Preparation method of Fe50Mn30Co10Cr10 alloy with super-high specific strength

Abstract

The application belongs to the field of high-entropy alloys, and particularly relates to a preparation method of an ultra-high strength and plasticity product Fe50Mn30Co10Cr10 alloy. Firstly, a cast slab is prepared through vacuum induction melting, then the cast slab is subjected to multi-pass hot rolling with a reduction ratio of 70% to 75%, and after pickling, the cast slab is subjected to multi-pass warm rolling with a reduction ratio of 80%, and finally, high-temperature short-time annealing is carried out at 1050 to 1150 DEG C to obtain a final annealing plate. In the application, the phase transformation behavior in the alloy deformation process is inhibited by controlling the hot rolling and warm rolling temperatures, and the rolling plasticity of the material is improved. Meanwhile, by optimizing the annealing process, the grains are refined as much as possible, and a certain dislocation density is retained, and the strength and plasticity of the alloy are improved through the comprehensive action of multiple strengthening mechanisms. The prepared Fe50Mn30Co10Cr10 alloy has a tensile strength of 1050 to 1280 MPa, an elongation of 35% to 58%, and a strength and plasticity product of 40 to 73 GPa.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of high-entropy alloys, and particularly relates to a preparation method of an ultra-high strength and plasticity product Fe50Mn30Co10Cr10 alloy. BACKGROUND

[0002] High-entropy alloys generally refer to alloys with five or more main elements, and the atomic ratio of each element is between 5% and 35%. High configurational entropy is considered to be conducive to forming a stable solid solution structure rather than a complex intermetallic compound. This special microstructure enables high-entropy alloys to have excellent performance. The metastable dual-phase structure of Fe 50 Mn 30 Co 10 Cr 10 High-entropy alloys are a new type of material developed in recent years. The alloy system has a low stacking fault energy, and the phase structure is unstable. Deformation can trigger the phase transformation induced plasticity (TRIP) effect and the twinning induced plasticity (TWIP) effect, thereby overcoming the strength-ductility balance of metal materials. It is a new type of high-entropy alloy with great development potential. However, the existing Fe 50 Mn 30 Co 10 Cr 10 The strength of the high-entropy alloy is not outstanding and needs to be further improved. In addition, high-entropy alloys generally have a high work hardening rate and are difficult to be plastically rolled.

[0003] From the currently published patents, there are few patents about strengthening Fe 50 Mn 30 Co 10 Cr 10 High-entropy alloys, and adding micro-alloying elements is one of the most common methods to enhance the strength of the alloy. Patent Publication No. CN114622120A reports a TRIP-assisted FeMnCoCrAl three-phase heterogeneous high-entropy alloy and a preparation method thereof. After adding an appropriate amount of Al element, the FCC (face-centered cubic lattice) → HCP (hexagonal close-packed lattice) phase transition is triggered, and a BCC (body-centered cubic lattice) third phase is introduced, which indeed improves the strength to a certain extent, but the elongation is also significantly reduced. Patent Publication No. CN114855097A also reports a method for improving the strength and low-temperature wear resistance of FeMnCoCr high-entropy alloy. The B element is added to the FeMnCoCr high-entropy alloy, and the results show that the yield strength and low-temperature wear resistance are improved to varying degrees. In addition, through appropriate processing and manufacturing methods, the grain size of the alloy is further refined, and the strength is further improved, but the ultimate tensile strength is only about 800 MPa, which obviously does not meet the demand for ultra-high strength. In Fe 50 Mn 30 Co 10 Cr 10The exploration of plastic rolling of high-entropy alloys is also less. In summary, the existing technical means cannot prepare high-entropy alloys with large reduction ratio and high strength-plasticity product 50 Mn 30 Co 10 Cr 10 There are still deficiencies in high-entropy alloys. SUMMARY

[0004] In view of the above problems of existing plastic rolling and low strength-plasticity product, the purpose of the present application is to provide a preparation method of ultra-high strength-plasticity product Fe50Mn30Co10Cr10 alloy, realizing large reduction ratio rolling and large improvement of strength-plasticity product of Fe50Mn30Co10Cr10.

[0005] The technical scheme of the present application is:

[0006] A preparation method of ultra-high strength-plasticity product Fe50Mn30Co10Cr10 alloy, which is carried out according to the following steps:

[0007] (1) Vacuum induction melting: high-purity metals of Fe, Mn, Co and Cr with purity greater than 99.9wt% are selected as raw materials, and the atomic ratio of each element is: Fe 50%, Mn 30%, Co 10%, and Cr 10%; the mixed material is placed into a vacuum induction furnace for melting according to the set composition, and then cast into a 20mm-thick as-cast slab in a square copper mold;

[0008] (2) Hot rolling: the as-cast slab is subjected to multi-pass hot rolling, the hot rolling reduction rate is 70% to 75%, the single-pass reduction rate is 20% to 30%, the opening rolling temperature is 1100℃ to 1150℃, the final rolling temperature is 1000℃ to 1020℃, and the hot-rolled plate is obtained by finally water cooling to room temperature;

[0009] (3) Warm rolling: after the hot-rolled plate is pickled to remove the iron oxide scale, it is heated to 260 to 310℃ in a resistance box furnace, and then subjected to multi-pass rolling by using a two-roll mill, the reduction rate is 80%, and the single-pass reduction rate is 15% to 30%, to obtain a warm-rolled plate;

[0010] (4) Final annealing: the warm-rolled plate is annealed to obtain a final product annealed plate, and argon gas is used as the protective gas during the annealing process.

[0011] The preparation method of ultra-high strength-plasticity product Fe50Mn30Co10Cr10 alloy, in step (2), the hot-rolled plate has a FCC and HCP dual-phase structure, and the volume ratio of the FCC phase is 80% to 90%.

[0012] The preparation method of ultra-high strength-plasticity product Fe50Mn30Co10Cr10 alloy, in step (3), the warm-rolled plate has a FCC single-phase structure.

[0013] The preparation method of the super high strength and plastic product Fe50Mn30Co10Cr10 alloy, in step (4), the annealing temperature of the warm-rolled plate is 1050-1150 DEG C, the heating rate is greater than or equal to 30 DEG C / s, the holding time is 20-25 s, and air cooling is carried out.

[0014] The preparation method of the super high strength and plastic product Fe50Mn30Co10Cr10 alloy, in step (4), the annealing plate is a critical complete recrystallization structure, and the average grain size is 0.8-1.5 microns.

[0015] The preparation method of the super high strength and plastic product Fe50Mn30Co10Cr10 alloy, in step (4), the annealing plate is a critical complete recrystallization structure, and the average grain size is 0.8-1.5 microns.

[0016] The preparation method of the super high strength and plastic product Fe50Mn30Co10Cr10 alloy, in step (4), the annealing plate is a critical complete recrystallization structure, and the average grain size is 0.8-1.5 microns.

[0017] The design idea of the application is:

[0018] Fe 50 Mn 30 Co 10 Cr 10 The maximum reduction rate of the high-entropy alloy cold-rolled at room temperature is about 60%, the HCP phase in the hot-rolled plate is reduced by controlling the hot-rolling temperature, the plasticity of the material is improved by subsequently adopting warm-rolling, and the phase change behavior in the warm-rolling process is strictly controlled, so that the deformed structure is a complete FCC structure. In the subsequent annealing process, high-temperature short-time annealing is adopted to refine the grains as much as possible, and a certain dislocation density is reserved, so as to improve the strength and plasticity of the alloy by the comprehensive action of fine-grain strengthening, dislocation strengthening, and TRIP and TWIP effects.

[0019] Compared with the prior art, the application has the following characteristics and advantages:

[0020] (1) The Fe50Mn30Co10Cr10 alloy is prone to cracks when rolled at room temperature with a reduction rate of more than 60%, and thinner materials cannot be prepared. The special warm-rolling process adopted in the application effectively improves the rolling plasticity of the material, and can be used to prepare thinner materials with a reduction rate of more than 80%.

[0021] (2) The application effectively controls the structure, size and phase change behavior of the deformed and heat-treated structure of the Fe50Mn30Co10Cr10 alloy through the integrated process design of hot-rolling, warm-rolling and annealing, so as to obtain a super-fine FCC single-phase recrystallization structure, which provides a structural basis for the improvement of strength and plasticity.

[0022] (3) The Fe50Mn30Co10Cr10 alloy involved in the present application has a strength of up to 1280 MPa and a plastic product of up to 73 GPa, which are respectively increased by more than 300 MPa and 40 GPa than those of the existing materials, and has very excellent comprehensive mechanical properties.

[0023] (4) No other valuable alloy strengthening elements are added in the present application, and a traditional rolling and heat treatment process optimization route is adopted, so that the production cost is low and batch production is suitable. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 The Fe50Mn30Co10Cr10 alloy hot-rolled plate prepared in Example 2 of the present application.

[0025] Figure 2 The Fe50Mn30Co10Cr10 alloy warm-rolled plate prepared in Example 2 of the present application.

[0026] Figure 3 The Fe50Mn30Co10Cr10 alloy annealed plate prepared in Example 2 of the present application.

[0027] Figure 4 The tensile curve of the Fe50Mn30Co10Cr10 alloy annealed plate prepared in Example 2 of the present application. In the figure, the horizontal coordinate Engineering strain is engineering strain (%), and the vertical coordinate Engineering stress is engineering stress (MPa).

[0028] Figure 5 The Fe50Mn30Co10Cr10 alloy cold-rolled plate prepared in Comparative Example 1.

[0029] Figure 6 The Fe50Mn30Co10Cr10 alloy annealed plate prepared in Comparative Example 1. DETAILED DESCRIPTION

[0030] In the specific implementation process, the application provides a preparation method of an ultra-high specific strength Fe50Mn30Co10Cr10 alloy, and the specific process is as follows: vacuum induction melting is used to obtain an original as-cast slab according to the element atomic percentage of Fe 50%, Mn 30%, Co 10%, and Cr 10%, then the as-cast slab is subjected to multi-pass hot rolling with a reduction of 70% to 75%, and after pickling, the multi-pass warm rolling with a reduction of 80% is performed, and finally high-temperature short-time annealing at 1050 to 1150 °C is performed to obtain the final annealed plate. By controlling the hot rolling temperature, cooling mode, warm rolling temperature, annealing heating rate, holding time and other parameters, a single-phase FCC ultra-fine recrystallized structure is obtained, and the specific strength of the material is significantly improved.

[0031] In the embodiment of the application, the electron backscatter diffraction (EBSD) system of the Zeiss Gemini-300 field emission electron microscope is used to observe the material structure, and the mechanical properties are measured by the SHIMADZU AGS-X universal tensile machine.

[0032] The application will be further described in detail through examples and comparative examples. Obviously, the described examples are only part of the examples of the application, rather than all the examples. Based on the examples in the application, all other examples obtained by those skilled in the art without creative labor are within the protection scope of the application.

[0033] Example 1

[0034] High-purity metals of Fe, Mn, Co and Cr with a purity of more than 99.9wt% are selected as raw materials, vacuum induction melting is performed according to the element atomic percentage of Fe 50%, Mn 30%, Co 10% and Cr 10%, and then the as-cast slab with a thickness of 20 mm is cast in a square copper mold. Subsequently, the as-cast slab is subjected to multi-pass hot rolling, the hot rolling reduction is 75%, the single-pass reduction is 20% to 30%, the opening rolling temperature is 1100 °C, the final rolling temperature is 1000 °C, and finally water cooling to room temperature is performed. Then, after the hot-rolled plate is pickled to remove the iron oxide scale, warm rolling at 280 °C is performed, the reduction is 80%, the single-pass reduction is 15% to 30%, and air cooling to room temperature is performed. Subsequently, the final Fe50Mn30Co10Cr10 alloy annealing plate is obtained by heating at 1100 °C for 20 s at a heating rate of 35 °C / s, and then air cooling to room temperature.

[0035] The microstructure of the hot-rolled plate in this example is a dual-phase structure of FCC and HCP, with the volume fraction of FCC phase being 82%. The warm-rolled plate has good shape and no cracks, and the microstructure of the warm-rolled plate is a single-phase structure of FCC. In addition, the microstructure of the annealed plate is a critical complete recrystallized structure, which is a single-phase structure of FCC, and the average grain size is 1.1 μm. The tensile strength of the annealed plate is 1160 MPa, the elongation is 36%, and the product of strength and elongation is 41.7 GPa.

[0036] Example 2

[0037] High-purity metals of Fe, Mn, Co and Cr with a purity of more than 99.9 wt% were selected as raw materials, and vacuum induction melting was performed according to the element atomic ratio of Fe 50%, Mn 30%, Co 10% and Cr 10%. Then, the cast slab with a thickness of 20 mm was cast in a square copper mold. Subsequently, the cast slab was subjected to multi-pass hot rolling, with a hot rolling reduction of 75% and a single-pass reduction of 20% to 30%, and the rolling temperature was 1150°C and the final rolling temperature was 1020°C, and finally water-cooled to room temperature. Then, the hot-rolled plate was pickled to remove the iron oxide scale, and then warm-rolled at 300°C, with a reduction of 80% and a single-pass reduction of 15% to 30%, and air-cooled to room temperature. Subsequently, the final Fe50Mn30Co10Cr10 alloy annealed plate was obtained by heating at 1100°C for 20 s with a heating rate of 35°C / s, and then air-cooled to room temperature.

[0038] As shown in FIG. 1, the microstructure of the hot-rolled plate in this example is a dual-phase structure of FCC and HCP, with the volume fraction of FCC phase being 89%. As shown in FIG. 2, the warm-rolled plate has good shape and no cracks, and the microstructure of the warm-rolled plate is a single-phase structure of FCC. As shown in FIG. 3, the microstructure of the annealed plate is a critical complete recrystallized structure, which is a single-phase structure of FCC, and the average grain size is 1.4 μm. As shown in FIG. 4, it can be seen from the tensile curve that the tensile strength of the annealed plate is 1280 MPa, the elongation is 58%, and the product of strength and elongation is 73 GPa. Figure 1 Figure 2 Figure 3 Figure 4

[0039] Example 3

[0040] ​​​​High purity metals of Fe, Mn, Co, Cr with purity more than 99.9wt% were used as raw materials. The composition of the raw materials was Fe 50%, Mn 30%, Co 10%, Cr 10% in atomic ratio. The raw materials were melted in a vacuum induction furnace and then cast into a 20mm thick as-cast slab in a square copper mold. The as-cast slab was then hot rolled in multiple passes with a total reduction of 75% and a single pass reduction of 20% to 30%. The hot rolling was performed at a starting temperature of 1150°C and a finishing temperature of 1020°C. The hot rolled plate was then water cooled to room temperature. The hot rolled plate was then pickled to remove the iron oxide scale and then warm rolled at 260°C with a total reduction of 80% and a single pass reduction of 15% to 30%. The warm rolled plate was then air cooled to room temperature. The warm rolled plate was then heated at 1050°C for 25s with a heating rate of 30°C / s and then air cooled to room temperature to obtain the final Fe50Mn30Co10Cr10 alloy annealed plate.

[0041] The hot rolled plate in this example had a dual phase structure of FCC and HCP with a volume fraction of FCC phase of 89%. The warm rolled plate had no cracks and had a FCC single phase structure. In addition, the annealed plate had a critical full recrystallized structure and a FCC single phase structure with an average grain size of 1.4μm. The annealed plate had a tensile strength of 1094MPa, an elongation of 42% and a product of strength and ductility of 45.9GPa.

[0042] Example 4

[0043] High purity metals of Fe, Mn, Co, Cr with purity more than 99.9wt% were used as raw materials. The composition of the raw materials was Fe 50%, Mn 30%, Co 10%, Cr 10% in atomic ratio. The raw materials were melted in a vacuum induction furnace and then cast into a 20mm thick as-cast slab in a square copper mold. The as-cast slab was then hot rolled in multiple passes with a total reduction of 75% and a single pass reduction of 20% to 30%. The hot rolling was performed at a starting temperature of 1150°C and a finishing temperature of 1020°C. The hot rolled plate was then water cooled to room temperature. The hot rolled plate was then pickled to remove the iron oxide scale and then warm rolled at 260°C with a total reduction of 80% and a single pass reduction of 15% to 30%. The warm rolled plate was then air cooled to room temperature. The warm rolled plate was then heated at 1050°C for 25s with a heating rate of 30°C / s and then air cooled to room temperature to obtain the final Fe50Mn30Co10Cr10 alloy annealed plate.

[0044] The hot rolled plate in this example had a dual phase structure of FCC and HCP with a volume fraction of FCC phase of 89%. The warm rolled plate had no cracks and had a FCC single phase structure. In addition, the annealed plate had a critical full recrystallized structure and a FCC single phase structure with an average grain size of 1.4μm. The annealed plate had a tensile strength of 1094MPa, an elongation of 42% and a product of strength and ductility of 45.9GPa.

[0045] Example 5

[0046] High purity metals of Fe, Mn, Co, Cr with purity more than 99.9wt% were used as raw materials, and vacuum induction melting was carried out according to the atomic ratio of Fe 50%, Mn 30%, Co 10%, and Cr 10%. Then the cast slabs with thickness of 20mm were cast in square copper mold. Subsequently, the cast slabs were hot-rolled in multiple passes with reduction of 75%, and single pass reduction of 20%~30%, and the hot-rolling temperature was 1100°C, and the final rolling temperature was 1020°C, and finally water-cooled to room temperature. Then the hot-rolled plate was pickled to remove the iron oxide skin, and then warm-rolled at 300°C with reduction of 80%, and single pass reduction of 15%~30%, and air-cooled to room temperature. Subsequently, the final Fe50Mn30Co10Cr10 alloy annealed plate was obtained by heating at 1050°C for 20s with heating rate of 35°C / s, and then air-cooled to room temperature.

[0047] The hot-rolled plate in this example was FCC and HCP dual-phase structure, and the volume ratio of FCC phase was 85%. The warm-rolled plate was crack-free, and the structure was FCC single-phase structure. In addition, the annealed plate was critical complete recrystallization structure, and was single-phase FCC structure, and the average grain size was 0.86μm. The tensile strength of the annealed plate was 1155MPa, the elongation was 44%, and the product of strength and ductility was 50.8GPa.

[0048] Comparative Example 1

[0049] High purity metals of Fe, Mn, Co, Cr with purity more than 99.9wt% were used as raw materials, and vacuum induction melting was carried out according to the atomic ratio of Fe 50%, Mn 30%, Co 10%, and Cr 10%. Then the cast slabs with thickness of 20mm were cast in square copper mold. Subsequently, the cast slabs were hot-rolled in multiple passes with reduction of 75%, and single pass reduction of 20%~30%, and the hot-rolling temperature was 1150°C, and the final rolling temperature was 1020°C, and finally water-cooled to room temperature. Then the hot-rolled plate was pickled to remove the iron oxide skin, and then room-temperature-rolled with reduction of 60%. Subsequently, the final Fe50Mn30Co10Cr10 alloy annealed plate was obtained by heating at 900°C for 120s, and then air-cooled to room temperature.

[0050] As shown in Figure 5 In this comparative example, the Fe50Mn30Co10Cr10 alloy cold-rolled plate with reduction of 60% had obvious large-size cracks, and the cold-rolled structure was FCC+HCP dual-phase structure, and the FCC content was 45%. As shown in Figure 6 The annealed plate had 2%z or so of HCP phase in the structure, and the average grain size was 2.2μm. The tensile strength of the annealed plate was 815MPa, the elongation was 34%, and the product of strength and ductility was 27.7GPa, which was significantly lower than the mechanical properties of the material in the present application.

[0051] The implementation result shows that the application controls the hot rolling and warm rolling temperature to inhibit the phase change behavior in the alloy deformation process and improves the rolling plasticity of the material. Meanwhile, by optimizing the annealing process, the grains are refined as much as possible, a certain dislocation density is reserved, and the strength and plasticity of the alloy are improved through the comprehensive action of various strengthening mechanisms.

Claims

1. A method for producing an ultra-high specific strength Fe50Mn30Co10Cr10 alloy, characterized by, The following steps are taken: (1) Vacuum induction melting: high-purity metals of Fe, Mn, Co, and Cr with a purity of more than 99.9wt% are selected as raw materials, and the atomic ratio of each element is: Fe 50%, Mn 30%, Co 10%, and Cr 10%; the mixed material is placed in a vacuum induction furnace according to the set composition, and then cast into a 20mm thick as-cast slab in a square copper mold; (2) Hot rolling: the as-cast slab is subjected to multi-pass hot rolling with a hot rolling reduction rate of 70% to 75% and a single-pass reduction rate of 20% to 30%, the starting rolling temperature is 1100°C to 1150°C, the final rolling temperature is 1000°C to 1020°C, and the hot rolled plate is finally water cooled to room temperature; (3) Warm rolling: after the hot rolled plate is pickled to remove the iron oxide scale, it is heated to 260 to 310°C in a resistance box furnace, and then subjected to multi-pass rolling using a two-roll mill with a reduction rate of 80% and a single-pass reduction rate of 15% to 30% to obtain a warm rolled plate; (4) Final annealing: the warm rolled plate is annealed to obtain a final product annealed plate, and argon gas is used as the protective gas during annealing; In step (2), the hot rolled plate has a FCC and HCP dual-phase structure, with the volume fraction of FCC phase being 80% to 90%; In step (3), the warm rolled plate has a FCC single-phase structure; In step (4), the annealing temperature of the warm rolled plate is 1050 to 1150°C, the heating rate is ≥30°C / s, the holding time is 20s to 25s, and air cooling is performed; In step (4), the annealed plate has a FCC single-phase structure; In step (4), the annealed plate has a critical complete recrystallized structure, and the average grain size is 0.8 to 1.5μm.

2. A process for the production of ultra-high specific strength Fe50Mn30Co10Cr10 alloy as claimed in claim 1, wherein, In step (4), the annealed plate has good plate shape without cracks, the tensile strength is 1050 to 1280MPa, the elongation is 35% to 58%, and the strength-plasticity product is 40 to 73GPa.

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