiles. This is typically achieved by altering the steel's matrix structure and precipitating two-phase particles, thereby increasing its strength and toughness. For example, Nathan A. Ley et al. used heat treatment to form an austenitic structure in Fe-30Mn-9Al-1C-1Si-0.7Mo, with a large amount of κ carbides precipitating. Chen Xingpin et al.'s research on Fe-30Mn-10Al-xC showed that increasing the C content transforms the steel's microstructure from a two-phase austenitic-ferrite structure to a one-phase austenitic structure, resulting in a continuous increase in steel strength.

[0004] However, due to its high aluminum and manganese content, the aforementioned Fe-Mn-Al-C low-density steel is prone to causing sticky slag and corrosion of the ladle during the smelting process. Furthermore, the high melting point of aluminum inclusions can easily lead to blockages and steel defects during continuous casting. Therefore, this steel grade is currently difficult to produce stably in large quantities. Summary of the Invention

[0005] This application provides a method for processing high-alumina manganese Fe-Mn-Al-C low-density steel. By adding microalloying elements and combining heat treatment, the method can ensure the performance required by high-alumina manganese Fe-Mn-Al-C low-density steel in the service environment. At the same time, it can enable stable industrial production of high-alumina manganese Fe-Mn-Al-C low-density steel, reduce the corrosion of the ladle due to sticky steel slag, and reduce blockage and steel defects during continuous casting and billet pulling.

[0006] In a first aspect, this application provides a method for processing high-alumina manganese-based Fe-Mn-Al-C low-density steel, the method comprising: Low-density steel with the composition of Fe-1.80Mn-1.05Al-0.09C-0.80Si-0.55(Ti+Ni+Nb) is provided; Heat treatment of low-density steel includes: heating the low-density steel to 1250℃ at a heating rate of 10℃ / min to 20℃ / min and holding it at that temperature to obtain heated low-density steel. The heated low-density steel is cooled to 1100℃~1150℃ at a cooling rate of 100℃ / min~150℃ / min and then rough rolled to obtain rough rolled low-density steel. The low-density steel that has been rough-rolled is cooled to 950℃~1000℃ at a cooling rate of 100℃ / min~150℃ / min and then finished-rolled to obtain finished low-density steel. The low-density steel that has been precision rolled is cooled to 500℃~550℃ at a cooling rate of 150℃ / min~200℃ / min to obtain cooled low-density steel. Cooled low-density steel is coiled to obtain coiled low-density steel. Air cooling was performed on the coiled low-density steel to obtain high-aluminum manganese Fe-Mn-Al-C low-density steel.

[0007] In some embodiments of this application, the step of heating low-density steel to 1250°C at a heating rate of 10°C / min to 20°C / min and holding it at that temperature to obtain heated low-density steel includes heating low-density steel to 1250°C at a heating rate of 10°C / min to 15°C / min and holding it at that temperature.

[0008] In some embodiments of this application, the step of cooling heated low-density steel to 1100°C~1150°C at a cooling rate of 100°C / min~150°C / min and then rough rolling it to obtain rough rolled low-density steel includes: cooling heated low-density steel to a rough rolling temperature of 1100°C~1150°C at a cooling rate of 100°C / min~140°C / min and then rough rolling it.

[0009] In some embodiments of this application, the deformation of the rough-rolled low-density steel is 35% to 45%.

[0010] In some embodiments of this application, the step of cooling the rough-rolled low-density steel to 950°C to 1000°C at a cooling rate of 100°C to 150°C / min and then finishing-rolling it to obtain finish-rolled low-density steel includes: cooling the rough-rolled low-density steel to 950°C to 1000°C at a cooling rate of 100°C to 135°C / min and then finishing-rolling it.

[0011] In some embodiments of this application, the deformation of the precision-rolled low-density steel is 25% to 35%.

[0012] In some embodiments of this application, the step of cooling the precision-rolled low-density steel to 500°C to 550°C at a cooling rate of 150°C / min to 200°C / min to obtain cooled low-density steel includes: cooling the precision-rolled low-density steel to 500°C to 550°C at a cooling rate of 150°C / min to 180°C / min.

[0013] Secondly, this application provides a high-alumina manganese Fe-Mn-Al-C low-density steel prepared by the above-mentioned preparation method, whose composition by mass percentage is: Mn, 1.8%~2.0%; Al, 1.05%~1.20%; C, 0.09%~0.12%; Si, 0.80%~1.1%; the total content of Ti, Ni and Nb is ≤0.55%, and the balance is iron and impurities remaining during the smelting process.

[0014] In some embodiments of this application, the density of the high-aluminum manganese Fe-Mn-Al-C low-density steel is 6.60 g / cm³. 3 ~6.79g / cm 3 .

[0015] In some embodiments of this application, the high-aluminum manganese Fe-Mn-Al-C low-density steel meets the following requirements: yield strength approximately 400MPa to 1100MPa, tensile strength 600MPa to 2000MPa, elongation 30% to 100%, and strength-ductility product 30GPa·% to 50GPa·%.

[0016] The processing method of high-alumina manganese Fe-Mn-Al-C low-density steel in this application embodiment, by adding microalloying elements and combining heat treatment, can ensure the performance required by high-alumina manganese Fe-Mn-Al-C low-density steel in service environment. At the same time, it can enable stable industrial production of high-alumina manganese Fe-Mn-Al-C low-density steel, reduce the corrosion of steel ladle due to sticky steel slag, and reduce blockage and steel defects during continuous casting and billet pulling. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments of this application will be briefly introduced below. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic flowchart of the processing method for high-alumina manganese Fe-Mn-Al-C low-density steel provided in the embodiments of this application.

[0019] Figure 2 This is a metallographic microstructure of the high-alumina manganese Fe-Mn-Al-C low-density steel provided in Example 1 of this application at a scale of 5 μm.

[0020] Figure 3 This is a metallographic microstructure of the high-aluminum manganese Fe-Mn-Al-C low-density steel provided in Example 2 of this application at a scale of 40 μm. Detailed Implementation

[0021] The features and exemplary embodiments of various aspects of this application will be described in detail below. To make the objectives, technical solutions, and advantages of this application clearer, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only intended to explain this application and not to limit it. For those skilled in the art, this application can be implemented without some of these specific details. The following description of the embodiments is merely to provide a better understanding of this application by illustrating examples.

[0022] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus that includes said element.

[0023] As described in the background section, Fe-Mn-Al-C low-density steel, due to its high aluminum and manganese content, is prone to causing sticky slag and corrosion of the ladle during the smelting process. Furthermore, the high melting point of aluminum inclusions easily leads to blockages and steel defects during continuous casting, making large-scale stable production of this steel grade currently difficult.

[0024] To address the aforementioned issues, the inventors used CCT curves to study the experimental steel and developed a suitable process route to improve the strength of the steel while ensuring its elongation.

[0025] Through CCT curve analysis, the inventors discovered that the steel grains are small, generally below 10 μm. This is because microalloying elements such as Al, Ti, and Nb in the steel can promote grain refinement to a certain extent. For example, Ti compounds can prevent austenite grain growth during heating, Nb compounds have a pinning effect on grain boundaries, and Nb atoms in solid solution have a dragging effect on grain boundaries, thus inhibiting austenite grain growth.

[0026] In static CCT experiments, the inventors discovered that when the cooling rate of steel is 0.5℃ / s, the microstructure of the steel mainly consists of ferrite, Mao islands, and pearlite, with bright white pearlite evenly distributed at the grain boundary junctions. When the cooling rate of steel is between 1℃ / s and 10℃ / s, the pearlite disappears, and the microstructure of the steel consists only of ferrite and Mao islands, with Mao islands distributed between the ferrite grain boundaries. When the cooling rate of steel is greater than 20℃ / s, the proportion of raised Mao islands in the microstructure of the steel increases significantly, and as the cooling rate continues to increase, the content of Mao islands continues to increase, and the morphology gradually changes from irregular blocky to strip-like.

[0027] As can be seen from the above, Mao islands always exist in steel structures with different cooling rates. This is because during the transformation of austenite to ferrite, carbon is continuously discharged to the grain boundaries, thus forming Mao islands at the ferrite grain boundaries.

[0028] In dynamic CCT experiments, the inventors discovered that, due to the applied deformation force on the steel, the dynamic ferrite grains were finer than those in the static CCT microstructure. However, both large and small ferrite grains existed, and the proportion of Mao islands was significantly reduced. This may be because plastic deformation induces an increase in ferrite nucleation sites, leading to the rapid formation of numerous fine ferrite particles. Carbon elements do not have enough time to migrate to the grain boundaries, resulting in a reduced proportion of Mao islands. Simultaneously, the fine ferrite particles recrystallize to form coarser ferrite grains, thus resulting in two different sized ferrite structures.

[0029] From the perspective of cooling rate, when the cooling rate is 0.5℃ / s, large lamellar pearlite structures exist in the microstructure; however, when the cooling rate increases to 1℃ / s, a small amount of pearlite still exists in the microstructure, which is different from the complete disappearance of pearlite in static CCT microstructure. This shows that applying deformation force is beneficial for pearlite formation.

[0030] When the cooling rate is 2℃ / s, the microstructure consists of ferrite and Mao islands. When the cooling rate is further increased to 20℃ / s to 10℃ / s, obvious bainite microstructure appears in the microstructure, and the proportion of bainite microstructure further increases with the increase of cooling rate, indicating that deformation is conducive to the formation of bainite.

[0031] The steel grade of this application forms a predominantly bainitic microstructure under high cooling rates. Compared to martensite, bainitic microstructure exhibits better strength and toughness. Furthermore, the relatively dispersed bainite and ferrite contribute to improved toughness. Simultaneously, the fine-grain strengthening and precipitation strengthening caused by microalloying elements also promote the strength and toughness of the experimental steel grade, enabling it to operate in more demanding environments.

[0032] To address the problems of the prior art, this application provides a method for processing high-alumina manganese-based Fe-Mn-Al-C low-density steel. The method for processing high-alumina manganese-based Fe-Mn-Al-C low-density steel provided in this application will be described below.

[0033] Figure 1 A schematic flowchart of the processing method for high-aluminum manganese Fe-Mn-Al-C low-density steel provided in this application embodiment is shown.

[0034] like Figure 1 As shown, the processing methods for high-aluminum manganese Fe-Mn-Al-C low-density steel include: Low-density steel with the composition of Fe-1.80Mn-1.05Al-0.09C-0.80Si-0.55(Ti+Ni+Nb) is provided; Heat treatment of low-density steel includes: Low-density steel is heated to 1250℃ at a heating rate of 10℃ / min to 20℃ / min and held at that temperature to obtain heated low-density steel. The heated low-density steel is cooled to a roughing temperature of 1100℃~1150℃ at a cooling rate of 100℃ / min~150℃ / min and then rough rolled to obtain the rough rolled low-density steel. Low-density steel that has undergone rough rolling is cooled to a finishing rolling temperature of 950℃~1000℃ at a cooling rate of 100℃ / min~150℃ / min and then finished rolled to obtain finished low-density steel. The low-density steel that has been precision rolled is cooled to 500℃~550℃ at a cooling rate of 150℃ / min~200℃ / min to obtain cooled low-density steel. Cooled low-density steel is coiled to obtain coiled low-density steel. Air cooling was performed on the coiled low-density steel to obtain high-aluminum manganese Fe-Mn-Al-C low-density steel.

[0035] The processing method for high-alumina manganese Fe-Mn-Al-C low-density steel provided in this application embodiment involves adding microalloying elements in combination with heat treatment. By adjusting the temperature, the microstructure of the low-density steel is adjusted. The microalloying elements, which have a low alloy content in the steel product, form fine grains, especially bainite and ferrite structures. This ensures the performance required by the high-alumina manganese Fe-Mn-Al-C low-density steel under service conditions. At the same time, it enables stable industrial production of high-alumina manganese Fe-Mn-Al-C low-density steel, reducing the corrosion of the ladle due to sticky slag, as well as blockages and steel defects during continuous casting and billet pulling.

[0036] In some embodiments of this application, the step of heating low-density steel to 1250°C at a heating rate of 10°C / min to 20°C / min and holding it at that temperature to obtain heated low-density steel includes heating low-density steel to 1250°C at a heating rate of 10°C / min to 15°C / min and holding it at that temperature.

[0037] The processing method for high-alumina manganese Fe-Mn-Al-C low-density steel provided in this application embodiment heats the low-density steel at the aforementioned heating rate, ensuring a uniform heating process and minimizing the impact of the heating process on the internal structure of the low-density steel. Furthermore, the heat preservation treatment of the low-density steel ensures a uniform heating temperature, facilitating subsequent rolling.

[0038] In some embodiments of this application, the step of cooling heated low-density steel to 1100°C~1150°C at a cooling rate of 100°C / min~150°C / min and then rough rolling it to obtain rough rolled low-density steel includes: cooling heated low-density steel to a rough rolling temperature of 1100°C~1150°C at a cooling rate of 100°C / min~140°C / min and then rough rolling it.

[0039] The processing method for high-aluminum manganese Fe-Mn-Al-C low-density steel provided in this application embodiment, through the aforementioned cooling rate, ensures that the steel maintains a suitable temperature during the roughing and subsequent finishing rolling processes, thereby making the entire rolling process stable and continuous and reducing the impact of drastic temperature changes on the steel.

[0040] In some embodiments of this application, the deformation of the rough-rolled low-density steel is 35% to 45%. Exemplarily, the rough-rolling deformation can be 36%, 37%, 38%, 39%, 40%, 42%, or 44%.

[0041] The processing method for high-alumina manganese Fe-Mn-Al-C low-density steel provided in this application embodiment reorganizes the microstructure of the low-density steel by using the above-mentioned rough rolling temperature, as well as the corresponding deformation amount and cooling rate of rough rolling.

[0042] In some embodiments of this application, the step of cooling the rough-rolled low-density steel to 950°C to 1000°C at a cooling rate of 100°C to 150°C / min and then finishing-rolling it to obtain finish-rolled low-density steel includes: cooling the rough-rolled low-density steel to 950°C to 1000°C at a cooling rate of 100°C to 135°C / min and then finishing-rolling it.

[0043] The processing method for high-alumina manganese Fe-Mn-Al-C low-density steel provided in this application adopts the above-mentioned temperature and cooling rate, which enables the low-density steel to be rolled stably in the finishing rolling process and allows the microstructure of the low-density steel to undergo subsequent reorganization.

[0044] In some embodiments of this application, the deformation of the low-density steel after finishing rolling is 25% to 35%. Exemplarily, the deformation of the low-density steel after finishing rolling during the finishing rolling process can be 26%, 27%, 28%, 30%, 31%, 32%, 34%, or 35%.

[0045] The processing method for high-aluminum manganese Fe-Mn-Al-C low-density steel provided in this application embodiment, combined with the above-mentioned temperature, finishing rolling and cooling rate, allows the microstructure of the low-density steel to undergo further appropriate deformation.

[0046] In some embodiments of this application, the step of cooling the precision-rolled low-density steel to 500°C to 550°C at a cooling rate of 150°C / min to 200°C / min to obtain cooled low-density steel includes: cooling the precision-rolled low-density steel to 500°C to 550°C at a cooling rate of 150°C / min to 180°C / min.

[0047] The processing method for high-aluminum manganese Fe-Mn-Al-C low-density steel provided in this application embodiment, through the above-mentioned cooling rate and temperature, and the combination of small amounts of titanium, niobium, and nickel elements in the steel composition, further refines the metallographic structure of the low-density steel, making the grains finer, thereby improving the mechanical properties of the low-density steel.

[0048] Secondly, this application provides a high-alumina manganese Fe-Mn-Al-C low-density steel prepared by the above-mentioned preparation method, whose composition by mass percentage is: Mn, 1.8%~2.0%; Al, 1.05%~1.20%; C, 0.09%~0.12%; Si, 0.80%~1.1%; the total content of Ti, Ni and Nb is ≤0.55%, and the balance is iron and impurities remaining during the smelting process.

[0049] In some embodiments, in order to improve the problem of large-scale stable production of magnetic steel during the smelting process, the inventors improved the composition of low-density steel and provided a high-alumina manganese Fe-Mn-Al-C low-density steel, whose composition by mass percentage is: Mn, 1.8%; Al, 1.05%; C, 0.09%; Si, 0.80%; the total content of Ti, Ni and Nb is ≤0.55%, and the balance is iron and impurities remaining from the smelting process.

[0050] In some embodiments of this application, the density of the high-aluminum manganese Fe-Mn-Al-C low-density steel is 6.60 g / cm³. 3 ~6.79g / cm 3 .

[0051] The high-aluminum manganese Fe-Mn-Al-C low-density steel of this application embodiment has a density that meets the above requirements, and can have high mechanical properties with a lighter weight, thereby meeting the requirements of automobile lightweighting.

[0052] In some embodiments of this application, the high-aluminum manganese Fe-Mn-Al-C low-density steel meets the following requirements: yield strength approximately 400MPa to 1100MPa, tensile strength 600MPa to 2000MPa, elongation 30% to 100%, and strength-ductility product 30GPa·% to 50GPa·%.

[0053] The high-alumina manganese Fe-Mn-Al-C low-density steel of this application embodiment is prepared according to the processing method of the high-alumina manganese Fe-Mn-Al-C low-density steel provided in the first aspect embodiment above, and has the above-mentioned good comprehensive properties.

[0054] The high-alumina manganese Fe-Mn-Al-C low-density steel of this application embodiment, by adding microalloying elements and combining it with the processing method of the high-alumina manganese Fe-Mn-Al-C low-density steel of this application embodiment, ensures the performance required by the steel in the service environment, which helps to further realize industrial production.

[0055] The technical solution of this application will be described in more detail below through a comparison of specific comparative examples and embodiments of high-aluminum manganese Fe-Mn-Al-C low-density steel.

[0056] Comparative Example 1 A method for preparing austenitic lightweight steel includes: smelting, preparing raw materials according to the following specific chemical composition ratios by mass percentage: carbon (C): 1.4%, aluminum (Al): 10%, manganese (Mn): 28%, balance iron (Fe), and unavoidable impurities. Smelting is carried out using a vacuum induction melting furnace (i.e., an RH furnace) to obtain a uniformly composed molten steel. Casting, pouring the smelted molten steel into a mold and solidifying to form a billet. Hot working, hot working the billet by heating it to 1150℃~1180℃ and hot rolling it to produce plates of the required dimensions. Solution treatment, heating the hot-worked plate to a high temperature of 1050~1080℃ and holding it for 1 hour to fully dissolve all elements into the austenite, followed by rapid cooling, i.e., cold quenching with water at 40℃, to retain the high-temperature austenitic structure to room temperature, thus obtaining austenitic lightweight steel. It should be noted that this austenitic lightweight steel is an existing lightweight steel and can be obtained through commercial channels.

[0057] Example 1 A high-alumina manganese Fe-Mn-Al-C low-density steel is provided, wherein the composition of the high-alumina manganese Fe-Mn-Al-C low-density steel, by mass percentage, is: Mn, 1.8%; Al, 1.05%; C, 0.09%; Si, 0.80%; the total content of Ti, Ni, and Nb is 0.55%, and the balance is iron and impurities remaining from the smelting process. The preparation method of this high-alumina manganese Fe-Mn-Al-C low-density steel includes: Heat treatment of high-aluminum manganese Fe-Mn-Al-C low-density steel includes: heating the high-aluminum manganese Fe-Mn-Al-C low-density steel to 1250℃ at a heating rate of 10℃ / min and holding it at that temperature for 10min to obtain heated low-density steel. The heated low-density steel was cooled to the roughing rolling temperature at a cooling rate of 100℃ / min and then rough rolled at a temperature of 1100℃~1130℃ to obtain rough-rolled low-density steel with a deformation of 40%. The low-density steel that has undergone rough rolling is then cooled to the finishing rolling temperature at a cooling rate of 120℃ / min and then finished rolled at a temperature of 950℃~980℃ to obtain finished low-density steel with a deformation of 30%. The low-density steel that has been precision rolled is cooled to 520℃~550℃ at a cooling rate of 150℃ / min to obtain cooled low-density steel. Cooled low-density steel is coiled to obtain coiled low-density steel. Air cooling is performed on the coiled low-density steel to obtain high-aluminum manganese Fe-Mn-Al-C low-density steel, which yields rolled plates with qualified mechanical properties.

[0058] Figure 2 The metallographic image of the high-alumina manganese Fe-Mn-Al-C low-density steel provided in Example 1 of this application is shown at a 5μm scale. In the image, M represents martensite, A represents austenite, B represents bainite, and F represents ferrite. Figure 2 Bainite and ferrite are still the main components, while martensite and austenite are present in smaller amounts.

[0059] Example 2 A high-alumina manganese Fe-Mn-Al-C low-density steel is provided, wherein the composition of the high-alumina manganese Fe-Mn-Al-C low-density steel, by mass percentage, is: Mn, 1.85%; Al, 1.15%; C, 0.10%; Si, 0.88%; the total content of Ti, Ni, and Nb is 0.53%, and the balance is iron and impurities remaining from the smelting process. The preparation method of this high-alumina manganese Fe-Mn-Al-C low-density steel includes: Heat treatment of high-aluminum manganese Fe-Mn-Al-C low-density steel includes: heating the high-aluminum manganese Fe-Mn-Al-C low-density steel to 1250℃ at a heating rate of 15℃ / min and holding it at that temperature for 10min to obtain heated low-density steel. The heated low-density steel was cooled to the roughing rolling temperature at a cooling rate of 120℃ / min and then rough rolled at a temperature of 1120℃~1140℃ to obtain rough rolled low-density steel with a deformation of 40%. The low-density steel that has undergone rough rolling is then cooled to the finishing rolling temperature at a cooling rate of 125℃ / min and then finished rolled at a temperature of 980℃~1010℃ to obtain finished low-density steel with a deformation of 30%. The low-density steel that has been precision rolled is cooled to 500℃~530℃ at a cooling rate of 160℃ / min to obtain cooled low-density steel. Cooled low-density steel is coiled to obtain coiled low-density steel. Air cooling is performed on the coiled low-density steel to obtain high-aluminum manganese Fe-Mn-Al-C low-density steel, which yields rolled plates with qualified mechanical properties.

[0060] Figure 3 The metallographic image of the high-alumina manganese Fe-Mn-Al-C low-density steel provided in Example 2 of this application is shown at the 40μm scale. Figure 3 In the image, the grayish-white part is bainite and the dark part is ferrite, indicating that the high-alumina manganese Fe-Mn-Al-C low-density steel prepared in Example 2 is still mainly composed of bainite and ferrite, with less martensite and austenite.

[0061] Example 3 A high-alumina manganese Fe-Mn-Al-C low-density steel is provided, wherein the composition of the high-alumina manganese Fe-Mn-Al-C low-density steel, by mass percentage, is: Mn, 1.8%; Al, 1.05%; C, 0.09%; Si, 0.80%; the total content of Ti, Ni, and Nb is ≤0.55%, and the balance is iron and impurities remaining from the smelting process. The preparation method of this high-alumina manganese Fe-Mn-Al-C low-density steel includes: Heat treatment is performed on high-aluminum manganese Fe-Mn-Al-C low-density steel, including heating the high-aluminum manganese Fe-Mn-Al-C low-density steel to 1250℃ at a heating rate of 10℃ / min and holding it for 10min to obtain heated low-density steel. The heated low-density steel was cooled to the roughing rolling temperature at a cooling rate of 130℃ / min and then rough rolled at a temperature of 1120℃~1150℃ to obtain rough rolled low-density steel with a deformation of 40%. The low-density steel that has been rough-rolled is then cooled to the finishing rolling temperature at a cooling rate of 130℃ / min and then finished rolled. The finishing rolling temperature is set at 980℃~1000℃ to obtain the finished low-density steel with a deformation of about 30%. The low-density steel that has been precision rolled is cooled to 500℃~525℃ at a cooling rate of 175℃ / s to obtain cooled low-density steel. Cooled low-density steel is coiled to obtain coiled low-density steel. Air cooling is performed on the coiled low-density steel to obtain high-aluminum manganese Fe-Mn-Al-C low-density steel, which yields rolled plates with qualified mechanical properties.

[0062] The basic metallographic microstructure of Example 3 and Figure 2 The composition remains consistent, still dominated by bainite and ferrite, with less martensite and austenite.

[0063] Table 1 The steel grade of this application, even after rapid cooling, still exhibits little or no lath martensite, bainite, and ferrite, which significantly promotes toughness. Simultaneously, precipitation strengthening and grain refinement also enhance the steel's strength. In summary, the processing method for high-alumina manganese Fe-Mn-Al-C low-density steel in this application improves slag viscosity and reduces the corrosion rate of the ladle, thereby lowering the steel density to a certain extent while maintaining optimal mechanical properties.

[0064] The above description is merely a specific implementation of this application. Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the corresponding processes in the foregoing method embodiments can be referred to, and will not be repeated here. It should be understood that the protection scope of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the protection scope of this application.

Claims

1. A method for processing high-aluminum manganese-based Fe-Mn-Al-C low-density steel, characterized in that, include: Low-density steel with the composition of Fe-1.80Mn-1.05Al-0.09C-0.80Si-0.55(Ti+Ni+Nb) is provided; Heat treatment of low-density steel includes: Low-density steel is heated to 1250℃ at a heating rate of 10℃ / min to 20℃ / min and held at that temperature to obtain heated low-density steel. The heated low-density steel is cooled to a roughing temperature of 1100℃~1150℃ at a cooling rate of 100℃ / min~150℃ / min and then rough rolled to obtain the rough rolled low-density steel. Low-density steel that has undergone rough rolling is cooled to a finishing rolling temperature of 950℃~1000℃ at a cooling rate of 100℃ / min~150℃ / min and then finished rolled to obtain finished low-density steel. The low-density steel that has been precision rolled is cooled to 500℃~550℃ at a cooling rate of 150℃ / min~200℃ / min to obtain cooled low-density steel. Cooled low-density steel is coiled to obtain coiled low-density steel. Air cooling was performed on the coiled low-density steel to obtain high-aluminum manganese Fe-Mn-Al-C low-density steel.

2. The processing method according to claim 1, characterized in that, The step of heating the low-density steel to 1250°C at a heating rate of 10°C / min to 20°C / min and holding it at that temperature includes heating the low-density steel to 1250°C at a heating rate of 10°C / min to 15°C / min and holding it at that temperature to obtain heated low-density steel.

3. The processing method according to claim 1, characterized in that, The step of cooling the heated low-density steel to a roughing temperature of 950℃~1050℃ at a cooling rate of 100℃ / min~150℃ / min and then roughing it includes cooling the heated low-density steel to a roughing temperature of 1100℃~1150℃ at a cooling rate of 100℃ / min~140℃ / s and then roughing it to obtain the rough-rolled low-density steel.

4. The processing method according to any one of claims 1-3, characterized in that, The deformation of the rough-rolled low-density steel is 35% to 45%.

5. The processing method according to any one of claims 1-3, characterized in that, The step of cooling the rough-rolled low-density steel to a finishing rolling temperature of 950℃~1000℃ at a cooling rate of 100℃ / min~150℃ / min to obtain finishing rolled low-density steel includes cooling the rough-rolled low-density steel to a finishing rolling temperature of 950℃~1000℃ at a cooling rate of 100℃ / min~135℃ / min to obtain finishing rolled low-density steel.

6. The processing method according to claim 5, characterized in that, The step of cooling the precision-rolled low-density steel to 500℃~550℃ at a cooling rate of 150℃ / min~200℃ / min to obtain cooled low-density steel includes cooling the precision-rolled low-density steel to 500℃~550℃ at a cooling rate of 150℃ / min~180℃ / min.

7. The processing method according to claim 6, characterized in that, The deformation of the precision-rolled low-density steel is 25% to 35%.

8. A high-aluminum manganese-based Fe-Mn-Al-C low-density steel, characterized in that, Prepared by the processing method according to any one of claims 1-7, the composition, by mass percentage, is: Mn, 1.8%–2.0%; Al, 1.05%–1.20%; C, 0.09%–0.12%; Si, 0.80%–1.1%; the total content of Ti, Ni, and Nb is ≤0.55%, and the balance is iron and impurities remaining from the smelting process.

9. The high-aluminum manganese-based Fe-Mn-Al-C low-density steel according to claim 8, characterized in that, Its density is 6.60 g / cm³ 3 ~6.79g / cm 3 .

10. The high-aluminum manganese-based Fe-Mn-Al-C low-density steel according to claim 8, characterized in that, The yield strength of high-alumina manganese Fe-Mn-Al-C low-density steel is approximately 400MPa to 1100MPa, the tensile strength is 600MPa to 2000MPa, the elongation is 30% to 100%, and the strength-ductility product is 30GPa·% to 50GPa·%.

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