阅读说明：本技术 一种高锰铁合金及其调控亚稳相的强韧化方法 (High-manganese-iron alloy and strengthening and toughening method for regulating metastable phase thereof ) 是由 陶庆 潘治州 沈承金 朱真才 彭玉兴 张天宇 沈刚 赖伟 于 2020-06-12 设计创作，主要内容包括：本发明涉及一种高锰铁合金及其调控亚稳相的强韧化方法,解决了现有高锰铁合金材料强韧性差的问题。高锰铁合金中各元素含量按原子百分比计为：Fe：40％～60％,Mn：25％～32％,Co：8％～12％,Cr：8％～12％,C：0～2.26％,其中Co与Cr为等原子比,各元素原子百分比之和为100％。高锰铁合金调控亚稳相的强韧化方法,包括如下步骤：步骤1：将制备得到的高锰铁合金进行热锻,热锻后将高锰铁合金快速取出,进行形变处理,然后快速入水冷却；步骤2：高锰铁合金形变处理后退火,空冷至室温。本发明通过调控高锰铁合金中的碳含量以及调控亚稳相的强韧化方法,提升高锰铁合金材料强韧性。(The invention relates to a high ferromanganese alloy and a strengthening and toughening method for regulating and controlling metastable phase thereof, which solves the problem of poor strengthening and toughening of the existing high ferromanganese alloy material. The high manganese iron alloy comprises the following elements in atomic percentage: fe: 40-60%, Mn: 25% -32%, Co: 8% -12%, Cr: 8% -12%, C: 0-2.26%, wherein the Co and the Cr are in equal atomic ratio, and the sum of the atomic percentages of the elements is 100%. The strengthening and toughening method for regulating and controlling the metastable phase of the high-manganese-iron alloy comprises the following steps of: step 1: carrying out hot forging on the prepared high-ferromanganese alloy, quickly taking out the high-ferromanganese alloy after the hot forging, carrying out deformation treatment, and then quickly cooling in water; step 2: and (4) annealing the high manganese iron alloy after deformation treatment, and cooling the high manganese iron alloy to room temperature. The invention improves the obdurability of the high-ferromanganese alloy material by regulating the carbon content in the high-ferromanganese alloy and regulating the strengthening and toughening method of the metastable phase.)

1. The high-manganese iron alloy is characterized in that the content of each element in the high-manganese iron alloy is as follows by atomic percent: fe: 40-60%, Mn: 25% -32%, Co: 8% -12%, Cr: 8% -12%, C: 0-2.26%, wherein the Co and the Cr are in equal atomic ratio, and the sum of the atomic percentages of the elements is 100%.

2. The high-manganese ferrous alloy according to claim 1, wherein the high-manganese ferrous alloy comprises the following elements in atomic percent: fe: 40-60%, Mn: 25% -32%, Co: 8% -12%, Cr: 8% -12%, C: 0-0.92%, wherein Co and Cr are in equal atomic ratio, and the sum of atomic percentages of all elements is 100%.

3. A strengthening and toughening method for regulating metastable phase of high ferromanganese alloy, which is used for strengthening and toughening the high ferromanganese alloy according to claims 1-2, and is characterized by comprising the following steps:

step 1: carrying out deformation treatment on the prepared high-ferromanganese alloy, quickly taking out the high-ferromanganese alloy after the deformation treatment, and quickly cooling the high-ferromanganese alloy in water;

step 2: and (4) annealing the high manganese iron alloy after deformation treatment, and cooling the high manganese iron alloy to room temperature.

4. The strengthening and toughening method for the high-ferromanganese alloy regulated metastable phase according to claim 3, wherein the deformation amount of the deformation treatment of the high-ferromanganese alloy in the step 1 is 40% -65%.

5. The metastable phase strengthening and toughening method of the high-ferromanganese alloy according to claim 3, wherein the step 1 is performed by a hot forging process.

6. The strengthening and toughening method of the high ferromanganese alloy regulated metastable phase as claimed in claim 5, wherein the hot forging temperature is 850-.

7. The method for strengthening and toughening the high ferromanganese alloy by controlling the metastable phase as claimed in claim 3, wherein the annealing temperature in the step 2 is 850-950 ℃, the annealing time is 1.5-2.5h, and the air cooling is carried out to the room temperature after the annealing.

8. The strengthening and toughening method for the high-ferromanganese alloy regulated metastable phase according to claims 3 to 7, wherein the preparation method for the high-ferromanganese alloy in the step 1 comprises the following steps:

step 11: preparing raw materials according to the components of the high-ferromanganese alloy, placing the raw materials into a vacuum induction smelting furnace, smelting and casting the raw materials in an argon atmosphere, and cooling the raw materials along with the furnace to prepare an ingot;

step 12: and placing the cast ingot in an argon atmosphere for remelting, floating slag and furnace cooling, and cutting to remove the upper-layer slag-containing part to prepare the high-manganese iron alloy.

9. The method for strengthening and toughening the high ferromanganese alloy with controlled metastable phase according to claim 8, wherein the smelting in step 11 is to heat the raw material to be completely molten and maintain 60s-120 s.

10. The strengthening and toughening method of the high ferromanganese alloy regulated metastable phase according to claim 8, wherein the temperature for remelting the ingot in the step 12 is controlled between 1500 ℃ and 1600 ℃, and the holding time is controlled between 40h and 50 h; and the heat preservation temperature for purifying the scum is 1500-1600 ℃, and the heat preservation time is more than 48 hours.

Technical Field

The invention relates to the technical field of advanced metal material preparation and processing, in particular to a high ferromanganese alloy and a strengthening and toughening method for regulating and controlling metastable phase thereof.

Background

With the progress of science and technology, metals produced by the traditional process can not meet the use requirements of human beings more and more, so that various types of alloys are developed by people and applied to various industries, and the foundation of modern material civilization is laid.

However, the use of the conventional alloy is limited by economic and ecological environmental aspects, and with the deep development of researchers on the conventional alloy, the optimization space of the strengthening method which combines strength and plasticity is limited. Meanwhile, the complex intermetallic compound causes the brittleness of the alloy to increase, and cannot meet the modern higher and higher use requirements, and most of the metallurgy mechanisms for increasing the strength often cause the reduction of the ductility of the alloy. Therefore, further optimization of the alloy system, improvement of the product of strength and ductility, and optimization of the matching of the strength and the ductility of the alloy material are needed.

Disclosure of Invention

In view of the above analysis, the embodiments of the present invention are directed to providing a high ferromanganese alloy and a method for toughening the high ferromanganese alloy by controlling metastable phase thereof, so as to solve the problem of poor toughness of the existing high ferromanganese alloy material.

The invention is realized by the following technical scheme:

a high-manganese-iron alloy comprises the following elements in atomic percentage: fe: 40-60%, Mn: 25% -32%, Co: 8% -12%, Cr: 8% -12%, C: 0-2.26%, wherein the Co and the Cr are in equal atomic ratio, and the sum of the atomic percentages of the elements is 100%.

Further, the content of each element in the high manganese iron alloy is as follows by atomic percentage: fe: 40-60%, Mn: 25% -32%, Co: 8% -12%, Cr: 8% -12%, C: 0-0.92%, wherein Co and Cr are in equal atomic ratio, and the sum of atomic percentages of all elements is 100%.

A strengthening and toughening method for regulating and controlling metastable phase of high ferromanganese alloy comprises the following steps:

step 1: carrying out deformation treatment on the prepared high-ferromanganese alloy, quickly taking out the high-ferromanganese alloy after deformation treatment, and quickly cooling in water;

step 2: and (4) annealing the high manganese iron alloy after deformation treatment, and cooling the high manganese iron alloy to room temperature.

Further, the deformation amount of the high manganese iron alloy deformation treatment in the step 1 is 40-65%.

Further, the deformation treatment in the step 1 adopts a hot forging process.

Further, the hot forging temperature is 850-950 ℃, and the heat preservation time is 10-15 min.

Further, the annealing temperature in the step 2 is 850-950 ℃, the annealing time is 1.5-2.5h, and the annealing is followed by air cooling to room temperature.

The preparation method of the high manganese iron alloy comprises the following steps:

step 11: preparing raw materials according to the components of the high-ferromanganese alloy, placing the raw materials into a vacuum induction smelting furnace, smelting and casting the raw materials in an argon atmosphere, and cooling the raw materials along with the furnace to prepare an ingot;

step 12: and placing the cast ingot in an argon atmosphere for remelting, floating slag and furnace cooling, and cutting to remove the upper-layer slag-containing part to prepare the high-manganese iron alloy.

Further, the smelting in the step 11 is to heat the raw materials to be completely molten and keep 60s-120 s.

Further, in the step 12, the remelting temperature of the cast ingot is controlled to be 1500-1600 ℃, and the heat preservation time is controlled to be 40-50 h; and the heat preservation temperature for purifying the scum is 1500-1600 ℃, and the heat preservation time is more than 48 hours.

Compared with the prior art, the invention can realize at least one of the following beneficial effects:

1. the invention realizes the regulation and control of the tissue proportion of the metastable HCP phase by adjusting the carbon content of the high-ferromanganese alloy system, and further realizes the strengthening and toughening of the high-ferromanganese alloy system by the thermomechanical treatment. The high manganese-iron alloy has a dual-phase structure of FCC + HCP, is strengthened and toughened through the coupling of TRIP and TWIP effects, and is improved in toughness through the reverse transformation of metastable incomplete dislocation and HCP phase in an FCC phase by using a method for controlling carbon content and thermomechanical treatment.

2. In the deformation treatment of the high ferromanganese alloy, stress induced martensite phase transformation occurs in the high ferromanganese alloy under the action of an external load in the hot forging process, so that a face-centered cubic (FCC) crystal phase in the high ferromanganese alloy begins to be converted into a hexagonal close-packed crystal phase (HCP), a TRIP effect is induced, and the strength and the plasticity of the high ferromanganese alloy are improved. In the annealing stage of the high ferromanganese alloy, metastable stacking faults may move in a lower energy direction, forming metastable mechanical HCP phases. Meanwhile, in the annealing process, annealing twin crystals are generated by a metastable mechanical HCP phase, the formation of the twin crystals in a high strain region is realized, the sliding of the region is prevented by a twin crystal boundary, and other regions with lower strain are promoted to deform through sliding, so that the uniform deformation of the high ferromanganese alloy is caused, the generation of necking is remarkably delayed, and the TWIP effect is caused. Under the synergistic effect of TRIP and TWIP effects, the plasticity of the high manganese iron alloy is improved. In addition, solid solution carbon atoms in the high ferromanganese alloy play a stabilizing role on an FCC phase, and can better play TRIP and TWIP effects. After the processes of carbon atom regulation and deformation treatment and annealing, the elongation of the high-manganese-iron alloy is improved by over 58 percent from the original 9.3 percent, the tensile strength is improved to over 810MPa from the original 391.8MPa, and the tensile strength and the elongation of the high-manganese-iron alloy are obviously improved.

3. The carbon atom radius of each element in the high manganese iron alloy is smaller, the atomic radius of the four elements of iron, manganese, cobalt and chromium is larger than the carbon atom radius, and the carbon atoms are always dissolved in a solid solution preferentially. The inventors have found through extensive studies that carbon atoms can be completely dissolved when the carbon atom content is within 0.92%, and that carbide begins to precipitate when the carbon atom content is higher than 0.92%. The atomic content of carbon element in the high manganese iron alloy is controlled within 2.26%, the high manganese alloy structure is regulated and controlled by regulating and controlling the carbon atom content, and an FCC and HCP dual-phase structure is obtained. If the content of the carbon element in the high-manganese iron alloy is higher than 2.26%, a large amount of carbon atoms can precipitate a large amount of carbides, only a large amount of stable FCC phases can be obtained, and a metastable HCP phase cannot be generated through deformation. Meanwhile, Mn element can adjust the stability of HCP phase, and realize recovery and recrystallization by utilizing the temperature change in the deformation and annealing process, and realize stable strengthening and toughening of the alloy after crystal grain re-growth and recrystallization.

In the invention, the technical schemes can be combined with each other to realize more preferable combination schemes. Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and drawings.

Drawings

The drawings are only for purposes of illustrating particular embodiments and are not to be construed as limiting the invention, wherein like reference numerals are used to designate like parts throughout.

FIG. 1 is a flow chart of a high ferromanganese alloy preparation and strengthening and toughening process;

FIG. 2 is a schematic view of the optical microstructure of the high ferromanganese alloy after hot forging annealing with a carbon content of 0;

FIG. 3 is an SEM image of the high ferromanganese alloy after hot forging annealing when the carbon content is 0;

FIG. 4 is a comparison of Vickers hardness of a high ferromanganese alloy after two hot forgings and two annealings when the carbon content is 0;

FIG. 5 is a graph showing the engineering stress-strain curves before and after the hot forging annealing of the high ferromanganese alloy with a carbon content of 0;

FIG. 6 is a schematic view of the optical microstructure of the high-Mn-Fe alloy after hot forging annealing with a carbon content of 0.92%;

FIG. 7 is an SEM image of the high-ferromanganese alloy after hot forging annealing with a carbon content of 0.92%;

FIG. 8 is a comparison of Vickers hardness of the high-manganese iron alloy before and after hot forging and two anneals with a carbon content of 0.92%;

FIG. 9 is a stress-strain curve of the high ferromanganese alloy before and after the hot forging annealing when the carbon content is 0.92%;

FIG. 10 is a schematic view of the optical microstructure of the high-Mn-Fe alloy after hot forging annealing at a carbon content of 2.26%;

FIG. 11 is an SEM image of the high-ferromanganese alloy after hot forging annealing with a carbon content of 2.26%;

FIG. 12 is a comparison of Vickers hardness of high-manganese iron alloys after hot forging and two anneals with a carbon content of 2.26%;

FIG. 13 is a graph of engineering stress-strain curves before and after hot forging annealing of a high ferromanganese alloy with a carbon content of 2.26%;

FIG. 14 is an XRD pattern of the high ferromanganese alloy after hot forging and annealing at a carbon content of 2.26%;

FIG. 15 is a flow chart of a high ferromanganese alloy preparation and another strengthening and toughening process.

Detailed Description

The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form a part hereof, and which together with the embodiments of the invention serve to explain the principles of the invention and not to limit its scope.

The invention provides a new idea of alloy design and processing aiming at strengthening and toughening of high-manganese-iron alloy steel, designs a high-manganese-iron alloy system, regulates and controls metastable phases by utilizing solid solution of carbon atoms, regulates and controls the tissue proportion of metastable HCP phases by regulating the carbon content, further realizes the strengthening and toughening of the material by matching with thermomechanical treatment, and strengthens and toughens the high-manganese alloy system.

The inventors have found through extensive studies that carbon atoms can be completely dissolved when the carbon atom content is within 0.92%, and carbide begins to precipitate when the carbon atom content is higher than 0.92%. The atomic content of carbon element in the high manganese iron alloy is controlled within 2.26%, the high manganese alloy structure is regulated and controlled by regulating and controlling the carbon atom content, and an FCC and HCP dual-phase structure is obtained. Meanwhile, Mn element can adjust the stability of HCP phase, and realize recovery and recrystallization by utilizing the temperature change in the deformation and annealing process, and realize stable strengthening and toughening of the alloy after crystal grain re-growth and recrystallization. The atomic radius of four elements of iron, manganese, cobalt and chromium of the high manganese-iron alloy is larger than that of carbon atoms, the carbon atom ratio is smaller, and the carbon atoms are always dissolved in a solid solution preferentially.

As shown in FIG. 1, the invention comprises two parts of the design of alloy components and the thermomechanical treatment process:

a first part: smelting and preparing a high manganese iron alloy system, adjusting the carbon concentration of the system to obtain an HCP + FCC dual-phase matrix structure, and gradually precipitating carbide in the system along with the increase of the carbon concentration.

A second part: the high manganese iron alloy system is subjected to thermomechanical treatment, the alloy obtained by smelting is subjected to hot forging or rolling and annealing, and the twin-phase matrix structure of FCC + HCP generates twin crystal induced plasticity (TWIP) and transformation induced plasticity (TRIP) effects and is simultaneously subjected to recovery recrystallization, so that the reinforcement and toughening of the alloy are realized.

On one hand, the invention provides a high manganese iron alloy, which comprises the following elements in percentage by atom (at.%): fe: 40-60%, Mn: 25% -32%, Co: 8% -12%, Cr: 8% -12%, C: 0-2.26%, wherein the Co and the Cr are in equal atomic ratio, and the sum of the atomic percentages of the elements is 100%.

In another possible design, the content of each element in the high ferromanganese alloy is, in atomic percent (at.%): fe: 40-60%, Mn: 25% -32%, Co: 8% -12%, Cr: 8% -12%, C: 0-0.92%, wherein Co and Cr are in equal atomic ratio, and the sum of atomic percentages of all elements is 100%.

On the other hand, the invention provides a preparation method of the high manganese iron alloy, which comprises the following steps:

step 1: preparing raw materials according to the components of the high-manganese ferroalloy, placing the raw materials into a vacuum induction smelting furnace, smelting and casting the raw materials in an argon atmosphere, and cooling the raw materials along with the furnace to form an ingot.

To prevent oxidation, the raw materials were melted in an argon atmosphere. In the smelting process of the raw materials, the raw materials are heated to be in a completely molten state and kept for 1-2min until the raw materials are uniformly mixed. And judging the sign of uniformly mixing the raw materials as forming vortex in molten metal.

Step 2: and placing the cast ingot in an argon atmosphere for remelting, floating slag and furnace cooling, and cutting to remove the upper-layer slag-containing part to prepare the high-manganese iron alloy.

Specifically, the remelting temperature of the cast ingot is controlled to be 1500-1600 ℃, and the heat preservation time is controlled to be 40-50 h. And (3) carrying out dross purification after remelting the cast ingot, wherein the dross purification temperature is 1500-1600 ℃, the heat preservation time is more than 48h, and removing the upper layer slag-containing part to obtain the high-ferromanganese alloy. The prepared high manganese alloy is a thermodynamic FCC phase and a thermodynamic HCP phase.

It should be noted that the remelting and dross purification processes of the high-ferromanganese alloy are performed at least once. The times of remelting the high manganese iron alloy and purifying the scum are related to the steel ingot smelting effect.

In one embodiment of the present invention, the preparation method of the high manganese iron alloy comprises the following steps:

step 1: according to the alloy component proportion, preparing raw materials, placing the raw materials in a quartz crucible with a spherical bottom, placing the quartz crucible in an induction coil of a vacuum induction smelting furnace, heating and smelting for 1-2min in an argon atmosphere until the raw materials are heated and completely melted and are uniformly mixed, and then casting the raw materials into a quartz crucible with a flat bottom and cooling the quartz crucible in the furnace to form an ingot.

Step 2: and remelting the cast ingot in an argon atmosphere at the temperature of 1500-1600 ℃, preserving heat for 40-50h, cooling dross in a furnace, and cutting to remove the upper-layer slag-containing part. And polishing the surface of the ingot after primary deslagging, removing oxide skin, and repeating the scum purification operation.

On the other hand, the invention provides a strengthening and toughening method for regulating and controlling metastable phase of the high ferromanganese alloy, as shown in fig. 1, comprising the following steps:

step 1: carrying out deformation treatment on the high-manganese iron alloy;

specifically, a hot forging process is adopted to carry out deformation treatment on the high-ferromanganese alloy, the prepared high-ferromanganese alloy is subjected to hot forging heat preservation at the temperature of 850-950 ℃, the hot forging heat preservation time is 10-15min, and the high-ferromanganese alloy is taken out quickly and cooled to room temperature by water.

Illustratively, the hot forging process can adopt air hammer forging, the deformation of the air hammer forging is 45% -65%, and the hot forging process is rapidly cooled by water. When the deformation is lower than 45%, the later strengthening and toughening effect on the high-manganese-iron alloy is influenced, and when the deformation is too high, carbide precipitation can occur, the brittleness is increased, and the surface of the alloy is cracked in the heat treatment process.

It should be noted that, during the hot forging process, the high-ferromanganese alloy undergoes stress-induced martensitic transformation under the action of an external load, so that the face-centered cubic (FCC) in the high-ferromanganese alloy begins to transform into a Hexagonal Close Packing (HCP), which causes the TRIP effect, and the strength and plasticity of the high-ferromanganese alloy are improved.

Step 2: performing water cooling after the high manganese iron alloy is subjected to deformation treatment, and then performing annealing heat treatment;

annealing heat treatment is carried out on the high manganese iron alloy after hot forging deformation treatment, the annealing temperature is controlled at 850 ℃ and 950 ℃, and the annealing time is 1.5-2.5 h; and air-cooling to room temperature after annealing. During the annealing phase, metastable stacking faults may move in the lower energy direction, forming metastable mechanical HCP phases. Meanwhile, in the annealing process, annealing twin crystals are generated by a metastable mechanical HCP phase, the formation of the twin crystals in a high strain region is realized, the sliding of the region is prevented by the twin crystal boundary, and other regions with lower strain are promoted to deform through sliding, so that the uniform deformation of the high manganese-iron alloy is caused, the generation of necking is delayed, and the TWIP effect is caused.

According to the invention, through a strengthening and toughening process combining deformation treatment and annealing heat treatment, the high-manganese-iron alloy obtains an FCC and metastable HCP dual-phase structure, and the plasticity of the high-manganese-iron alloy is improved under the synergistic effect of TRIP and TWIP effects. Meanwhile, solid-dissolved carbon atoms in the high-ferromanganese alloy play a stabilizing role on an FCC phase, so that TRIP and TWIP effects in the high-ferromanganese alloy can be better exerted, and the tensile strength and the elongation of the high-ferromanganese alloy are obviously improved.

When the high ferromanganese alloy is subjected to deformation treatment, hot forging is performed at least once; the annealing process is performed at least once. According to the requirement of high manganese alloy material on performance, hot forging and annealing heat treatment operations can be set for many times.

In one embodiment of the present invention, as shown in fig. 15, when the high manganese alloy is subjected to the deformation treatment, a heat treatment process of two times of hot forging and two times of annealing are adopted, and the two times of hot forging and the two times of annealing are alternately performed. Specifically, the method comprises the following steps:

first hot forging: controlling the temperature at 850 ℃ and 950 ℃, keeping the temperature for 10-15min, and cooling to room temperature by water. After the first hot forging, the deformation of the high manganese iron alloy is 55-65%.

First annealing: carrying out first annealing on the high-manganese iron alloy by water cooling after first hot forging; the annealing temperature is controlled at 850-; and after the first annealing, cooling the steel to room temperature by water.

And (3) hot forging for the second time: controlling the temperature at 850 ℃ and 950 ℃, keeping the temperature for 10-15min, and cooling to room temperature by water. The deformation after the second hot forging is 40-50%. And cooling the water to room temperature after the second hot forging.

Annealing for the second time; the temperature of the second annealing is controlled at 850-950 ℃, the heat preservation time is 1h-1.5h, and the air cooling is carried out to the room temperature after the second annealing.

According to the invention, when the carbon content in the high-ferromanganese alloy is controlled to be 0-2.26%, the high-ferromanganese alloy obtains an FCC and metastable mechanical HCP dual-phase structure through solid-dissolved carbon atom regulation and control organization by hot forging and annealing heat treatment, and simultaneously stabilizes an FCC phase through solid-dissolved carbon atoms, so that TRIP and TWIP effects are better exerted. If the atomic content of carbon in the high ferromanganese alloy is higher than 2.26%, a large amount of carbon stabilizes an FCC phase and cannot generate an HCP phase through shearing, the existence of a metastable HCP phase is ensured by controlling the carbon content to provide strength, meanwhile, the phase stability of the HCP phase can be adjusted by Mn element, and stable strengthening and toughening of the alloy can be realized by utilizing recovery recrystallization in the deformation and annealing processes.

The method combines the design ideas of high-manganese TRIP steel and alloy, controls the content of carbon, obtains a dual-phase structure of an FCC matrix structure and a metastable HCP phase by combining strengthening and toughening operations of deformation treatment and annealing heat treatment, and explores a new idea based on the combined strengthening and toughening of the dual-phase structure + TRIP + TWIP. The invention can promote the exploration and application expansion of the alloying principle of carbon element in a high manganese-iron alloy system, can fully play the TRIP and TWIP effects from the aspect of regulating and controlling the components of a phase structure, and has positive significance for improving the product of strength and elongation of steel and optimizing the strong plasticity matching.